[alsa-devel] Still have choppy audio using 1.0.17

[Gustavo da Silva Serra]

Is it possible to detect this situation with alsa API, i.e., at 
application level?

Thanks.

Gustavo da Silva Serra escreveu:
> I have discovered something else: I am display the current buffer 
> pointer (capture pointer and buffer pointer), when choppy audio occurs 
> the playback pointer is printed as a given value and, after, the capture 
> pointer has the same value. For example, a normal situation would be:
>
> Playback pointer: 3000
> Capture pointer: 1000
> Playback pointer: 4000
> Capture pointer: 2000
> Playback pointer: 0000
> Capture pointer: 3000
>
> A choppy audio situation would be:
>
> Playback pointer: 3000
> Capture pointer: 3000
> Playback pointer: 4000
> Capture pointer: 4000
> Playback pointer: 0000
> Capture pointer: 0000
>
> The following situation is NOT choppy:
>
> Capture pointer: 3000
> Playback pointer: 3000
> Capture pointer: 4000
> Playback pointer: 4000
> Capture pointer: 0000
> Playback pointer: 0000
>
> Thanks any reply.
>
> Gustavo da Silva Serra escreveu:
>   
>> I am tracing aloop execution and the choppy audio happens when an 
>> application (capture or playback) opens the device while another one is 
>> capturing or playing. It seems to me, I may be completely wrong, that 
>> the problem could be a synchronization issue (a critical region with no 
>> mutexes, for instance). I analysed the sound wave with Audacity while in 
>> choppy audio condition and I realized that there are silent gaps, 
>> miliseconds with no sound at all (as if some buffer pointer was lost, 
>> for example).
>>
>> I haven't received any answer from you =(
>> What do you think that is happening?
>>
>> Thanks in advance.
>>
>> Gustavo da Silva Serra escreveu:
>>   
>>     
>>> I have been trying for many weeks to solve this problem, but with no 
>>> success. After updating to Alsa 1.0.17, which include changes to aloop, 
>>> I still have choppy audio. I will try to summarize what happens:
>>>
>>> - I need to use aloop, if I change to a sound card all the problems are 
>>> gone;
>>> - After some time of continuous play, applications start to reproduce 
>>> choppy audio. Choppy audio doesn't happens all the time;
>>> - If I repeatedly start and stop my sound capture application choppy 
>>> audio occur sooner;
>>> - Start/stop my application restores the sound quality (after some tryies);
>>> - This happens with ALSA applications (xine, vlc) and OSS emulated;
>>> - I have tryied many period_size and buffer_size in asound.conf, now I 
>>> am using 960 for period and 3840 for buffer. As I decrease period size, 
>>> the audio quality improves, but choppy audio still happens;
>>> - I test for overrun but no errors occur.
>>> - I am using block mode, interleaved, 44100, 16 bit, 2 channels
>>> - I am using dmix, dsnoop, removing them does not correct the audio
>>>
>>> These are some of the information I have, I don't know if is is enough. 
>>> If necessary I can provide any other information.
>>> What do you suggest that I do? Are there any known issues or 
>>> configuration requirements?
>>>
>>> Thanks in advance.
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>>>   
>>>     
>>>       
>>   
>>     
>
>
>   


-- 
Gustavo da Silva Serra        gustavo.serra at tet.com.br
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