ExynosVideoEncodeAccelerator

content/common/gpu/media/exynos_video_encode_accelerator.cc

Index: content/common/gpu/media/exynos_video_encode_accelerator.cc
diff --git a/content/common/gpu/media/exynos_video_encode_accelerator.cc b/content/common/gpu/media/exynos_video_encode_accelerator.cc
new file mode 100644
index 0000000000000000000000000000000000000000..340b7c8b6f6621df991549d60b0426cf76d008b3
--- /dev/null
+++ b/content/common/gpu/media/exynos_video_encode_accelerator.cc
@@ -0,0 +1,1468 @@
+// Copyright (c) 2013 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "content/common/gpu/media/exynos_video_encode_accelerator.h"
+
+#include <fcntl.h>
+#include <linux/videodev2.h>
+#include <poll.h>
+#include <sys/eventfd.h>
+#include <sys/ioctl.h>
+
+#include "base/callback.h"
+#include "base/debug/trace_event.h"
+#include "base/message_loop/message_loop_proxy.h"
+#include "base/posix/eintr_wrapper.h"
+#include "media/base/bitstream_buffer.h"
+
+#define NOTIFY_ERROR(x)                                            \
+  do {                                                             \
+    SetEncoderState(kError);                                       \
+    DLOG(ERROR) << "calling NotifyError(): " << x;                 \
+    NotifyError(x);                                                \
+  } while (0)
+
+#define IOCTL_OR_ERROR_RETURN(fd, type, arg)                       \
+  do {                                                             \
+    if (HANDLE_EINTR(ioctl(fd, type, arg) != 0)) {                 \
+      DPLOG(ERROR) << __func__ << "(): ioctl() failed: " << #type; \
+      NOTIFY_ERROR(kPlatformFailureError);                         \
+      return;                                                      \
+    }                                                              \
+  } while (0)
+
+#define IOCTL_OR_ERROR_RETURN_FALSE(fd, type, arg)                 \
+  do {                                                             \
+    if (HANDLE_EINTR(ioctl(fd, type, arg) != 0)) {                 \
+      DPLOG(ERROR) << __func__ << "(): ioctl() failed: " << #type; \
+      NOTIFY_ERROR(kPlatformFailureError);                         \
+      return false;                                                \
+    }                                                              \
+  } while (0)
+
+namespace content {
+
+namespace {
+
+const char kExynosGscDevice[] = "/dev/gsc1";
+const char kExynosMfcDevice[] = "/dev/mfc-enc";
+
+// File descriptors we need to poll, one-bit flag for each.
+enum PollFds {
+  kPollGsc = (1 << 0),
+  kPollMfc = (1 << 1),
+};
+
+}  // anonymous namespace
+
+struct ExynosVideoEncodeAccelerator::BitstreamBufferRef {
+  BitstreamBufferRef(int32 id, scoped_ptr<base::SharedMemory> shm, size_t size)
+      : id(id), shm(shm.Pass()), size(size) {}
+  const int32 id;
+  const scoped_ptr<base::SharedMemory> shm;
+  const size_t size;
+};
+
+
+ExynosVideoEncodeAccelerator::GscInputRecord::GscInputRecord()
+    : at_device(false) {}
+
+ExynosVideoEncodeAccelerator::GscOutputRecord::GscOutputRecord()
+    : at_device(false), mfc_input(-1) {}
+
+ExynosVideoEncodeAccelerator::MfcInputRecord::MfcInputRecord()
+    : at_device(false) {
+  fd[0] = fd[1] = -1;
+}
+
+ExynosVideoEncodeAccelerator::MfcOutputRecord::MfcOutputRecord()
+    : at_device(false) {}
+
+ExynosVideoEncodeAccelerator::ExynosVideoEncodeAccelerator(
+    media::VideoEncodeAccelerator::Client* client)
+    : child_message_loop_proxy_(base::MessageLoopProxy::current()),
+      weak_this_ptr_factory_(this),
+      weak_this_(weak_this_ptr_factory_.GetWeakPtr()),
+      client_ptr_factory_(client),
+      client_(client_ptr_factory_.GetWeakPtr()),
+      encoder_thread_("ExynosEncoderThread"),
+      encoder_state_(kUninitialized),
+      output_buffer_byte_size_(0),
+      stream_header_size_(0),
+      input_format_fourcc_(0),
+      output_format_fourcc_(0),
+      gsc_fd_(-1),
+      gsc_input_streamon_(false),
+      gsc_input_buffer_queued_count_(0),
+      gsc_output_streamon_(false),
+      gsc_output_buffer_queued_count_(0),
+      mfc_fd_(-1),
+      mfc_input_streamon_(false),
+      mfc_input_buffer_queued_count_(0),
+      mfc_output_streamon_(false),
+      mfc_output_buffer_queued_count_(0),
+      device_poll_thread_("ExynosEncoderDevicePollThread"),
+      device_poll_interrupt_fd_(-1) {
+  DCHECK(client_);
+}
+
+ExynosVideoEncodeAccelerator::~ExynosVideoEncodeAccelerator() {
+  DCHECK(!encoder_thread_.IsRunning());
+  DCHECK(!device_poll_thread_.IsRunning());
+
+  if (device_poll_interrupt_fd_ != -1) {
+    HANDLE_EINTR(close(device_poll_interrupt_fd_));
+    device_poll_interrupt_fd_ = -1;
+  }
+  if (mfc_fd_ != -1) {
+    DestroyMfcInputBuffers();
+    DestroyMfcOutputBuffers();
+    HANDLE_EINTR(close(mfc_fd_));
+    mfc_fd_ = -1;
+  }
+  if (gsc_fd_ != -1) {
+    DestroyGscInputBuffers();
+    DestroyGscOutputBuffers();
+    HANDLE_EINTR(close(gsc_fd_));
+    gsc_fd_ = -1;
+  }
+}
+
+void ExynosVideoEncodeAccelerator::Initialize(
+    media::VideoFrame::Format input_format,
+    const gfx::Size& input_visible_size,
+    media::VideoCodecProfile output_profile,
+    uint32 initial_bitrate) {
+  DVLOG(3) << "Initialize(): input_format=" << input_format
+           << ", input_visible_size=" << input_visible_size.ToString()
+           << ", output_profile=" << output_profile
+           << ", initial_bitrate=" << initial_bitrate;
+
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+  DCHECK_EQ(encoder_state_, kUninitialized);
+
+  input_visible_size_ = input_visible_size;
+  input_allocated_size_.SetSize((input_visible_size_.width() + 0xF) & ~0xF,
+                                (input_visible_size_.height() + 0xF) & ~0xF);
+  converted_visible_size_.SetSize((input_visible_size_.width() + 0x1) & ~0x1,
+                                  (input_visible_size_.height() + 0x1) & ~0x1);
+  converted_allocated_size_.SetSize(
+      (converted_visible_size_.width() + 0xF) & ~0xF,
+      (converted_visible_size_.height() + 0xF) & ~0xF);
+  output_visible_size_ = converted_visible_size_;
+
+  switch (input_format) {
+    case media::VideoFrame::RGB32:
+      input_format_fourcc_ = V4L2_PIX_FMT_RGB32;
+      break;
+    case media::VideoFrame::I420:
+      input_format_fourcc_ = V4L2_PIX_FMT_YUV420M;
+      break;
+    default:
+      NOTIFY_ERROR(kInvalidArgumentError);
+      return;
+  }
+
+  if (output_profile >= media::H264PROFILE_MIN &&
+      output_profile <= media::H264PROFILE_MAX) {
+    output_format_fourcc_ = V4L2_PIX_FMT_H264;
+  } else {
+    NOTIFY_ERROR(kInvalidArgumentError);
+    return;
+  }
+
+  // Open the color conversion device.
+  DVLOG(2) << "Initialize(): opening GSC device: " << kExynosGscDevice;
+  gsc_fd_ =
+      HANDLE_EINTR(open(kExynosGscDevice, O_RDWR | O_NONBLOCK | O_CLOEXEC));
+  if (gsc_fd_ == -1) {
+    DPLOG(ERROR) << "Initialize(): could not open GSC device: "
+                 << kExynosGscDevice;
+    NOTIFY_ERROR(kPlatformFailureError);
+    return;
+  }
+
+  // Capabilities check.
+  struct v4l2_capability caps;
+  memset(&caps, 0, sizeof(caps));
+  const __u32 kCapsRequired = V4L2_CAP_VIDEO_CAPTURE_MPLANE |
+                              V4L2_CAP_VIDEO_OUTPUT_MPLANE | V4L2_CAP_STREAMING;
+  IOCTL_OR_ERROR_RETURN(gsc_fd_, VIDIOC_QUERYCAP, &caps);
+  if ((caps.capabilities & kCapsRequired) != kCapsRequired) {
+    DLOG(ERROR) << "Initialize(): ioctl() failed: VIDIOC_QUERYCAP: "
+                   "caps check failed: 0x" << std::hex << caps.capabilities;
+    NOTIFY_ERROR(kPlatformFailureError);
+    return;
+  }
+
+  // Open the video encoder device.
+  mfc_fd_ =
+      HANDLE_EINTR(open(kExynosMfcDevice, O_RDWR | O_NONBLOCK | O_CLOEXEC));
+  if (mfc_fd_ == -1) {
+    DPLOG(ERROR) << "Initialize(): could not open MFC device: "
+                 << kExynosMfcDevice;
+    NOTIFY_ERROR(kPlatformFailureError);
+    return;
+  }
+
+  memset(&caps, 0, sizeof(caps));
+  IOCTL_OR_ERROR_RETURN(mfc_fd_, VIDIOC_QUERYCAP, &caps);
+  if ((caps.capabilities & kCapsRequired) != kCapsRequired) {
+    DLOG(ERROR) << "Initialize(): ioctl() failed: VIDIOC_QUERYCAP: "
+                   "caps check failed: 0x" << std::hex << caps.capabilities;
+    NOTIFY_ERROR(kPlatformFailureError);
+    return;
+  }
+
+  // Create the interrupt fd.
+  DCHECK_EQ(device_poll_interrupt_fd_, -1);
+  device_poll_interrupt_fd_ = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC);
+  if (device_poll_interrupt_fd_ == -1) {
+    DPLOG(ERROR) << "Initialize(): eventfd() failed";
+    NOTIFY_ERROR(kPlatformFailureError);
+    return;
+  }
+
+  DVLOG(3)
+      << "Initialize(): input_visible_size_=" << input_visible_size_.ToString()
+      << ", input_allocated_size_=" << input_allocated_size_.ToString()
+      << ", converted_visible_size_=" << converted_visible_size_.ToString()
+      << ", converted_allocated_size_=" << converted_allocated_size_.ToString()
+      << ", output_visible_size_=" << output_visible_size_.ToString();
+
+  if (!CreateGscInputBuffers() || !CreateGscOutputBuffers())
+    return;
+
+  // MFC setup for encoding is rather particular in ordering:
+  //
+  // 1. Format (VIDIOC_S_FMT) set first on OUTPUT and CAPTURE queues.
+  // 2. VIDIOC_REQBUFS, VIDIOC_QBUF, and VIDIOC_STREAMON on CAPTURE queue.
+  // 3. VIDIOC_REQBUFS (and later VIDIOC_QBUF and VIDIOC_STREAMON) on OUTPUT
+  //    queue.
+  //
+  // Unfortunately, we cannot do (3) in Initialize() here since we have no
+  // buffers to QBUF in step (2) until the client has provided output buffers
+  // through UseOutputBitstreamBuffer().  So, we just do (1), and the
+  // VIDIOC_REQBUFS part of (2) here.  The rest is done the first time we get
+  // a UseOutputBitstreamBuffer() callback.
+
+  if (!SetMfcFormats())
+    return;
+
+  RequestEncodingParametersChangeTask(initial_bitrate, kInitialFramerate);

