Re: [AD] Audio addon API / Re: Renaming of functions in kcm_audio addon

[Evert Glebbeek <eglebbk@xxxxxxxxxx>]

On 26-Nov-08, at 10:55 PM, Peter Wang wrote:
> On 2008-11-26, Evert Glebbeek <eglebbk@xxxxxxxxxx> wrote:
> > 1. Rename al_load_sample -> al_load_sample_data()
>
> Ok.

Done.

> I'm not sure it's quite right.  Most games like to play multiple
> instances of the same sample data simultaneously, e.g. gun shots.

Right. Hadn't thought of that, or rather, I hadn't considered that  
that wouldn't be possible. That is a bit of a pain. Actually, how does  
one play multiple instances of the sample at a time through A5's API?  
You cannot attach the same ALLEGRO_SAMPLE to more than one mixer at a  
time and calling al_play_sample() again seems to reset the voice to  
the beginning of the sample rather than play a new instance of it  
(from looking at the code, I haven't actually tried this yet).

> 2. Have a function that creates and plays an ALLEGRO_SAMPLE from an
> ALLEGRO_SAMPLE_DATA, attaching it to the default mixer.

al_play_sample_data(ALLEGRO_SAMPLE_DATA*)?

> 3. Allow ALLEGRO_SAMPLEs to be "detachable", i.e. automatically
> destroy themselves when finished playing.  Only non-looping samples  
> can
> be detached.  Maybe the function for (2) should always create detached
> samples.

One minor problem with this: the sample would need to be destroyed by  
the function that monitors playing samples, but that's specific to  
each driver. In other words, every driver would have to check whether  
the sample has to be destroyed and do that when necessary. It  
shouldn't be necessary to do that on the level of each driver. The  
pain can be eased somewhat by making a function  
"_al_destroy_detachable_sample()", but it's still a bit ugly.

Instead, maybe al_play_sample_data() should create a new thread where  
a new sample is created from the sample data, the sample is played  
(the thread rests until it is done playing) and then destroyed. It's a  
bit hackish though.

One snag: with such a system, how would one check whether the sound is  
still playing? You can't query an ALLEGRO_SAMPLE_DATA object and the  
ALLEGRO_SAMPLE is hidden from the user.

> 4. When the audio addon is shut down, samples should automatically be
> destroyed.  When Allegro is shut down, sample datas should  
> automatically
> be destroyed.

Yes.

Evert