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

chrome/browser/chromeos/login/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 "chrome/browser/chromeos/login/webm_encoder.h"
+
+#include "base/bind.h"
+#include "base/file_util.h"
+#include "base/logging.h"
+#include "content/public/browser/browser_thread.h"
+#include "libyuv/convert.h"
+#include "libyuv/video_common.h"
+#include "third_party/skia/include/core/SkBitmap.h"
+#include "ui/gfx/image/image_skia.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
+}
+
+using content::BrowserThread;
+
+namespace {
+
+// Number of encoder threads to use.
+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.
+void Ebml_SerializeUnsigned32(EbmlGlobal *ebml,
+                              unsigned long class_id,
+                              uint64_t value) {
+  unsigned char 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);
+}
+
+}  // namespace
+
+namespace chromeos {
+
+WebmEncoder::WebmEncoder(const FilePath& output_path,
+                         unsigned 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));
+}
+
+void WebmEncoder::EncodeFromSprite(const SkBitmap& sprite,
+                                   int fps_n,
+                                   int fps_d) {
+  DCHECK(!sprite.isNull() && !sprite.empty());
+
+  width_ = sprite.width();
+  height_ = sprite.width();
+  fps_.num = fps_n;
+  fps_.den = fps_d;
+
+  size_t uv_stride = (width_ + 1) / 2;
+  size_t y_size = width_ * height_;
+  size_t uv_size = uv_stride * uv_stride;
+  size_t frame_size = y_size + 2 * uv_size;
+  size_t frame_count = sprite.height() / width_;  // Sprite is tiled vertically.
+
+  yuv_frame_.reset(new uint8[frame_size]);
+  uint8* y = yuv_frame_.get();
+  uint8* u = y + y_size;
+  uint8* v = y + y_size + uv_size;
+
+  vpx_image_t image;

[jkoleszar, 2012/07/17 18:33:34]

Can simplify this block to:

  vpx_img_wrap(&image, VPX_IMG_FMT_I420, width_, height_, 1, yuv_frame_.get())

[Ivan Korotkov, 2012/07/18 12:35:10]

Cool, thanks.

+  image.fmt = VPX_IMG_FMT_I420;
+  image.w = width_;
+  image.d_w = width_;
+  image.h = height_;
+  image.d_h = height_;
+  image.planes[VPX_PLANE_Y] = y;
+  image.stride[VPX_PLANE_Y] = width_;
+  image.planes[VPX_PLANE_U] = u;
+  image.stride[VPX_PLANE_U] = uv_stride;
+  image.planes[VPX_PLANE_V] = v;
+  image.stride[VPX_PLANE_V] = uv_stride;
+
+  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);
+  DCHECK_EQ(VPX_CODEC_OK, ret);
+
+  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;
+
+  WriteWebmHeader();
+
+  for (size_t frame = 0; frame < frame_count; ++frame) {
+    int res = libyuv::ConvertToI420(
+        src, src_frame_size,
+        y, width_,

[jkoleszar, 2012/07/17 18:33:34]

if you want, you can remove all these variables and knowledge of the yuv
internals (plane offsets, strides, etc) from this function by pulling the data
from the image descriptor set up by vpx_img_wrap()

[Ivan Korotkov, 2012/07/18 12:35:10]

Makes sense.

+        u, uv_stride,
+        v, uv_stride,
+        0, crop_y,                // src origin
+        width_, sprite.height(),  // src size
+        width_, height_,          // dest size
+        libyuv::kRotate0,
+        libyuv::FOURCC_ARGB);
+    DCHECK_EQ(0, res);
+    crop_y += height_;
+
+    ret = vpx_codec_encode(&codec, &image, frame, 1, 0, deadline_);
+    DCHECK_EQ(VPX_CODEC_OK, ret);
+
+    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);
+    }
+  }
+
+  vpx_codec_destroy(&codec);
+
+  WriteWebmFooter();
+}
+
+void WebmEncoder::WriteWebmHeader() {
+  output_ = file_util::OpenFile(output_path_, "wb");
+  DCHECK(output_);
+
+  // Global header.
+  StartSubElement(EBML); {
+    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.
+}
+
+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 *
+      static_cast<uint64_t>(fps_.den) / fps_.num * packet->data.frame.pts;

[jkoleszar, 2012/07/17 18:33:34]

multiply by pts before the divide.

[Ivan Korotkov, 2012/07/18 12:35:10]

Done.

+
+  DVLOG(1) << "Video packet @" << pts_ms << " ms "
+           << packet->data.frame.sz << " bytes "
+           << (is_keyframe ? "K" : "");
+
+  Ebml_WriteID(&ebml_writer_, SimpleBlock);
+
+  unsigned long block_length = (packet->data.frame.sz + 4) | 0x10000000;
+  EbmlSerializeHelper(&block_length, 4);
+
+  unsigned char track_number = 1 | 0x80;
+  EbmlSerializeHelper(&track_number, 1);
+
+  EbmlSerializeHelper(&pts_ms, 2);
+
+  unsigned char 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);
+}
+
+void WebmEncoder::WriteWebmFooter() {
+  EndSubElement();  // Cluster
+  EndSubElement();  // Segment
+  DCHECK(ebml_sub_elements_.empty());
+  file_util::CloseFile(output_);
+}
+
+void WebmEncoder::StartSubElement(unsigned long class_id) {
+  Ebml_WriteID(&ebml_writer_, class_id);
+  ebml_sub_elements_.push(ftell(output_));
+  uint64_t unknown_len = 0x01FFFFFFFFFFFFFFLLU;
+  Ebml_Serialize(&ebml_writer_, &unknown_len, sizeof(unknown_len), 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.
+  fseek(output_, start_pos, SEEK_SET);
+  EbmlSerializeHelper(&size, 8);
+
+  // Restore write position.
+  fseek(output_, end_pos, SEEK_SET);
+}
+
+void WebmEncoder::EbmlWrite(const void* buffer,
+                            unsigned long len) {
+  unsigned long ret = fwrite(buffer, 1, len, output_);
+  CHECK_EQ(len, ret);
+}
+
+template <class T>
+void WebmEncoder::EbmlSerializeHelper(const T* buffer, unsigned long len) {
+  for (unsigned long i = len; i-- > 0; ) {
+    char 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();
+  }
+}
+
+}  // namespace chromeos