OPV - max bitrate is not a limit

[ADLANCAS]

Hi,

Last weekend I´ve made some tests about maximum bitrate that reaches when coding CCE using OPV.
Parameter max Bitrate works like a "target", but normally CCE uses higher values when necessary.
I tried also to set DVD compliant parameter. It´s better but not enough. I notted lower levels of maximum bitrate. Unfortunatelly, sometimes higher values were also present.
I´d use this DVD compliant parameter if my source was D1, but with half-D1, image is padded.
My solution in this moment was to reduce max bitrate to avoid higher values.

Is there a tool too check max bitrate than window from CCE ( BitrateView doesn´t work well)
Make sense my thoughts ?


Thanks,

Alexandre

PS.: I´m using CCE 2.70.02.09
Edit: changed Title.

[RB]

BitrateViewer is quite accurate, where are you having problems with it?

[ADLANCAS]

I´ve compared the same m2v file in:
Bitrate Viewer = 6877 (PEAK)
Mplex = 9096400 bits/sec
bbMPEG = 9032800 bits/sec

:confused:

[ADLANCAS]

No comments:(

Ok, I openned a thread in DVD2SVCD area. I hope that someone can help me there.
Here is a link: http://forum.doom9.org/showthread.php?s=&postid=538600#post538600

Thanks,

Alexandre

[RB]

Well, CCE sometimes just doesn't keep the bitrate limits in OPV mode as you have noticed. Just decrease max. bitrate to something like 7000 kbps in this case. As for which bitrate reported by the tools you mentioned is correct, I have no idea :) I'd trust what CCE reports in its "Advanced VBR Settings" statistics.

[ADLANCAS]

Decrease max bitrate to 7000!
Oh, I´ve already decrease from 9000 to 8000, then now to 7000 ?:eek:
What I can understand in your words is there is no way to make a safe solution in this case (DVD compliant).
I´m just curious about tools that uses OPV like D2SRoba+DVD2SVCD+MdvdAuth. Do you know how this control is used by such tools? or is it possible to have also this high bitrates ?

Thanks,

Alexandre

Edit:
Somethings are so easy when we know how it works...:o
I couldn´t handle correctly VBR Advanced Settings.
Sequence was:
- create .vaf file;
- select multipass vbr; (because Bit allocation was not available)
- Bit allocation (using existing file);
In Current Gop Information and in the graphic show lower values than in coding window.
In Stream information shows fixed low values too.
:confused:

[ADLANCAS]

To be (almost) sure that is DVD compliant, I used to avoid higher bitrates that could be created by CCE with:
OPV
Q = greater than 25
max video bitrate = 8000

Is it safe to use low Q value in OPV mode ?

Please post your experiences.

Alexandre

[drob]

I always use max of 9500 and average Q of 1-25, not a single problem.

[Amnon82]

8000 is a good value. 9500 is sometimes to high. Especially when using DTS ;)

[Mug Funky]

2-pass seems to have a more solid max bitrate than any of CCE's 1-pass options (including CBR!).

i've noticed it doesn't handle multiangle + multiple audio tracks very well (ie rigidly set max bitrate of 7000, with equalize GOPs turned on and fixed VBV or whatever it's called, or just DVD multiangle set). spruce will spit out it's encodes on compiling.

HC will keep a max bitrate very rigidly, but it'll also block out a little more when it hits the max, and will be a fair bit slower.

however, as you're probably discovering there's no really consistent measure of max bitrate, and it's not really the encoder's fault if it satisfies it's own requirement of max bitrate, as MPEG in their wisdom have left the wording very open-ended, hence authoring programs, players and encoders will all have different ideas about what they can tolerate, even assuming "perfect" media (which in these dark times is pretty hard to come by, even with commercial replicators!).

bottom line is, if your authoring app handles it, and it plays fine on all your players, then it is fine :) if it doesn't work it's not too difficult to re-encode just the part that's going too high.

[ADLANCAS]

Normally I use only ac3 192Kbps.

however, as you're probably discovering there's no really consistent measure of max bitrate

Yes, this comes from mpucoder:http://forum.doom9.org/showthread.php?p=837545#post837545
Bitrate viewers (any of them) do not analyse video bitrates from a multiplexer's point of view, ie they only show the maximum bitrate per picture. But multiplexing does not work on a per picture basis, but on a sliding window of approximately (depending on the muxer) 7 frames working with a 232K buffer.

No more OPV users here ?

[drob]

Max bitrate actually depends on your DVD player, some can handle higher bitrates better then others, mine handles max of 9500 just fine, on the other hand i saw some chock on 9000.

[Trahald]

VBV compliance is more important than max bitrate. basically.. what mug said.. if the authoring app is ok with it (most apps check for underruns) . then it will be fine.

[ADLANCAS]

Is there a way to check if it´s VBV compliant ?
:stupid:

[Trahald]

only way i know of is to mux it with something that will check for compliancy.. muxman 15 is free. get it at www.mpucoder.com and will check for it. mux your video with the all the audio you intend to have with it. it will complain if there are underruns. (it may still complete the compile so check the c:\muxman.log)

[ADLANCAS]

Thanks for info!
I'll check it