[hshi1, 2013/08/13 17:11:20]

Where is this "kInitialFramerate" defined?

[sheu, 2013/08/14 01:00:42]

Uhh.. it actually went into exynos_video_*decode*_accelerator.h.

Fixed.

+
+  // VIDIOC_REQBUFS on CAPTURE queue.
+  if (!CreateMfcOutputBuffers())
+    return;
+
+
+  if (!encoder_thread_.Start()) {
+    DLOG(ERROR) << "Initialize(): encoder thread failed to start";
+    NOTIFY_ERROR(kPlatformFailureError);
+    return;
+  }
+
+  SetEncoderState(kInitialized);
+
+  child_message_loop_proxy_->PostTask(
+      FROM_HERE, base::Bind(&Client::NotifyInitializeDone, client_));
+
+  child_message_loop_proxy_->PostTask(
+      FROM_HERE,
+      base::Bind(&Client::RequireBitstreamBuffers,
+                 client_,
+                 gsc_input_buffer_map_.size(),
+                 input_allocated_size_,
+                 output_buffer_byte_size_));
+}
+
+void ExynosVideoEncodeAccelerator::Encode(
+    const scoped_refptr<media::VideoFrame>& frame,
+    bool force_keyframe) {
+  DVLOG(3) << "Encode(): force_keyframe=" << force_keyframe;
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+
+  encoder_thread_.message_loop()->PostTask(
+      FROM_HERE,
+      base::Bind(&ExynosVideoEncodeAccelerator::EncodeTask,
+                 base::Unretained(this),
+                 frame,
+                 force_keyframe));
+}
+
+void ExynosVideoEncodeAccelerator::UseOutputBitstreamBuffer(
+    const media::BitstreamBuffer& buffer) {
+  DVLOG(3) << "UseOutputBitstreamBuffer(): id=" << buffer.id();
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+
+  if (buffer.size() < output_buffer_byte_size_) {
+    NOTIFY_ERROR(kInvalidArgumentError);
+    return;
+  }
+
+  scoped_ptr<base::SharedMemory> shm(
+      new base::SharedMemory(buffer.handle(), false));
+  if (!shm->Map(buffer.size())) {
+    NOTIFY_ERROR(kPlatformFailureError);
+    return;
+  }
+
+  scoped_ptr<BitstreamBufferRef> buffer_ref(
+      new BitstreamBufferRef(buffer.id(), shm.Pass(), buffer.size()));
+  encoder_thread_.message_loop()->PostTask(
+      FROM_HERE,
+      base::Bind(&ExynosVideoEncodeAccelerator::UseOutputBitstreamBufferTask,
+                 base::Unretained(this),
+                 base::Passed(&buffer_ref)));
+}
+
+void ExynosVideoEncodeAccelerator::RequestEncodingParametersChange(
+    uint32 bitrate,
+    uint32 framerate) {
+  DVLOG(3) << "RequestEncodingParametersChange(): bitrate=" << bitrate
+           << ", framerate=" << framerate;
+  if (bitrate < 1 || framerate < 1) {
+    DLOG(ERROR) << "RequestEncodingParametersChange(): "
+                   "invalid bitrate=" << bitrate
+                << " or framerate=" << framerate;
+    NOTIFY_ERROR(kInvalidArgumentError);
+    return;
+  }
+  encoder_thread_.message_loop()->PostTask(
+      FROM_HERE,
+      base::Bind(
+          &ExynosVideoEncodeAccelerator::RequestEncodingParametersChangeTask,
+          base::Unretained(this),
+          bitrate,
+          framerate));
+}
+
+void ExynosVideoEncodeAccelerator::Destroy() {
+  DVLOG(3) << "Destroy()";
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+
+  // We're destroying; cancel all callbacks.
+  client_ptr_factory_.InvalidateWeakPtrs();
+
+  // If the encoder thread is running, destroy using posted task.
+  if (encoder_thread_.IsRunning()) {
+    encoder_thread_.message_loop()->PostTask(
+        FROM_HERE,
+        base::Bind(&ExynosVideoEncodeAccelerator::DestroyTask,
+                   base::Unretained(this)));
+    // DestroyTask() will cause the encoder_thread_ to flush all tasks.

[Ami GONE FROM CHROMIUM, 2013/08/13 18:13:19]

s/flush all tasks/turn all tasks into no-ops as state will be kError/

[sheu, 2013/08/14 01:00:42]

Done.

+    encoder_thread_.Stop();
+  } else {
+    // Otherwise, call the destroy task directly.
+    DestroyTask();
+  }
+
+  // Set to kError state just in case.
+  SetEncoderState(kError);
+
+  delete this;
+}
+
+// static
+std::vector<media::VideoEncodeAccelerator::SupportedProfile>
+ExynosVideoEncodeAccelerator::GetSupportedProfiles() {
+  std::vector<SupportedProfile> profiles(1);
+  SupportedProfile& profile = profiles[0];
+  profile.profile = media::H264PROFILE_MAIN;
+  profile.max_resolution.SetSize(1920, 1088);
+  profile.max_framerate.numerator = 30;
+  profile.max_framerate.denominator = 1;
+  return profiles;
+}
+
+void ExynosVideoEncodeAccelerator::EncodeTask(
+    const scoped_refptr<media::VideoFrame>& frame, bool force_keyframe) {
+  DVLOG(3) << "EncodeTask(): force_keyframe=" << force_keyframe;
+  DCHECK_EQ(encoder_thread_.message_loop(), base::MessageLoop::current());
+  DCHECK_NE(encoder_state_, kUninitialized);
+
+  if (encoder_state_ == kError) {
+    DVLOG(2) << "EncodeTask(): early out: kError state";
+    return;
+  }
+
+  encoder_input_queue_.push_back(frame);
+  EnqueueGsc();
+
+  if (force_keyframe) {
+    struct v4l2_ext_control ctrls[1];
+    struct v4l2_ext_controls control;
+    memset(&ctrls, 0, sizeof(ctrls));
+    memset(&control, 0, sizeof(control));
+    ctrls[0].id    = V4L2_CID_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE;
+    ctrls[0].value = V4L2_MPEG_MFC51_VIDEO_FORCE_FRAME_TYPE_I_FRAME;
+    control.ctrl_class = V4L2_CTRL_CLASS_MPEG;
+    control.count = 1;
+    control.controls = ctrls;
+    IOCTL_OR_ERROR_RETURN(mfc_fd_, VIDIOC_S_EXT_CTRLS, &control);

[Ami GONE FROM CHROMIUM, 2013/08/13 18:13:19]

Please comment to this effect here.

