[FFmpeg-trac] #10666(avcodec:new): [Android] MediaCodec h264 decoder is much slower than native h264 decoder

[FFmpeg]

#10666: [Android] MediaCodec h264 decoder is much slower than native h264 decoder
-------------------------------------+-------------------------------------
             Reporter:  bubbleguuum  |                     Type:  defect
               Status:  new          |                 Priority:  normal
            Component:  avcodec      |                  Version:
                                     |  unspecified
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 I've been benchmarking MediaCodec decoder performance for various codecs
 and although most MediaCodec decoders are faster than native, the
 h264_mediacodec decoder is noticeably slower, as in 2 to 3 times slower.

 I'm using a custom FFmpeg 6.1 Android build, benchmark realized on a
 Google Pixel 4a
 running latest Android 13


 Benchmark result on a test h264 video with characteristics:

 {{{
 Duration: 00:09:56.50, start: 0.000000, bitrate: 4421 kb/s
 Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive),
 1920x1080 [SAR 1:1 DAR 16:9], 4087 kb/s, 24 fps, 24 tbr, 90k tbn (default)
 }}}

 With native h264 decoding:

 {{{
 % ffmpeg -benchmark -i /sdcard/Movies/bigbuckbunny1080p.mp4 -an -f null -
 ...
 [out#0/null @ 0xb4000075e4c27a90] video:6710kB audio:0kB subtitle:0kB
 other streams:0kB global headers:0kB muxing overhead: unknown
 frame=14315 fps=216 q=-0.0 Lsize=N/A time=00:09:56.41 bitrate=N/A
 speed=8.99x
 bench: utime=375.794s stime=10.060s rtime=66.314s
 bench: maxrss=131580kB
 }}}

 With h264_mediacodec decoder:

 {{{
 % ./ffmpeg -benchmark -c:v h264_mediacodec -i
 /sdcard/Movies/bigbuckbunny1080p.mp4   -an -f null -
 ...
 [out#0/null @ 0xb400007530d54f90] video:6710kB audio:0kB subtitle:0kB
 other streams:0kB global headers:0kB muxing overhead: unknown
 frame=14315 fps=104 q=-0.0 Lsize=N/A time=00:09:56.41 bitrate=N/A
 speed=4.33x
 bench: utime=60.108s stime=23.083s rtime=137.887s
 bench: maxrss=132824kB
 }}}


 So 8.99x speed for native vs 4.33x for h264_mediacodec.
 Also, it seems the lower the resolution of the input video, the wider the
 gap is: on a 1024x436 video I observe a x3 difference!

 Seems surprising there is such a gap in performance, especially since
 other decoders are faster (except also vp9_mediacodec which is a tiny bit
 slower than native).

 Maybe it is due to the h264 native decoder being super optimized, but I
 thought I would report it for reference.
-- 
Ticket URL: <https://trac.ffmpeg.org/ticket/10666>
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