Anyone know much about video encoding?

[lil nublet]

I recorded a film the other night but it's an mpeg about 2.5GB! I know you can get a DVD down 700MB with excellent quality. Question is, how is it done and what is used? I was gonna use Vegas but someone said to use Auto GK. Opinions?

[Takeshi]

It all depends.

You want to fit onto a 700MB CD to play on a standalone DVD player?

[lil nublet]

No. just create a 700MB file so it takes up less space on my disk.

[Takeshi]

Then your options can be DivX, Xvid, wmv, rmvb, all compressed formats.

But, since you seemed to have captured TV to your PC as mpeg (you didn't say mpeg-1 or 2), you might reduce the size in the first place by having lower bitrates. This will avoid time consuming re-encoding from mpeg which is itself a losey compressed format. But to restrict file size down to 700MB you most likely would need to re-encode again.

Edited August 9, 2006 by Takeshi

[CoffeeFiend]

As Takeshi said, you can almost use any format. Size is affected by bitrate (size = bitrate * length) - resolution or actual codec used doesn't matter. Not all codecs will look alike at lower bitrates though.

If it doesn't have to play on a DVD player or "divx player" then I would personallly suggest using a very good and recent codec: H.264 (MPEG4 AVC). Any good implementation will work just fine (x264, Ateme - from Nero, etc). Looks even better than divx and xvid (which are you next best option IMHO).

[Sat_dish]

IMHO I like Real Media Encoder. Depending on how small you would like to get your movies compressed. I am getting near DVD quality video and the final size is around 250 megs. Now this does take a little bit of time to compress and I have found that on slower computers > 1 gig seem to have problems sometimes. A good program to start with is autorv10, it's mainly for dvd ripping but it has a very nice gui and lets you know what is going on. I personally don't like Divx or H.264 as they seem to suck when trying to get a smaller size then 700 megs. I hope this helps

[LLXX]

I use Virtualdub, it works with any existing codecs you have and its extendable too.

[Takeshi]

I'm not familiar with the newer codecs and formats but the correct approach would be to decide on the codec and format first, then decide on the program. The prog is just a tool to do a particular job.

It's like when you want to make a text document, you decide which format first, be it txt, doc or pdf, then on which program: Notepad, Word or Acrobat.

Video encoding is a huge subject and we're spoilt with too many choices. My own view on TV or VHS capture is, you already spend time doing real time capturing the video on HD. Avoid re-encoding if possible. HDs are cheap nowadays.

[CoffeeFiend]

I'm not familiar with the newer codecs and formats but the correct approach would be to decide on the codec and format first, then decide on the program. The prog is just a tool to do a particular job.

Picking codec first is indeed the main thing. Hence my MPEG4 recommendations As for the program, they're not quite all the same... I'd second the Virtualdub choice (or Gordian Knot to automate things somewhat - AGK if one really can't figure out GK), but I'd definitely stay away from Real's junk... I'd willingly install spyware on my system before that stuff.

Avoid re-encoding if possible. HDs are cheap nowadays.

Reencoding only takes 5 minutes to setup at worst (let it happen while @ work, going shopping or out, or even overnight). HD space may be cheap nowadays, but not enough to keep uneccesarily large AV files around. I've got 4 300GB'ers for a small video server, and it's all filled with mpeg4. I'm already out of space. Ideally (using mpeg4), I'd need two or three times that. Now if I was using large MPEG2 files or not reencoding anything... Say, fifty drives or so? Even if 300GB'ers are ~100$ nowadays, that's still a good chuck of change. Quality loss if using decent codecs will be minimal anyways.

[Takeshi]

With due respect, everyone's requirements are not necessarily identical. Your scenario of running a video server and streaming video is not necessarily the same as that of the original poster or myself, who records TV only occasionally. All we can do is make an informed choice.

The poster has captured analogue video (presumably of lowish resolution) to mepg already, and only 2.5GB, not a large uncompressed AVI, so re-encoding down to 700MB would save 1.7GB. Yes it's a saving in HD space but I wouldn't do it myself for all it's worth.

I don't download ripped DVDs so I can't comment on their qualities after re-encoding.

Edited August 11, 2006 by Takeshi

[Jeremy]

You're going to get a different answer from everyone, really. If you have a 2.5 GB MPEG-1 and want to fit it on a 700 MB CD, just use VirtualDub and XviD and use the bitrate calculator to determine the maximum you can use without exceeding the capacity of the CD, encode it using 2-pass. Play it on your PC to see if you're happy with it. If so, burn it to CD. if not, give us a shout again on the forum and provide a screenshot of a frame so we can see the quality you might be potentially concerned with.

[Fredledingue]

I use AviUtl which I find better than virtual dub for editing (cuting, cropping etc)

But it doesn't always handle all formats and all filesize correctly nowadays. Worth a try anyway, it's free.

This is a tutorial I wrote in english for this software:

http://www.geocities.com/fredledingo/aviutl.htm

Here you will find my bitrate calculator in vbs (no need to instal external softwares):

http://www.geocities.com/fredledingo/vbscripts.htm

(scroll down to "Scripts for more specific operations")

Also check doom9: Everything you need is there (except AviUtl, why I don't know.)

http://www.doom9.org/index.html?/guides.htm

If you want to avoid reencoding, and if your PC is fast enough, most capture card come with capture software able to encode directly in AVI of any format beside mpeg 1 and 2.

Virtual Dub is also an excellent tool for video capture.

Modern computers can easily capture in MS mpeg4-V2, DivX or Xvid without dropping frame.

While MS mpeg4-V2 may be the safest as frame drops are concerned.

Capturing sound directly in mp3 is not recommanded for synchronization reasons but converting only sound with virtual dub afterward is very fast and easy.

IMO, mpeg-2 is only useful if you want to save your vid on DVD.

HTH

Edited August 13, 2006 by Fredledingue

[Jeremy]

IMO, mpeg-2 is only useful if you want to save your vid on DVD.

I agree, because MPEG-2 looks better at the same bitrate than MPEG-1 and AVI more at the same than MPEG-2. The new x264 codec looks better than XvID but isn't 100% stable and requires more CPU usage than XviD. Plus, I'm sure for hardcore quality tweakers and people who know their configs more than others can get the best quality out of their bitrate, especially if they are AviSynth users...

But first rule of thumb... it all depends on your source.

Edited August 13, 2006 by Jeremy