Android: enable H264&VP8 HW accelerator for MediaRecorder

media/ffmpeg/ffmpeg_common.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/ffmpeg/ffmpeg_common.h"
 
 #include "base/logging.h"
 #include "base/sha1.h"
 #include "base/strings/string_number_conversions.h"
 #include "base/strings/string_split.h"
@@ skipping 488 matching lines @@
     coded_size = visible_rect.size();
   }
 
   // Pad out |coded_size| for subsampled YUV formats.
   if (format != PIXEL_FORMAT_YV24) {
     coded_size.set_width((coded_size.width() + 1) / 2 * 2);
     if (format != PIXEL_FORMAT_YV16)
       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.
   ColorSpace color_space = AVColorSpaceToColorSpace(codec_context->colorspace,
                                                     codec_context->color_range);
   if (color_space == COLOR_SPACE_UNSPECIFIED) {
     // Otherwise, assume that SD video is usually Rec.601, and HD is usually
     // Rec.709.
     color_space = (natural_size.height() < 720) ? COLOR_SPACE_SD_REC601
                                                 : COLOR_SPACE_HD_REC709;
@@ skipping 228 matching lines @@
 }
 
 int32_t HashCodecName(const char* codec_name) {
   // Use the first 32-bits from the SHA1 hash as the identifier.
   int32_t hash;
   memcpy(&hash, base::SHA1HashString(codec_name).substr(0, 4).c_str(), 4);
   return hash;
 }
 
 }  // namespace media