2-Pass VBR behaving close to a CBR approach

The latest mpeg-2 encoder in Premiere and Encore seems to be very limited in its ability to vary the bitrate, even though I typically set it to the 2-pass VBR setting and the quality slider to "5". I monitor the playback bitrate with PowerDVD ("Show information" enabled) (because it works and it's what I have). Typically, with other encoders and commercial discs, true black will drop below 1Mb/second while the average rate can be greatly exceeded by a factor of twice on high motion or fade in/out points. I'm finding that Encore 2.0 varies little from the "Target bitrate" setting even when the minimum is set to 1.5 and the maximum is set to a high number (8 or even 9 Mbs). Even on true black the target bitrate is nearly reached! Fade-ins don't get extra help! This is wasteful and doesn't look as good as it could.
Am I missing something, or is this encoder tragically inflexible?

>So what does that say for other encoders where the bitrate varies widely -- very low when nearly still, very high on motion/fades... It just seems to me that it is [wasting] using bandwidth independently from how the picture quality appears to the eye.
"Other encoders" aren't as good as the MainConcept encoder included with Encore and Premiere. Not even CinemaCraft, which has a very loyal and vocal following.
No matter what encoder is used, however, a VBR transcode *must* maintain an average bit rate when the file is taken as a whole. For every valley, there must be a corresponding peak, and vice-versa. The encoder must figure out where to put those peaks and valleys.
The only advantage to VBR transcoding, ever, is if you are forced to lower the average bit rate to fit your program on disc. If disc space is not an issue, then VBR has no advantage over CBR, and all you have done is waste time transcoding.
>But it rarely falls very far below the target.
Check the results of my test that I posted - I got very low bitrates on black frames.
>So MC's not too happy with the video chain here.
I'd start with double-checking your source video field order in Premiere, and your Premiere project settings for the project field order. They must match, or you will get the effect you are seeing. What happens when you display your video + titles from the Premiere timeline on an external interlaced monitor?
I'll run a test here to see if I can duplicate the HuffYUV PAR issue.
-Jeff

Similar Messages

How to choose between CBR and 2-Pass VBR ?

Hi,
I know alot of virtual ink has flowed about this topic, but I couldnt find the answer I need.
I'm compressing an 83minute feature film to DVD. Source material is 10bit Uncompressed YUV from PAL DigiBeta, sent directly from FCP to Compressor. Compressor is at version 2.0.1, and all ProApp and QT updates are applied.
Compressing at a CBR (ie: 1pass) with a data rate of 7.4Mbps gives a .m2v file size of about 3.3GB and takes about 3hours.
Compressing at 2-Pass VBR with a max data rate of 7.4Mbps gives a file size of about 3.9GB and takes 12 hours+.
Shouldnt the two pass be smaller given the same max data rate?
When I compare the two visually, I cannot tell any difference between them. I'm looking at areas with alot of motion, or with fine detail, or camera movement, but they look about the same.
How to decide which to use?
Many thanks....
G5 Dual2.0 (PCI-X), 4.5GB RAM, 23" Cinema Display, PB G4 Mac OS X (10.4.6)

Hi There
CBR compression is generally better quality - especially out of Compressor 2 - but usually a higher file size that VBR - can't explain your result there. Check fades, dissolves, small text and camera movement for comparsion between the two mpegs. If you still can't tell the difference then use the bigger one if you have the room, if you don't use the smaller one. If the larger file is better but you're worried about disc space then build your disc using the lager one anyway. If after your created the VIDEO_TS file it still too big use DVD2ONE or DVD Remaster to shrink it back down - I doubt you'd see any visiual difference.
Hope that helps
Cheers
B

Constant Bit Rate or One Pass VBR?

