[FFmpeg-user] Unable to accurately split vmaf calculation

[tarun singhal]

Hi,

I am trying to split vmaf calculation work across multiple threads by
logically dividing the video ( not literally )

I tried following 2 commands to do vmaf on a 20.08 sec ( 477 frames ) video

*For 1st 10 second: *

*ffmpeg -i transcodedA.mp4 -i sourceA.mxf -filter_complex
"[0:v][1:v]scale2ref=flags=bicubic[encoded][source];[source]format=pix_fmts=yuv420p,trim=start=0,trim=end=10,setpts=PTS-STARTPTS[source2];[encoded]trim=start=0,trim=end=10,setpts=PTS-STARTPTS[encoded1];[encoded1][source2]libvmaf=feature='name=psnr|name=float_ssim|name=float_ms_ssim':n_threads=4:log_fmt=json:log_path=A0-10.json"
-f null -*


*For remaining part of video:*

*ffmpeg -i transcodedA.mp4 -i sourceA.mxf -filter_complex
"[0:v][1:v]scale2ref=flags=bicubic[encoded][source];[source]format=pix_fmts=yuv420p,trim=start=10,setpts=PTS-STARTPTS[source2];[encoded]trim=start=10,setpts=PTS-STARTPTS[encoded1];[encoded1][source2]libvmaf=feature='name=psnr|name=float_ssim|name=float_ms_ssim':n_threads=4:log_fmt=json:log_path=A10-20.json"
-f null -*

But in both output files, collectively I get only 465 frames, that means 13
frames missing. What can I do that ensure no frame is missed?



Regards,
Tarun Singhal