[FFmpeg-devel] [PATCH] rematrix DPLII fix for channel downmixing. Surround now adds to front rather than taking away.

Peter Robertson Peter at CorrosiveTruths.org
Sat Mar 15 18:31:42 CET 2014

On 15/03/14 16:51, Hendrik Leppkes wrote:
> On Sat, Mar 15, 2014 at 4:46 PM, Peter Robertson
> <Peter at corrosivetruths.org> wrote:
>> This fixes a problem where trying to convert gameplay sound to Dolby Pro
>> Logic II would result in a left channel that would be missing the sounds
>> that were in center and back left at the same time. I also applied it to
>> Dolby Pro Logic as it should work the same way. Sorry if I've done
>> anything wrong, first patch. Fixes #3455
> The encoding matrix for DPL/DPLII is defined by Dolby, and only sounds
> good if you use a DPL compatible decoder to reconstruct the original
> signal.
> Its not necessarily supposed to be played as stereo through stereo speakers.
> All Information I could find about DPL encoding suggests that the
> implementation is correct as it is today. Left channel subtracts both
> surrounds, and right channel adds them.
> - Hendrik
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Yes, I can see the information seems to agree with you.

Maybe my solution has not fixed the problem, but compensated for it somehow?

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