[sheu, 2013/08/14 01:00:42]

Done.

+  }
+}
+
+void ExynosVideoEncodeAccelerator::UseOutputBitstreamBufferTask(
+    scoped_ptr<BitstreamBufferRef> buffer_ref) {
+  DVLOG(3) << "UseOutputBitstreamBufferTask(): id=" << buffer_ref->id;
+  DCHECK_EQ(encoder_thread_.message_loop(), base::MessageLoop::current());
+
+  encoder_output_queue_.push_back(
+      linked_ptr<BitstreamBufferRef>(buffer_ref.release()));
+  EnqueueMfc();
+
+  if (encoder_state_ == kInitialized) {
+    // Finish setting up our MFC OUTPUT queue.  See: Initialize().
+    // VIDIOC_REQBUFS on OUTPUT queue.
+    if (!CreateMfcInputBuffers())
+      return;
+    if (!StartDevicePoll())
+      return;
+    encoder_state_ = kEncoding;
+  }
+}
+
+void ExynosVideoEncodeAccelerator::DestroyTask() {
+  DVLOG(3) << "DestroyTask()";
+
+  // DestroyTask() should run regardless of encoder_state_.
+
+  // Stop streaming and the device_poll_thread_.
+  StopDevicePoll();
+
+  // Set our state to kError.  Just in case.

[Ami GONE FROM CHROMIUM, 2013/08/13 18:13:19]

This isn't "just in case" because you promise it in a comment above ("flush all
tasks").  This comment should reflect that this is done to no-op out any pending
tasks.

[sheu, 2013/08/14 01:00:42]

Done.

+  encoder_state_ = kError;
+}
+
+void ExynosVideoEncodeAccelerator::ServiceDeviceTask() {
+  DVLOG(3) << "ServiceDeviceTask()";
+  DCHECK_EQ(encoder_thread_.message_loop(), base::MessageLoop::current());
+  DCHECK_NE(encoder_state_, kUninitialized);
+  DCHECK_NE(encoder_state_, kInitialized);
+
+  if (encoder_state_ == kError) {
+    DVLOG(2) << "ServiceDeviceTask(): early out: kError state";
+    return;
+  }
+
+  DequeueGsc();
+  DequeueMfc();
+  EnqueueGsc();
+  EnqueueMfc();
+
+  // Clear the interrupt fd.
+  if (!ClearDevicePollInterrupt())
+    return;
+
+  unsigned int poll_fds = 0;
+  // Add GSC fd, if we should poll on it.
+  // GSC has to wait until both input and output buffers are queued.
+  if (gsc_input_buffer_queued_count_ > 0 && gsc_output_buffer_queued_count_ > 0)
+    poll_fds |= kPollGsc;
+  // Add MFC fd, if we should poll on it.
+  // MFC can be polled as soon as either input or output buffers are queued.
+  if (mfc_input_buffer_queued_count_ + mfc_output_buffer_queued_count_ > 0)
+    poll_fds |= kPollMfc;
+
+  // ServiceDeviceTask() should only ever be scheduled from DevicePollTask(),
+  // so either:
+  // * device_poll_thread_ is running normally

[Ami GONE FROM CHROMIUM, 2013/08/13 18:13:19]

This is now a single-bullet list headed by "either".  Did you mean to have an
asterisk bullet on the next line, or what?

[sheu, 2013/08/14 01:00:42]

A linebreak sneaked in somehow.  Fixed.

+  //
+  //   device_poll_thread_ scheduled us, but then a DestroyTask() shut it down,
+  //   in which case we're in kError state, and we should have early-outed
+  //   already.
+  DCHECK(device_poll_thread_.message_loop());
+  // Queue the DevicePollTask() now.
+  device_poll_thread_.message_loop()->PostTask(
+      FROM_HERE,
+      base::Bind(&ExynosVideoEncodeAccelerator::DevicePollTask,
+                 base::Unretained(this),
+                 poll_fds));
+
+  DVLOG(2) << "ServiceDeviceTask(): buffer counts: ENC["
+           << encoder_input_queue_.size() << "] => GSC["
+           << gsc_free_input_buffers_.size() << "+"
+           << gsc_input_buffer_queued_count_ << "/"
+           << gsc_input_buffer_map_.size() << "->"
+           << gsc_free_output_buffers_.size() << "+"
+           << gsc_output_buffer_queued_count_ << "/"
+           << gsc_output_buffer_map_.size() << "] => "
+           << mfc_ready_input_buffers_.size() << " => MFC["
+           << mfc_free_input_buffers_.size() << "+"
+           << mfc_input_buffer_queued_count_ << "/"
+           << mfc_input_buffer_map_.size() << "->"
+           << mfc_free_output_buffers_.size() << "+"
+           << mfc_output_buffer_queued_count_ << "/"
+           << mfc_output_buffer_map_.size() << "] => OUT["
+           << encoder_output_queue_.size() << "]";
+}
+
+void ExynosVideoEncodeAccelerator::EnqueueGsc() {
+  DVLOG(3) << "EnqueueGsc()";
+  DCHECK_EQ(encoder_thread_.message_loop(), base::MessageLoop::current());
+
+  const int old_gsc_inputs_queued = gsc_input_buffer_queued_count_;
+  while (!encoder_input_queue_.empty() && !gsc_free_input_buffers_.empty()) {
+    if (!EnqueueGscInputRecord())
+      return;
+  }
+  if (old_gsc_inputs_queued == 0 && gsc_input_buffer_queued_count_ != 0) {
+    // We started up a previously empty queue.
+    // Queue state changed; signal interrupt.
+    if (!SetDevicePollInterrupt())
+      return;
+    // Start VIDIOC_STREAMON if we haven't yet.
+    if (!gsc_input_streamon_) {
+      __u32 type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+      IOCTL_OR_ERROR_RETURN(gsc_fd_, VIDIOC_STREAMON, &type);
+      gsc_input_streamon_ = true;
+    }
+  }
+
+  // Enqueue a GSC output, only if we need one.  GSC output buffers write
+  // directly to MFC input buffers, so we'll have to check for free MFC input
+  // buffers as well.
+  // GSC is liable to race conditions if more than one output buffer is
+  // simultaneously enqueued, so enqueue just one.

[Ami GONE FROM CHROMIUM, 2013/08/13 18:13:19]

crbug for the GSC race conditions?

