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I'm ripping video from a bunch of ancient MiniDV tapes using, after much trial and error, some almost as ancient Mac hardware and iMovie HD 6.0.5. This is working well except that it will only create a contiguous video clip of about 12.6 GB in size. If the total video is larger than that, it creates a second clip that is usually about 500 MB.

I want to join these two clips in the "best" way possible - meaning with ffmpeg throwing as few errors as possible, and the audio / video staying in sync.

I'm currently using the following command line in a bash shell:

for f in *.dv ; do echo file '$f' >> list.txt; done && ffmpeg -f concat -safe 0 -i list.txt -c copy stitched-video.dv && rm list.txt

This seems to be working well, and using the 'eyeball' check, sync seems to be preserved.

However, I do get the following error message when ffmpeg starts in on the second file:

Non-monotonous DTS in output stream 0:1; previous: 107844491, current: 107843736; changing to 107844492. This may result in incorrect timestamps in the output file.

Since I know just enough about ffmpeg to be dangerous, I don't understand the significance of this message.

Can anyone suggest changes to my ffmpeg command that will fix whatever ffmpeg is telling me is going wrong?

I'm going to be working on HD MiniDV tapes next, and, because they suffer from numerous dropouts, my task is going to become more complex, so I'd like to nail this one.

Thanks!

as suggested below ffprobe for the two files

Input #0, dv, from 'file1.dv': Metadata: timecode : 00:00:00;22 Duration: 00:59:54.79, start: 0.000000, bitrate: 28771 kb/s Stream #0:0: Video: dvvideo, yuv411p, 720x480 [SAR 8:9 DAR 4:3], 25000 kb/s, 29.97 fps, 29.97 tbr, 29.97 tbn Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s

Input #0, dv, from 'file2.dv': Metadata: timecode : 00:15:06;19 Duration: 00:02:04.09, start: 0.000000, bitrate: 28771 kb/s Stream #0:0: Video: dvvideo, yuv411p, 720x480 [SAR 8:9 DAR 4:3], 25000 kb/s, 29.97 fps, 29.97 tbr, 29.97 tbn Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s

Dave Lang
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  • It's likely related to the differences in timebase (compare the `tbn` of your input files via `ffprobe`). [This answer](https://stackoverflow.com/a/56002050/4516027) should help. – kesh Mar 29 '22 at 21:58
  • ffprobe shows both files as "29.97 tbn" - thanks for the pointer to that other answer, though – Dave Lang Mar 29 '22 at 22:05
  • Adding the ffprobe logs of the first 2 files to the post may be helpful – kesh Mar 29 '22 at 23:23
  • Input #0, dv, from 'file1.dv': Metadata: timecode : 00:00:00;22 Duration: 00:59:54.79, start: 0.000000, bitrate: 28771 kb/s Stream #0:0: Video: dvvideo, yuv411p, 720x480 [SAR 8:9 DAR 4:3], 25000 kb/s, 29.97 fps, 29.97 tbr, 29.97 tbn Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s – Dave Lang Mar 29 '22 at 23:42
  • Input #0, dv, from 'file2.dv': Metadata: timecode : 00:15:06;19 Duration: 00:02:04.09, start: 0.000000, bitrate: 28771 kb/s Stream #0:0: Video: dvvideo, yuv411p, 720x480 [SAR 8:9 DAR 4:3], 25000 kb/s, 29.97 fps, 29.97 tbr, 29.97 tbn Stream #0:1: Audio: pcm_s16le, 48000 Hz, stereo, s16, 1536 kb/s – Dave Lang Mar 29 '22 at 23:43
  • I strongly recommend putting those in your post (not in comments) via edit feature – kesh Mar 29 '22 at 23:49

0 Answers0