Re: Application hangs with different period sizes

[Gustavo da Silva Serra <gustavo.serra@tet.com.br>]

Sorry, I didn't read the log.

I don't know where you can find this limitation, the only thing I know 
is that a specific model of Audigy, for example, seems to support only 
two periods.
Can't you just use 1024 or 512? I don't know why the application 
crashes, it is something that is beyond my knowledge, sorry.


anuj aggarwal escreveu:
> I think the library/driver is able to configure the way user has 
> requested. See the logs (in my first mail) which confirm that the 
> requested period size has been taken for configuration.
>
> Where can I found the limitation in the driver code/spec which says 
> that these period sizes are not supported? Any suggestion is most 
> welcome...
>
> Thanks,
> Anuj
>
> On Thu, Jul 3, 2008 at 6:30 PM, Gustavo da Silva Serra 
> <gustavo.serra@tet.com.br <mailto:gustavo.serra@tet.com.br>> wrote:
>
>     I think that snd_pcm_hw_params_set_period_size_near() will not
>     return an error, but you must check the "val" parameter, is it
>     returning the same value that you passed?
>
>     "Some periods are not supported" means that some cards may not
>     support periods that aren't power of two. I am not sure, since I
>     am new to ALSA and I am working most with aloop.
>
>     anuj aggarwal escreveu:
>
>         I am doing the same. I used
>         snd_pcm_hw_params_set_period_size_near() to set the period
>         size and checked the return value also; it was not an error.
>
>         I have one more question. When you say 'Some periods are not
>         supported', what does that mean? What are the constraints
>         which make some periods not-supported by the audio codec driver?
>
>         On Thu, Jul 3, 2008 at 5:11 PM, Gustavo da Silva Serra
>         <gustavo.serra@tet.com.br <mailto:gustavo.serra@tet.com.br>
>         <mailto:gustavo.serra@tet.com.br
>         <mailto:gustavo.serra@tet.com.br>>> wrote:
>
>            Do you check the result of the function that sets the
>         period size?
>            Some periods are not supported and you can't assume that
>         they are
>            valid and proceed in your application. Use
>            snd_pcm_hw_params_set_period_time_near to see what is the
>         nearest
>            possible value for period.
>          
>          <http://www.alsa-project.org/alsa-doc/alsa-lib/group___p_c_m___h_w___params.html#gf5e53bcb748185a4da3b8538720a5792>
>
>            anuj aggarwal escreveu:
>
>                My audio driver supports buffer sizes from 128 to 32768 and
>                period sizes
>                from 8 to 2048. I am trying to set the period size as 1030
>                (just a random
>                number between 8 & 2048, but not multiple of 2^n) and
>         buffer
>                size as
>                16*buffer_size (i.e. 16480). The output is as follows:
>
>                Buffer size range from 128 to 32768
>                Period size range from 8 to 2048
>                Request period size 1030 and got 1030
>                Plug PCM: Hardware PCM card 0 'TWL4030' device 0
>         subdevice 0
>                Its setup is:
>                 stream       : PLAYBACK
>                 access       : RW_INTERLEAVED
>                 format       : S16_LE
>                 subformat    : STD
>                 channels     : 2
>                 rate         : 44100
>                 exact rate   : 44100 (44100/1)
>                 msbits       : 16
>                 buffer_size  : 16480
>                 period_size  : 1030
>                 period_time  : 23356
>                 tstamp_mode  : NONE
>                 period_step  : 1
>                 avail_min    : 1030
>                 start_threshold  : 16480
>                 stop_threshold   : 16480
>                 silence_threshold: 0
>                 silence_size : 0
>                 boundary     : 1080033280
>
>                The problem with this setup is the application just hangs
>                without playing
>                anything. If I use period size as 2048, the app plays
>         the song
>                but clips the
>                last part of it. If I use 1024/512, it works fine.
>
>                I have tried alsa lib version 1.0.15 & 1.0.16 but the
>         problem
>                persists. Is
>                there anything wrong with my app or audio driver?
>
>                Please help.
>
>                Thanks in advance,
>                Anuj Aggarwal
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>
>         -- 
>         Best Regards,
>         Anuj Aggarwal
>
>
>
>
>
> -- 
> Best Regards,
> Anuj Aggarwal