+  if (gsc_input_buffer_queued_count_ != 0 &&
+      gsc_output_buffer_queued_count_ == 0 &&
+      !gsc_free_output_buffers_.empty() && !mfc_free_input_buffers_.empty()) {
+    const int old_gsc_outputs_queued = gsc_output_buffer_queued_count_;
+    if (!EnqueueGscOutputRecord())
+      return;
+    if (old_gsc_outputs_queued == 0 && gsc_output_buffer_queued_count_ != 0) {
+      // We just started up a previously empty queue.
+      // Queue state changed; signal interrupt.
+      if (!SetDevicePollInterrupt())
+        return;
+      // Start VIDIOC_STREAMON if we haven't yet.
+      if (!gsc_output_streamon_) {
+        __u32 type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+        IOCTL_OR_ERROR_RETURN(gsc_fd_, VIDIOC_STREAMON, &type);
+        gsc_output_streamon_ = true;
+      }
+    }
+  }
+  DCHECK_LE(gsc_output_buffer_queued_count_, 1);
+}
+
+void ExynosVideoEncodeAccelerator::DequeueGsc() {
+  DVLOG(3) << "DequeueGsc()";
+  DCHECK_EQ(encoder_thread_.message_loop(), base::MessageLoop::current());
+
+  // Dequeue completed GSC input (VIDEO_OUTPUT) buffers, and recycle to the free
+  // list.
+  struct v4l2_buffer dqbuf;
+  struct v4l2_plane planes[3];
+  while (gsc_input_buffer_queued_count_ > 0) {
+    DCHECK(gsc_input_streamon_);
+    memset(&dqbuf, 0, sizeof(dqbuf));
+    memset(&planes, 0, sizeof(planes));
+    dqbuf.type     = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+    dqbuf.memory   = V4L2_MEMORY_USERPTR;
+    dqbuf.m.planes = planes;
+    dqbuf.length   = arraysize(planes);
+    if (HANDLE_EINTR(ioctl(gsc_fd_, VIDIOC_DQBUF, &dqbuf)) != 0) {
+      if (errno == EAGAIN) {
+        // EAGAIN if we're just out of buffers to dequeue.
+        break;
+      }
+      DPLOG(ERROR) << "DequeueGsc(): ioctl() failed: VIDIOC_DQBUF";
+      NOTIFY_ERROR(kPlatformFailureError);
+      return;
+    }
+    GscInputRecord& input_record = gsc_input_buffer_map_[dqbuf.index];
+    DCHECK(input_record.at_device);
+    DCHECK(input_record.frame.get());
+    input_record.at_device = false;
+    input_record.frame = NULL;
+    gsc_free_input_buffers_.push_back(dqbuf.index);
+    gsc_input_buffer_queued_count_--;
+  }
+
+  // Dequeue completed GSC output (VIDEO_CAPTURE) buffers, and recycle to the
+  // free list.  Queue the corresponding MFC buffer to the GSC->MFC holding
+  // queue.
+  while (gsc_output_buffer_queued_count_ > 0) {
+    DCHECK(gsc_output_streamon_);
+    memset(&dqbuf, 0, sizeof(dqbuf));
+    memset(&planes, 0, sizeof(planes));
+    dqbuf.type     = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+    dqbuf.memory   = V4L2_MEMORY_DMABUF;
+    dqbuf.m.planes = planes;
+    dqbuf.length   = 2;
+    if (HANDLE_EINTR(ioctl(gsc_fd_, VIDIOC_DQBUF, &dqbuf)) != 0) {
+      if (errno == EAGAIN) {
+        // EAGAIN if we're just out of buffers to dequeue.
+        break;
+      }
+      DPLOG(ERROR) << "DequeueGsc(): ioctl() failed: VIDIOC_DQBUF";
+      NOTIFY_ERROR(kPlatformFailureError);
+      return;
+    }
+    GscOutputRecord& output_record = gsc_output_buffer_map_[dqbuf.index];
+    DCHECK(output_record.at_device);
+    DCHECK(output_record.mfc_input != -1);
+    mfc_ready_input_buffers_.push_back(output_record.mfc_input);
+    output_record.at_device = false;
+    output_record.mfc_input = -1;
+    gsc_free_output_buffers_.push_back(dqbuf.index);
+    gsc_output_buffer_queued_count_--;
+  }
+}
+void ExynosVideoEncodeAccelerator::EnqueueMfc() {
+  DVLOG(3) << "EnqueueMfc()";
+  DCHECK_EQ(encoder_thread_.message_loop(), base::MessageLoop::current());
+
+  // Enqueue all the MFC inputs we can.
+  const int old_mfc_inputs_queued = mfc_input_buffer_queued_count_;
+  while (!mfc_ready_input_buffers_.empty()) {
+    if (!EnqueueMfcInputRecord())
+      return;
+  }
+  if (old_mfc_inputs_queued == 0 && mfc_input_buffer_queued_count_ != 0) {
+    // We just started up a previously empty queue.
+    // Queue state changed; signal interrupt.
+    if (!SetDevicePollInterrupt())
+      return;
+    // Start VIDIOC_STREAMON if we haven't yet.
+    if (!mfc_input_streamon_) {
+      __u32 type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+      IOCTL_OR_ERROR_RETURN(mfc_fd_, VIDIOC_STREAMON, &type);
+      mfc_input_streamon_ = true;
+    }
+  }
+
+  // Enqueue all the MFC outputs we can.
+  const int old_mfc_outputs_queued = mfc_output_buffer_queued_count_;
+  while (!mfc_free_output_buffers_.empty() && !encoder_output_queue_.empty()) {
+    if (!EnqueueMfcOutputRecord())
+      return;
+  }
+  if (old_mfc_outputs_queued == 0 && mfc_output_buffer_queued_count_ != 0) {
+    // We just started up a previously empty queue.
+    // Queue state changed; signal interrupt.
+    if (!SetDevicePollInterrupt())
+      return;
+    // Start VIDIOC_STREAMON if we haven't yet.
+    if (!mfc_output_streamon_) {
+      __u32 type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+      IOCTL_OR_ERROR_RETURN(mfc_fd_, VIDIOC_STREAMON, &type);
+      mfc_output_streamon_ = true;
+    }
+  }
+}
+
+void ExynosVideoEncodeAccelerator::DequeueMfc() {
+  DVLOG(3) << "DequeueMfc()";
+  DCHECK_EQ(encoder_thread_.message_loop(), base::MessageLoop::current());
+
+  // Dequeue completed MFC input (VIDEO_OUTPUT) buffers, and recycle to the free
+  // list.
+  struct v4l2_buffer dqbuf;
+  struct v4l2_plane planes[2];
+  while (mfc_input_buffer_queued_count_ > 0) {
+    DCHECK(mfc_input_streamon_);
+    memset(&dqbuf, 0, sizeof(dqbuf));
+    memset(&planes, 0, sizeof(planes));
+    dqbuf.type     = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+    dqbuf.memory   = V4L2_MEMORY_MMAP;
+    dqbuf.m.planes = planes;
+    dqbuf.length   = 2;
+    if (HANDLE_EINTR(ioctl(mfc_fd_, VIDIOC_DQBUF, &dqbuf)) != 0) {
+      if (errno == EAGAIN) {
+        // EAGAIN if we're just out of buffers to dequeue.
+        break;
+      }
+      DPLOG(ERROR) << "DequeueMfc(): ioctl() failed: VIDIOC_DQBUF";
+      NOTIFY_ERROR(kPlatformFailureError);
+      return;
+    }
+    MfcInputRecord& input_record = mfc_input_buffer_map_[dqbuf.index];
+    DCHECK(input_record.at_device);
+    input_record.at_device = false;
+    mfc_free_input_buffers_.push_back(dqbuf.index);
+    mfc_input_buffer_queued_count_--;
+  }
+
+  // Dequeue completed MFC output (VIDEO_CAPTURE) buffers, and recycle to the
+  // free list.  Notify the client that an output buffer is complete.
+  while (mfc_output_buffer_queued_count_ > 0) {
+    DCHECK(mfc_output_streamon_);
+    memset(&dqbuf, 0, sizeof(dqbuf));
+    memset(planes, 0, sizeof(planes));
+    dqbuf.type     = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+    dqbuf.memory   = V4L2_MEMORY_USERPTR;
+    dqbuf.m.planes = planes;
+    dqbuf.length   = 1;
+    if (HANDLE_EINTR(ioctl(mfc_fd_, VIDIOC_DQBUF, &dqbuf)) != 0) {
+      if (errno == EAGAIN) {
+        // EAGAIN if we're just out of buffers to dequeue.
+        break;
+      }
+      DPLOG(ERROR) << "DequeueMfc(): ioctl() failed: VIDIOC_DQBUF";
+      NOTIFY_ERROR(kPlatformFailureError);
+      return;
+    }
+    const bool key_frame = ((dqbuf.flags & V4L2_BUF_FLAG_KEYFRAME) != 0);
+    const size_t output_size = dqbuf.m.planes[0].bytesused;
+    MfcOutputRecord& output_record = mfc_output_buffer_map_[dqbuf.index];
+    DCHECK(output_record.at_device);
+    DCHECK(output_record.buffer_ref.get());
+    uint8* data =
+        reinterpret_cast<uint8*>(output_record.buffer_ref->shm->memory());
+    if (stream_header_size_ == 0) {
+      // Assume that the first buffer dequeued is the stream header.
+      stream_header_size_ = output_size;
+      stream_header_.reset(new uint8[stream_header_size_]);
+      memcpy(stream_header_.get(), data, stream_header_size_);
+    }
+    if (key_frame &&
+        output_buffer_byte_size_ - stream_header_size_ >= output_size) {
+      // Insert stream header before every keyframe.
+      memmove(data + stream_header_size_, data, output_size);
+      memcpy(data, stream_header_.get(), stream_header_size_);
+    }
+    DVLOG(3) << "DequeueMfc(): returning "
+                "bitstream_buffer_id=" << output_record.buffer_ref->id
+             << ", key_frame=" << key_frame;
+    child_message_loop_proxy_->PostTask(
