[FFmpeg-devel] [PATCH] raw demuxer for Chinese AVS elementary streams

[Michael Niedermayer]

On Fri, Feb 20, 2009 at 07:04:32PM +0100, Stefan Gehrer wrote:
> Michael Niedermayer wrote:
> > On Thu, Feb 19, 2009 at 09:33:54PM +0100, Stefan Gehrer wrote:
> >> Hi,
> >>
> >> attached patch adds $subject. This makes it possible to test the
> >> two samples at
> >> http://samples.mplayerhq.hu/AVS/issue767/
> >> Unfortunately these samples do not work properly yet, only the
> >> I-Frames.
> >> You can see that the patch contains a probe function and I was
> >> trying to make that probing fairly restrictive. However, my feeling
> >> is that a probing function is a slightly dangerous addition unless
> >> tested against a large number of samples, which I didn't do.
> >> So it might be better to consider the patch for after the release ...
> > 
> > i think the probe function should be improved a bit more if possible
> > for example there are quite a few 0x1XX codes that are neither checked
> > for being within a valid range nor trigger detection failure
> 
> Okay, choose any combination of further restrictions you like:
> 
> 1. The slice start codes are 0x100 to 01xAF. Since slices in AVS are
> whole macroblock lines and the start code represents the vertical
> macroblock coordinate, this could be restricted e.g. to 0x43 maximum
> to support up to 1088 pixels vertically

is it allowed for a single slice to contain more than 1 row? 


> 
> 2. 0x1B4 is labelled as reserved in AVS and could trigger detection
> failure

yes


> 
> 3. Bail out if the first byte after 0x1B0 (sequence header, profile_id)
> is not 0x20. For all AVS samples I know of it has this value,
> corresponding to JiZhun profile.

but does AVS allow other values?

[...]
-- 
Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

In fact, the RIAA has been known to suggest that students drop out
of college or go to community college in order to be able to afford
settlements. -- The RIAA
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