Guard against midstream audio configuration changes.

media/filters/audio_file_reader.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/audio_file_reader.h"
 
 #include "base/logging.h"
 #include "base/time.h"
 #include "media/base/audio_bus.h"
 #include "media/ffmpeg/ffmpeg_common.h"
 #include "media/filters/ffmpeg_glue.h"
 
 namespace media {
 
 AudioFileReader::AudioFileReader(FFmpegURLProtocol* protocol)
     : codec_context_(NULL),
       stream_index_(0),
-      protocol_(protocol) {
+      protocol_(protocol),
+      channels_(0),
+      sample_rate_(0),
+      av_sample_format_(0) {
 }
 
 AudioFileReader::~AudioFileReader() {
   Close();
 }
 
-int AudioFileReader::channels() const {
-  return codec_context_->channels;
-}
-
-int AudioFileReader::sample_rate() const {
-  return codec_context_->sample_rate;
-}
-
 base::TimeDelta AudioFileReader::duration() const {
   const AVRational av_time_base = {1, AV_TIME_BASE};
 
   // Add one microsecond to avoid rounding-down errors which can occur when
   // |duration| has been calculated from an exact number of sample-frames.
   // One microsecond is much less than the time of a single sample-frame
   // at any real-world sample-rate.
   return ConvertFromTimeBase(
       av_time_base, glue_->format_context()->duration + 1);
 }
@@ skipping 60 matching lines @@
   }
 
   // Verify the channel layout is supported by Chrome.  Acts as a sanity check
   // against invalid files.  See http://crbug.com/171962
   if (ChannelLayoutToChromeChannelLayout(
           codec_context_->channel_layout, codec_context_->channels) ==
       CHANNEL_LAYOUT_UNSUPPORTED) {
     return false;
   }
 
+  // Store initial values to guard against mid-frame configuration changes.
+  channels_ = codec_context_->channels;
+  sample_rate_ = codec_context_->sample_rate;
+  av_sample_format_ = codec_context_->sample_fmt;
+
   return true;
 }
 
 void AudioFileReader::Close() {
   if (codec_context_) {
     avcodec_close(codec_context_);
     codec_context_ = NULL;
   }
 }
 
@@ skipping 49 matching lines @@
       if (!frame_decoded)
         continue;
 
       // Determine the number of sample-frames we just decoded.  Check overflow.
       int frames_read = av_frame->nb_samples;
       if (frames_read < 0) {
         continue_decoding = false;
         break;
       }
 
+      if (av_frame->sample_rate != sample_rate_ ||
+          av_frame->channels != channels_ ||
+          av_frame->format != av_sample_format_) {
+        DLOG(ERROR) << "Unsupported mid-frame configuration change!"

[scherkus (not reviewing), 2013/02/12 02:16:56]

consistent terminology nit: s/mid-frame/mid-stream/

[DaleCurtis, 2013/02/12 02:41:24]

Done.

+                    << " Sample Rate: " << av_frame->sample_rate << " vs "
+                    << sample_rate_
+                    << ", Channels: " << av_frame->channels << " vs "
+                    << channels_
+                    << ", Sample Format: " << av_frame->format << " vs "
+                    << av_sample_format_;
+
+        // This is an unrecoverable error, so bail out.
+        continue_decoding = false;
+        break;
+      }
+
       // Truncate, if necessary, if the destination isn't big enough.
       if (current_frame + frames_read > audio_bus->frames())
         frames_read = audio_bus->frames() - current_frame;
 
       // Deinterleave each channel and convert to 32bit floating-point with
       // nominal range -1.0 -> +1.0.  If the output is already in float planar
       // format, just copy it into the AudioBus.
       if (codec_context_->sample_fmt == AV_SAMPLE_FMT_FLT) {
         float* decoded_audio_data = reinterpret_cast<float*>(av_frame->data[0]);
         int channels = audio_bus->channels();
@@ skipping 22 matching lines @@
   // Zero any remaining frames.
   audio_bus->ZeroFramesPartial(
       current_frame, audio_bus->frames() - current_frame);
 
   // Returns the actual number of sample-frames decoded.
   // Ideally this represents the "true" exact length of the file.
   return current_frame;
 }
 
 }  // namespace media