+        FROM_HERE,
+        base::Bind(&Client::BitstreamBufferReady,
+                   client_,
+                   output_record.buffer_ref->id,
+                   dqbuf.m.planes[0].bytesused,
+                   key_frame));
+    output_record.at_device = false;
+    output_record.buffer_ref.reset();
+    mfc_free_output_buffers_.push_back(dqbuf.index);
+    mfc_output_buffer_queued_count_--;
+  }
+}
+
+bool ExynosVideoEncodeAccelerator::EnqueueGscInputRecord() {
+  DVLOG(3) << "EnqueueGscInputRecord()";
+  DCHECK(!encoder_input_queue_.empty());
+  DCHECK(!gsc_free_input_buffers_.empty());
+
+  // Enqueue a GSC input (VIDEO_OUTPUT) buffer for an input video frame
+  scoped_refptr<media::VideoFrame> frame = encoder_input_queue_.front();
+  const int gsc_buffer = gsc_free_input_buffers_.back();
+  GscInputRecord& input_record = gsc_input_buffer_map_[gsc_buffer];
+  DCHECK(!input_record.at_device);
+  DCHECK(!input_record.frame.get());
+  struct v4l2_buffer qbuf;
+  struct v4l2_plane qbuf_planes[3];
+  memset(&qbuf, 0, sizeof(qbuf));
+  memset(qbuf_planes, 0, sizeof(qbuf_planes));
+  qbuf.index    = gsc_buffer;
+  qbuf.type     = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+  qbuf.memory   = V4L2_MEMORY_USERPTR;
+  qbuf.m.planes = qbuf_planes;
+  switch (input_format_fourcc_) {
+    case V4L2_PIX_FMT_RGB32: {
+      qbuf.m.planes[0].bytesused = input_allocated_size_.GetArea() * 4;
+      qbuf.m.planes[0].length    = input_allocated_size_.GetArea() * 4;
+      qbuf.m.planes[0].m.userptr = reinterpret_cast<unsigned long>(
+          frame->data(media::VideoFrame::kRGBPlane));
+      qbuf.length = 1;
+      break;
+    }
+    case V4L2_PIX_FMT_YUV420M: {
+      qbuf.m.planes[0].bytesused = input_allocated_size_.GetArea();
+      qbuf.m.planes[0].length    = input_allocated_size_.GetArea();
+      qbuf.m.planes[0].m.userptr = reinterpret_cast<unsigned long>(
+          frame->data(media::VideoFrame::kYPlane));
+      qbuf.m.planes[1].bytesused = input_allocated_size_.GetArea() / 4;
+      qbuf.m.planes[1].length    = input_allocated_size_.GetArea() / 4;
+      qbuf.m.planes[1].m.userptr = reinterpret_cast<unsigned long>(
+          frame->data(media::VideoFrame::kUPlane));
+      qbuf.m.planes[2].bytesused = input_allocated_size_.GetArea() / 4;
+      qbuf.m.planes[2].length    = input_allocated_size_.GetArea() / 4;
+      qbuf.m.planes[2].m.userptr = reinterpret_cast<unsigned long>(
+          frame->data(media::VideoFrame::kVPlane));
+      qbuf.length = 3;
+      break;
+    }
+    default:
+      NOTREACHED();
+      NOTIFY_ERROR(kIllegalStateError);
+      return false;
+  }
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_QBUF, &qbuf);
+  input_record.at_device = true;
+  input_record.frame = frame;
+  encoder_input_queue_.pop_front();
+  gsc_free_input_buffers_.pop_back();
+  gsc_input_buffer_queued_count_++;
+  return true;
+}
+
+bool ExynosVideoEncodeAccelerator::EnqueueGscOutputRecord() {
+  DVLOG(3) << "EnqueueGscOutputRecord()";
+  DCHECK(!gsc_free_output_buffers_.empty());
+  DCHECK(!mfc_free_input_buffers_.empty());
+
+  // Enqueue a GSC output (VIDEO_CAPTURE) buffer.
+  const int gsc_buffer = gsc_free_output_buffers_.back();
+  const int mfc_buffer = mfc_free_input_buffers_.back();
+  GscOutputRecord& output_record = gsc_output_buffer_map_[gsc_buffer];
+  MfcInputRecord& input_record = mfc_input_buffer_map_[mfc_buffer];
+  DCHECK(!output_record.at_device);
+  DCHECK_EQ(output_record.mfc_input, -1);
+  DCHECK(!input_record.at_device);
+  struct v4l2_buffer qbuf;
+  struct v4l2_plane qbuf_planes[2];
+  memset(&qbuf, 0, sizeof(qbuf));
+  memset(qbuf_planes, 0, sizeof(qbuf_planes));
+  qbuf.index            = gsc_buffer;
+  qbuf.type             = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+  qbuf.memory           = V4L2_MEMORY_DMABUF;
+  qbuf.m.planes         = qbuf_planes;
+  qbuf.m.planes[0].m.fd = input_record.fd[0];
+  qbuf.m.planes[1].m.fd = input_record.fd[1];
+  qbuf.length           = 2;
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_QBUF, &qbuf);
+  output_record.at_device = true;
+  output_record.mfc_input = mfc_buffer;
+  mfc_free_input_buffers_.pop_back();
+  gsc_free_output_buffers_.pop_back();
+  gsc_output_buffer_queued_count_++;
+  return true;
+}
+
+bool ExynosVideoEncodeAccelerator::EnqueueMfcInputRecord() {
+  DVLOG(3) << "EnqueueMfcInputRecord()";
+  DCHECK(!mfc_ready_input_buffers_.empty());
+
+  // Enqueue a MFC input (VIDEO_OUTPUT) buffer.
+  const int mfc_buffer = mfc_ready_input_buffers_.front();
+  MfcInputRecord& input_record = mfc_input_buffer_map_[mfc_buffer];
+  DCHECK(!input_record.at_device);
+  struct v4l2_buffer qbuf;
+  struct v4l2_plane qbuf_planes[2];
+  memset(&qbuf, 0, sizeof(qbuf));
+  memset(qbuf_planes, 0, sizeof(qbuf_planes));
+  qbuf.index     = mfc_buffer;
+  qbuf.type      = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+  qbuf.memory    = V4L2_MEMORY_MMAP;
+  qbuf.m.planes  = qbuf_planes;
+  qbuf.length    = 2;
+  IOCTL_OR_ERROR_RETURN_FALSE(mfc_fd_, VIDIOC_QBUF, &qbuf);
+  input_record.at_device = true;
+  mfc_ready_input_buffers_.pop_front();
+  mfc_input_buffer_queued_count_++;
+  return true;
+}
+
+bool ExynosVideoEncodeAccelerator::EnqueueMfcOutputRecord() {
+  DVLOG(3) << "EnqueueMfcOutputRecord()";
+  DCHECK(!mfc_free_output_buffers_.empty());
+  DCHECK(!encoder_output_queue_.empty());
+
+  // Enqueue a MFC output (VIDEO_CAPTURE) buffer.
+  linked_ptr<BitstreamBufferRef> output_buffer = encoder_output_queue_.back();
+  const int mfc_buffer = mfc_free_output_buffers_.back();
+  MfcOutputRecord& output_record = mfc_output_buffer_map_[mfc_buffer];
+  DCHECK(!output_record.at_device);
+  DCHECK(!output_record.buffer_ref.get());
+  struct v4l2_buffer qbuf;
+  struct v4l2_plane qbuf_planes[1];
+  memset(&qbuf, 0, sizeof(qbuf));
+  memset(qbuf_planes, 0, sizeof(qbuf_planes));
+  qbuf.index                 = mfc_buffer;
+  qbuf.type                  = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+  qbuf.memory                = V4L2_MEMORY_USERPTR;
+  qbuf.m.planes              = qbuf_planes;
+  qbuf.m.planes[0].bytesused = output_buffer->size;
+  qbuf.m.planes[0].length    = output_buffer->size;
+  qbuf.m.planes[0].m.userptr =
+      reinterpret_cast<unsigned long>(output_buffer->shm->memory());
+  qbuf.length                = 1;
+  IOCTL_OR_ERROR_RETURN_FALSE(mfc_fd_, VIDIOC_QBUF, &qbuf);
+  output_record.at_device = true;
+  output_record.buffer_ref = output_buffer;
+  encoder_output_queue_.pop_back();
+  mfc_free_output_buffers_.pop_back();
+  mfc_output_buffer_queued_count_++;
+  return true;
+}
+
+bool ExynosVideoEncodeAccelerator::StartDevicePoll() {
+  DVLOG(3) << "StartDevicePoll()";
+  DCHECK_EQ(encoder_thread_.message_loop(), base::MessageLoop::current());
+  DCHECK(!device_poll_thread_.IsRunning());
+
+  // Start up the device poll thread and schedule its first DevicePollTask().
+  if (!device_poll_thread_.Start()) {
+    DLOG(ERROR) << "StartDevicePoll(): Device thread failed to start";
+    NOTIFY_ERROR(kPlatformFailureError);
+    return false;
+  }
+  // Enqueue a poll task with no devices to poll on -- it will wait only on the
+  // interrupt fd.
+  device_poll_thread_.message_loop()->PostTask(
+      FROM_HERE,
+      base::Bind(&ExynosVideoEncodeAccelerator::DevicePollTask,
+                 base::Unretained(this),
+                 0));
+
+  return true;
+}
+
+bool ExynosVideoEncodeAccelerator::StopDevicePoll() {
+  DVLOG(3) << "StopDevicePoll()";
+
+  // Signal the DevicePollTask() to stop, and stop the device poll thread.
+  if (!SetDevicePollInterrupt())
+    return false;
+  device_poll_thread_.Stop();
+  // Clear the interrupt now, to be sure.
+  if (!ClearDevicePollInterrupt())
+    return false;
+
+  // Stop streaming.
+  if (gsc_input_streamon_) {
+    __u32 type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+    IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_STREAMOFF, &type);
+  }
+  gsc_input_streamon_ = false;
+  if (gsc_output_streamon_) {
+    __u32 type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+    IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_STREAMOFF, &type);
