Fix incorrect opus seek preroll and flaky pre-skip removal.

media/filters/opus_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/opus_audio_decoder.h"
 
 #include <cmath>
 
 #include "base/single_thread_task_runner.h"
 #include "base/sys_byteorder.h"
@@ skipping 227 matching lines @@
   if (extra_data->num_streams + extra_data->num_coupled != extra_data->channels)
     DVLOG(1) << "Inconsistent channel mapping.";
 
   for (int i = 0; i < extra_data->channels; ++i)
     extra_data->stream_map[i] = *(data + kOpusExtraDataStreamMapOffset + i);
   return true;
 }
 
 OpusAudioDecoder::OpusAudioDecoder(
     const scoped_refptr<base::SingleThreadTaskRunner>& task_runner)
-    : task_runner_(task_runner),
-      opus_decoder_(NULL),
-      start_input_timestamp_(kNoTimestamp()) {}
+    : task_runner_(task_runner), opus_decoder_(nullptr) {}
 
 std::string OpusAudioDecoder::GetDisplayName() const {
   return "OpusAudioDecoder";
 }
 
 void OpusAudioDecoder::Initialize(const AudioDecoderConfig& config,
                                   const InitCB& init_cb,
                                   const OutputCB& output_cb) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   InitCB bound_init_cb = BindToCurrentLoop(init_cb);
@@ skipping 25 matching lines @@
   task_runner_->PostTask(FROM_HERE, closure);
 }
 
 OpusAudioDecoder::~OpusAudioDecoder() {
   DCHECK(task_runner_->BelongsToCurrentThread());
 
   if (!opus_decoder_)
     return;
 
   opus_multistream_decoder_ctl(opus_decoder_, OPUS_RESET_STATE);
-  ResetTimestampState();
   CloseDecoder();
 }
 
 void OpusAudioDecoder::DecodeBuffer(
     const scoped_refptr<DecoderBuffer>& input,
     const DecodeCB& decode_cb) {
   DCHECK(task_runner_->BelongsToCurrentThread());
   DCHECK(!decode_cb.is_null());
   DCHECK(input.get());
 
   // Libopus does not buffer output. Decoding is complete when an end of stream
   // input buffer is received.
   if (input->end_of_stream()) {
     decode_cb.Run(kOk);
     return;
   }
 
   // Make sure we are notified if http://crbug.com/49709 returns.  Issue also
   // occurs with some damaged files.
   if (input->timestamp() == kNoTimestamp()) {
     DLOG(ERROR) << "Received a buffer without timestamps!";
     decode_cb.Run(kDecodeError);
     return;
   }
 
-  // Apply the necessary codec delay.
-  if (start_input_timestamp_ == kNoTimestamp())
-    start_input_timestamp_ = input->timestamp();
-  if (!discard_helper_->initialized() &&
-      input->timestamp() == start_input_timestamp_) {
-    discard_helper_->Reset(config_.codec_delay());
-  }
-
   scoped_refptr<AudioBuffer> output_buffer;
 
   if (!Decode(input, &output_buffer)) {
     decode_cb.Run(kDecodeError);
     return;
   }
 
   if (output_buffer.get()) {
     output_cb_.Run(output_buffer);
   }
@@ skipping 73 matching lines @@
   }
 
   status = opus_multistream_decoder_ctl(
       opus_decoder_, OPUS_SET_GAIN(opus_extra_data.gain_db));
   if (status != OPUS_OK) {
     DLOG(ERROR) << "Failed to set OPUS header gain; status="
                 << opus_strerror(status);
     return false;
   }
 
-  discard_helper_.reset(
-      new AudioDiscardHelper(config_.samples_per_second(), 0));
-  start_input_timestamp_ = kNoTimestamp();
+  ResetTimestampState();
   return true;
 }
 
 void OpusAudioDecoder::CloseDecoder() {
   if (opus_decoder_) {
     opus_multistream_decoder_destroy(opus_decoder_);
-    opus_decoder_ = NULL;
+    opus_decoder_ = nullptr;
   }
 }
 
 void OpusAudioDecoder::ResetTimestampState() {
-  discard_helper_->Reset(
-      discard_helper_->TimeDeltaToFrames(config_.seek_preroll()));
+  discard_helper_.reset(
+      new AudioDiscardHelper(config_.samples_per_second(), 0));
+  discard_helper_->Reset(config_.codec_delay());
 }
 
 bool OpusAudioDecoder::Decode(const scoped_refptr<DecoderBuffer>& input,
                               scoped_refptr<AudioBuffer>* output_buffer) {
   // Allocate a buffer for the output samples.
   *output_buffer = AudioBuffer::CreateBuffer(
       config_.sample_format(),
       config_.channel_layout(),
       ChannelLayoutToChannelCount(config_.channel_layout()),
       config_.samples_per_second(),
@@ skipping 23 matching lines @@
   }
 
   // Trim off any extraneous allocation.
   DCHECK_LE(frames_decoded, output_buffer->get()->frame_count());
   const int trim_frames = output_buffer->get()->frame_count() - frames_decoded;
   if (trim_frames > 0)
     output_buffer->get()->TrimEnd(trim_frames);
 
   // Handles discards and timestamping.  Discard the buffer if more data needed.
   if (!discard_helper_->ProcessBuffers(input, *output_buffer))
-    *output_buffer = NULL;
+    *output_buffer = nullptr;
 
   return true;
 }
 
 }  // namespace media