michaelni at gmx.at
Tue Apr 24 21:18:24 CEST 2012
On Tue, Apr 24, 2012 at 01:22:23PM +0200, Peter B. wrote:
> Quoting Tim Nicholson <nichot20 at yahoo.com>:
> >On 20/04/12 14:50, Michael Niedermayer wrote:
> >>Ive just commited some changes to the ffv1 codec v1.3
> >>Whats new:
> >>mandatory CRC on the global header
> >Sounds good.
> Definitely. Thanks Michael!
> One question about that: For which content-parts (frames?) are CRCs
> stored in there?
They are on the global header and slices
each frame is split into several slices. These slices also allow
multithreaded decoding and encoding.
> FFv1's strength and major field of application seems to be in the
> archival domain rather than production or on-site recording.
> Therefore, its requirements to be able to support mid-stream changes
> seems questionable from my point of view.
> Information like TFF/BFF, aspect ratio, etc. must be provided
> somehow - and I am not sure where this information could be gathered
> from automatically (except field-order, maybe).
> So, if there is a mid-stream change of e.g. aspect ratio, who, when,
> and especially *how* should this information be provided to the
The application using ffv1 would provide this information, if it
does not, default "unknown" values should be stored in ffv1.
In terms of implementation in libavcodec, the sample_aspect_ratio
and other fields of AVFrame store this information and the encoder
Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
Opposition brings concord. Out of discord comes the fairest harmony.
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