Re: Why use more than 2 buffers?

Chris Robinson wrote:
> On Thursday 10 December 2009 2:31:16 pm Nate Foreman wrote:
>   
>> We all know that OpenAl sources are capable of queuing multiple buffers
>> for playback.  The question is, why would you ever need to queue more
>> than 2 buffers at a given time?  Aren't two buffers sufficient for the
>> double-buffering technique used to continuously streaming audio data?
>>     
>
> It depends on how your code is structured and the app's needs. When streaming 
> compressed files, it could help to have smaller buffers so you don't waste too 
> much time decoding a large chunk during a frame. It also helps to buffer in 
> small amounts if you need to regularly check on other components of the app 
> and can't wait too long to fill in more data. And it usually helps to have a 
> significant length of audio buffered so the source won't accidentally stall if 
> you can't process the queue in time. The smaller the buffers are, the more 
> you'll need to protect against stalls.
>   

I tried for quite a while to get a VoIP-type application working with 
two buffers, but still have an acceptable latency.  Plus, with two 
fixed-sized buffers, it was difficult to figure out what to do when you 
ran out of incoming audio.  Did they stop talking (in which case I 
should fill the rest of the buffer with silence and queue it), or is 
there just network congestion (in which case I should wait for more data 
and restart the stream when I get it).

Ultimately, it was much simpler (and much cleaner code) to just 
allocate, fill, and queue a buffer for each packet of audio, and then 
unqueue and delete it when it was done.  Possibly less efficient, but 
much easier to read, maintain, and modify.

--"J"

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