[vox-tech] wincast tv: video4linux and copying movies

[Mark K. Kim]

On Tue, 14 Oct 2003 p@dirac.org wrote:

> sam, just so i have some extra lingo, what are some other "container
> formats" besides AVI?

Quicktime can also store video/audio in various codecs.  Not sure if the
"generic" format lets you store in a noncompressed codec but probably.

> and what's the difference between MPEG-2 and MPEG-4 which ryan
> suggested?  are the "-2" and "-4" what people call "layer", as in "mpeg
> layer 3"?  so is MPEG both an audio and a video encoding scheme?

MPEG2 and MPEG4 is different than MP3.  MPEG2 and MPEG4 are for both audio
and video.  MP3 is only the audio subcomponent of MPEG2 (layer 3 of
MPEG2.)  There's no such thing as MPEG3 because the MPEG3 standard was
scrapped before it was completed.

MPEG2 is used on DVDs.  MPEG4, by far, has better compression.  If you
wanna fit 1 hour+ of video on a CD, use MPEG4.

> it looks like this process is similar to making mp3's.  first you rip,
> then you encode.  probably because, as ryan pointed out, encoding is an
> expensive process.  so here is what i gather from everybody's replies:

yep.

> 1. it looks like i have a few choices for ripping to disk:
>
>    mplayer
>    xawtv
>    nuppelvideo
>    mjpegtools

I've had a hard time getting TV signal on mplayer because you gotta set
the channels and such by setting the frequencies which is just a hassle to
fiddle with.  But I'm sure it's doable.  xawtv is a much easier to use,
though, since you use it to view TV channels anyway, and you get a menu
for saving the video.

I haven't used nuppelvideo or mjpegtools.  I've never heard of nuppelvideo
and I didn't know mjpegtools lets you save video from v4l devices.

> 2. and a few choices for encoding:
>
>    mencoder (part of mplayer distribution)
>    mjpegtools
>    ffmpeg
>    transcode

I highly recommend mencoder because it lets you use virtually any codec it
understands (virtually everything out there) to record.  So you get a lot
of choices, which usually means you can pick the best codec available.
Others seem to let you encode only in MPEG1 or 2, if it offers you any
choice at all.

> 3. between ripping and encoding, ryan gave a suggestion on basic editing
>    like cutting out commercials or "upcoming attractions" of movies that
>    were released 5 years ago (i hate the fact that they put upcoming
>    attraction on videos that i purchase).  a few is ok, but sometimes
>    they really let it get out of hand).
>
>    avidemux

It's a good idea but a lot of hassle, I think.  If you can script it, more
power to ya.  mpgtx also lets you chop/split/join mpeg1 videos but you'll
probably lose some quality since you'd need to encode it to mpeg1 before
recoding it to mpeg4.

> also, sometimes i see people write "DivX ;-)".  what exactly does that
> smiley face mean?  and what exactly is DivX anyhow?

"DivX ;-)" is the name of the codec.  They changed the name to "DivX"
a while ago, though.  "Divx", of course, was that proprietary Circuit City
DVD format that died a long time ago, and "DivX ;-)" was a name making fun
of it... now that "DivX ;-)" changed its name, it can be a little
confusing to talk about the Circuit City's DVD format without getting it
confused with "DviX ;-)" but that's life.

DivX's compression is definitely better than MPEG2.  And somehow MPEG4 and
DivX is related but I'm not exactly sure how.  They seem to either share
compression techniques or have the ability to embed one format in the
other, or it's just a different name for the same thing -- I'm not sure.
Anyway, MPEG4 and DivX are very comparable and a video made in one format
seems to be playable in a player that understands the other format.

-Mark

-- 
Mark K. Kim
http://www.cbreak.org/
PGP key available on the website
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