[FFmpeg-devel] [PATCH 1/3] avcodec/alsdec: Limit maximum channels to 64

[Michael Niedermayer]

On Mon, Aug 19, 2019 at 05:09:37PM +0200, Thilo Borgmann wrote:
> Am 19.08.19 um 14:27 schrieb Michael Niedermayer:
> > On Mon, Aug 19, 2019 at 07:41:43AM +0200, Thilo Borgmann wrote:
> >> Am 19.08.19 um 01:30 schrieb Michael Niedermayer:
> >>> There seems to be no limit in the specification and upto 64k could be stored
> >>> 64 is chooses as limit as thats also used for AAC and is what a int64 mask
> >>> can handle
> >>>
> >>> An alternative to this patch would be a max_channels variable
> >>
> >> There's a conformance file containing 512 channels, that should be the default max value.
> > 
> > will apply with that value later
> 
> Decoding of that is already stopped via FF_SANE_NB_CHANNELS in lavc/internal.h.
> That is currently set to 256U. I guess pushing that to 512U might already be enough without any change to single decoders?

the problem of out of memory is that the als decoder allocates some pretty
large things per channel. A check on channels needs to happen before
this.
The existing checks didnt achieve that.

I can of course post a patchset that uses FF_SANE_NB_CHANNELS in als and
bump it to the next number if people prefer this ?

Note though that increasing FF_SANE_NB_CHANNELS may also increase timeouts
in other decoders.


> 
> Once fixed, I will add a FATE test for the 512 channel conformance file.

thx

> 
> -Thilo
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Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

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