Re: Still have choppy audio using 1.0.17

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

If I keep the difference between the playback and capture pointers at 
one period, no choppy audio occurs. If the difference is 0, 2 or 5 
periods for example, choppy audio will always occur. Any ideas why?


Gustavo da Silva Serra escreveu:
> 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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>>>> Alsa-devel@alsa-project.org
>>>> http://mailman.alsa-project.org/mailman/listinfo/alsa-devel
>>>>
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>>>>
>>>>   
>>>>     
>>>>       
>>>>         
>>>   
>>>     
>>>       
>>   
>>     
>
>
>   


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