[FFmpeg-user] V_QUICKTIME used as codec ID for DPX/TIFF rewrapped to Matroska

Carl Eugen Hoyos ceffmpeg at gmail.com
Sat Dec 8 14:38:33 EET 2018

2018-12-08 13:10 GMT+01:00, Kieran O Leary <kieran.o.leary at gmail.com>:
> Hi Carl,
> On Sat, Dec 8, 2018 at 11:00 AM Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:
>> 2018-12-08 11:46 GMT+01:00, Kieran O Leary <kieran.o.leary at gmail.com>:
>> > When re-wrapping DPX or TIFF images to Matroska, it appears that
>> > FFmpeg uses the V_QUICKTIME codec ID.
>> Where can I find the specification for tiff in matroska and dpx in
>> matroska?
> I don't think they exist - this remuxing is most likely not common/never
> used. I'll get in touch with the CELLAR/IETF list and see if anyone has any
> ideas.

> Also, as per my last email, DPX is fine - V_MS/VFW/FOURCC / dpx . I
> just had a crappy command line :(

I don't think it's fine: You are using a very unusual fourcc to put something
in matroska that is not meant to be there, expect massive compatibility

>> > Why is this used?
>> > Would something like V_UNCOMPRESSED (for raw TIFF anyhow)
>> > be more appropriate/
>> If you use -vcodec rawvideo instead of tiff or dpx (which are not
>> rawvideo) you get V_UNCOMPRESSED but note that matroska
>> is not a useful container for rawvideo because it is not well
>> defined, use nut instead.
> Cool, but why is a QuickTime ID used ? Is this some sort of generic
> fallback that ffmpeg uses?

Just like the V_MS/VFW/FOURCC codec id above for avi, there is
also a QuickTime fallback defined for Matroska (not by FFmpeg),
tiff happens to be defined for QuickTime but not in avi, therefore
the QuickTime code point is used for Matroska.
Contrary to dpx above, this can at least be argued to be following
some standard.

Carl Eugen

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