+  }
+  gsc_output_streamon_ = false;
+  if (mfc_input_streamon_) {
+    __u32 type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+    IOCTL_OR_ERROR_RETURN_FALSE(mfc_fd_, VIDIOC_STREAMOFF, &type);
+  }
+  mfc_input_streamon_ = false;
+  if (mfc_output_streamon_) {
+    __u32 type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+    IOCTL_OR_ERROR_RETURN_FALSE(mfc_fd_, VIDIOC_STREAMOFF, &type);
+  }
+  mfc_output_streamon_ = false;
+
+  // Reset all our accounting info.
+  encoder_input_queue_.clear();
+  gsc_free_input_buffers_.clear();
+  for (size_t i = 0; i < gsc_input_buffer_map_.size(); ++i) {
+    GscInputRecord& input_record = gsc_input_buffer_map_[i];
+    input_record.at_device = false;
+    input_record.frame = NULL;
+    gsc_free_input_buffers_.push_back(i);
+  }
+  gsc_input_buffer_queued_count_ = 0;
+  gsc_free_output_buffers_.clear();
+  for (size_t i = 0; i < gsc_output_buffer_map_.size(); ++i) {
+    GscOutputRecord& output_record = gsc_output_buffer_map_[i];
+    output_record.at_device = false;
+    output_record.mfc_input = -1;
+    gsc_free_output_buffers_.push_back(i);
+  }
+  gsc_output_buffer_queued_count_ = 0;
+  mfc_ready_input_buffers_.clear();
+  mfc_free_input_buffers_.clear();
+  for (size_t i = 0; i < mfc_input_buffer_map_.size(); ++i) {
+    MfcInputRecord& input_record = mfc_input_buffer_map_[i];
+    input_record.at_device = false;
+    mfc_free_input_buffers_.push_back(i);
+  }
+  mfc_input_buffer_queued_count_ = 0;
+  mfc_free_output_buffers_.clear();
+  for (size_t i = 0; i < mfc_output_buffer_map_.size(); ++i) {
+    MfcOutputRecord& output_record = mfc_output_buffer_map_[i];
+    output_record.at_device = false;
+    output_record.buffer_ref.reset();
+    mfc_free_output_buffers_.push_back(i);
+  }
+  mfc_output_buffer_queued_count_ = 0;
+  encoder_output_queue_.clear();
+
+  DVLOG(3) << "StopDevicePoll(): device poll stopped";
+  return true;
+}
+
+bool ExynosVideoEncodeAccelerator::SetDevicePollInterrupt() {
+  DVLOG(3) << "SetDevicePollInterrupt()";
+
+  // We might get called here if we fail during initialization, in which case we
+  // don't have a file descriptor.
+  if (device_poll_interrupt_fd_ == -1)
+    return true;
+
+  const uint64 buf = 1;
+  if (HANDLE_EINTR((write(device_poll_interrupt_fd_, &buf, sizeof(buf)))) <
+      static_cast<ssize_t>(sizeof(buf))) {
+    DPLOG(ERROR) << "SetDevicePollInterrupt(): write() failed";
+    NOTIFY_ERROR(kPlatformFailureError);
+    return false;
+  }
+  return true;
+}
+
+bool ExynosVideoEncodeAccelerator::ClearDevicePollInterrupt() {
+  DVLOG(3) << "ClearDevicePollInterrupt()";
+
+  // We might get called here if we fail during initialization, in which case we
+  // don't have a file descriptor.
+  if (device_poll_interrupt_fd_ == -1)
+    return true;
+
+  uint64 buf;
+  if (HANDLE_EINTR(read(device_poll_interrupt_fd_, &buf, sizeof(buf))) <
+      static_cast<ssize_t>(sizeof(buf))) {
+    if (errno == EAGAIN) {
+      // No interrupt flag set, and we're reading nonblocking.  Not an error.
+      return true;
+    } else {
+      DPLOG(ERROR) << "ClearDevicePollInterrupt(): read() failed";
+      NOTIFY_ERROR(kPlatformFailureError);
+      return false;
+    }
+  }
+  return true;
+}
+
+void ExynosVideoEncodeAccelerator::DevicePollTask(unsigned int poll_fds) {
+  DVLOG(3) << "DevicePollTask()";
+  DCHECK_EQ(device_poll_thread_.message_loop(), base::MessageLoop::current());
+  DCHECK_NE(device_poll_interrupt_fd_, -1);
+
+  // This routine just polls the set of device fds, and schedules a
+  // ServiceDeviceTask() on encoder_thread_ when processing needs to occur.
+  // Other threads may notify this task to return early by writing to
+  // device_poll_interrupt_fd_.
+  struct pollfd pollfds[3];
+  nfds_t nfds;
+
+  // Add device_poll_interrupt_fd_;
+  pollfds[0].fd = device_poll_interrupt_fd_;
+  pollfds[0].events = POLLIN | POLLERR;
+  nfds = 1;
+
+  // Add GSC fd, if we should poll on it.
+  // GSC has to wait until both input and output buffers are queued.
+  if (poll_fds & kPollGsc) {
+    DVLOG(3) << "DevicePollTask(): adding GSC to poll() set";
+    pollfds[nfds].fd = gsc_fd_;
+    pollfds[nfds].events = POLLIN | POLLOUT | POLLERR;
+    nfds++;
+  }
+  if (poll_fds & kPollMfc) {
+    DVLOG(3) << "DevicePollTask(): adding MFC to poll() set";
+    pollfds[nfds].fd = mfc_fd_;
+    pollfds[nfds].events = POLLIN | POLLOUT | POLLERR;
+    nfds++;
+  }
+
+  // Poll it!
+  if (HANDLE_EINTR(poll(pollfds, nfds, -1)) == -1) {
+    DPLOG(ERROR) << "DevicePollTask(): poll() failed";
+    NOTIFY_ERROR(kPlatformFailureError);
+    return;
+  }
+
+  // All processing should happen on ServiceDeviceTask(), since we shouldn't
+  // touch encoder state from this thread.
+  encoder_thread_.message_loop()->PostTask(
+      FROM_HERE,
+      base::Bind(&ExynosVideoEncodeAccelerator::ServiceDeviceTask,
+                 base::Unretained(this)));
+}
+
+void ExynosVideoEncodeAccelerator::NotifyError(Error error) {
+  DVLOG(1) << "NotifyError(): error=" << error;
+
+  if (!child_message_loop_proxy_->BelongsToCurrentThread()) {
+    child_message_loop_proxy_->PostTask(
+        FROM_HERE,
+        base::Bind(
+            &ExynosVideoEncodeAccelerator::NotifyError, weak_this_, error));
+    return;
+  }
+
+  if (client_) {
+    client_->NotifyError(error);
+    client_ptr_factory_.InvalidateWeakPtrs();
+  }
+}
+
+void ExynosVideoEncodeAccelerator::SetEncoderState(State state) {
+  DVLOG(3) << "SetEncoderState(): state=" << state;
+
+  // We can touch encoder_state_ only if this is the encoder thread or the
+  // encoder thread isn't running.
+  if (encoder_thread_.message_loop() != NULL &&
+      encoder_thread_.message_loop() != base::MessageLoop::current()) {
+    encoder_thread_.message_loop()->PostTask(
+        FROM_HERE,
+        base::Bind(&ExynosVideoEncodeAccelerator::SetEncoderState,
+                   base::Unretained(this),
+                   state));
+  } else {
+    encoder_state_ = state;
+  }
+}
+
+void ExynosVideoEncodeAccelerator::RequestEncodingParametersChangeTask(
+    uint32 bitrate,
+    uint32 framerate) {
+  DVLOG(3) << "RequestEncodingParametersChangeTask(): bitrate=" << bitrate
+           << ", framerate=" << framerate;
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+
+  struct v4l2_ext_control ctrls[1];
+  struct v4l2_ext_controls control;
+  memset(&ctrls, 0, sizeof(ctrls));
+  memset(&control, 0, sizeof(control));
+  ctrls[0].id    = V4L2_CID_MPEG_VIDEO_BITRATE;
+  ctrls[0].value = bitrate;
+  control.ctrl_class = V4L2_CTRL_CLASS_MPEG;
+  control.count = arraysize(ctrls);
+  control.controls = ctrls;
+  IOCTL_OR_ERROR_RETURN(mfc_fd_, VIDIOC_S_EXT_CTRLS, &control);
+
+  struct v4l2_streamparm parms;
+  memset(&parms, 0, sizeof(parms));
+  parms.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+  // Note that we are provided "frames per second" but V4L2 expects "time per
+  // frame"; hence we provide the reciprocal of the framerate here.
+  parms.parm.output.timeperframe.numerator = 1;
+  parms.parm.output.timeperframe.denominator = framerate;
+  IOCTL_OR_ERROR_RETURN(mfc_fd_, VIDIOC_S_PARM, &parms);
+}
+
+bool ExynosVideoEncodeAccelerator::CreateGscInputBuffers() {
+  DVLOG(3) << "CreateGscInputBuffers()";
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+  DCHECK_EQ(encoder_state_, kUninitialized);
+  DCHECK(!gsc_input_streamon_);
+
+  struct v4l2_control control;
+  memset(&control, 0, sizeof(control));
+  control.id    = V4L2_CID_ROTATE;
+  control.value = 0;
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_S_CTRL, &control);
+
+  // HFLIP actually seems to control vertical mirroring for GSC, and vice-versa.
+  memset(&control, 0, sizeof(control));
+  control.id    = V4L2_CID_HFLIP;
+  control.value = 0;
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_S_CTRL, &control);
+
+  memset(&control, 0, sizeof(control));
+  control.id    = V4L2_CID_VFLIP;
+  control.value = 0;
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_S_CTRL, &control);
+
+  memset(&control, 0, sizeof(control));
+  control.id    = V4L2_CID_GLOBAL_ALPHA;

