the thing that looks like bad API design is that snd_pcm_sw_params_current() exists and snd_pcm_hw_params_current() does not. I think it wouldn't even hurt if snd_pcm_hw_params_t would be cached in the lib for that. Maybe in a later ALSA revision, ALSA kernel support for that could be implemented.
Thanks, Florian Takashi Iwai wrote: > > At Fri, 04 Oct 2002 11:04:23 -0700, > Florian Bomers wrote: > > > > Jaroslav Kysela wrote: > > > > > > On Thu, 3 Oct 2002, Florian Bomers wrote: > > > > > > > Hi, > > > > > > > > there is snd_pcm_sw_params_current() but not snd_pcm_hw_params_current(). How > > > > can I get the current hardware configuration for a given snd_pcm_t handle ? Am >I > > > > missing something ? > > > > > > Hardware parameters must be configured from application all time. > > > > So that means that I need to cache hw params if I ever want to use them again ? > > E.g. my app does this: > > > > open(), set hw params, set sw params > > free hw params and sw params to save memory > > > > work with the device: start/write/stop/etc. > > > > When I now want to know the buffer size, I would like to obtain the current hw > > params which I had set above to the pcm handle. > > > > I understand that I initially need to set hw params to a pcm handle before I > > could get current hw params, but once I did that, especially in prepared/running > > state, the device has well-defined hw params and why shouldn't people be allowed > > to query them ? > > simply because the query function is not implemented on the kernel > side :) > > or, we can add the code to alsa-lib to duplicate the hw_params / > sw_params privately, and returns it via the query function. > but it's not much different fromt keeping hw_params or sw_params > record in the application by yourself. > > please note that on the kernel, hw_params and sw_params are not stored > as they are but their members are copied to runtime struct. so if the > query api is implemented, we need a function to convert from runtime > to hw_params or sw_params. > > Takashi > > ------------------------------------------------------- > This sf.net email is sponsored by:ThinkGeek > Welcome to geek heaven. > http://thinkgeek.com/sf > _______________________________________________ > Alsa-devel mailing list > [EMAIL PROTECTED] > https://lists.sourceforge.net/lists/listinfo/alsa-devel -- Florian Bomers Java Sound Java Software/Sun Microsystems, Inc. http://java.sun.com/products/java-media/sound/ ------------------------------------------------------- This sf.net email is sponsored by:ThinkGeek Welcome to geek heaven. http://thinkgeek.com/sf _______________________________________________ Alsa-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/alsa-devel
