[LAU] Phonic Helix Board 24 on Fedora

Pieter Palmers pieterp at joow.be
Tue Feb 17 16:36:00 EST 2009

Fernando Lopez-Lezcano wrote:
> On Tue, 2009-02-17 at 19:45 +0100, Pieter Palmers wrote:
>> Fons Adriaensen wrote:
>>> On Mon, Feb 16, 2009 at 03:40:47PM -0800, Fernando Lopez-Lezcano wrote:
>>>> The issue has nothing to do with the rt patch or running with -R, it is
>>>> just the wrong (newer) firewire stack.
>>> Hmm, is that the new fireware stack that Pieter 
>>> told me about (IIRC at the door of the LAC2008
>>> LSN location) and that would actually allow to
>>> simplify FFADO ??
>> Indeed, that's the one. Unfortunately I didn't get around implementing 
>> FFADO support for it yet. Mostly due to lack of time. And because it 
>> does lack some features we need, which don't seem to be high on the 
>> priority list (e.g. support for multiple streams). Besides, the authors 
>> claim backward compatibility at the library level, i.e. libraw1394 users 
>> like FFADO shouldn't have to care.
> My experience with this is that it currently does not work. Booting into
> the new stack, even with libraw1394 2.x, breaks FFADO. It does work fine
> with the old stack (same everything else). 

Oops... after rereading my own text I realize that I left out this 
crucial bit of information. Indeed, even though the idea is that it is 
compatible, reality is that it is not.

Thanks for the clarification,


> -- Fernando
>> But shifting it all to the 1394 guys is not completely fair. I do admit 
>> that we are not very noisy towards them. I guess that once more distro's 
>> start using the new stack that will change.
>> But almost a year has passed since LAC'08 and my views on the topic have 
>> evolved a bit. While from a theoretical perspective it should be 
>> possible to implement FFADO in userspace, there are some issues that 
>> make life a bit harder than it should be. And if it were only software 
>> things I could think about fixing them. But there are also some 
>> hardware-level issues that need workarounds that can't be done in 
>> userspace. If you want more details, I suggest we discuss that at the 
>> entrance of some obscure venue in Parma ;).
>> The bottom line is that I am planning to, using the current FFADO 
>> codebase as a reference, port the streaming code to the kernel, with a 
>> direct interface to ALSA. That should bring a performance improvement 
>> too. And it will also lighten the burden of supporting the zillion audio 
>> API's Linux developers seem to need.
>> Greets,
>> Pieter

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