[cros] Implement WebM encoder/muxer for animated avatar capture.

media/webm/chromeos/webm_encoder.cc

+// Copyright (c) 2012 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 "media/webm/chromeos/webm_encoder.h"
+
+#include "base/bind.h"
+#include "base/file_util.h"
+#include "base/logging.h"
+#include "base/memory/scoped_generic_obj.h"
+#include "libyuv/convert.h"
+#include "libyuv/video_common.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+
+extern "C" {
+// Getting the right degree of C compatibility has been a constant struggle.
+// - Stroustrup, C++ Report, 12(7), July/August 2000.
+#define private priv
+#include "third_party/libvpx/source/libvpx/libmkv/EbmlIDs.h"
+#include "third_party/libvpx/source/libvpx/libmkv/EbmlWriter.h"
+#undef private
+}
+
+// Number of encoder threads to use.
+static const int kNumEncoderThreads = 2;
+
+// Need a fixed size serializer for the track ID. libmkv provides a 64 bit
+// one, but not a 32 bit one.
+static void Ebml_SerializeUnsigned32(EbmlGlobal* ebml,
+                                     unsigned long class_id,
+                                     uint64_t value) {
+  uint8 size_serialized = 4 | 0x80;
+  Ebml_WriteID(ebml, class_id);
+  Ebml_Serialize(ebml, &size_serialized, sizeof(size_serialized), 1);
+  Ebml_Serialize(ebml, &value, sizeof(value), 4);
+}
+
+// Wrapper functor for vpx_codec_destroy().
+class VpxCodecDestroyHelper {
+ public:
+  void operator()(vpx_codec_ctx_t* codec) {
+    vpx_codec_destroy(codec);
+  }
+};
+
+namespace media {
+
+namespace chromeos {
+
+WebmEncoder::WebmEncoder(const FilePath& output_path,
+                         int bitrate,
+                         bool realtime)
+    : bitrate_(bitrate),
+      deadline_(realtime ? VPX_DL_REALTIME : VPX_DL_GOOD_QUALITY),
+      output_path_(output_path) {
+  ebml_writer_.write_cb = base::Bind(
+      &WebmEncoder::EbmlWrite, base::Unretained(this));
+  ebml_writer_.serialize_cb = base::Bind(
+      &WebmEncoder::EbmlSerialize, base::Unretained(this));
+}
+
+bool WebmEncoder::EncodeFromSprite(const SkBitmap& sprite,
+                                   int fps_n,
+                                   int fps_d) {
+  DCHECK(!sprite.isNull() && !sprite.empty());

[scherkus (not reviewing), 2012/07/20 19:20:51]

nit: separate the DCHECKs

[Ivan Korotkov, 2012/07/23 18:57:52]

Done.

+
+  width_ = sprite.width();
+  height_ = sprite.width();
+  fps_.num = fps_n;
+  fps_.den = fps_d;
+
+  size_t y_size = width_ * height_;
+  size_t uv_size = ((width_ + 1) / 2) * ((height_ + 1) / 2);
+  size_t frame_size = y_size + 2 * uv_size;
+  size_t frame_count = sprite.height() / width_;  // Sprite is tiled vertically.

[scherkus (not reviewing), 2012/07/20 19:20:51]

do we need to do any alignment / padding for our yuv data?

for reference see what we do in VideoFrame::AllocateYUV()
http://src.chromium.org/viewvc/chrome/trunk/src/media/base/video_frame.cc?vie...

[Ivan Korotkov, 2012/07/23 18:57:52]

Right, libyuv states that 16-byte alignment is more efficient. I've switched
from vpx_img_wrap to vpx_img_alloc which takes care about aligning now.

