[FFmpeg-devel] [RFC] LPCM 24 bits support

[Lars Täuber]

On Fri, 18 Apr 2008 22:08:24 +0200 Michael Niedermayer <michaelni at gmx.at> wrote:
> On Fri, Apr 18, 2008 at 09:05:23PM +0200, Lars T?uber wrote:
> > On Fri, 18 Apr 2008 15:39:43 +0200 Michael Niedermayer <michaelni at gmx.at> wrote:
> > > On Thu, Apr 17, 2008 at 10:13:40PM +0200, Lars T?uber wrote:
[...]
> > > > +            while (n--) {
> > > > +                ap = audio24;
> > > > +                src_LSB = src + avctx->channels * 2 * 2;
> > > > +
> > > 
> > > > +                if (avctx->bits_per_sample == 20)
> > > > +                    for (c=0; c < avctx->channels; c++, src+=4, src_LSB++ ) {
> > > > +                        *ap++ = src[0]<<16 | src[1]<<8 | (*src_LSB & 0xf0);
> > > > +                        *ap++ = src[2]<<16 | src[3]<<8 | (*src_LSB & 0x0f)<<4;
> > > > +                    }
> > > 
> > > Is there something that prevents channels from being larger than 8?
> > 
> > Yes, because it's calculated as shown above. (There are only 3 bits that tell the number of channels)
> > 
> > > The array should either be sized related to MAX_CHANNELS or channels be
> > > checked against the size of the array.
> > 
> > the widest sample size is 24 bits*channels => fit into int
> > channels <= 8
> > exactly 2 samples per block
> > => max 2*8 ints/block
> > 
> > Is that enough to be safe?
> 
> Well, what if someone would store CODEC_ID_PCM_DVD in for example .mkv .avi
> .mov  ...

I added a check.
Lars
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