[Ami GONE FROM CHROMIUM, 2013/08/13 18:13:19]

I wonder if it's worth asserting that A==0xFF somewhere for RGBA inputs.
Maybe only in !NDEBUG.  Or maybe not.

[sheu, 2013/08/14 01:00:42]

I'm gonna say, not really worth it.  We're converting to NV12 to input to the
encoder anyways, and (1) NV12 has no alpha and (2) since when did H264 have
chroma keying?

+  control.value = 255;
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_S_CTRL, &control);
+
+  struct v4l2_format format;
+  memset(&format, 0, sizeof(format));
+  format.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+  format.fmt.pix_mp.width  = input_allocated_size_.width();
+  format.fmt.pix_mp.height = input_allocated_size_.height();
+  format.fmt.pix_mp.pixelformat = input_format_fourcc_;
+  switch (input_format_fourcc_) {
+    case V4L2_PIX_FMT_RGB32:
+      format.fmt.pix_mp.plane_fmt[0].sizeimage =
+          input_allocated_size_.GetArea() * 4;
+      format.fmt.pix_mp.plane_fmt[0].bytesperline =
+          input_allocated_size_.width() * 4;
+      format.fmt.pix_mp.num_planes = 1;
+      break;
+    case V4L2_PIX_FMT_YUV420M:
+      format.fmt.pix_mp.plane_fmt[0].sizeimage =
+          input_allocated_size_.GetArea();
+      format.fmt.pix_mp.plane_fmt[0].bytesperline =
+          input_allocated_size_.width();
+      format.fmt.pix_mp.plane_fmt[1].sizeimage =
+          input_allocated_size_.GetArea() / 4;
+      format.fmt.pix_mp.plane_fmt[1].bytesperline =
+          input_allocated_size_.width() / 2;

[Ami GONE FROM CHROMIUM, 2013/08/13 18:13:19]

D'oh!  Of course.

+      format.fmt.pix_mp.plane_fmt[2].sizeimage =
+          input_allocated_size_.GetArea() / 4;
+      format.fmt.pix_mp.plane_fmt[2].bytesperline =
+          input_allocated_size_.width() / 2;
+      format.fmt.pix_mp.num_planes = 3;
+      break;
+    default:
+      NOTREACHED();
+      NOTIFY_ERROR(kIllegalStateError);
+      return false;
+  }
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_S_FMT, &format);
+
+  struct v4l2_crop crop;
+  memset(&crop, 0, sizeof(crop));
+  crop.type     = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+  crop.c.left   = 0;
+  crop.c.top    = 0;
+  crop.c.width  = input_visible_size_.width();
+  crop.c.height = input_visible_size_.height();
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_S_CROP, &crop);
+
+  struct v4l2_requestbuffers reqbufs;
+  memset(&reqbufs, 0, sizeof(reqbufs));
+  reqbufs.count  = kGscInputBufferCount;
+  reqbufs.type   = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+  reqbufs.memory = V4L2_MEMORY_USERPTR;
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_REQBUFS, &reqbufs);
+
+  DCHECK(gsc_input_buffer_map_.empty());
+  gsc_input_buffer_map_.resize(reqbufs.count);
+  for (size_t i = 0; i < gsc_input_buffer_map_.size(); ++i)
+    gsc_free_input_buffers_.push_back(i);
+
+  return true;
+}
+
+bool ExynosVideoEncodeAccelerator::CreateGscOutputBuffers() {
+  DVLOG(3) << "CreateGscOutputBuffers()";
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+  DCHECK_EQ(encoder_state_, kUninitialized);
+  DCHECK(!gsc_output_streamon_);
+
+  struct v4l2_format format;
+  memset(&format, 0, sizeof(format));
+  format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+  format.fmt.pix_mp.width = converted_allocated_size_.width();
+  format.fmt.pix_mp.height = converted_allocated_size_.height();
+  format.fmt.pix_mp.pixelformat = V4L2_PIX_FMT_NV12M;
+  format.fmt.pix_mp.plane_fmt[0].sizeimage =
+      converted_allocated_size_.GetArea();
+  format.fmt.pix_mp.plane_fmt[1].sizeimage =
+      converted_allocated_size_.GetArea() / 2;
+  format.fmt.pix_mp.plane_fmt[0].bytesperline =
+      converted_allocated_size_.width();
+  format.fmt.pix_mp.plane_fmt[1].bytesperline =
+      converted_allocated_size_.width();
+  format.fmt.pix_mp.num_planes = 2;
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_S_FMT, &format);
+
+  struct v4l2_crop crop;
+  memset(&crop, 0, sizeof(crop));
+  crop.type     = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+  crop.c.left   = 0;
+  crop.c.top    = 0;
+  crop.c.width  = converted_visible_size_.width();
+  crop.c.height = converted_visible_size_.height();
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_S_CROP, &crop);
+
+  struct v4l2_requestbuffers reqbufs;
+  memset(&reqbufs, 0, sizeof(reqbufs));
+  reqbufs.count  = kGscOutputBufferCount;
+  reqbufs.type   = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+  reqbufs.memory = V4L2_MEMORY_DMABUF;
+  IOCTL_OR_ERROR_RETURN_FALSE(gsc_fd_, VIDIOC_REQBUFS, &reqbufs);
+
+  DCHECK(gsc_output_buffer_map_.empty());
+  gsc_output_buffer_map_.resize(reqbufs.count);
+  for (size_t i = 0; i < gsc_output_buffer_map_.size(); ++i)
+    gsc_free_output_buffers_.push_back(i);
+  return true;
+}
+
+bool ExynosVideoEncodeAccelerator::SetMfcFormats() {
+  DVLOG(3) << "SetMfcFormats()";
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+  DCHECK(!mfc_input_streamon_);
+  DCHECK(!mfc_output_streamon_);
+
+  // VIDIOC_S_FMT on OUTPUT queue.
+  struct v4l2_format format;
+  memset(&format, 0, sizeof(format));
+  format.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+  format.fmt.pix_mp.width = input_allocated_size_.width();
+  format.fmt.pix_mp.height = input_allocated_size_.height();
+  format.fmt.pix_mp.pixelformat = V4L2_PIX_FMT_NV12M;
+  format.fmt.pix_mp.num_planes = 2;
+  IOCTL_OR_ERROR_RETURN_FALSE(mfc_fd_, VIDIOC_S_FMT, &format);
+  // We read direct from GSC, so we rely on the HW not changing our set
+  // size/stride.
+  DCHECK_EQ(format.fmt.pix_mp.plane_fmt[0].sizeimage,
+            static_cast<__u32>(input_allocated_size_.GetArea()));
+  DCHECK_EQ(format.fmt.pix_mp.plane_fmt[0].bytesperline,
+            static_cast<__u32>(input_allocated_size_.width()));
+  DCHECK_EQ(format.fmt.pix_mp.plane_fmt[1].sizeimage,
+            static_cast<__u32>(input_allocated_size_.GetArea() / 2));
+  DCHECK_EQ(format.fmt.pix_mp.plane_fmt[1].bytesperline,
+            static_cast<__u32>(input_allocated_size_.width()));
+
+  struct v4l2_crop crop;
+  memset(&crop, 0, sizeof(crop));
+  crop.type     = V4L2_BUF_TYPE_VIDEO_OUTPUT;
+  crop.c.left   = 0;
+  crop.c.top    = 0;
+  crop.c.width  = input_visible_size_.width();
+  crop.c.height = input_visible_size_.height();
+  IOCTL_OR_ERROR_RETURN_FALSE(mfc_fd_, VIDIOC_S_CROP, &crop);
+
+  // VIDIOC_S_FMT on CAPTURE queue.
+  output_buffer_byte_size_ = kMfcOutputBufferSize;
+  memset(&format, 0, sizeof(format));
+  format.type                   = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+  format.fmt.pix_mp.width       = output_visible_size_.width();
+  format.fmt.pix_mp.height      = output_visible_size_.height();
+  format.fmt.pix_mp.pixelformat = output_format_fourcc_;
+  format.fmt.pix_mp.plane_fmt[0].sizeimage = output_buffer_byte_size_;
+  format.fmt.pix_mp.num_planes  = 1;
+  IOCTL_OR_ERROR_RETURN_FALSE(mfc_fd_, VIDIOC_S_FMT, &format);
+
+  struct v4l2_ext_control ctrls[6];

[Ami GONE FROM CHROMIUM, 2013/08/13 18:13:19]

You might enjoy a form more like: 

struct v4l2_ext_control ctrls[] = {
    { V4L2_CID_MPEG_VIDEO_B_FRAMES, 0 },
    { V4L2_CID_MPEG_VIDEO_FRAME_RC_ENABLE, 1 },
    ...
};

which would
- allow you to drop the "6" here
- allow you to drop the explicit subscripting below
- drop a bunch of boilerplate
- avoid the need for the memset.

