[FFmpeg-devel] FFV1.3

Michael Niedermayer 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:
> >>Hi
> >>
> >>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
> encoder?

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
uses them


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

Opposition brings concord. Out of discord comes the fairest harmony.
-- Heraclitus
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