Re: [Gap-dev-discuss] Cynthiune : add an alsa backend for linux

[Sebastian Reitenbach]

 Hi Philippe

On Thursday, May 3, 2012 14:49 CEST, Philippe Roussel <address@hidden> wrote:

> Hi,
>
> Le 03/05/2012 11:17, Sebastian Reitenbach a écrit :
> >
> > On Thursday, May 3, 2012 10:19 CEST, Philippe Roussel <address@hidden> 
> > wrote:
> >
> >> Hi,
> >>
> >> Le 03/05/2012 00:40, Riccardo Mottola a écrit :
> >>> Hi,
> >>>
> >>> I commited the ALSA backend. I removed the migration/preferences stuff
> >>> because I disagree with it, but I changed the defaults and tweaked the
> >>> makefiles to isntall in the correct place.
> >>>
> >>> It appears to work for me! I get an exception and I'll track it down
> >>> hopefully, but check if what's in the repo works with you.
> >>
> >> It does, as expected :o)
> >>
> >>> Actually, with ALSA and OSS we are quite "served" as far as backends go.
> >>
> >> How about your *BSD systems ?
> >
> > I just checked and it compiles still all fine for me on OpenBSD. Still need 
> > to test
> > it though. I'm still struggling with the Sndio Output Backend, exploring 
> > multiple
> > ways to get around the issue I have.
> > Do you can send the libao backend you wrote? If the libao backend works
> > reliably, then I think it would be the preferred way to go for OpenBSD, and
> > maybe other *BSD for the time being. I still can work/experiment with the
> > Sndio backend, but would have much less pressure to get it done ;)

>
> Here's what I sent Riccardo off list.
>
> Let me know of this works for you.

I tested on OpenBSD, and it generally works. But it seems, you are facing 
exactly the same problem
like I do. I tested playing FLAC and MP3 files, works well. But I have one FLAC 
file in my playlist
which has a bit rate of 16000Hz, all the other MP3 files have 44100Hz.

When the sound output is stopped, and I just double click the FLAC file or any 
MP3, it starts
playing that file, with the right bit rate.
But when the playlist is playing, and it jumps from a 44100Hz MP3 to the 16000 
FLAC file,
then the FLAC file is played too fast. When I start playing music by double 
clicking the 16000Hz
FLAC file, and it then jumps to the 44100Hz MP3, the MP3 is played too slow.
I added a NSLog in the metthod like this:

- (BOOL) prepareDeviceWithChannels: (unsigned int) numberOfChannels
                           andRate: (unsigned long) sampleRate
{
NSLog(@"prepareDevice: Channels: %u rate: %lu", numberOfChannels, sampleRate);
  format.channels = (int)numberOfChannels;
  format.rate = (int)sampleRate;
...


and on the console, I see, when it automatically jumps to the next song, the 
method is called
with the right bit rate, but the rate is not changed correctly while the play 
thread is still running.

I thought about using a lock, so that in the playing thread, so the 
prepareDeviceWithChannels
creates a lock to pause the playing thread. Then when this thread is paused 
playing, it makes the
changes to the bit rate, and maybe channels, and then the lock will be opened 
again, and
then the play thread will start playing again. But I haven't yet figured out, 
how to get that right,
since I still run into race conditions between the threads.

The test FLAC file I use can be found here.
http://code.google.com/p/cs-4244-mkl/source/browse/trunk/project-4/GSTT/mike-test.flac?r=202

cheers,
Sebastian

>
> Thanks,
> Philippe