[FFmpeg-devel] [PATCH 1/5] lavc : yami : add libyami decoder/encoder

Jun Zhao mypopydev at gmail.com
Wed Aug 17 03:56:08 EEST 2016

On 2016/8/17 2:33, Mark Thompson wrote:
> On 16/08/16 09:51, Jun Zhao wrote:
>> barry at barry:~/Source/video/yami/ffmpeg_libyami$ ./ffmpeg -y -vaapi_device /dev/dri/card0 -hwaccel vaapi -hwaccel_output_format vaapi -i ../ffmpeg_yami_testcase/skyfall2-trailer.mp4 -an -vf 'format=nv12|vaapi,hwupload' -c:v h264_vaapi -profile 77 -level:v 40  -b 4000k  output_vaapi_transcode.mp4
>> ...
>> barry at barry:~/Source/video/yami/ffmpeg_libyami$ mediainfo output_vaapi_transcode.mp4 
>> File size                                : 69.8 MiB
>> ...
>> barry at barry:~/Source/video/yami/ffmpeg_libyami$ ./ffmpeg -y -c:v libyami_h264 -i ../ffmpeg_yami_testcase/skyfall2-trailer.mp4 -c:v libyami_h264 output_yami_transcode.mp4 
>> ...
>> barry at barry:~/Source/video/yami/ffmpeg_libyami$ mediainfo output_yami_transcode.mp4 
>> File size                                : 74.2 MiB
> I'm assuming you are trying to show them with identical options?  Since the hardware is the same, you really should be able to get those two encodes to produce pretty much identical results.
> Here I think the significant difference is probably that h264_vaapi is using 2 B-frames by default, but there might be more subtle differences to remove as well.
> - Mark

Hi, Mark:

I just used this show how to run ffmpeg/vaapi and ffmpeg/libyami :)

For the performance gap, I think the root cause is that ffmpeg/vaapi transcode use VPP in the pipeline, but ffmpeg/libyami transcode without VPP.

I will double-check this case.

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