> The resulting .mp4 is flagged as VFR which is not what I expected nor > wanted.
I am using v4l2_m2m on a Pi and getting constant framerate (although still not correct) so it is at least possible: Frame rate mode : Constant Frame rate : 13.508 FPS Original frame rate : 15.000 FPS > I was hoping to use VBR rather than CBR but can't find a way to set > it. Looking at the Pi V4L2 controls it appears to support VBR, but ffmpeg must set the correct values. A quick Google says to use -q:v instead of -b:v, e.g. https://slhck.info/video/2017/02/24/vbr-settings.html I'm streaming off the Pi camera in variable framerate mode (at max 15 fps), so I'm trying to get frames duplicated as necessary to maintain a fixed 15 fps on the output. I was using the `-r` option for this to set the output framerate so possibly adding this might help, as it doesn't look like you're telling ffmpeg what output framerate to use. Possibly if the input file is VFR it might be carrying that flag across. I am also using this option to try to fix up the timestamps: -bsf "setts=ts=N*(1/${FPS})*100000,h264_metadata=tick_rate=$[$FPS * 2]" However this doesn't seem to be working right and appears to be what is marking the output as 13.5 fps instead of 15 fps. So if anyone knows what is wrong with my calculations please let me know. Unfortunately this doesn't work too well for streaming as ffplay likes to keep a 10-15 second buffer so the streamed video has an enormous delay. I suspect it's something to do with these timestamps as the instant I stop streaming, ffplay suddenly rushes through the 10 second buffer at 60 fps. I just wish I could figure out how to tell ffplay not to buffer quite so much video! I have tried various combinations of -sync ext -fflags nobuffer -flags low_delay -strict experimental -vf setpts=N/40/TB -an -fast -noframedrop -probesize 32 but none of them make much difference which is what leads me to think the issue might be on the encoding side. Cheers, Adam. _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".
