How come a 45min svcd can fit onto an 80min cd?

[saetji]

I have a cd- capacity 700mb, 80mins
How come a 45 min svcd can fit on it? I thought that u could only get 40 mins onto it. Is it me going barmey or is there an explanation as to why this can happen

[banjazzer]

It depends whether you are talking about a constant bitrate SVCD encoded at the maximum allowed bitrate, or a variable bitrate SVCD which is encoded at varying bitrates up to the maximum. In the latter case you can get 50-60 minutes per 80 minute CD at comparable quality.

[saetji]

wowies. U know everything.

Thanx

[banjazzer]

U know everything.

Unfortunately, not.

[wulf109]

CBR or VBR make no difference. It's the average bitrate. 45 mniutes will fit at a bitrate of 2100-2300 depending on the audio bitrate whether you use CBR or VBR.

[banjazzer]

CBR or VBR make no difference.

Smartass, the standard SVCD templates in CCE and TMPG are CBR at around 2500 kbps, which is why some people think you can only fit around 40 minutes per 80 minute CD. Of course you can have CBR at much less than 2500 (if you are visually challenged). The whole point is you can get more on a disc at comparable quality if you use sensible VBR settings. Which is why I compared constant bitrate SVCD encoded at the maximum allowed bitrate, with variable bitrate. I'm not sure whether you are obtuse or just plain pedantic.

[wulf109]

I am at least polite and can tolerate other viewpoints. If you encode a file at 2520CBR and get artifacts,reencodeing in VBR with the maximum set to 2520 will not improve image quality. Since the maximum is 2520 I assume the average will be less that 2520.
Sure you'll have a smaller file but the quality will be worse.
People who use VBR mode to reduce file size and sqeeze more minutes on an SVCD are missing the point of VBR mode.

[MaDmiZe]

wulf109:
The point of VBR is that it changes.....why have a CBR of 2520 when there are scenes with little action and dark colors that dont even need half this bitrate to look flawless....VBR can look as good taking less space...that is what VBR was made for.
For all:
Of course if you have two movies with the same average bitrate and length, they will by approximately the same size. What was said is that a VBR file can have the same high bitrate scenes as CBR and also have very very low bitrate scenes....thus yeilding a lower average bitrate and smaller file size. Which equals more minutes per disc....as stated above.

[banjazzer]

If you encode a file at 2520CBR and get artifacts,reencodeing in VBR with the maximum set to 2520 will not improve image quality.

Show me where I said it would. The limitation of CBR SVCD at maximum bitrate is the time available per CD , due to using maximum bitrate even when not necessary. A uniformly black screen will still command the maximum permissable bitrate. Instead of 40 minutes you can get 50-60 minutes at comparable quality. That is, comparable not better.

[ViewBoy]

I have a cd- capacity 700mb, 80mins
How come a 45 min svcd can fit on it? I thought that u could only get 40 mins onto it. Is it me going barmey or is there an explanation as to why this can happen

have a look at Kwags KVCD templates, http://www.kvcd.net,
You'd be amazed at how much you can fit on a CD.

[Merla]

also thankful for that answer =)

[Betamax]

If your source has a very high quality (meaning : dv source, 720x480/576, coded at approx. 3.5MB/sec, interlaced) you can get about 55minutes of SVCD at 1x 80minutes disc (using about 1885kbps/CBR, audio according svcd specifications : 44.1khz, 16bit, 224kbps)

I do so and realy I don't see any artefacts or what so ever (quality is still better compared with a vhs of over 6months old).

While these results are already great, I don't see why I should spend more time by using VBR.
A movie of 55minutes to SVCD takes less than 4hours in CBR, in VBR it would be somewhere around 8hours.