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

Michael Niedermayer michaelni
Fri Feb 20 20:02:33 CET 2009

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


> 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
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20090220/ae5107eb/attachment.pgp>

More information about the ffmpeg-devel mailing list