CBR, VBR, CQ, etc

[afreitas]

There are a lot of informations about VBR, CBR, CQ in theses forums but Ive still not be able to make my mind about with one produces the better results.

I read that if I dont care about the file size, I should use CBR. If I want the best quality and small file size I should use VBR with 2 or more pass.

Ive seen most of comercial DVDs are using something about 4000kbps - 6000kbps in 720x480. So if I would like to use 352x480 I should stay with 2000 - 3000 (halt the size). SVCDs can use something about 2500kbps, so its the halt of 2000 and 3000kbps, but they use 480x480. Using 352x480 would allow me to get better picture than SVCDs.

Now lets go to the question:
Ive been using CCE for MPEG2 conversion and with CBR at 2500kbps. I could see throw bitrate viewer that CCE sometimes even in CBR has peaks above 2500kbps and that wouldnt be good in my DVD players.
VBR with a min and max would save me from this problem. Maybe 2 pass could be better yet.
I think CBR would produce better results.

If I dont care about the file size neither about the enconding time and I would like to stay with 352x480-MPEG2 at max 2500kbps, what would be better? CBR? VBR? CQ? If other than CBR, what are your suggestions?

I really did a lot of test before going to ask in this forum. My source are VHSC tapes from camcorder. If good sources, I get good quality at any type of enconding (CBR, VBR, etc). My main problem is with bad sources.

Thanks in advance any help.

[banjazzer]

CBR gives worst quality, because it is a dumb mode. Even a blank screen will be encoded at a fixed bitrate! It's a total waste for SVCD.

VBR is next best. It's not part of the spec for VCD, but will work on some DVD players. CQ is the best for SVCD for reasons I won't go into, but check out http://tangentsoft.net/video/mpeg/enc-modes.html 8)

[VidGuy]

IMHO - if size doesn't matter, use TMPGEnc's CQ mode with a CQ value of 75 or 80.

This gives a very hard-to-beat picture. CQ of 80 has better "Q" characteristics than CCE using it's Q:20 (according to CCE a Q of 0-40 is what to use for the very best 1-pass encoding). If you use Teco Bitrate viewer, you can see the min/max values of the "Q" value.
At CQ 80 - you get around min 6.0, max 6.3

For CCE Q:25 you get around 4.7 min, 9.0-11.0 max.

CQ does a very good job of keeping the quality constant, while CCE's single pass let's it wander more.

If size matters, then you want to use CCE's 3 or 4 passes to get the best quality you can for a given size, and then maybe even use the "Getting the best out of CCE" guide over at Doom9 (although it's somewhat painful, it does work well).

[smokingweed3000]

CQ 85 gets very good quality if u set to about 2200-2350 max and 700-800 min.
Dont ever use CBR, its a waste of time and size.
VBR is also good if u have a certain size u want to obtain and cant go over. I still recommand CQ at the above settings though.

[afreitas]

CBR gives worst quality, because it is a dumb mode. Even a blank screen will be encoded at a fixed bitrate! It's a total waste for SVCD.

VBR is next best. It's not part of the spec for VCD, but will work on some DVD players. CQ is the best for SVCD for reasons I won't go into, but check out http://tangentsoft.net/video/mpeg/enc-modes.html 8)

This link is very important for all newbies like me

I read all the reviews and now this topic is very clear for me

Thanks!

[Devnull]

You should also keep the encoding time in mind. 2-pass vbr takes 2x as long as cbr. CBR is not that bad for a smaller video, I do things in cbr sometimes, though vbr is a lot better for dvd rips and such.

[vitualis]

People are often confused about these things...

SVCD has a max. bitrate for video at approx. 2500 kbit/s.

Thus, CBR at 2500 kbit/s is the BEST possible quality attainable by a SVCD. Although it is a wasteful use of bitrate, the quality is NOT "shit".

I'm not entirely sure of this, but with CBR (and the use of the buffer), the apparent "bitrate" of any immediate part of the video can spike above 2500 kbit/s. This isn't a problem though, I believe.

Using a constant bitrate at a level lower than the max, then the quality will potentially be less than a VBR clip with the same average bitrate as VBR then is more efficient.

Regards.

[afreitas]

Hmm... How much can we trust in Bitrate Viewer?

I tried the same video, the same setting, etc, etc

1) CBR 2520kbps
Peak Avarage
Bitrate 2460 2342
Q level 14.41 11.25

2) CQ=95
Peak Avarage
Bitrate 2477 2333
Q level 14.36 11.28

3) CQ=90
Peak Avarage
Bitrate 2464 2331
Q level 14.21 11.25

and last
4) CQ=85
Peak Avarage
Bitrate 2301 2177
Q level 15.53 11.39

Did I mention Im a newbie? I dont understand very well this but I think less Q level, less compression, so better quality. Should I stay with CQ=90?!? Thats very weird...

Remember, my source was from a camcorder and its not so clean...

[DVantrease]

I use CQ_VBR. Now when someone told me that CQ means 'constant quality', I immediatly started putting mine on 100 (max). That was an assumption on my part, is this wrong?

[banjazzer]

Thus, CBR at 2500 kbit/s is the BEST possible quality attainable by a SVCD. Although it is a wasteful use of bitrate, the quality is NOT "shit".

CBR for VCD at 1150 kbps is not the best quality available for VCD. If your player accepts non-compliant VCD you can get much better quality, or conversely a lot more movie, on a standard CD. 8)

[offline]

vitualis
Thus, CBR at 2500 kbit/s is the BEST possible quality attainable by a SVCD.

If you are saying the best possible quality of picture can
be obtained at CBR 2500 kbit/s compared to multi pass CQ at
2500 kbit/s then I'd have to strongly disagree.

[banjazzer]

I use CQ_VBR. Now when someone told me that CQ means 'constant quality', I immediatly started putting mine on 100 (max). That was an assumption on my part, is this wrong?

Follow the link in my earlier post to find out about CQ and what it means. 8)

[energy80s]

CBR at 352x576(480) and 2496kbps will give the best quality available for MPEG2 coded CD-R's. This is known as D2 resolution and is a damn sight more compatible with DVD players than SVCD is. Maximum running time will be 40 mins per 700mb disc. Encode time will be less than half that of VBR files and with better quality. VBR is only used to reduce file sizes. Also up the audio sampling to 48k, this is standard DVD format and will play on every DVD player on the planet that supports CD-R discs.

[vitualis]

CBR for VCD at 1150 kbps is not the best quality available for VCD. If your player accepts non-compliant VCD you can get much better quality, or conversely a lot more movie, on a standard CD. 8)

"non-compliant" VCDs ARE NOT VCDs are they?

Thus, 1150 kbps is not only the BEST QUALITY available, but the ONLY bitrate available.

Regards.

[vitualis]

If you are saying the best possible quality of picture can
be obtained at CBR 2500 kbit/s compared to multi pass CQ at
2500 kbit/s then I'd have to strongly disagree.

Read what I wrote properly. The best possible quality for a compliant SVCD is CBR 2500 kbit/s.

VBR in any mode with an average of 2500 kbit/s and ALSO a max. bitrate of 2500 kbit/s (that is, maintaining SVCD compliance) actually identical to CBR 2500 kbit/s (think about the maths). Every extra pass just means you waste more time.

If you set a max. bitrate higher than 2500 kbit/s with a VBR encoding then it goes without saying that the quality can be higher. But your disc will no longer be compliant either.

Regards.