Video Compression

trythil · Post by **trythil** » Sun Jan 25, 2004 2:21 am

NicholasDWolfwood wrote:MPEG-1 isn't frame accurate when seeking without it indexed. MPEG-2 is frame accurate IIRC with or without the index file.

Neither are frame-accurate without an index of some sort. B-frames will screw just about any improperly equipped editing system.

trythil · Post by **trythil** » Sun Jan 25, 2004 2:34 am

Oh yeah, forgot about this.

the Black Monarch wrote:How does high-res (640x480), low-bitrate (1mbps) MPEG-2 stand up to MPEG-1 for internet distribution purposes?

It depends. As usual, you're trying to make a comparison with too many unknowns.

What resolution are you preparing the MPEG-1 at? What bitrate?
Is it going to be the same bitrate and resolution as the MPEG-2?
What MPEG-2 encoder? What MPEG-1 encoder? Is it the same encoder?

MPEG-2 video, as a rule, generally works best for high-bitrate applications.

MPEG-2 video streams are also notoriously legally encumbered. As you know, DVDs make use of MPEG-2 video. The thought of perfect Digital Restrictions Management (ok, fine, Digital Rights Management) has replaced the joy of sex for every male in the legal departments of every film and video corporation on the planet.

On Windows, you will probably end up playing MPEG-2 video data in two ways:

(1) Using a licensed software DVD player.
(2) Using WMP/some other DirectShow-based player and making use of a DirectShow filter installed by said licensed software DVD player.

In both of these cases, it is highly probable that the developer of the playback software went out of their way to make MPEG-2 playback the way you want it more of a bitch than taming Katherine. There do, of course, exist free, unencumbered solutions, but they are still largely regulated to operating systems for terrorists.

The upshot: People will probably find themselves REALLY pissed off when they can't do what they want to do with your file. For example, every Friday, I start the anime club off with a mix of AMVs. Sometimes this includes MPEG-2s given to me on CD from AMVers I've met at cons. Getting MPEG-2s to play in a mixed playlist of MPEG-1, XviD, and other stuff is a real pain in the ass.

Tab. · Post by **Tab.** » Sun Jan 25, 2004 2:55 am

As a rule, mpeg 2 is not tuned for low bitrate because it has no mechanisms to improve over mpeg 1 in that area. Mpeg 4 was designed for this. It's pretty nonsensical to use mpeg 2 at a rate that could be handled by mpeg 1, for all the mentioned reasons (low compatibility, no quality gain). I'm not sure if there would be any gain to seek from using mpeg 2 at the higher 640x480 resolution, it'd be interesting to do some tests on that.

Ari: I don't think mpg2 is a standard extension for mpeg systems.. mpeg 2 is conventionally mp(e)g, m2v (just video), vob (for DVD), and like dbv or something for digital broadcast.

Arigatomina · Post by **Arigatomina** » Sun Jan 25, 2004 3:00 am

Tab. wrote:Ari: I don't think mpg2 is a standard extension for mpeg systems.. mpeg 2 is conventionally mp(e)g, m2v (just video), vob (for DVD), and like dbv or something for digital broadcast.

I have never used it as a compression method, but I've talked to a few who have and they say you wouldn't *have* an mpeg2 vid at 45mbs for distribution - yet I've run across some that only play in BSPlayer (a freebie player I googled for specifically to play some odd mpeg2 vids). And then there are some very strange ones that have a 'layer' error in BSPlayer and only work in Winamp 1.87 (and others I know had the same problem with the same vids).

So am I thinking of a different compression (the mpeg2 vs mpg2) or is it just that I'm missing a codec somewhere? o.O

Tab. · Post by **Tab.** » Sun Jan 25, 2004 3:25 am

Sounds more like the result of someone being stupid, or a very obscure encoder with off naming conventions.
Hm. I know there's no such thing as mpg2 compression, anyway.

the Black Monarch · Post by **the Black Monarch** » Thu Jan 29, 2004 3:46 am

trythil wrote:What resolution are you preparing the MPEG-1 at? What bitrate? Is it going to be the same bitrate and resolution as the MPEG-2?
What MPEG-2 encoder? What MPEG-1 encoder? Is it the same encoder?

Okay, let me rephrase:

I want to use TMPEGenc to encode a video at 640x480 resolution and 1 or 2 mbits/sec. Assuming VBR, maximum MSP, and other such goodies (but not b-frames), what will the quality difference be at each bitrate?

Qyot27 · Post by **Qyot27** » Fri Jan 30, 2004 4:54 pm

Well, I have several different encodes I make of my vids, all aimed for different purposes:

One VCD encode for general DVD-player enjoyment (MPEG-1, 1150kbps)
One SVCD encode for high-res DVD-player enjoyment (MPEG-2, 3500kbps)
One DVD encode for whenever I can get a DVD-player that supports miniDVD or whenever I can get DVD burning software and a DVD-R drive (MPEG-2, 5000kbps, AC3 Audio 192kbps)

My DVD files used to be the highest quality encode I would do, but that was when I was still making DVD files at 3000kbps. I've actually run comparisons between MPEG-2 and MPEG-4 (using DivX), and I've found that DivX 5.0.5 set on Quantizer 1 will output a file with the exact same quality as my 5000kbps DVD file, but will be about 3800-4000kbps. So, in other words:

One MPEG-4 encode for archive purposes (DivX 5.0.5, Quantizer 1, MP3 Audio 192kbps)

My early distro copies were the VCD encodes I would do, but I've since made the switch to higher-quality DivX:

One MPEG-4 encoded at a res around 480x352 for distro purposes (DivX 5.0.5, Original 1-pass 3500kbps, MP3 Audio 160kbps).

Tab. · Post by **Tab.** » Fri Jan 30, 2004 5:50 pm

Qyot27 wrote:One SVCD encode for high-res DVD-player enjoyment (MPEG-2, 3500kbps)

SVCD spec only supports up to 2756 kbps combined bitrate :|

Qyot27 · Post by **Qyot27** » Fri Jan 30, 2004 7:09 pm

Tab. wrote:
Qyot27 wrote:One SVCD encode for high-res DVD-player enjoyment (MPEG-2, 3500kbps)
SVCD spec only supports up to 2756 kbps combined bitrate

Okay, so sue me, XSVCD. It plays on my DVD player, anyway. That's all that matters.

Sarcastic Assassin · Post by **Sarcastic Assassin** » Sun Feb 01, 2004 12:34 am

Your question seems to be aimed at what codec to use for distribution. I personally think XviD/DivX (w/AVI, and MP3 audio) is the MP3 of videos (ie, great quality at low file size).