[FFmpeg-user] Quicktime Non-monotonous DTS in output stream 0:1

[Carl Eugen Hoyos]

Hi Ben!

2018-12-07 19:23 GMT+01:00, Benjamin Turkus <benjaminturkus at nypl.org>:

> I've been transcoding a bunch of v210/pcm quicktime files to ffv1/pcm mkv,
> and I keep receiving "Non-monotonous DTS in output stream 0:1" messages,
> and sometimes even "DTS out of order" warnings. I can't find any reason why
> the errors are occurring when they do, but I'm assuming there's something
> funky is going on in the originals. I've dug through the list-serv, but
> most of the advice that I've found seems to focus on concat-related DTS
> issues.
>
> While there doesn't seem to be anything wrong with the resulting mkvs, I'm
> wondering if there might be a better way to smooth out whatever's going on
> during the transcode. I've played around with things like "-fflags
> +genpts+igndts," but haven't noticed any improvement.

> And when I add in a
> "-af aresample=async=1," it does seem to get rid the "non-monotonous"
> message, but I still get a "DTS out of order."

This cannot have much effect because of "-acodec copy".

> Any advice or thoughts—about what's going on with these files, or a
> different transcoding approach—would be appreciated. Rights issues could
> make sharing samples a little tricky, but I might be able to make it happen.

> Without async

> (is there such a thing as too uncut? Apologies):

No!
(In reality: Of course, but users can only be flamed for too cut, not
too uncut.)

> pamis-iMac:dts pamiaudio$ ffmpeg -i mao_212027_v01_pm.mov -map 0 -dn -c:v
> ffv1 -level 3 -coder 1 -context 1 -g 1 -slicecrc 1 -slices 24 -field_order
> bt -vf setfield=bff,setdar=4/3 -color_primaries smpte170m -color_range tv
> -color_trc bt709 -colorspace smpte170m -c:a copy mao_212027_v01_pm.mkv

You can test "-acodec pcm_s24le" instead of "-acodec copy". This
does not affect the quality and should not have a speed impact.
I wonder what the issue is though, ffprobe (and ffmpeg -debug_ts)
allow to check the input timestamps, maybe the file is a little strange.

Sorry for the late answer!

Carl Eugen