Fwd: Gstreamer source code development (for SGTL5000+alsa+GStreamer)

[Sebastian Dröge]

On Do, 2015-06-04 at 19:21 +0200, Carlos de Paz wrote:

> > Dear all,
> > 
> > 
> > We are involved in a project with an embedded system based on
> > SGTL5000 audio chip.
> > So following modules are involved:
> > - SGTL5000 driver
> > - Kernel: alsa
> > - Alsa-lib
> > - GStreamer
> > - Qt app
> > 
> > 
> > We had some problems to manage the audio card (SGTL5000) from
> > GStreamer+alsamixer (amixer). For that reason me need to understand
> > GStreamer source code in more detail.
> > 
> > 
> > Basically, we see that:
> > - SGTL5000 can be configured by I2C protocol messages to set active
> > input (Line in OR Mic OR I2S_IN), internal audio switch and output
> > (Line out)
> > - GStreamer "takes" audio input by alsasrc and "puts" audio output
> > by alsasink
> > - How both match, meaning where does GStreamer "take" and "put"
> > audio samples?
> > - ISSUE When audio comes from Line in and goes to Line out, volume
> > element does nothing
> > (as if audio just flows from SGTL5000 line in to SGTL5000 line out
> > WITHOUT being processed by GStreamer (software) volume element
> > 
> > 
> > (Hope I explained right)
> > 
> > 
> > QUESTION: Is there any document describing the platform (high level
> > description) other than:
> > - Class description
> > in http://www.freedesktop.org/software/gstreamer-sdk/data/docs/2012.5/gstreamer-0.10/
> > - GStreamer Application Development Manual (0.10.36)

Everything on gstreamer.com and having the name "gstreamer-sdk" is based
on an old GStreamer version (0.10) and not the recent 1.x release
series. It also has nothing to do with the GStreamer project
unfortunately, the official website is at
http://gstreamer.freedesktop.org

There you can also find some further documentation:
http://gstreamer.freedesktop.org/documentation/

For example the Application Development Manual is a good starting point
to learn about how GStreamer works in general:
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/manual/html/index.html
and the Plugin Writer's Guide for some starter information about how to
write plugins (but read the Application Development Manual first)
http://gstreamer.freedesktop.org/data/doc/gstreamer/head/pwg/html/index.html


More low-level design documentation can be found here:
http://cgit.freedesktop.org/gstreamer/gstreamer/tree/docs/design/
and in the code.

-- 
Sebastian Dröge, Centricular Ltd · http://www.centricular.com
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