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

[Kieran O Leary]

On Sat, Dec 8, 2018 at 12:38 PM Carl Eugen Hoyos <ceffmpeg at gmail.com> wrote:

> 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
> issues.
>

Good point.


>
> >> > 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.
>

This all makes sense to me and it's incredibly helpful. I see the TIFF
mapping in the QuickTime spec now.
So I guess that TIFF, and DPX need to be mapped in the Matroska
specification?

Best,

Kieran.