[FFmpeg-user] Output image sequence duplicate first image

[Edward Park]

Hi,

> /usr/src/app # ffmpeg -y -i /data/vod-storage-dev/source/testfile.mxf -r 20/60 -s 283x159 -frames:v 10 -pix_fmt yuvj420p -c:v mjpeg  /data/vod-storage-dev/temp_out/1cq8tq69tkumv1es0zxeb0ty4qa_%03d.jpeg
...
>    Stream #0:0: Video: mpeg2video, yuv422p(tv, top first), 1920x1080 [SAR 1:1 DAR 16:9], 50000 kb/s, 25 fps, 25 tbr, 25 tbn, 50 tbc
>    Metadata:
>      file_package_umid: 0x060A2B340101010501010D001324CF5D529471346A24CF5D00529471346A2401
...
>    Stream #0:0: Video: mjpeg, yuvj420p(pc), 283x159 [SAR 848:849 DAR 16:9], q=2-31, 200 kb/s, 0.33 fps, 0.33 tbn, 0.33 tbc
>    Metadata:
>      file_package_umid: 0x060A2B340101010501010D001324CF5D529471346A24CF5D00529471346A2401
>      encoder         : Lavc58.54.100 mjpeg
>    Side data:
>      cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1
> frame=   10 fps=3.0 q=1.6 Lsize=N/A time=00:00:30.00 bitrate=N/A dup=0 drop=583 speed= 8.9x    
> video:51kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: unknown

If this is accurate, it looks like you have asked it to produce 20 frames in 60 seconds, or 1/3 fps, or 1 frame every 3 seconds regardless of input framerate, whatever. It will drop frames, duplicate frames, do what is needed to keep 1/3 frames per second constant output. You've also specified that you want 10 frames total. at 1/3 fps that runs 30 seconds. I'm not sure why the first and second are always duplicates, it doesn't look like any frames were duplicated. (at 0.33fps if two frames were exactly the same when they weren't duplicated, maybe it was frozen in the source?)

Regards,
Ted