[gstreamer-bugs] [Bug 315121] alsasink doesn't work unless passing hw:0

[GStreamer (bugzilla.gnome.org)]

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 GStreamer | gst-plugins | Ver: 0.8.10





------- Additional Comments From Tim-Philipp Müller  2005-10-07 19:09 -------
I've looked into this a bit and it looks to me like there are basically two
kinds of problems:

 (a) probing the 'default' device often returns useless values (if there's a
     plug layer it will claim to support any format it can convert into a
     supported hardware format, which is more or less anything; oh, and it
     reports values like max_channels=10000 and stuff like that; probing a
     specified device (hw:0, dmix:0) gives more realistic and useful results)

 (b) I think there's something not quite kosher in how we use period_size.
     This pipeline for example doesn't work right 

        sinesrc ! audio/x-raw-int,rate=22050 ! alsasink device=default

     It gives intermittent/distorted sound output on both my desktop 
     (via6x6 card) and the laptop (intel8x0).

     Using the same value for period-size that is returned by 

       snd_pcm_hw_params_get_period_size()

     makes things work for me. This value tends to be lower than the value
     of 8192 that we use as default value (this is usually the case for other
     rates/configurations as well).
     I'm not really sure what the significance of this value is, but maybe
     we should have a -1 default value here (=use what's returned by the above
     function) and only configure a fixed value if the user explicitely set it.


I've got somewhat ugly patches for both of these that need some cleaning up and
will put together a small test application that tests a variety of output
formats, so we can easily test these and other possible fixes on a variety of
hardware.

Just as a random update.


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