Merge 21935 - Fixes an audio playback regression caused by seeking in audio/v...

media/filters/audio_renderer_base.cc

 // Copyright (c) 2009 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 <algorithm>
+
 #include "media/base/filter_host.h"
 #include "media/filters/audio_renderer_base.h"
 
 namespace media {
 
 // The maximum size of the queue, which also acts as the number of initial reads
 // to perform for buffering.  The size of the queue should never exceed this
 // number since we read only after we've dequeued and released a buffer in
 // callback thread.
 //
@@ skipping 122 matching lines @@
   size_t dest_written = 0;
 
   // The timestamp of the last buffer written during the last call to
   // FillBuffer().
   base::TimeDelta last_fill_buffer_time;
   {
     AutoLock auto_lock(lock_);
 
     // Mute audio by returning 0 when not playing.
     if (state_ != kPlaying) {
-      return 0;
+      // TODO(scherkus): To keep the audio hardware busy we write at most 8k of
+      // zeros.  This gets around the tricky situation of pausing and resuming
+      // the audio IPC layer in Chrome.  Ideally, we should return zero and then
+      // the subclass can restart the conversation.
+      const size_t kZeroLength = 8192;
+      dest_written = std::min(kZeroLength, dest_len);
+      memset(dest, 0, dest_written);
+      return dest_written;
     }
 
     // Save a local copy of last fill buffer time and reset the member.
     last_fill_buffer_time = last_fill_buffer_time_;
     last_fill_buffer_time_ = base::TimeDelta();
 
     // Loop until the buffer has been filled.
     while (dest_len > 0 && !queue_.empty()) {
       scoped_refptr<Buffer> buffer = queue_.front();
 
@@ skipping 105 matching lines @@
   // TODO(scherkus): might be handy to support NULL parameters.
   std::string mime_type;
   return media_format.GetAsString(MediaFormat::kMimeType, &mime_type) &&
       media_format.GetAsInteger(MediaFormat::kChannels, channels_out) &&
       media_format.GetAsInteger(MediaFormat::kSampleRate, sample_rate_out) &&
       media_format.GetAsInteger(MediaFormat::kSampleBits, sample_bits_out) &&
       mime_type.compare(mime_type::kUncompressedAudio) == 0;
 }
 
 }  // namespace media