On Wed, Oct 16, 2019 at 14:10:58 +0200, Roman Huy-Prech wrote: > and the least amount of arguments needed to reproduce: > https://bitdash-a.akamaihd.net/content/sintel/hls/1500kbit/seq-38.ts
Incorrect URL, this is the correct one: https://bitdash-a.akamaihd.net/content/sintel/hls/video/1500kbit/seq-38.ts > Original Chunk: > Duration: 00:00:02.00, start: 76.083333, bitrate: 919 kb/s > > Using -copyts I can copy over the timings. Good. But I want 300k. > ffmpeg -i seq-38.ts -vf scale=320:240 -f mpegts -muxdelay 0 -copyts > -vcodec libx264 -crf 19 -y seq-38-copyts.ts && ffprobe seq-38-copyts.ts > Duration: 00:00:02.00, start: 76.083333, bitrate: 245 kb/s You should always provide us with the command and its complete, uncut console output. In this case, thanks to the sample (almost), we can reproduce, but it's nicer to see *your* actual results, not our own. > Now I'm combining the two, I have the correct start time again, but wtf? > 11696 kb/s? > ffmpeg -i seq-38.ts -vf scale=320:240 -f mpegts -muxdelay 0 -copyts > -vcodec libx264 -crf 19 -y -muxrate 300k seq-38-copyts.ts && ffprobe > seq-38-copyts.ts > Duration: 00:00:02.00, start: 76.083333, bitrate: 11696 kb/s Apparently, ffmpeg is taking the additional 78 seconds offset from the copyts into consideration: > frame= 48 fps= 15 q=-1.0 Lsize= 2856kB time=00:01:17.95 bitrate= > 300.1kbits/s speed=24.3x > video:54kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing > overhead: 5149.501953% (This is what we ask for the complete output for - we can point out where iut shows you the issue!) Note that ffmpeg thinks it encoded 1:17.95 (not 0:02.00) at 300.1kbits/s. (See all that muxing overhead!) Looking at my resulting file size, that's even quite precisely correct: (no. of bytes in filesize, times bits in a byte, divided by assumed length in seconds, is the bit rate:) $ calc "2924340 / 77.95 * 8" ~300124.69531751122514432328 Except that the resulting video isn't actually 77.95 seconds long. ;-) Therefore, the resulting overall bit rate is wrong. So I believe copyts is confusing the muxrate calculation, pretty much like the guess in your second e-mail. I consider it a bug. (BTW, there do exist other external tools to pad an MPEG-TS to a CBR. ffmpeg's MPEG-TS does have some deficits, but this isn't supposed to be one of them.) Cheers, Moritz _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
