[Qemu-devel] esd audio output patch and debuging.

[Frederick Reeve]

Hello.

Attached you will find a patch for esd audio support in QEMU.  It is more or 
less a large modification of audio/wavaudio.c. The patch will apply against the 
latest tarball release http://fabrice.bellard.free.fr/qemu/qemu-0.8.2.tar.gz 
(0.8.2 at the time of this writing).  You will of course need libesd to compile 
this.  To apply and test on linux/*nix simply:

$ cd qemu-src-dir
$ patch -Np1 -i path/to/patch/file
$ ./configure --enable-esd
$ make
$ sudo make install
$ export QEMU_AUDIO_DRV=esd
$ qemu (your options here) -soundhw es1370

You will also need to make sure esd is running when you do that of course.  
Sorry if that is insulting your intelegence.  I just wanted to make everything 
very clear.

Now, I would not have you thinking this patch is a ready to go.  I am writing 
this email because I am having a little trouble with this.  It outputs sound 
fine but it produces artafacts.  I'm not sure of the cause.  Though I think it 
may have to do with frame alignment or with the conversion process (see code).  
It sounds like its clipping at high sample volume but this is the first time I 
have done anything with audio programing.  I had planed to submit a completed 
patch but...  anyway if anyone can point me in the right direction I would 
appreciate it.  Alternately if you just want to fix it that would be great to. 
:-)

Just a note also on esd as far as I can tell it only supports 8 and 16 bit 
unsigned.

You may be wondering why with all the sound support options qemu has that I 
would want to write another one.  Here is the logic.  I am running an LTSP 
server setup.  The servers I use have no sound card at all.  Yet all the 
programs run on that server.  The clients however have sound cards.  None of 
QEMUs sound outputs will work without a sound card with the exeption of wav.  
None of QEMUs sound outputs can be broadcast over a network to clients but esd 
can.  In short esd support allows me to run many QEMU copies on a server and 
output the audio to client terminals with out the server even having a sound 
card.  esd is old but its about the only well supported option for network 
audio output in both linux distros and LTSP.

Background:  I am maintaining LTSP servers for small elementy schools with "no 
budget".  I currently maintain these networks for free to help with education 
though they may be offering me a job in the future.  The teachers require a 
small few windows programs that do not run under wine.  So I pipe qemu over the 
thin terms and use gdm so when they log into a qemu session it just pulls up 
windows full screen.  Howerver they have resently needed sound and yes they 
actualy need it (though I whish I could say they didn't).  School will be 
starting on september 4 and I am trying to be ready.

Anyway if you have any questions or I can help at all let me know.
If you can see what is wrong or have sugestions I welcome help.  Also if you 
know of a better way that I would be happy to here it but after looking at our 
situation I think this sound module is the path of least resistance.

I thank you also for QEMU it has been a huge boon to the schools.

Thanks

Frederick

qemu-0.8.2-esd.patch
Description: Binary data