media: Add support for playback of VP8 Alpha video streams

media/filters/vpx_video_decoder.cc

Index: media/filters/vpx_video_decoder.cc
diff --git a/media/filters/vpx_video_decoder.cc b/media/filters/vpx_video_decoder.cc
index 0b92a7d8459c4e152bbd7261b56ce7dcc1c32ffe..76054eb1cbd26dd087782f94c606c9f119c4280e 100644
--- a/media/filters/vpx_video_decoder.cc
+++ b/media/filters/vpx_video_decoder.cc
@@ -11,6 +11,7 @@
 #include "base/logging.h"
 #include "base/message_loop_proxy.h"
 #include "base/string_number_conversions.h"
+#include "base/sys_byteorder.h"
 #include "media/base/bind_to_loop.h"
 #include "media/base/decoder_buffer.h"
 #include "media/base/demuxer_stream.h"
@@ -20,15 +21,6 @@
 #include "media/base/video_frame.h"
 #include "media/base/video_util.h"
 
-// Include libvpx header files.
-// VPX_CODEC_DISABLE_COMPAT excludes parts of the libvpx API that provide
-// backwards compatibility for legacy applications using the library.
-#define VPX_CODEC_DISABLE_COMPAT 1
-extern "C" {
-#include "third_party/libvpx/source/libvpx/vpx/vpx_decoder.h"
-#include "third_party/libvpx/source/libvpx/vpx/vp8dx.h"
-}
-
 namespace media {
 
 // Always try to use three threads for video decoding.  There is little reason
@@ -58,13 +50,11 @@ static int GetThreadCount() {
 VpxVideoDecoder::VpxVideoDecoder(
     const scoped_refptr<base::MessageLoopProxy>& message_loop)
     : message_loop_(message_loop),
-      state_(kUninitialized),
-      vpx_codec_(NULL) {
+      state_(kUninitialized) {
 }
 
 VpxVideoDecoder::~VpxVideoDecoder() {
   DCHECK_EQ(kUninitialized, state_);
-  CloseDecoder();
 }
 
 void VpxVideoDecoder::Initialize(
@@ -92,45 +82,60 @@ void VpxVideoDecoder::Initialize(
   status_cb.Run(PIPELINE_OK);
 }
 
-bool VpxVideoDecoder::ConfigureDecoder() {
-  const VideoDecoderConfig& config = demuxer_stream_->video_decoder_config();
-  if (!config.IsValidConfig()) {
-    DLOG(ERROR) << "Invalid video stream config: "
-                << config.AsHumanReadableString();
-    return false;
-  }
-
-  if (config.codec() != kCodecVP9)
-    return false;
-
-  CloseDecoder();
-
-  vpx_codec_ = new vpx_codec_ctx();
+static scoped_ptr<vpx_codec_ctx, VpxDeleter> InitializeVpxContext(
+    scoped_ptr<vpx_codec_ctx, VpxDeleter> context,
+    const VideoDecoderConfig& config) {
+  context.reset(new vpx_codec_ctx());
   vpx_codec_dec_cfg_t vpx_config = {0};
   vpx_config.w = config.coded_size().width();
   vpx_config.h = config.coded_size().height();
   vpx_config.threads = GetThreadCount();
 
-  vpx_codec_err_t status = vpx_codec_dec_init(vpx_codec_,
-                                              vpx_codec_vp9_dx(),
+  vpx_codec_err_t status = vpx_codec_dec_init(context.get(),
+                                              config.codec() == kCodecVP9 ?
+                                                  vpx_codec_vp9_dx() :
+                                                  vpx_codec_vp8_dx(),
                                               &vpx_config,
                                               0);
   if (status != VPX_CODEC_OK) {
     LOG(ERROR) << "vpx_codec_dec_init failed, status=" << status;
-    delete vpx_codec_;
-    vpx_codec_ = NULL;
+    context.reset();
+  }
+  return context.Pass();
+}
+
+bool VpxVideoDecoder::ConfigureDecoder() {
+  const VideoDecoderConfig& config = demuxer_stream_->video_decoder_config();
+  if (!config.IsValidConfig()) {
+    DLOG(ERROR) << "Invalid video stream config: "
+                << config.AsHumanReadableString();
     return false;
   }
 
-  return true;
-}
+  const CommandLine* cmd_line = CommandLine::ForCurrentProcess();
+  bool can_handle = false;
+  if (cmd_line->HasSwitch(switches::kEnableVp9Playback) &&
+      config.codec() == kCodecVP9) {
+    can_handle = true;
+  }
+  if (cmd_line->HasSwitch(switches::kEnableVp8AlphaPlayback) &&
+      config.codec() == kCodecVP8 && config.format() == VideoFrame::YV12A) {
+    can_handle = true;
+  }
+  if (!can_handle)
+    return false;
+
+  vpx_codec_ = InitializeVpxContext(vpx_codec_.Pass(), config);
+  if (!vpx_codec_.get())
+    return false;
 
-void VpxVideoDecoder::CloseDecoder() {
-  if (vpx_codec_) {
-    vpx_codec_destroy(vpx_codec_);
-    delete vpx_codec_;
-    vpx_codec_ = NULL;
+  if (config.format() == VideoFrame::YV12A) {
+    vpx_codec_alpha_ = InitializeVpxContext(vpx_codec_alpha_.Pass(), config);
+    if (!vpx_codec_alpha_.get())
+      return false;
   }
+
+  return true;
 }
 
 void VpxVideoDecoder::Read(const ReadCB& read_cb) {
@@ -246,7 +251,7 @@ void VpxVideoDecoder::DecodeBuffer(
   }
 
