MPEG1 VS MPEG2 COMPRESSION RATIO?

[Trenton_Net]

Hi,

I was wondering if you encoded a disk exactly like an SVCD but instead of using mpeg2 which is a pain, and you used Mpeg1, how would the size/compression ratio be effected?

Is Mpeg2 compression so great that I would expect a significant decrease in space? I mean at least enough so that a regular movie will no longer fit on 2 Disks?

Thanks a bunch guys,

[Greg12]

mpeg 1 files for me are about 50 megs smaller than mpeg 2 files.

[Trenton_Net]

Sounds interesting. So If I encoded a VCD at 480x480 like an SVCD, but in mpeg1, is it reasonable to expect that if the player is SVCD compatible that it will accept it? I suppose my biggest concern is file sizes. If I made a VBR VCD, at 480x480 would the sizes be bigger or smaller than its mpeg2 counterpart?

If you had to pick a more standard size, most people encode in Pal for the extra resolution right?

[vitualis]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
On 2001-08-22 06:06:29, Trenton_Net wrote:
Sounds interesting. So If I encoded a VCD at 480x480 like an SVCD, but in mpeg1, is it reasonable to expect that if the player is SVCD compatible that it will accept it? I suppose my biggest concern is file sizes. If I made a VBR VCD, at 480x480 would the sizes be bigger or smaller than its mpeg2 counterpart?</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

No, it is not reasonable to expect the player to play it as you've just made yourself an XVCD that deviates for the VCD specs signficantly in a number of ways. However, you could try it out as many modern DVD players are quite relaxed in what they can play.

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>If you had to pick a more standard size, most people encode in Pal for the extra resolution right? </BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

I suggest that you encode in the TV format used in your locality. The quality between NTSC and PAL is more complex than just resolution and overall, PAL and NTSC have about the same visual "quality".

Regards.

[aldus4]

@Trenton_Net

I think you need a bit of help with clarifying what you mean. The stream type VCD,SVCD is defined by the compression format i.e. mpeg1 or mpeg2. Mpeg1 being VCD and mpeg2 being SVCD. Any deviation from the standards (standards as in the "what is" section) is then named XVCD i.e. XSVCD.

The frame size has little to do with the overall file size, the same can be said about the compression format mpeg1 and mpeg2. The main difference in quality and file size is achieved by the bitrate you use. Mpeg1 can use a bitrate up to 5000kb/sec - whereas Mpeg2 can go up to about 10000kb/sec. Usage of Mpeg2 below 2000kb/sec is not advisable as this produces many artifacts.

Another important setting of usage is if you are using a constant (CBR) or variable (VBR) bitrate in your conversions or captures - naturally this will influence your file size as well.

I hope this has clarified some points of concern.

If you would like to read more about mpeg's, I would suggest you visit http://www.mpeg.org

<font size=-1>[ This Message was edited by: aldus4 on 2001-08-22 10:53:22 ]</font>

[Trenton_Net]

Thanks, I appologise for my lack of depth or detail.

What ment to say was that IF a dvd player will accept a format that deviates from a standard, is it safe to assume that it would output with the correct aspect ratio, etc if it was saved in one of the standard resolutions?

For instance, a non complient xVCD with a SVCD resolution standard of 480x480.

Im guessing even though DVD players know how to deal with resolutions that are standard like 480x480, the video must be 100% in that format before it will treat and acknolege as such.

Well as for the Mpeg1 VS mpeg2 thing, I think I big part of it is space. There is vertualy no reason to goto Mpeg2 if it dosn't save space on the CD. it seems mpeg2 gives alot more trouble than mpeg1.

Thanks a bunch.

[Cart Wheel]

In theory, there should be little difference between MPEG-1 and MPEG-2 for progressive video. MPEG-2 should do a better job with interlaced video.

However, an important factor is the quality of the encoder. MPEG-1 has been around longer, so the encoders are sometimes a bit better.

-Cart
http://www.geocities.com/lukesvideo/index.html