Add callback in VideoDecoder and AudioDecoder to return decoded frames.

media/filters/ffmpeg_video_decoder.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/filters/ffmpeg_video_decoder.h"
 
 #include <algorithm>
 #include <string>
 
 #include "base/bind.h"
@@ skipping 117 matching lines @@
   video_frame.swap(reinterpret_cast<VideoFrame**>(&frame->opaque));
 
   // The FFmpeg API expects us to zero the data pointers in
   // this callback
   memset(frame->data, 0, sizeof(frame->data));
   frame->opaque = NULL;
 }
 
 void FFmpegVideoDecoder::Initialize(const VideoDecoderConfig& config,
                                     bool low_delay,
-                                    const PipelineStatusCB& status_cb) {
+                                    const PipelineStatusCB& status_cb,
+                                    const OutputCB& output_cb) {
   DCHECK(task_runner_->BelongsToCurrentThread());
-  DCHECK(decode_cb_.is_null());
   DCHECK(!config.is_encrypted());
+  DCHECK(!output_cb.is_null());
 
   FFmpegGlue::InitializeFFmpeg();
 
   config_ = config;
   PipelineStatusCB initialize_cb = BindToCurrentLoop(status_cb);
 
   if (!config.IsValidConfig() || !ConfigureDecoder(low_delay)) {
     initialize_cb.Run(DECODER_ERROR_NOT_SUPPORTED);
     return;
   }
 
+  output_cb_ = BindToCurrentLoop(output_cb);
+
   // Success!
   state_ = kNormal;
   initialize_cb.Run(PIPELINE_OK);
 }
 
 void FFmpegVideoDecoder::Decode(const scoped_refptr<DecoderBuffer>& buffer,
                                 const DecodeCB& decode_cb) {
   DCHECK(task_runner_->BelongsToCurrentThread());
+  DCHECK(buffer);
   DCHECK(!decode_cb.is_null());
   CHECK_NE(state_, kUninitialized);
-  CHECK(decode_cb_.is_null()) << "Overlapping decodes are not supported.";
-  decode_cb_ = BindToCurrentLoop(decode_cb);
+
+  DecodeCB decode_cb_bound = BindToCurrentLoop(decode_cb);
 
   if (state_ == kError) {
-    base::ResetAndReturn(&decode_cb_).Run(kDecodeError, NULL);
+    decode_cb_bound.Run(kDecodeError);
     return;
   }
 
   // Return empty frames if decoding has finished.
   if (state_ == kDecodeFinished) {
-    base::ResetAndReturn(&decode_cb_).Run(kOk, VideoFrame::CreateEOSFrame());
+    output_cb_.Run(VideoFrame::CreateEOSFrame());
+    decode_cb_bound.Run(kOk);
     return;
   }
 
-  DecodeBuffer(buffer);
-}
-
-void FFmpegVideoDecoder::Reset(const base::Closure& closure) {
-  DCHECK(task_runner_->BelongsToCurrentThread());
-  DCHECK(decode_cb_.is_null());
-
-  avcodec_flush_buffers(codec_context_.get());
-  state_ = kNormal;
-  task_runner_->PostTask(FROM_HERE, closure);
-}
-
-void FFmpegVideoDecoder::Stop() {
-  DCHECK(task_runner_->BelongsToCurrentThread());
-
-  if (state_ == kUninitialized)
-    return;
-
-  ReleaseFFmpegResources();
-  state_ = kUninitialized;
-}
-
-FFmpegVideoDecoder::~FFmpegVideoDecoder() {
-  DCHECK_EQ(kUninitialized, state_);
-  DCHECK(!codec_context_);
-  DCHECK(!av_frame_);
-}
-
-void FFmpegVideoDecoder::DecodeBuffer(
-    const scoped_refptr<DecoderBuffer>& buffer) {
-  DCHECK(task_runner_->BelongsToCurrentThread());
-  DCHECK_NE(state_, kUninitialized);
-  DCHECK_NE(state_, kDecodeFinished);
-  DCHECK_NE(state_, kError);
-  DCHECK(!decode_cb_.is_null());
-  DCHECK(buffer);
+  DCHECK_EQ(state_, kNormal);
 
