On Fri, 16 Mar 2018 11:17:19 +0100, Oleksandr Andrushchenko wrote: > > +Konrad > > On 03/15/2018 10:29 PM, Takashi Iwai wrote: > > On Thu, 15 Mar 2018 14:39:33 +0100, > > Oleksandr Andrushchenko wrote: > >> On 03/15/2018 03:23 PM, Takashi Iwai wrote: > >>> On Thu, 15 Mar 2018 13:20:14 +0100, > >>> Oleksandr Andrushchenko wrote: > >>>> On 03/15/2018 01:59 PM, Takashi Sakamoto wrote: > >>>>> Hi, > >>>>> > >>>>> On Mar 15 2018 19:45, Oleksandr Andrushchenko wrote: > >>>>>> Is it possible for user-space to reduce configuration space > >>>>>> with snd_pcm_hw_params_set_rate_minmax and then change it > >>>>>> with another snd_pcm_hw_params_set_rate_minmax with values > >>>>>> out of the reduced config? > >>>>>> > >>>>>> For example, the initial min/max is 44100/48000 and I set 44100 > >>>>>> first, e.g. > >>>>>> > >>>>>> snd_pcm_hw_params_set_rate_minmax(handle, hw_params, 44100, 0, 44100, 0) > >>>>>> > >>>>>> and then want > >>>>>> > >>>>>> snd_pcm_hw_params_set_rate_minmax(handle, hw_params, 48000, 0, 48000, 0) > >>>>>> > >>>>>> Obviously, the last call fails as we have already a reduced > >>>>>> space of [44100; 44100]. > >>>>>> > >>>>>> Is there a way I can still set the range to [48000; 48000]? > >>>>>> > >>>>>> Thank you, > >>>>>> Oleksandr > >>>>>> > >>>>>> P.S. This is in context of work done for [1] > >>>>>> > >>>>>> [1] https://www.spinics.net/lists/alsa-devel/msg75382.html > >>>>> We can't. Once shrinking available interval of a parameter, we cannot > >>>>> expand it again without initializing the parameter on memory object for > >>>>> 'struct snd_pcm_hw_params_t', in which actual layout is never disclosed > >>>>> to user applications. > >>>> So, this effectively means that this is a one way road, if you need to > >>>> change > >>>> some parameter you'll need to start all over, so the whole configuration > >>>> space remains consistent :( > >>> Yes, that's the design. The only way to expand is to reset the whole, > >>> space and reduce again to the given size. > >>> > >> Clear, thank you > >>>>> If you can initialize whole the parameters, snd_pcm_hw_params_any() is > >>>>> available for your purpose, then set min/max rate again. > >>>> This is what I do now but... > >>>>> But just for > >>>>> one of the parameters, in my opinion, we need to open an internal > >>>>> API; snd_pcm_hw_param_any()[1]. > >>>> IMO, this will lead to the false assumption that configuration is possible. > >>>> For example, I set 4 channels and 44100, but then, after > >>>> snd_pcm_hw_params_any, > >>>> set 48000 and might assume that the configuration is still > >>>> possible. But this may not > >>>> be true: it is true for the configuration returned by snd_pcm_hw_param_any > >>>> as we don't know about 4 channels yet. But might not be allowed if we > >>>> want 4 channels > >>>> and 48000 at the same time. > >>> Right. At the point where snd_pcm_hw_params_any() is called, the > >>> whole configuration gets reset. That's the reason I thought we may > >>> need to pass all 5 parameters in the query protocol. > >> Yes, I now start thinking of the same, e.g. if we pass > >> all 5 parameters (mask for formats and intervals for rate, channels, > >> buffer and period), then on backend side I can do something like: > >> > >> 1. snd_pcm_hw_params_any > >> 2. snd_pcm_hw_params_set_format_mask > >> 3. snd_pcm_hw_params_set_rate_minmax > >> 4. snd_pcm_hw_params_set_channels_minmax > >> 5. snd_pcm_hw_params_set_buffer_size_minmax > >> 6. snd_pcm_hw_params_set_period_size_minmax > >> > >> So, when finished the above confirms that configuration is possible. > >> The only concern here is that so many calls on backend side > >> might introduce start-up latency on frontend side though > >> > >>> IOW, the query stuff won't be modal, it just tries to reduce the given > >>> configuration space to the acceptable ranges. > >> Do you think the above solution with 5 parameters and the > >> corresponding snd_pcm_hw_params_set_xxx calls will do? > > I guess so, but let's model & test :) > I did some testing: > - frontend driver [1] > - sndif protocol [2] > - backend changes [3] > > All seem to work now when I pass all 5 parameters while querying. > The only scary thing is that I had to change the size of > requests/responses in the sndif protocol from 32 to 64 bytes :( You may split the protocol from a single shot to a sequence, too, if the size really matters :) > Takashi, could you please have a quick look and tell me if > this is what you expect? Through a quick glance, it looks good to me. If it works, even better. thanks, Takashi _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxx http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
