[linux-dvb] Re: Adding V4L interface to budget cards

[Michael Hunold <hunold-ml@web.de>]

Hello Rene,

> after reading documentation of new FFMPEG 0.4.6 I got the idea to add a
> libavfomat-based V4L-device to the DVB-driver, which decodes TS to standard
> YUV (or whatever is used on the V4L-interface).
> 
> This would allow programs like XawTV to watch TV without having a own
> MPEG-TS decoder. Standard TV-software could handle the DVBs like a analogue
> TV-card (except tuning-parameters, of course).
> 
> Comments?

Bad idea -- you basically just move around the MPEG-TS decoder from 
userspace to kernel space, which is generally a "bad idea"[tm].

The decoding is time-consuming and sometimes error-prone, so you better 
leave it in user-space, really. You would have to deal with far too much 
stuff in that poor little kernel module...

Why don't you use something like this to watch tv?
 > cat /dev/dvb/adapter0/dvr0 | ts2ps 0 0 | mplayer -

It gives you the same functionality as using "xawtv"...

> Rene

What you could do, however, is use "fusd":
http://www.circlemud.org/~jelson/software/fusd/

Quote from their homepage:

 > FUSD (pronounced fused) is a Linux framework for proxying device file
 > callbacks into user-space, allowing device files to be implemented by
 > daemons instead of kernel code. Despite being implemented in
 > user-space, FUSD devices can look and act just like any other file
 > under /dev which is implemented by kernel callbacks.

So you could basically put the "ts2ps" and ps-to-yuv/rgb conversion into 
  a fusd-driver and provide a Video4Linux-compatible /dev/video device 
like this, if you really want to.

CU
Michael.





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