On Mon, 2003-07-21 at 02:36, Matthew S. Hallacy wrote:
> > Someday, when processors are running in the tens of gigahertz, dedicated
> > hardware won't be needed because the GNU Radio project will then be able
> > to decode the various modulation schemes in realtime.  But, that's quite
> > a while off..
> 
> My P233MMX can decode a 16mbit MPEG-2 stream under linux, no need for 
> any terribly high end hardware. MythTV requires more power because it's
> time shifting, so it's reading from the tuner device, encoding to mjpeg
> or divx (if it's not from a hardware encoder), and writing out to a ring 
> buffer while another thread is reading off that same ringbuffer, decoding
> it, then sending it to the video card.

Er, well, I was referring to the difficulty of demodulating digital
transmissions in 8VSB, QAM64, QAM128, etc., which is an entirely
different problem.

If MPEG2 decoding has gotten so good, I'm pretty amazed -- one of the
big reasons I had for upgrading to my 1.3GHz system (which was pretty
top-of-the-line at the time) was because I couldn't adequately play
movies on my 350 MHz AMD K6-2 (but it's entirely possible that the
Pentium chip could outperform the my old AMD chip if floating-point
decoding is used..)

> Eventually the ITVC15 MPEG-1/2 decoder on the WinTV PVR will be hashed out,
> and MythTV will be able to use it for video output, this will further lower
> the amount of CPU required for a decent PVR.

Definitely.  A user with that setup would have something very much like
a real TiVo, and I recall that they have processors in the range of
50-150 MHz (maybe a little faster).  Of course, this also means that CPU
power for doing anything else is pretty limited, and decoding most
non-MPEG1/2 material would probably be difficult.

-- 
 _  _  _  _ _  ___    _ _  _  ___ _ _  __   I saw a subliminal
/ \/ \(_)| ' // ._\  / - \(_)/ ./| ' /(__   advertising executive, but
\_||_/|_||_|_\\___/  \_-_/|_|\__\|_|_\ __)  only for a second.
[ Mike Hicks | http://umn.edu/~hick0088/ | mailto:hick0088 at tc.umn.edu ]
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