Of course, it might also not actually work, so there's that.

[sheu, 2013/08/14 01:00:42]

There are more members to v4l2_ext_control than just those, though.  And
initialize-by-member-name in a struct brace initializer is a compiler extension.

+  struct v4l2_ext_controls control;
+  memset(&ctrls, 0, sizeof(ctrls));
+  memset(&control, 0, sizeof(control));

[Ami GONE FROM CHROMIUM, 2013/08/13 18:13:19]

Please comment of the magical values that they are received wisdom.

[sheu, 2013/08/14 01:00:42]

Done.

+  // No B-frames, for lowest decoding latency.
+  ctrls[0].id    = V4L2_CID_MPEG_VIDEO_B_FRAMES;
+  ctrls[0].value = 0;
+  // Enable and configure dynamic bitrate control.
+  ctrls[1].id    = V4L2_CID_MPEG_VIDEO_FRAME_RC_ENABLE;
+  ctrls[1].value = 1;
+  ctrls[2].id    = V4L2_CID_MPEG_MFC51_VIDEO_RC_REACTION_COEFF;
+  ctrls[2].value = 10;
+  ctrls[3].id    = V4L2_CID_MPEG_MFC51_VIDEO_RC_FIXED_TARGET_BIT;
+  ctrls[3].value = 1;
+  ctrls[4].id    = V4L2_CID_MPEG_VIDEO_H264_MAX_QP;
+  ctrls[4].value = 51;
+  // Separate stream header so we can cache it and insert into the stream.
+  ctrls[5].id    = V4L2_CID_MPEG_VIDEO_HEADER_MODE;
+  ctrls[5].value = V4L2_MPEG_VIDEO_HEADER_MODE_SEPARATE;
+  control.ctrl_class = V4L2_CTRL_CLASS_MPEG;
+  control.count = arraysize(ctrls);
+  control.controls = ctrls;
+  IOCTL_OR_ERROR_RETURN_FALSE(mfc_fd_, VIDIOC_S_EXT_CTRLS, &control);
+
+  return true;
+}
+
+bool ExynosVideoEncodeAccelerator::CreateMfcInputBuffers() {
+  DVLOG(3) << "CreateMfcInputBuffers()";
+  // This function runs on encoder_thread_ after output buffers have been
+  // provided by the client.
+  DCHECK_EQ(encoder_thread_.message_loop(), base::MessageLoop::current());
+  DCHECK(!mfc_input_streamon_);
+
+  struct v4l2_requestbuffers reqbufs;
+  memset(&reqbufs, 0, sizeof(reqbufs));
+  reqbufs.count = 1;  // Driver will allocate the appropriate number of buffers.
+  reqbufs.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+  reqbufs.memory = V4L2_MEMORY_MMAP;
+  IOCTL_OR_ERROR_RETURN_FALSE(mfc_fd_, VIDIOC_REQBUFS, &reqbufs);
+
+  DCHECK(mfc_input_buffer_map_.empty());
+  mfc_input_buffer_map_.resize(reqbufs.count);
+  for (size_t i = 0; i < mfc_input_buffer_map_.size(); ++i) {
+    MfcInputRecord& input_record = mfc_input_buffer_map_[i];
+    for (int j = 0; j < 2; ++j) {
+      // Export the DMABUF fd so GSC can write to it.
+      struct v4l2_exportbuffer expbuf;
+      memset(&expbuf, 0, sizeof(expbuf));
+      expbuf.type  = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+      expbuf.index = i;
+      expbuf.plane = j;
+      expbuf.flags = O_CLOEXEC;
+      IOCTL_OR_ERROR_RETURN_FALSE(mfc_fd_, VIDIOC_EXPBUF, &expbuf);
+      input_record.fd[j] = expbuf.fd;
+    }
+    mfc_free_input_buffers_.push_back(i);
+  }
+
+  return true;
+}
+
+bool ExynosVideoEncodeAccelerator::CreateMfcOutputBuffers() {
+  DVLOG(3) << "CreateMfcOutputBuffers()";
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+  DCHECK(!mfc_output_streamon_);
+
+  struct v4l2_requestbuffers reqbufs;
+  memset(&reqbufs, 0, sizeof(reqbufs));
+  reqbufs.count = kMfcOutputBufferCount;
+  reqbufs.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+  reqbufs.memory = V4L2_MEMORY_USERPTR;
+  IOCTL_OR_ERROR_RETURN_FALSE(mfc_fd_, VIDIOC_REQBUFS, &reqbufs);
+
+  DCHECK(mfc_output_buffer_map_.empty());
+  mfc_output_buffer_map_.resize(reqbufs.count);
+  for (size_t i = 0; i < mfc_output_buffer_map_.size(); ++i)
+    mfc_free_output_buffers_.push_back(i);
+
+  return true;
+}
+
+void ExynosVideoEncodeAccelerator::DestroyGscInputBuffers() {
+  DVLOG(3) << "DestroyGscInputBuffers()";
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+  DCHECK(!gsc_input_streamon_);
+
+  struct v4l2_requestbuffers reqbufs;
+  memset(&reqbufs, 0, sizeof(reqbufs));
+  reqbufs.count = 0;
+  reqbufs.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+  reqbufs.memory = V4L2_MEMORY_USERPTR;
+  if (HANDLE_EINTR(ioctl(gsc_fd_, VIDIOC_REQBUFS, &reqbufs)) != 0)
+    DPLOG(ERROR) << "DestroyGscInputBuffers(): ioctl() failed: VIDIOC_REQBUFS";
+
+  gsc_input_buffer_map_.clear();
+  gsc_free_input_buffers_.clear();
+}
+
+void ExynosVideoEncodeAccelerator::DestroyGscOutputBuffers() {
+  DVLOG(3) << "DestroyGscOutputBuffers()";
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+  DCHECK(!gsc_output_streamon_);
+
+  struct v4l2_requestbuffers reqbufs;
+  memset(&reqbufs, 0, sizeof(reqbufs));
+  reqbufs.count = 0;
+  reqbufs.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+  reqbufs.memory = V4L2_MEMORY_DMABUF;
+  if (HANDLE_EINTR(ioctl(gsc_fd_, VIDIOC_REQBUFS, &reqbufs)) != 0)
+    DPLOG(ERROR) << "DestroyGscOutputBuffers(): ioctl() failed: VIDIOC_REQBUFS";
+
+  gsc_output_buffer_map_.clear();
+  gsc_free_output_buffers_.clear();
+}
+
+void ExynosVideoEncodeAccelerator::DestroyMfcInputBuffers() {
+  DVLOG(3) << "DestroyMfcInputBuffers()";
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+  DCHECK(!mfc_input_streamon_);
+
+  struct v4l2_requestbuffers reqbufs;
+  memset(&reqbufs, 0, sizeof(reqbufs));
+  reqbufs.count = 0;
+  reqbufs.type = V4L2_BUF_TYPE_VIDEO_OUTPUT_MPLANE;
+  reqbufs.memory = V4L2_MEMORY_MMAP;
+  if (HANDLE_EINTR(ioctl(mfc_fd_, VIDIOC_REQBUFS, &reqbufs)) != 0)
+    DPLOG(ERROR) << "DestroyMfcInputBuffers(): ioctl() failed: VIDIOC_REQBUFS";
+
+  mfc_input_buffer_map_.clear();
+  mfc_free_input_buffers_.clear();
+}
+
+void ExynosVideoEncodeAccelerator::DestroyMfcOutputBuffers() {
+  DVLOG(3) << "DestroyMfcOutputBuffers()";
+  DCHECK(child_message_loop_proxy_->BelongsToCurrentThread());
+  DCHECK(!mfc_output_streamon_);
+
+  struct v4l2_requestbuffers reqbufs;
+  memset(&reqbufs, 0, sizeof(reqbufs));
+  reqbufs.count = 0;
+  reqbufs.type = V4L2_BUF_TYPE_VIDEO_CAPTURE_MPLANE;
+  reqbufs.memory = V4L2_MEMORY_USERPTR;
+  if (HANDLE_EINTR(ioctl(mfc_fd_, VIDIOC_REQBUFS, &reqbufs)) != 0)
+    DPLOG(ERROR) << "DestroyMfcOutputBuffers(): ioctl() failed: VIDIOC_REQBUFS";
+
+  mfc_output_buffer_map_.clear();
+  mfc_free_output_buffers_.clear();
+}
+
+}  // namespace content