[FFmpeg-devel] [PATCH 2/2] Fix side channels when XCh extension is present

[Kostya]

On Sat, Jul 10, 2010 at 09:47:58PM +0100, Nick Brereton wrote:
> Patch 2/2 to fix side channels when DTS-ES matrix is flagged *and*
> DTS-ES discrete is also present in XCh extension.

First, this is not unified diff, so it's not a patch in strict sense :)
And can you guarantee it's always correct mapping for channels (sorry,
don't have specs at hand) i.e. it does not depend on amode?

> Index: libavcodec/dca.c
> ===================================================================
> --- libavcodec/dca.c	(previous working copy)
> +++ libavcodec/dca.c	(working copy)
> 1395a1396,1409
> > 
> >         /* If this was marked as a DTS-ES stream we need to subtract back- */
> >         /* channel from SL & SR to remove matrixed back-channel signal */
> >         if((s->source_pcm_res & 1) && s->xch_present) {
> >             float* back_chan = s->samples + s->channel_order_tab[s->xch_base_channel] * 256;
> >             float* lt_chan   = s->samples + s->channel_order_tab[s->xch_base_channel - 2] * 256;
> >             float* rt_chan   = s->samples + s->channel_order_tab[s->xch_base_channel - 1] * 256;
> >             int j;
> >             for(j = 0; j < 256; ++j) {
> >                 lt_chan[j] -= (back_chan[j] - s->add_bias) * 0.707107f;
> >                 rt_chan[j] -= (back_chan[j] - s->add_bias) * 0.707107f;
> >             }
> >         }
> >