Driver for a codec with built-in DSP for MP3 playback

Driver for a codec with built-in DSP for MP3 playback

[Dajun Chen]

Hi all,

I am wondering where to find the guidances of developing a device driver for
a codec device which has a built-in DSP for MP3 (and tracks in other format)
playback and recording?

Regards

David

Re: Driver for a codec with built-in DSP for MP3 playback

[Mark Brown]

On Mon, Mar 15, 2010 at 02:02:39PM +0000, Dajun Chen wrote:

> I am wondering where to find the guidances of developing a device driver for
> a codec device which has a built-in DSP for MP3 (and tracks in other format)
> playback and recording?

OOI which device?

I'm not sure what you mean by guidance here.  The standard thing would
be to do it as a regular CODEC driver with a custom interface for
userspace (eg, gstreamer) to talk to.  The best way of handling DAPM
will depend on implementation but probably representing the output of
the DSP as an input pin will be easiest.

Re: Driver for a codec with built-in DSP for MP3 playback

[Dajun Chen]

Hi,

I mean example code of a driver which works either on PCM and MP3 (or other
compressed) audio stream.

Reagrds

David
On Mon, Mar 15, 2010 at 2:14 PM, Mark Brown <
broonie@opensource.wolfsonmicro.com> wrote:

> On Mon, Mar 15, 2010 at 02:02:39PM +0000, Dajun Chen wrote:
>
> > I am wondering where to find the guidances of developing a device driver
> for
> > a codec device which has a built-in DSP for MP3 (and tracks in other
> format)
> > playback and recording?
>
> OOI which device?
>
> I'm not sure what you mean by guidance here.  The standard thing would
> be to do it as a regular CODEC driver with a custom interface for
> userspace (eg, gstreamer) to talk to.  The best way of handling DAPM
> will depend on implementation but probably representing the output of
> the DSP as an input pin will be easiest.
>

Re: Driver for a codec with built-in DSP for MP3 playback

[Mark Brown]

On Mon, Mar 15, 2010 at 04:01:34PM +0000, Dajun Chen wrote:

Please don't top post, lack of context makes it difficult to follow the
thread of discussion.

> I mean example code of a driver which works either on PCM and MP3 (or other
> compressed) audio stream.

ALSA only handles PCM streams itself, compressed audio needs to be
handled separately.  The TI DSP stuff is one example of handling
compressed audio, or the Intel Moorestown drivers, but since there's no
standard for that stuff at the kernel level there's not much to look at.

Re: Driver for a codec with built-in DSP for MP3 playback

[Dajun Chen]

Thanks.

Please would you point me the place to see the TI and Intel drivers?

Regards

David

On Mon, Mar 15, 2010 at 4:15 PM, Mark Brown <
broonie@opensource.wolfsonmicro.com> wrote:

> On Mon, Mar 15, 2010 at 04:01:34PM +0000, Dajun Chen wrote:
>
> Please don't top post, lack of context makes it difficult to follow the
> thread of discussion.
>
> > I mean example code of a driver which works either on PCM and MP3 (or
> other
> > compressed) audio stream.
>
> ALSA only handles PCM streams itself, compressed audio needs to be
> handled separately.  The TI DSP stuff is one example of handling
> compressed audio, or the Intel Moorestown drivers, but since there's no
> standard for that stuff at the kernel level there's not much to look at.
>

Re: Driver for a codec with built-in DSP for MP3 playback

[Mark Brown]

On Mon, Mar 15, 2010 at 04:41:44PM +0000, Dajun Chen wrote:

> Thanks.

In my last reply I said "Please don't top post, lack of context makes it
difficult to follow the thread of discussion.".  This is standard
etiquette for Linux mailing lists.

> Please would you point me the place to see the TI and Intel drivers?

Search the mailing list archive to the Moorestown driver, it's been
posted here at least once.  The TI stuff is in the OMAP git trees I
believe.