Android: enable H264&VP8 HW accelerator for MediaRecorder

media/ffmpeg/ffmpeg_common.cc

Index: media/ffmpeg/ffmpeg_common.cc
diff --git a/media/ffmpeg/ffmpeg_common.cc b/media/ffmpeg/ffmpeg_common.cc
index 950b9c0fd103672103d65048a7ad47ab48b89ee7..a241e0491bffc8f5b8ee35073dca92e858d55916 100644
--- a/media/ffmpeg/ffmpeg_common.cc
+++ b/media/ffmpeg/ffmpeg_common.cc
@@ -506,10 +506,13 @@ bool AVStreamToVideoDecoderConfig(const AVStream* stream,
       coded_size.set_height((coded_size.height() + 1) / 2 * 2);
   }
 
-  AVDictionaryEntry* webm_alpha =
-      av_dict_get(stream->metadata, "alpha_mode", nullptr, 0);
-  if (webm_alpha && !strcmp(webm_alpha->value, "1")) {
-    format = PIXEL_FORMAT_YV12A;
+  // H264 doesn't support alpha mode.
+  if (codec != kCodecH264) {

[emircan, 2017/04/07 17:33:04]

Why is this necessary? Is there problem with playing alpha?

[braveyao, 2017/04/08 00:56:26]

Yes there is problem with playing back H264 recording since HW H264 doesn't
support alpha and there is no SW H264 to fallback.
And according to the developer, alpha mode here is only for WebM/VPx.

[emircan, 2017/04/10 21:18:09]

Alpha recording would only happen for WebM/VPx as well, see VPX recorder
changes. There is no alpha recording for H264 right now, it will be dropped.
What is the exact problem with H264 playback here?

[braveyao, 2017/04/14 22:28:28]

I don't understand your concern here.
Since HW H264 doesn't support alpha, it will fail to decode when ffmpeg_demuxer
asks for PIXEL_FORMAT_YV12A during playing back H264 recording.
Also, gpu_video_decoder([1]) will reject the decoding request because of it.
[1]:
https://cs.chromium.org/chromium/src/media/filters/gpu_video_decoder.cc?dr=CS...

[emircan, 2017/04/17 17:24:06]

Note: This issue was resolved on https://codereview.chromium.org/2815303005/.

[braveyao, 2017/04/17 18:09:27]

Acknowledged.

+    AVDictionaryEntry* webm_alpha =
+        av_dict_get(stream->metadata, "alpha_mode", nullptr, 0);
+    if (webm_alpha && !strcmp(webm_alpha->value, "1")) {
+      format = PIXEL_FORMAT_YV12A;
+    }
   }
 
   // Prefer the color space found by libavcodec if available.