[pulseaudio-discuss] SBC XQ for PA 13.0

Pali Rohár pali.rohar at gmail.com
Sat Dec 7 18:30:41 UTC 2019

On Saturday 07 December 2019 21:09:04 Andrey Semashev wrote:
> However, I can still hear compression artefacts on quiet or nearly silent
> audio sections, which sound like high-pitch squeaking sounds. It can often
> be heard on various music fade out sections. I don't know if this is
> inherrent from SBC codec itself or is a deficiency of libsbc implementation,
> or the headphones. These artefacts are my main complaint about SBC.

See very nice description about this problem https://habr.com/en/post/456182/
Probably your headphones cripple audio by filters when SBC is used...

> Which brings me to my question to PA developers. Would an addition of
> support for AAC be possible?

My A2DP patch series brings new pulseaudio API for implementing new A2DP
codecs. So yes, additional support for other A2DP codecs with my patch
series is possible. My patch series contains support for aptX, aptX-HD
and FastStream A2DP codecs.

But... you need a library for encoding and decoding that codec ...

> pulseaudio-modules-bt uses libfdk-aac to implement AAC, and if possible, I
> would prefer that library as it provides the best quality available on
> Linux. However, if licensing is an issue, there is also a built-in
> implementation in ffmpeg.

FDK-AAC library is incompatible with any version of the GNU GPL license
and therefore it is not possible to use it in any GPL licensed software,
like pulseaudio. See: https://www.gnu.org/licenses/license-list.html#fdk

If there is other AAC library which license allows usage it in
pulseaudio then it could be possible. Just somebody needs to write it.

Pali Rohár
pali.rohar at gmail.com
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