> On Feb 27, 2022, at 10:49 PM, Adam Nielsen via ffmpeg-user > <ffmpeg-user@ffmpeg.org> wrote: > >> Would it be worthy feature request to allow drawtext to accept >> integer values N > 1, and then reload the text file every Nth frame? >> It seems like a win for CPU and I/O loading, with the benefit of >> being fully backward compatible with existing scripts that read in >> every 1 frame (e.g. reload=1). >> >> Or are there downsides to this that I’m not seeing? > > I thought about something similar as I'm also overlaying infrequently > changed data (temperature) onto video. > > However I ended up putting the file on a tmpfs partition so there's no > actual disk IO, the whole thing sits in memory anyway. > > Have you tried benchmarking to see how much benefit you'd get from this > optimisation? You could check CPU usage and I/O load with reload=1 and > again with reload=0 and see what the difference is. Let us know what > you find, as I haven't actually tried this myself so it would be > interesting to know what the impact is of reading the file on every > frame. > >> * and yes, I’m writing to weather.tmp and cping to weather.txt to >> prevent a file I/O collision. > > Do you mean "mv" instead of "cp"? I don't think "cp" is atomic but > "mv" is. Using "cp" won't break anything but you might get a frame > here or there with incomplete data.
Thanks for the tip about mv vs cp. I originally had mv, per the documentation, but then I changed it to cp during troubleshooting because I couldn’t figure out why my temp file kept disappearing, LOL. I’ve changed it back to mv. Regarding I/O load, I know it’s probably negligible, but it just offends my sensibilities to read something 11,999 times for no reason. And if this feature gets implemented (thank you, Gyan!!!) then I won’t have to worry about where I put the tmp file. _______________________________________________ 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".
