tv tuner/video

Francois.CAU at Francois.CAU at
Tue Nov 23 23:45:34 EST 1999

> 1. What is the state of tv card support on LinuxPPC? I've searched the 
> linuxppc-dev logs and seen some announcements of bt848 support. 

The bttv driver (driver for bt848 based cards) is working on LinuxPPC.
> 2. The bt848 cards I've seen seems to offer v. limited real-time continuous 
> capture (320 x240 == 1/4 NTSC); I don't know if this is a limitation of the 
> chipset or the cards. I'm looking for full streaming PAL capture to memory. 
> Is this beyond the bandwidth of PCI? If so, is it usual for cards that 
> offer this to do hardware compression first?

The PCI bandwidth is large enough for video. TV applications like xawtv 
have 2 modes: 
- Overlay, where the TV card is PCI-bus-master and directly writes in the 
video memory. 
- Grabbing, where the application grabs each picture, and then displays it 
on the screen. You can even process the pictures before displaying them.

The bottle-neck for continuous capture of un-compressed, full-size video 
comes from the hard-disk.


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