[linux-dvb] Re: LinuxDVB V4 API questions II

[Johannes Stezenbach <js@convergence.de>]

On Tue, Apr 06, 2004 at 06:12:30PM +0200, Michael Hunold wrote:
> On 04/06/04 12:39, Alasdair FARMER wrote:
> 
> >2) Audio implementation.  I am curious why you have decided to implement
> >an Audio API rather than adopt the decoder / renderer separation that 
> exists
> >for video.
> 
> Hm, do you really think that the current approach is really a 
> full-featured audio API?
> 
> >As there are a number of well defined API's to support 
> >video/graphics rendering it makes sense to decouple the presentation 
> of the
> >data from the LinuxDVB API and leave it up to the decoder.  So, following
> >that line of reasoning, why was the same approach not taken with audio ? 
> >There are a number of well defined Audio presentation/rendering API's 
> available
> >- for example the ALSA API.  It would seem to make more sense - less work
> > and for a more coherent and holistically consistent solution to leave the
> > presentation of the audio to the audio API's...
> 
> IMHO the audio part was designed to only provide access to the audio 
> features that are special to an MPEG audio decoder without having to 
> hassle with other sound subsystems.
> 
> For a full-featured STB you'll need to implement ALSA or OSS access 
> anyway, the audio API is no replacement for that. In that case you can 
> simply start/stop the decoder via DVB, but need to access everything 
> else via ALSA.

It is actually just the opposite.

We used OSS for mixer control in a simple STB, and
evaluated OSS and ALSA for possible use in advanced
STBs. However, OSS is too limited and ALSA too involved :-(
(like PCM recording and MIDI sequencer support, a large
userspace library which supports format conversions and tons
of stuff...)

The current V4 draft tries to match the features present
in some of todays STB chips. The goal is DVB-application
portability. If it were possible to use OSS to implement
all necessary mixer stuff for the STB chips in question I
would do it. But ALSA is IMHO not an option for embedded stuff.

I wish someone would prove me wrong.


Regards,
Johannes


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