[FFmpeg-devel] [PATCH] dca: map xxch side channels to AV_CH_SIDE_LEFT/RIGHT instead of REAR.

Nick Brereton nick at nbrereton.net
Wed Jul 11 14:38:29 CEST 2012

On 2012-07-11 00:25, Michael Niedermayer wrote:

> On Tue, Jul 10, 2012 at 10:34:49PM +0100, Nick Brereton wrote:
>> On 2012-07-09 11:04, Hendrik Leppkes wrote:
>>> On Mon, Jul 9, 2012 at 11:44 AM, Benjamin Larsson
>>> <benjamin at southpole.se [1]>wrote:
>>>> OK MvH Benjamin Larsson
>>> I talked to Nick directly, and he'll be looking at the code as soon
>>> as he finds the time to diagnose the other issues i reported, maybe
>>> we should hold this until then. - Hendrik
>>> _______________________________________________ ffmpeg-devel 
>>> mailing
>>> list ffmpeg-devel at ffmpeg.org [2]
>>> http://ffmpeg.org/mailman/listinfo/ffmpeg-devel [3]
>> In re the first problem, DTS seem to have a greater variety of
>> flavours than ffmpeg does; the net result is that I've had to 
>> compress
>> some of the positions. In this case DCA_XXCH_SIDE_REAR_LEFT/RIGHT
>> (which are reserved for the core channels only) are not used and are
>> replaced with DCA_XXCH_SIDE_SURROUND_LEFT/RIGHT which I had guessed
>> (wrongly) were similar to DCA_XXCH_SURROUND_REAR_LEFT/RIGHT. I think
>> your fix is a reasonable solution in this case; you should also make
>> the av_log message on line 2282 an error message. Are there a
>> proscribed set of allowable speaker configurations for XXCH? If 
>> there
>> are it might help to clean this up somewhat. The code that undoes 
>> the
>> embedded down-mix is a bit fragile as you've noted & in this case 
>> gets
>> the wrong channels to remove the down-mix from (it winds up
> eliminating
>> itself instead). I'll try a different solution over the weekend.
> should i apply the patch or wait?
> if wait, do you have some git clone of ffmpeg from where i can after
> you have found a solution just pull all needed changes ?
> thanks
> [...]
> -- Michael GnuPG fingerprint: 
> 9FF2128B147EF6730BADF133611EC787040B0FAB
> The misfortune of the wise is better than the prosperity of the fool. 
> --
> Epicurus

Please apply this patch.

I'm still curious to know if DTS have any rules about combining 
channels for XXCH as otherwise there is always going to be a risk of 
channels 'colliding' in the ffmpeg scheme.


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