[NTLUG:Discuss] Voodoo3 3000 TV Out

[Dan Carlson]

Not to butt in, but here's my experience with home-brew linux-based pvr
functionality:

If you want to do record/playback on a single machine attached to a TV then
the mjpegtools package is all you need.  Use the lavrec program to capture
audio/video to a quicktime mjpeg lav file, and use lavplay or any quicktime
player to play it back.   This works well and the video quality is
excellent, but the mjpeg files are large and the bit rates are high, so you
do need big fast disks.  Typical space requirement is 1-3 M bytes per
second, which is 3.6 to 10.8 GB per hour.  Theoretically you could run this
over a network, but frequent starts, stops, pauses occur making it annoying
to watch.  But it works fine when you playback directly from the hard disk.
On the good news side, it only takes 10-15 % of a 2 GHz P4 to perform the
mjpeg capture.

BTW: The main reason for capturing to a quicktime file with lavrec instead
of an avi file is that lavrec does not support the OpenDML spec, so its avi
files are limitted to 2GB max size, which usually isn't enough.  If you
must use avi it is capable of capturing to multiple files.  I prefer not to
do that because it tends to make post-processing more difficult.

You can also use a lav2yuv / yuvdenoise / yuvscaler / mpeg2enc / mp2enc /
mplex pipeline or sequence to convert the mjpeg quicktime lav file to a
DVD-compliant mpeg2 program stream file that can be burned to DVD and
played on standalone DVD players.  The catch: Unless you've got a lot of
very fast CPUs, you won't be able to do this in real-time.  But converting
2-4 hours a day on a single CPU is doable, with very good video quality.

The mjpegtools / mpeg2enc pipeline is not considered to be real-time, but
it is starting to get close.  On my 2 GHz P4 I get good quality using
parameters that result in 3-4X real-time encode times.  In a year or so an
SMP system with two hyperthreading P4's should be able to do this in
real-time...

I have tried some of the other mpeg2 encoders that claim to be real-time,
but so far I haven't been able to find anything that A) Actually works, and
B) Gives good quality, and C) Produces true DVD-compliant streams that
common authoring software will accept and standalone players will play.
Doesn't mean there aren't any out there, but if there are I haven't found
them.  If anybody knows of any, please tell me about them.

Another alternative for pvr functionality is Real Networks' RealProducer,
which does both capture and encode to RealMedia format.  The advantage of
this approach is that it actually works very well.  I can do two
capture/encodes simultaneously on my 2 GHz P4, with 20-30% of the CPU left
over for other purposes.  The video quality is very good at a 1.5 M bits
per second data rate, which results in 650-700 M bytes per hour.  The 1.5 M
bits per second data rate moves very well over a 100-BaseT network, letting
you playback on various client machines around the house while the server
is busy doing two other capture/encodes.  RealPlayer has reasonable
keyboard shortcuts that make it fairly easy (with a little practice) to
skip over commercial breaks.  The biggest disadvantage: RealMedia is a
proprietary format, it can only be played back with RealPlayer, and there
are few third-party tools that can post-process it or convert it to other
formats.  Another disadvantage: You can't play back the rm file until the
capture/encode is complete.

Currently I use RealProducer for the bulk of the "throw-away" programs that
I record.  Since they are throw-away, it doesn't matter that I can't
convert to other formats.  For archiving the really important stuff (i.e.
Star Trek, of course) I use the mjpegtools chain to produce mpeg2 program
streams that I write to DVD and play in standalone DVD players.  I do
expect that 1-2 years from now I should be able to switch over to true
real-time mpeg2 entirely.

Dan Carlson

----- Original Message -----
From: <MontyS at videopost.com>
To: <discuss at ntlug.org>
Sent: Tuesday, June 25, 2002 1:16 PM
Subject: RE: [NTLUG:Discuss] Voodoo3 3000 TV Out


> Greetings.
>
> Tell me more about your setup, if you don't mind.  My home VHS machine is
> about dust, and I really don't want to buy another one, and I don't want
to
> play the TIVO/REPLAY game.
>
> Do you have a program that drives the box similar to a vcr?  What type of
> codec are you using for video storage?  How much and what type of storage
do
> you have?  Have you been able to get decent quality video with real-time
> playout?
>
> Any other information would be greatly appreciated.
>
> Hope you don't mind the questions.  I have been wanting to do this for a
> while now, but haven't had the time/money to pursue it.
>
> I feel like a kid looking through the window of a candy store.  Or, me
> looking at a Corvette...
>
> Thanks.
>
> Monty
>
> -----Original Message-----
> From: TJ Davis [SMTP:TJDavis at sagu.edu]
> Sent: Tuesday, June 25, 2002 10:05 AM
> To: 'discuss at ntlug.org'
> Subject: [NTLUG:Discuss] Voodoo3 3000 TV Out
>
> Greetings!  I am running Redhat Linux 7.3 with a Voodoo3 3000 video
> card.  I am trying to make this a multimedia machine to record onto and
> watch movies off of.  I will eventually get an ATI All-In-Wonder but I
came
> by the Voodoo for real cheap (free) so I am going to use it for now.
> Anyways, I have the s-video out plugged into my tv.  It probably does not
> matter but my TV is a 51" Phillips.  The TV is receiving the signal and
> looks great during bootup but as soon as the GUI initiliazes it becomes
> fuzzy lines.  I assume that this is a problem with my Refresh Rate but I
am
> not all that great with the XF86Config file and am not sure if I have
> changed it right.  Can someone help me or point me to a place where I can
> get some step-by-step instructions on how to configure my XF86Config to
work
> best for a TV?  Thank you VERY much.
>
> T.J. Davis
> Southwestern A/G University
> Information Technology
> tjdavis at sagu.edu
> 1 Timothy 4:12
>
>
>