+
+  yuv_frame_.reset(new uint8[frame_size]);
+
+  vpx_image_t image;
+  vpx_img_wrap(&image, VPX_IMG_FMT_I420, width_, height_, 1, yuv_frame_.get());
+
+  vpx_codec_ctx_t codec;
+  const vpx_codec_iface_t* codec_iface = vpx_codec_vp8_cx();
+  DCHECK(codec_iface);
+  vpx_codec_err_t ret = vpx_codec_enc_config_default(codec_iface, &config_, 0);
+  DCHECK_EQ(VPX_CODEC_OK, ret);
+
+  config_.rc_target_bitrate = bitrate_;
+  config_.g_w = width_;
+  config_.g_h = height_;
+  config_.g_pass = VPX_RC_ONE_PASS;
+  config_.g_profile = 0;          // Default profile.
+  config_.g_threads = kNumEncoderThreads;
+  config_.rc_min_quantizer = 0;
+  config_.rc_max_quantizer = 63;  // Maximum possible range.
+  config_.g_timebase.num = fps_.den;
+  config_.g_timebase.den = fps_.num;
+  config_.kf_mode = VPX_KF_AUTO;  // Auto key frames.
+
+  ret = vpx_codec_enc_init(&codec, codec_iface, &config_, 0);
+  if (VPX_CODEC_OK != ret)
+    return false;
+  // Ensure that codec context is freed after return.
+  ScopedGenericObj<vpx_codec_ctx_t*, VpxCodecDestroyHelper> codec_ptr(&codec);
+
+  SkAutoLockPixels lock_sprite(sprite);
+
+  const uint8* src = reinterpret_cast<const uint8*>(sprite.getAddr32(0, 0));
+  size_t src_frame_size = sprite.getSize();
+  int crop_y = 0;
+
+  if (!WriteWebmHeader())
+    return false;
+
+  for (size_t frame = 0; frame < frame_count; ++frame) {
+    int res = libyuv::ConvertToI420(
+        src, src_frame_size,

[scherkus (not reviewing), 2012/07/20 19:20:51]

sanity check: does libyuv have any assumptions on alignment or padding for input
+ output?

+        image.planes[VPX_PLANE_Y], image.stride[VPX_PLANE_Y],
+        image.planes[VPX_PLANE_U], image.stride[VPX_PLANE_U],
+        image.planes[VPX_PLANE_V], image.stride[VPX_PLANE_V],
+        0, crop_y,                // src origin
+        width_, sprite.height(),  // src size
+        width_, height_,          // dest size
+        libyuv::kRotate0,
+        libyuv::FOURCC_ARGB);
+    if (res)
+      return false;
+    crop_y += height_;
+
+    ret = vpx_codec_encode(&codec, &image, frame, 1, 0, deadline_);
+    if (VPX_CODEC_OK != ret)
+      return false;
+
+    vpx_codec_iter_t iter = NULL;
+    const vpx_codec_cx_pkt_t* packet;
+    while ((packet = vpx_codec_get_cx_data(&codec, &iter))) {
+      if (packet->kind == VPX_CODEC_CX_FRAME_PKT)
+        WriteWebmBlock(packet);
+    }
+  }
+
+  return WriteWebmFooter();
+}
+
+bool WebmEncoder::WriteWebmHeader() {
+  output_ = file_util::OpenFile(output_path_, "wb");
+  if (!output_)
+    return false;
+
+  // Global header.
+  StartSubElement(EBML); {

[scherkus (not reviewing), 2012/07/20 19:20:51]

we have a style guide for a reason and I don't find the if/do-while appearance
to add that much so I don't see why we'd warrant the exception here

the additional scope levels are fine but we should have { } by themselves on
separate lines

[Ivan Korotkov, 2012/07/23 18:57:52]

Done.

