[FFmpeg-trac] #8216(ffmpeg:new): Very slow yuv file writer

FFmpeg trac at avcodec.org
Thu Oct 3 19:56:08 EEST 2019

#8216: Very slow yuv file writer
             Reporter:  xiaotiansf   |                     Type:  defect
               Status:  new          |                 Priority:  important
            Component:  ffmpeg       |                  Version:
             Keywords:  slow YUV     |  unspecified
  writer                             |               Blocked By:
             Blocking:               |  Reproduced by developer:  1
Analyzed by developer:  1            |
 -c:v libopenh264 -i solo.mp4 -map 0:v -an -pix_fmt yuv420p -y solo.yuv
 ffmpeg is built on
 ./configure --toolchain=msvc --enable-asm --enable-x86asm --arch=x86_64
 --disable-shared --enable-static --enable-gpl --enable-libopenh264
 libopenh264 is built on

 The problems observed using profile tool

 1. Writing output YUV (file_write in libavformat/file.c) uses about 95%
 overal time which makes overall progress exceptional slow.
 2. ffmpeg Benchmark log shows that the overall speeds becomes slower and
 slower from start to end.
 3. By commenting out file_write in libavformat/file.c, it takes no time to
 finish the entire process.

Ticket URL: <https://trac.ffmpeg.org/ticket/8216>
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