-----Original Message----- From: stan <ghjeold_i_mwee@xxxxxxx> To: Sergei Steshenko <steshenko_sergei@xxxxxxx> Date: Tue, 01 Jul 2008 06:50:50 -0700 Subject: Re: which are the ieces of ALSA source code responsiblefor setting sample rate ? > > Sergei Steshenko wrote: > > Hello All, > > > > as already known, I am one of those who advocate the possibility to mandate sample rate and not let applications to change it. > > > > I think a possible, though ugly, solution is like this: > > > > 1) to locate pieces of ALSA code responsible for setting sample rate; > > 2) to change (in my own copy) the pieces so they would know only one sample rate; > > 3) to compile and install the modified code. > > > > I also think that I would like to have an ALSA snapshot per sample rate and will uninstall/install the snapshot I need > > - most likely the two most used will be for 44100Hz and 48000Hz sample rates. > > > > So, which are the pieces ? > > > > Thanks, > > Sergei. > > > > > Why not write a small program that calls the alsa interface and sets the > rate to whatever you want. This must be how the applications you are > concerned about are doing it. The api call is snd_pcm_hw_params_set_rate. > > From the alsa-project api > > int snd_pcm_hw_params_set_rate ( snd_pcm_t > <http://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m.html#gb5676348e7618b444e28907607660cef> > * /pcm/, > > > snd_pcm_hw_params_t > <http://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m.html#g232a2e2b6bb7bb2dca2885eec2e095b3> > * /params/, > > > unsigned int /val/, > > > int /dir/ > > ) > > > > Restrict a configuration space to contain only one rate. > > *Parameters:* > > /pcm/ PCM handle > > /params/ Configuration space > > /val/ approximate rate > > /dir/ Sub unit direction > > *Returns:* > 0 otherwise a negative error code if configuration space would > become empty > > Wanted exact value is <,=,> val following dir (-1,0,1) > > As was many times explained in this list, applications can change the rate. So, if I write and run such a program, and then start an application that can change sample rate, it will, and this is what I want to avoid. I was thinking of modifying the piece of code which reports audio card capabilities - if such a piece exists. For each version (for each sample rate) the piece of code will report just _one_ sample rate, so hopefully the rest of ALSA won't even try to set a different sample rate. Thanks, Sergei. ------------------------------------------------------------------------- Check out the new SourceForge.net Marketplace. It's the best place to buy or sell services for just about anything Open Source. http://sourceforge.net/services/buy/index.php _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
