[LAD] mixing while using libao and libsndfile

Paul Davis paul at linuxaudiosystems.com
Tue May 17 12:08:00 UTC 2016


Your design is way too simple and fundamentally wrong.

If you want low latency you need to use a pull model (aka callback model)
for audio i/o to the device. Let the device tell you when it wants audio
data, and deliver it,on time, without blocking (which means no on-demand
file i/o in the same thread as the device audio i/o). See
http://www.rossbencina.com/code/real-time-audio-programming-101-time-waits-for-nothing

On Tue, May 17, 2016 at 4:26 AM, David Griffith <dave at 661.org> wrote:

> On Tue, 17 May 2016, Andrea Del Signore wrote:
>
> On Tue, May 17, 2016 at 12:25 AM, David Griffith <dave at 661.org> wrote:
>> On Mon, 16 May 2016, Andrea Del Signore wrote:
>>
>> > I'm not simply trying to mix two files.  My main project is a
>> > game engine in which two sounds are allowed at any one time.
>> > For instance, there can be constant background music punctuated
>> > by sound effects.  I can't get these to mix correctly.
>>
>> Hi,
>>
>> in that case you can just skip the right number of frames before starting
>> playing sounds.
>>
>> I modified my code to take the start time for each file and schedule the
>> play time with frame accuracy.
>>
>> http://pastebin.com/0PMyfPvK
>>
>> If you want your timing to be sample accurate the algorithm is a bit more
>> complex.
>>
>
> That won't work.  Your code schedules things ahead of time before anything
> else happens.  I need to be able to fire off sound effects the instant the
> player does something to cause them.  I can't know in advance.
>
> --
> David Griffith
> dave at 661.org
> _______________________________________________
> Linux-audio-dev mailing list
> Linux-audio-dev at lists.linuxaudio.org
> http://lists.linuxaudio.org/listinfo/linux-audio-dev
>
>
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