   // During decode, because reads are issued asynchronously, it is possible to
   // receive multiple end of stream buffers since each decode is acked. When the
   // first end of stream buffer is read, FFmpeg may still have frames queued
   // up in the decoder so we need to go through the decode loop until it stops
   // giving sensible data.  After that, the decoder should output empty
   // frames.  There are three states the decoder can be in:
   //
   //   kNormal: This is the starting state. Buffers are decoded. Decode errors
   //            are discarded.
   //   kFlushCodec: There isn't any more input data. Call avcodec_decode_video2
   //                until no more data is returned to flush out remaining
   //                frames. The input buffer is ignored at this point.
   //   kDecodeFinished: All calls return empty frames.
   //   kError: Unexpected error happened.
   //
   // These are the possible state transitions.
   //
-  // kNormal -> kFlushCodec:
-  //     When buffer->end_of_stream() is first true.
+  // kNormal -> kDecodeFinished:
+  //     When EOS buffer is received.
   // kNormal -> kError:
   //     A decoding error occurs and decoding needs to stop.
-  // kFlushCodec -> kDecodeFinished:
-  //     When avcodec_decode_video2() returns 0 data.
-  // kFlushCodec -> kError:
-  //     When avcodec_decode_video2() errors out.
   // (any state) -> kNormal:
   //     Any time Reset() is called.
 
-  // Transition to kFlushCodec on the first end of stream buffer.
-  if (state_ == kNormal && buffer->end_of_stream()) {
-    state_ = kFlushCodec;
+  // Flush the decoder after receiving EOS buffer.
+  if (buffer->end_of_stream()) {
+    scoped_refptr<VideoFrame> video_frame;
+    do {
+      if (!FFmpegDecode(buffer, &video_frame)) {
+        state_ = kError;
+        decode_cb_bound.Run(kDecodeError);
+        return;
+      }
+      if (video_frame)
+        output_cb_.Run(video_frame);
+    } while (video_frame);
+    output_cb_.Run(VideoFrame::CreateEOSFrame());
+    state_ = kDecodeFinished;
+  } else {
+    scoped_refptr<VideoFrame> video_frame;
+    if (!FFmpegDecode(buffer, &video_frame)) {
+      state_ = kError;
+      decode_cb_bound.Run(kDecodeError);
+      return;
+    }
+    if (video_frame)
+      output_cb_.Run(video_frame);

[xhwang, 2014/05/29 22:15:14]

You can probably wrap l.223-230 into a helper function since it's the same as
l.212-218.

[Sergey Ulanov, 2014/06/03 00:08:11]

Formatted this code to avoid duplication.

   }
 
-  scoped_refptr<VideoFrame> video_frame;
-  if (!FFmpegDecode(buffer, &video_frame)) {
-    state_ = kError;
-    base::ResetAndReturn(&decode_cb_).Run(kDecodeError, NULL);
+  decode_cb_bound.Run(kOk);
+}
+
+void FFmpegVideoDecoder::Reset(const base::Closure& closure) {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  avcodec_flush_buffers(codec_context_.get());
+  state_ = kNormal;
+  task_runner_->PostTask(FROM_HERE, closure);
+}
+
+void FFmpegVideoDecoder::Stop() {
+  DCHECK(task_runner_->BelongsToCurrentThread());
+
+  if (state_ == kUninitialized)
     return;
-  }
 
-  if (!video_frame.get()) {
-    if (state_ == kFlushCodec) {
-      DCHECK(buffer->end_of_stream());
-      state_ = kDecodeFinished;
-      base::ResetAndReturn(&decode_cb_)
-          .Run(kOk, VideoFrame::CreateEOSFrame());
-      return;
-    }
+  ReleaseFFmpegResources();
+  state_ = kUninitialized;
+}
 
-    base::ResetAndReturn(&decode_cb_).Run(kNotEnoughData, NULL);
-    return;
-  }
-
-  base::ResetAndReturn(&decode_cb_).Run(kOk, video_frame);
+FFmpegVideoDecoder::~FFmpegVideoDecoder() {
+  DCHECK_EQ(kUninitialized, state_);
+  DCHECK(!codec_context_);
+  DCHECK(!av_frame_);
 }
 
 bool FFmpegVideoDecoder::FFmpegDecode(
     const scoped_refptr<DecoderBuffer>& buffer,
     scoped_refptr<VideoFrame>* video_frame) {
   DCHECK(video_frame);
 
   // Reset frame to default values.
   avcodec_get_frame_defaults(av_frame_.get());
 
@@ skipping 87 matching lines @@
   if (!codec || avcodec_open2(codec_context_.get(), codec, NULL) < 0) {
     ReleaseFFmpegResources();
     return false;
   }
 
   av_frame_.reset(av_frame_alloc());
   return true;
 }
 
 }  // namespace media