+    Ebml_SerializeUnsigned(&ebml_writer_, EBMLVersion, 1);
+    Ebml_SerializeUnsigned(&ebml_writer_, EBMLReadVersion, 1);
+    Ebml_SerializeUnsigned(&ebml_writer_, EBMLMaxIDLength, 4);
+    Ebml_SerializeUnsigned(&ebml_writer_, EBMLMaxSizeLength, 8);
+    Ebml_SerializeString(&ebml_writer_, DocType, "webm");
+    Ebml_SerializeUnsigned(&ebml_writer_, DocTypeVersion, 2);
+    Ebml_SerializeUnsigned(&ebml_writer_, DocTypeReadVersion, 2);
+  } EndSubElement();  // EBML
+
+  // Single segment with a video track.
+  StartSubElement(Segment); {
+    StartSubElement(Info); {
+      // All timecodes in the segment will be expressed in milliseconds.
+      Ebml_SerializeUnsigned(&ebml_writer_, TimecodeScale, 1000000);
+    } EndSubElement();  // Info
+
+    StartSubElement(Tracks); {
+      StartSubElement(TrackEntry); {
+        Ebml_SerializeUnsigned(&ebml_writer_, TrackNumber, 1);
+        Ebml_SerializeUnsigned32(&ebml_writer_, TrackUID, 1);
+        Ebml_SerializeUnsigned(&ebml_writer_, TrackType, 1);  // Video
+        Ebml_SerializeString(&ebml_writer_, CodecID, "V_VP8");
+
+        StartSubElement(Video); {
+          Ebml_SerializeUnsigned(&ebml_writer_, PixelWidth, width_);
+          Ebml_SerializeUnsigned(&ebml_writer_, PixelHeight, height_);
+          Ebml_SerializeUnsigned(&ebml_writer_, StereoMode, 0);  // Mono
+          float fps = static_cast<float>(fps_.num) / fps_.den;
+          Ebml_SerializeFloat(&ebml_writer_, FrameRate, fps);
+        } EndSubElement();  // Video
+      } EndSubElement();  // TrackEntry
+    } EndSubElement();  // Tracks
+
+    StartSubElement(Cluster); {
+      Ebml_SerializeUnsigned(&ebml_writer_, Timecode, 0);
+    }  // Cluster left open.
+  }  // Segment left open.
+
+  return true;
+}
+
+void WebmEncoder::WriteWebmBlock(const vpx_codec_cx_pkt_t* packet) {
+  bool is_keyframe = packet->data.frame.flags & VPX_FRAME_IS_KEY;
+  int64_t pts_ms = 1000 * packet->data.frame.pts * fps_.den / fps_.num;
+
+  DVLOG(1) << "Video packet @" << pts_ms << " ms "
+           << packet->data.frame.sz << " bytes "
+           << (is_keyframe ? "K" : "");
+
+  Ebml_WriteID(&ebml_writer_, SimpleBlock);
+
+  uint32 block_length = (packet->data.frame.sz + 4) | 0x10000000;
+  EbmlSerializeHelper(&block_length, 4);
+
+  uint8 track_number = 1 | 0x80;
+  EbmlSerializeHelper(&track_number, 1);
+
+  EbmlSerializeHelper(&pts_ms, 2);
+
+  uint8 flags = 0;
+  if (is_keyframe)
+    flags |= 0x80;
+  if (packet->data.frame.flags & VPX_FRAME_IS_INVISIBLE)
+    flags |= 0x08;
+  EbmlSerializeHelper(&flags, 1);
+
+  EbmlWrite(packet->data.frame.buf, packet->data.frame.sz);
+}
+
+bool WebmEncoder::WriteWebmFooter() {
+  EndSubElement();  // Cluster
+  EndSubElement();  // Segment
+  DCHECK(ebml_sub_elements_.empty());
+  return file_util::CloseFile(output_);
+}
+
+void WebmEncoder::StartSubElement(unsigned long class_id) {
+  Ebml_WriteID(&ebml_writer_, class_id);
+  ebml_sub_elements_.push(ftell(output_));
+  static const uint64_t kUnknownLen = 0x01FFFFFFFFFFFFFFLLU;
+  EbmlSerializeHelper(&kUnknownLen, 8);
+}
+
+void WebmEncoder::EndSubElement() {
+  DCHECK(!ebml_sub_elements_.empty());
+
+  long int end_pos = ftell(output_);
+  long int start_pos = ebml_sub_elements_.top();
+  ebml_sub_elements_.pop();
+
+  uint64_t size = (end_pos - start_pos - 8) | 0x0100000000000000ULL;
+  // Seek to the beginning of the sub-element and patch in the calculated size.
+  if (fseek(output_, start_pos, SEEK_SET))
+    LOG(ERROR) << "Error writing to " << output_path_.value();
+  EbmlSerializeHelper(&size, 8);
+
+  // Restore write position.
+  if (fseek(output_, end_pos, SEEK_SET))
+    LOG(ERROR) << "Error writing to " << output_path_.value();
+}
+
+void WebmEncoder::EbmlWrite(const void* buffer,
+                            unsigned long len) {
+  if (fwrite(buffer, 1, len, output_) != len)

[Nikita (slow), 2012/07/20 15:26:09]

Please flip error bit on WebmEncoder instance if fwrite / fseek fails for some
reason.

+    LOG(ERROR) << "Error writing to " << output_path_.value();
+}
+
+template <class T>
+void WebmEncoder::EbmlSerializeHelper(const T* buffer, unsigned long len) {
+  for (int i = len - 1; i >= 0; i--) {
+    uint8 c = *buffer >> (i * CHAR_BIT);
+    EbmlWrite(&c, 1);
+  }
+}
+
+void WebmEncoder::EbmlSerialize(const void* buffer,
+                                int buffer_size,
+                                unsigned long len) {
+  switch (buffer_size) {
+    case 1:
+      return EbmlSerializeHelper(static_cast<const int8_t*>(buffer), len);
+    case 2:
+      return EbmlSerializeHelper(static_cast<const int16_t*>(buffer), len);
+    case 4:
+      return EbmlSerializeHelper(static_cast<const int32_t*>(buffer), len);
+    case 8:
+      return EbmlSerializeHelper(static_cast<const int64_t*>(buffer), len);
+    default:
+      NOTREACHED() << "Invalid EbmlSerialize length: " << len;
+  }
+}
+
+}  // namespace chromeos
+
+}  // namespace media