Fix seeking when the start time is non-zero.

media/filters/ffmpeg_audio_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_audio_decoder.h"
 
 #include "base/callback_helpers.h"
 #include "base/single_thread_task_runner.h"
 #include "media/base/audio_buffer.h"
 #include "media/base/audio_bus.h"
@@ skipping 243 matching lines @@
   //     Any time Reset() is called.
 
   // Make sure we are notified if http://crbug.com/49709 returns.  Issue also
   // occurs with some damaged files.
   if (!buffer->end_of_stream() && buffer->timestamp() == kNoTimestamp()) {
     DVLOG(1) << "Received a buffer without timestamps!";
     decode_cb.Run(kDecodeError, NULL);
     return;
   }
 
-  if (!buffer->end_of_stream() && !discard_helper_->initialized() &&

[acolwell GONE FROM CHROMIUM, 2014/06/10 23:20:38]

with your changes to the demuxer, can we DCHECK(buffer->timestamp() >=
base::TimeDelta() now just to make sure negative values can't sneak in anymore.

[DaleCurtis, 2014/06/11 16:59:07]

Should be okay. I'll have to test though.

[DaleCurtis, 2014/06/12 00:21:55]

I've added the DCHECK to the demuxer.  However, it exposed some issues with how
FFmpeg is setting start_time during MP3 demuxing.  It seems wrong, so I've
pinged upstream.  With a local patch things seem to pass nicely.

-      codec_context_->codec_id == AV_CODEC_ID_VORBIS &&
-      buffer->timestamp() < base::TimeDelta()) {
-    // Dropping frames for negative timestamps as outlined in section A.2
-    // in the Vorbis spec. http://xiph.org/vorbis/doc/Vorbis_I_spec.html
-    const int discard_frames =
-        discard_helper_->TimeDeltaToFrames(-buffer->timestamp());
-    discard_helper_->Reset(discard_frames);
-  }
-
   // Transition to kFlushCodec on the first end of stream buffer.
   if (state_ == kNormal && buffer->end_of_stream()) {
     state_ = kFlushCodec;
   }
 
   if (!FFmpegDecode(buffer)) {
     state_ = kError;
     decode_cb.Run(kDecodeError, NULL);
     return;
   }
@@ skipping 169 matching lines @@
 
   ResetTimestampState();
   return true;
 }
 
 void FFmpegAudioDecoder::ResetTimestampState() {
   discard_helper_->Reset(config_.codec_delay());
 }
 
 }  // namespace media