[libav-devel] [PATCH 4/4] dcadec: Support for xll (lossless extension)

Niels Möller nisse at lysator.liu.se
Fri Jun 13 13:03:39 CEST 2014


Luca Barbato <lu_zero at gentoo.org> writes:

> Which channel layout are we missing?

The problem is when the xll data contains additional channels, not just
residuals to be added to the core channels. In this case, one ought to
extract the data on which channels they are from the xll headers,
translate to a libav channel mask, and permute the channels if needed.
(At least if that information is specified; I think dca can describe the
channels also in terms of angles for appropriate location of the
speakers, and that's more difficult to translate).

The current code doesn't do that at all, it just checks the total number
of channels and then uses the default layout for that number. Which
seems to work fine with the 7.1 file I tested, but not in general.

Regards,
/Niels

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