[pulseaudio-discuss] Sample format of default source

Magnus Hjorth magnus.hjorth at home.se
Wed Mar 18 13:52:26 PDT 2009

Lennart Poettering wrote:
> On Mon, 16.03.09 20:14, Magnus Hjorth (magnus.hjorth at home.se) wrote:
>> Hi,
>> I'm trying to find a way in libpulse to query the sample format of the  
>> default source. Passing NULL to pa_context_get_source_info_by_name does  
>> not seem to work ("invalid argument").
> Hmm, why would you want to query this? Smells like you are working on
> some racy code.
I'm aware that this is racy, and a check again after recording has 
started (using pa_stream_get_index and pa_context_get_source_info) is 
needed to verify that that this hasn't changed.

What I'm doing is, I'm writing a PulseAudio driver for my sound file 
editor, and for recording I want to do the following:

- Get a list of supported recording format(s) before recording starts. 
This is what the above is for.

- Start recording with one of the supported formats. At this point, a 
check that the supported format hasn't changed is made.

- Make sure as far as possible that the format corresponds to the actual 
format of the input, so we're not actually recording 8 kHz mono when we 
think we're recording in high quality, for example.

> Try passing "@DEFAULT_SOURCE@" as sink name in pa_context_get_source_info_by_name().

Best regards,

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