How to choose between openH264 and x264 decoder

Turn from: Https://stackoverflow.com/questions/42220081/how-to-choose-between-openh264-and-x264-decoder

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The I ' m using the dev build, zeranoe.com which has OpenH264 and libx264 in it. How can I choose between this two decoders to compare the decoding speed? avcodec_find_decoder (avcodecid.av_codec_id_h264); Only gives me the name "H264" but which decoder is it? and tries to force a specific decoder failed, like: codec = Avcodec_find_decoder _by_name ("x264"); codec = Avcodec_find_decoder _by_name ("libx264"); Which Other options I have to improve the decoding speed of Avcodec_decode_video2 for highres (4k and higher) R TSP video streams?

Answer:

FFmpeg can use OpenH264 (named libopenh264 into FFmpeg) to decode in addition to the native FFmpeg H.264 decoder (named H264 ). There are also several supported hardware assisted, H.264 I ' m not decoders to go into but about going. Caveats

OpenH264 can only decode constrained Baseline profiles, so it usefulness may limited.

The native FFmpeg H.264 decoder has threading (frame and capabilities) slice but not. ffmpeg CLI Tool examples

It appears you ' re working with the FFmpeg libraries, but here are some using examples.

To choose the decoder your want use the-c:v input option. Below are two decoding benchmark using the null examples. The-map option is also used so only the (a) video stream is decoded and to ignore other, non-video streams such as AU Dio. Native FFmpeg H.264 decoder

$ ffmpeg-benchmark-i input.mp4-map 0:v:0-f null-
bench:utime=23.557s
bench:maxrss=57752kb
Real    0m3 .834s
user    0m23.573s
sys     0m0.213s

libopenh264

$ ffmpeg-benchmark-c:v libopenh264-i input.mp4-map 0:v:0-f null-
bench:utime=20.927s
bench:maxrss=37404kb< C2/>real    0m21.002s
user    0m20.940s
sys     0m0.060s

Benchmark Time

The benchmark option outputs user CPU time, not the elapsed real time. If you are want real time as OK add the time command before the FFmpeg command (if you are ' re on Linux). I added the outputs from the example (the last three lines) for comparison purposes. To verify the desired decoder is being used

View the console output. For example using the native H.264 decoder:

Stream mapping:
  stream #0:0-> #0:0 (h264 (native)-> wrapped_avframe (native))

Using libopenh264:

Stream mapping:
  stream #0:0-> #0:0 (H264 (libopenh264)-> wrapped_avframe (native))

Weird. Ffmpeg-h decoder=h264 does not show openh264 as a decoder.

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The I ' m using the dev build, zeranoe.com which has OpenH264 and libx264 in it. How can I choose between this two decoders to compare the decoding speed? avcodec_find_decoder (avcodecid.av_codec_id_h264); Only gives me the name "H264" but which decoder is it? and tries to force a specific decoder failed, like: codec = Avcodec_find_decoder _by_name ("x264"); codec = Avcodec_find_decoder _by_name ("libx264"); Which Other options I have to improve the decoding speed of Avcodec_decode_video2 for highres (4k and higher) R TSP video streams?