[alsa-devel] Application hangs with different period sizes

[anuj aggarwal]

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 at 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 at tet.com.br <mailto:gustavo.serra at 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