[wellylug] Video Catpure device in Linux

[Ewen McNeill]

In message <429BBFA8.1020000 at archnetnz.com>, Chris Hodgetts writes:
>Pentium III - 500mhz machine, (from /proc/cpuinfo - 448.058)  [...]
>If the encoding is done in Software then his box will not be fast enough 
>to do real-time encoding will it? 

No, a Pentium III/500 MHz wouldn't be fast enough to do full frame MPEG
encoding in real time.   My 2.1GHz Athlon (Athlon XP 2700+) manages full
frame MPEG encoding in about "time and a half" (and of course nearly
twice as long as that if doing two passes).  I tend to record with something
more real-time suitable, and then reencode as a batch ("at") job if
necessary.

You might manage to get away with it if you were to use, eg, 1/4 frame,
and perhaps skip frames, but it'd still be fairly tight.  And skipping
frames can look a bit ugly.

A card that does the encoding in hardware will work well in a lower
powered machine.  But you end up encoding precisely what you receive,
rather than getting to do any cleanups prior to encoding.  (Eg, I've
found the actual used size of TV transmissions varies quite a bit, so it
can be handy to crop off the blank edges before encoding.  Deinterlacing
is also very useful, and often improves compression ratios.)

Ewen