[pulseaudio-discuss] [PATCH v4 0/7] New API for Bluetooth A2DP codecs

[Luiz Augusto von Dentz]

Hi Pali,

On Tue, Jan 15, 2019 at 10:34 AM Pali Rohár <pali.rohar at gmail.com> wrote:
>
> On Tuesday 15 January 2019 10:06:14 Luiz Augusto von Dentz wrote:
> > Hi Pali,
> >
> > On Mon, Jan 14, 2019 at 8:24 PM Pali Rohár <pali.rohar at gmail.com> wrote:
> > >
> > > This is 4th version of my patch series for modular A2DP codec API and
> > > aptX support.
> > >
> > > This patch series provides new modular API for Bluetooth A2DP codecs,
> > > clean up module-bluez5-device and bluez5-util to be codec independent
> > > and convert SBC codec into this new API for A2DP codecs. Also it adds
> > > support for aptX, aptX HD and FastStream A2DP codecs.
> >
> > It is a bit better since you are introducing a table to add codecs,
> > though what I suggested was having the codecs as separated modules
> > which then register with bluetooth modules to make their codec
> > available. Anyway Im fine with just having a table, at least it is not
> > using #ifdef everywhere.
>
> I think that table is better then having to call module init function
> for each codec, so codec would register into pulseaudio.
>
> With table there is just one ifdef -- for including codec into table,
> which is (at least for me) easier to use or extend.

Fair enough, I just thought that having as a plugin may make sense to
pass parameters to the codecs, though we don't have anything like that
currently so we can probably leave it for later if we find it really
necessary.

> > Speaking about aptX, there seems to be 2 libs supporting it,
> > libavcodec and your openaptx, we should probably settle in just one,
> > probably the one that easier to find packages.
>
> In v3 (and therefore also in v4) I updated automake and autoconf code
> for openaptx so there is no hardcoded aptx path. This should work as
> expected.
>
> Anyway, more people are still asking for pkg-config file for openaptx.
> So if you really think that it would help something, I can include code
> into libopenaptx which generates simple pc file at install step. But I'm
> still a bit sceptical that such pc file is useful for simple library
> which do not have any compile flags and no specific link flags...
>
> So is not current autoconf code for aptX in v4 enough?
>
> About libavcodec detection of aptX. It is not easy. You need runtime
> code which ask libavcodec if aptX is support or not. So you cannot write
> just compile check macro in autoconf which returns true/false (aptX is
> supported or not). Runtime code means no possibility to cross compile,
> plus needs to have this runtime code also in pulseaudio to verify that
> configuration detected at compile time matches configuration at
> pulseaudio runtime.

Alright, well perhaps instead of building as external dependency we
could have the openaptx code include in the PA source tree and
compiled as local library as we probably don't expect any other users,
or do we?

About libavcodec, or gstreamer, the codecs are detected at runtime
thus I guess having them as plugins makes more sense, so I guess it is
not a bad ideia to register the codecs at runtime after all. Anyway we
need to reuse part of the code for D-Bus handling, etc, since those
frameworks normally only deal with the codec payload not the
signalling.

> --
> Pali Rohár
> pali.rohar at gmail.com



-- 
Luiz Augusto von Dentz