Enable pcm_s32le audio decoding.

To accomodate this change, a new kSampleFormatS24 has been introduced.
It is only used with S24LE PCM input. FFmpeg treats pcm_s24le as an
encoded format that can be decoded into s32le samples; kSampleFormatS24
only exists on the Chrome side to distinguish FFmpeg's pcm_s24le from
pcm_s32le, both of which use Chrome's catch-all kCodecPCM codec and
the same real sample format.

BUG=557170,internal b/22378279
TEST=media_unittests --gtest_filter=AudioBufferTest.*
media_unittests --gtest_filter=PipelineIntegrationTest.S32PlaybackHashed

Review URL: https://codereview.chromium.org/1422113002

Cr-Commit-Position: refs/heads/master@{#361545}

3 files changed, 32 insertions, 16 deletions

diff --git a/media/ffmpeg/ffmpeg_common.cc b/media/ffmpeg/ffmpeg_common.cc
index c9d8669..772b41d 100644
--- a/media/ffmpeg/ffmpeg_common.cc
+++ b/media/ffmpeg/ffmpeg_common.cc
@@ -74,6 +74,7 @@ static AudioCodec CodecIDToAudioCodec(AVCodecID codec_id) {
     case AV_CODEC_ID_PCM_U8:
     case AV_CODEC_ID_PCM_S16LE:
     case AV_CODEC_ID_PCM_S24LE:
+    case AV_CODEC_ID_PCM_S32LE:
     case AV_CODEC_ID_PCM_F32LE:
       return kCodecPCM;
     case AV_CODEC_ID_PCM_S16BE:
@@ -117,8 +118,10 @@ static AVCodecID AudioCodecToCodecID(AudioCodec audio_codec,
           return AV_CODEC_ID_PCM_U8;
         case kSampleFormatS16:
           return AV_CODEC_ID_PCM_S16LE;
-        case kSampleFormatS32:
+        case kSampleFormatS24:
           return AV_CODEC_ID_PCM_S24LE;
+        case kSampleFormatS32:
+          return AV_CODEC_ID_PCM_S32LE;
         case kSampleFormatF32:
           return AV_CODEC_ID_PCM_F32LE;
         default:
@@ -244,14 +247,18 @@ static int VideoCodecProfileToProfileID(VideoCodecProfile profile) {
   return FF_PROFILE_UNKNOWN;
 }
 
-SampleFormat AVSampleFormatToSampleFormat(AVSampleFormat sample_format) {
+SampleFormat AVSampleFormatToSampleFormat(AVSampleFormat sample_format,
+                                          AVCodecID codec_id) {
   switch (sample_format) {
     case AV_SAMPLE_FMT_U8:
       return kSampleFormatU8;
     case AV_SAMPLE_FMT_S16:
       return kSampleFormatS16;
     case AV_SAMPLE_FMT_S32:
-      return kSampleFormatS32;
+      if (codec_id == AV_CODEC_ID_PCM_S24LE)
+        return kSampleFormatS24;
+      else
+        return kSampleFormatS32;
     case AV_SAMPLE_FMT_FLT:
       return kSampleFormatF32;
     case AV_SAMPLE_FMT_S16P:
@@ -272,6 +279,8 @@ static AVSampleFormat SampleFormatToAVSampleFormat(SampleFormat sample_format) {
       return AV_SAMPLE_FMT_U8;
     case kSampleFormatS16:
       return AV_SAMPLE_FMT_S16;
+    // pcm_s24le is treated as a codec with sample format s32 in ffmpeg
+    case kSampleFormatS24:
     case kSampleFormatS32:
       return AV_SAMPLE_FMT_S32;
     case kSampleFormatF32:
@@ -293,8 +302,8 @@ bool AVCodecContextToAudioDecoderConfig(const AVCodecContext* codec_context,
 
   AudioCodec codec = CodecIDToAudioCodec(codec_context->codec_id);
 
-  SampleFormat sample_format =
-      AVSampleFormatToSampleFormat(codec_context->sample_fmt);
+  SampleFormat sample_format = AVSampleFormatToSampleFormat(
+      codec_context->sample_fmt, codec_context->codec_id);
 
   ChannelLayout channel_layout = ChannelLayoutToChromeChannelLayout(
       codec_context->channel_layout, codec_context->channels);
diff --git a/media/ffmpeg/ffmpeg_common.h b/media/ffmpeg/ffmpeg_common.h
index 7938a32..955ee64 100644
--- a/media/ffmpeg/ffmpeg_common.h
+++ b/media/ffmpeg/ffmpeg_common.h
@@ -123,7 +123,7 @@ MEDIA_EXPORT AVCodecID VideoCodecToCodecID(VideoCodec video_codec);
 
 // Converts FFmpeg's audio sample format to Chrome's SampleFormat.
 MEDIA_EXPORT SampleFormat
-AVSampleFormatToSampleFormat(AVSampleFormat sample_format);
+AVSampleFormatToSampleFormat(AVSampleFormat sample_format, AVCodecID codec_id);
 
 // Converts FFmpeg's pixel formats to its corresponding supported video format.
 MEDIA_EXPORT VideoPixelFormat
diff --git a/media/ffmpeg/ffmpeg_common_unittest.cc b/media/ffmpeg/ffmpeg_common_unittest.cc
index aa8a06d..9a73587 100644
--- a/media/ffmpeg/ffmpeg_common_unittest.cc
+++ b/media/ffmpeg/ffmpeg_common_unittest.cc
@@ -161,17 +161,24 @@ TEST_F(FFmpegCommonTest, VerifyFormatSizes) {
   for (AVSampleFormat format = AV_SAMPLE_FMT_NONE;
        format < AV_SAMPLE_FMT_NB;
        format = static_cast<AVSampleFormat>(format + 1)) {
-    SampleFormat sample_format = AVSampleFormatToSampleFormat(format);
-    if (sample_format == kUnknownSampleFormat) {
-      // This format not supported, so skip it.
-      continue;
+    std::vector<AVCodecID> codec_ids(1, AV_CODEC_ID_NONE);
+    if (format == AV_SAMPLE_FMT_S32)
+      codec_ids.push_back(AV_CODEC_ID_PCM_S24LE);
+    for (const auto& codec_id : codec_ids) {
+      SampleFormat sample_format =
+          AVSampleFormatToSampleFormat(format, codec_id);
+      if (sample_format == kUnknownSampleFormat) {
+        // This format not supported, so skip it.
+        continue;
+      }
+
+      // Have FFMpeg compute the size of a buffer of 1 channel / 1 frame
+      // with 1 byte alignment to make sure the sizes match.
+      int single_buffer_size =
+          av_samples_get_buffer_size(NULL, 1, 1, format, 1);
+      int bytes_per_channel = SampleFormatToBytesPerChannel(sample_format);
+      EXPECT_EQ(bytes_per_channel, single_buffer_size);
     }
-
-    // Have FFMpeg compute the size of a buffer of 1 channel / 1 frame
-    // with 1 byte alignment to make sure the sizes match.
-    int single_buffer_size = av_samples_get_buffer_size(NULL, 1, 1, format, 1);
-    int bytes_per_channel = SampleFormatToBytesPerChannel(sample_format);
-    EXPECT_EQ(bytes_per_channel, single_buffer_size);
   }
 }