[mythtv] 3 Channels Simultaneously, just expand with a DSP
mbox at cloppy.net
mbox at cloppy.net
Wed Feb 5 16:50:40 EST 2003
I expect to, other do, why would one do that?
Isn't it common to watch a channel whilst recording another one? Then we should
be able to run record+liveTV, those are 2 channels.
Whilst ads pop out, one may want to zap and delay liveTV. There would be the
need for 3rd channel abord?
3 data streams may then be the minimal. We may even expect a 4th stream if we
consider managing data in the background (e.g. mp3, DivX or SVCD generation) or
video editing (camera stream, ads cut-out, ...).
So some people may enjoy to handle up to 3-4 data streams on a single box (or
shared on back/front end).
For the time being I forgot dual CPU box (too loud, too hot) and will not start
with back/front ends (too expensive assuming this back end should be a fast
dual CPU). Did anyone think about pluging in some dedicated MPEG DSPs in a free
Take a look at the linux parallele processing FAQ, chapter 5.2, "Did You DSP
Take a look at commercial PVRs, commercial set top boxes, chips and
architectures designed for such intesive video applications: they are all build
around grabber/DSP/PCI chipets. We have grabbers and PCI slots, we need DSPs :-)
This is an example of what is required to speed up real time MPEG
compression/conversion, a huge 4 GFLOPS/6400 MIPS CPU expansion:
That one may cost several $10.000... We just have to find out who designed the
affordable and documented PC compatible DSP board?
The CPU will then just have to handle data exchanges accros PCI bus, boards,
drives and network. Further advantage would be DSP code, codecs being
accessible to GNU community and MythTV quality not being dependant of hardware
and hardcoded bundled TV/DSP boards.
Could anyone dig out such a DSP board, inexpensive (the chip itself, RISC or
FPGA, costs around $25 for q25.000), with linux drivers for realtime video
streams processing? Is any one close to and may contact Analog, Cyrix, Texas or
Please, put that DSP on the wish list, your PII 800MHz will enjoy such
You will think I'm dreaming but I often noticed what I dreamed about is
downloadable somewhere from internet :-)
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