[alsa-devel] Still have choppy audio using 1.0.17

[Gustavo da Silva Serra]

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.
>> _______________________________________________
>> Alsa-devel mailing list
>> Alsa-devel at alsa-project.org
>> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
>>
>> __________ NOD32 3191 (20080616) Information __________
>>
>> This message was checked by NOD32 antivirus system.
>> http://www.eset.com
>>
>>
>>
>>   
>>     
>
>
>   


-- 
Gustavo da Silva Serra        gustavo.serra at tet.com.br
———————————————————————————
Tools & Technologies - T&T Engenheiros Associados Ltda.
Projetos de SW & HW - Desenvolvendo soluções.
Rua Riachuelo, 1098 Conj. 1204
Centro - Porto Alegre - CEP 90010-272
Fone DDR: (51)3220-3290
Fone/Fax: (51)3220-3220 / 3220-3206
http://www.tet.com.br/                                             tet at tet.com.br