   // Any successful decode counts!
-  if (buffer->GetDataSize()) {
+  if (buffer->GetDataSize() && buffer->GetSideDataSize()) {
     PipelineStatistics statistics;
     statistics.video_bytes_decoded = buffer->GetDataSize();
     statistics_cb_.Run(statistics);
@@ -270,7 +275,7 @@ bool VpxVideoDecoder::Decode(
   // Pass |buffer| to libvpx.
   int64 timestamp = buffer->GetTimestamp().InMicroseconds();
   void* user_priv = reinterpret_cast<void*>(&timestamp);
-  vpx_codec_err_t status = vpx_codec_decode(vpx_codec_,
+  vpx_codec_err_t status = vpx_codec_decode(vpx_codec_.get(),
                                             buffer->GetData(),
                                             buffer->GetDataSize(),
                                             user_priv,
@@ -282,7 +287,7 @@ bool VpxVideoDecoder::Decode(
 
   // Gets pointer to decoded data.
   vpx_codec_iter_t iter = NULL;
-  const vpx_image_t* vpx_image = vpx_codec_get_frame(vpx_codec_, &iter);
+  const vpx_image_t* vpx_image = vpx_codec_get_frame(vpx_codec_.get(), &iter);
   if (!vpx_image) {
     *video_frame = NULL;
     return true;
@@ -293,7 +298,45 @@ bool VpxVideoDecoder::Decode(
     return false;
   }
 
-  CopyVpxImageTo(vpx_image, video_frame);
+  const vpx_image_t* vpx_image_alpha = NULL;
+  if (vpx_codec_alpha_.get() && buffer->GetSideDataSize() >= 8) {
+    // Pass alpha data to libvpx.
+    int64 timestamp_alpha = buffer->GetTimestamp().InMicroseconds();
+    void* user_priv_alpha = reinterpret_cast<void*>(&timestamp_alpha);
+
+    // First 8 bytes of side data is side_data_id in big endian.
+    const uint64 side_data_id = base::NetToHost64(
+        *(reinterpret_cast<const uint64*>(buffer->GetSideData())));
+    if (side_data_id == 1) {
+      status = vpx_codec_decode(vpx_codec_alpha_.get(),
+                                buffer->GetSideData() + 8,
+                                buffer->GetSideDataSize() - 8,
+                                user_priv_alpha,
+                                0);
+
+      if (status != VPX_CODEC_OK) {
+        LOG(ERROR) << "vpx_codec_decode() failed on alpha, status=" << status;
+        return false;
+      }
+
+      // Gets pointer to decoded data.
+      vpx_codec_iter_t iter_alpha = NULL;
+      vpx_image_alpha = vpx_codec_get_frame(vpx_codec_alpha_.get(),
+                                            &iter_alpha);
+      if (!vpx_image_alpha) {
+        *video_frame = NULL;
+        return true;
+      }
+
+      if (vpx_image_alpha->user_priv !=
+          reinterpret_cast<void*>(&timestamp_alpha)) {
+        LOG(ERROR) << "Invalid output timestamp on alpha.";
+        return false;
+      }
+    }
+  }
+
+  CopyVpxImageTo(vpx_image, vpx_image_alpha, video_frame);
   (*video_frame)->SetTimestamp(base::TimeDelta::FromMicroseconds(timestamp));
   return true;
 }
@@ -307,7 +350,8 @@ void VpxVideoDecoder::DoReset() {
 }
 
 void VpxVideoDecoder::CopyVpxImageTo(
-    const vpx_image* vpx_image,
+    const struct vpx_image* vpx_image,
+    const struct vpx_image* vpx_image_alpha,
     scoped_refptr<VideoFrame>* video_frame) {
   CHECK(vpx_image);
   CHECK_EQ(vpx_image->d_w % 2, 0U);
@@ -319,11 +363,14 @@ void VpxVideoDecoder::CopyVpxImageTo(
   gfx::Size natural_size =
       demuxer_stream_->video_decoder_config().natural_size();
 
-  *video_frame = VideoFrame::CreateFrame(VideoFrame::YV12,
+  *video_frame = VideoFrame::CreateFrame(vpx_codec_alpha_.get() ?
+                                             VideoFrame::YV12A :
+                                             VideoFrame::YV12,
                                          size,
                                          gfx::Rect(size),
                                          natural_size,
                                          kNoTimestamp());
+
   CopyYPlane(vpx_image->planes[VPX_PLANE_Y],
              vpx_image->stride[VPX_PLANE_Y],
              vpx_image->d_h,
@@ -336,6 +383,17 @@ void VpxVideoDecoder::CopyVpxImageTo(
              vpx_image->stride[VPX_PLANE_V],
              vpx_image->d_h / 2,
              *video_frame);
+  if (!vpx_codec_alpha_.get())
+    return;
+  if (!vpx_image_alpha) {
+    MakeOpaqueAPlane(vpx_image->stride[VPX_PLANE_Y], vpx_image->d_h,
+                     *video_frame);
+    return;
+  }
+  CopyAPlane(vpx_image_alpha->planes[VPX_PLANE_Y],
+             vpx_image->stride[VPX_PLANE_Y],
+             vpx_image->d_h,
+             *video_frame);
 }
 
 }  // namespace media