I'm about to burn a 90 minute DVD and I don't know if I should use CBR or One Pass. The footage is old and has lots of noise. My bit rate equation (560/x) comes out to about 6.2. If I use One Pass VBR can I go higher on the max than 6.2? I know I'll need a little room for audio. I'm going to use an
A/C at 192. What do you think?
John

The footage is old and has lots of noise.
Then it might need a higher bitrate. . . Even though the noise is ugly, at a low bitrate it would get even uglier.
Noise has a lot of info , it's like (for lack of a better example) a shot of a tree with lots of leaves blowing around. Lots of information which needs a higher bitrate to do it justice.
Just like David pointed out, do a test & see what is needed for your footage.
Bill
PowerMac G5 Dual 2GHz Mac OS X (10.4.3) DVD Studio Pro 4.02 + Windows XP

Is two-pass VBR not needed if less than 60 minutes?

Just curious... I've read that single-pass will result in the same quality as two-pass for projects less than 60 minutes.

Single pass may result in superior quality. Two pass VBR is necessary to squeeze file sizes and bit rates to fit within DVD parameters.
x

2 pass VBR dissolve problems poll?

OK,
This is driving me nuts and I'm curious how many others are in the same boat. When encoding to m2v in 2 pass mode, no matter what I do about 1/2 my dissolves turn into blotchy messes. Apple tells me I'm the first (and only) one to report this problem. Working with apple I have tried everything they had to offer and no improvement. I have read the discussions and have tried those other fixes posted (i.e. inserting encoding markers in trouble spots).
I am curious how many of you are in the same spot? Have you actually tried to trouble shoot with Apple Tech Support? Did they basically give up on you like they have on me (even though the problem has not been solved Apple says they will only continue to talk with me if I buy the 799 per year support package) Has anyone found an actual fix to this issue?
Also I have tried downloading some demo's of other encoders. Using the same test file (a self contained QT) I have none of the same problems. The best one so far has been MCCoder, but have not been able to get the audio to work with that. The video was even better than Bitvice. I must admit I really like the look of the video that comes out of compressor in 2 pass vbr mode, but if I can't get the dissolves to work its useless.
I'm not thrilled that it looks like my only alternative is going to be to buy a new encoder. It does not seem right to me that if there is a problem with this software that Apple is not taking responsibility to fix it. My thought is if there were enough of us this with the same issue, somehow we could make something happen. Perhaps Apple is counting on either there are not enough of us, or that we won't be able to communicate with each other and organize.
I remain,
frustrated in San Francisco
Art B.

I think, encode markers are something that should not be needed unless trying to squeeze the last bit of quality out of a low(-ish) bitrate encode. Dissolves and scene changes and such are something a compressor should detect by itself and act accordingly - but this is just an opinion on how things should be.
Burner issues should be easy to distinguish from compressor issues. Issues caused by burner will probably manifest themselves similar to a scratched DVD or a bad signal in digital television broadcast, whereas issues from Compressor should appear less "out-of-the-place" (for example, a green square in the middle of sky would be out-of-the-place)
Maybe you could put your reference .mov online along with the bad .m2v encode of it and let others with good compressor setups take a shot at encoding it.

2 Pass VBR Stops Responding

Hi Guys
I'm using Win7 on a Dell Precision M6700 with a Nvidia Quadro K3000M. When I'm working on the timeline, the preview is smooth and sharp but my exports are a bit disappointing. So I thought I'd try setting 2 Pass VBR as well as checking render at max depth and max render quality. My export settings are H.264 and match source - high bitrate. I can export with 1 pass together with checking max depth and quality, but if I change it to 2 pass, Pr stops responding anywhere from 2% on pass 1 to 50% of the 2nd pass. Frustratingly it also kicks it into only using Mercury playback software only and I have to exit Pr and re-start the program a couple of times to get it back.
Does anyone have any ideas; is it my settings? I know 2 pass was buggy a few versions ago but I thought it was fixed?
Regards,
Graham

I find the improvement noticeable, however I use a free encoder. It's definitely more work and requires an understanding of the encoding process and how the many parameters will affect the outcome.
MeGUI/x264 Settings - Wikibooks, open books for an open world

H.264 .mov files problem with 2-pass vbr in DVD SP4

I have converted some VHS tapes by connecting the VCR to my camcorder (as a AC/DC bridge) and the camcorder to my macbook pro via firewire, and record using FCP into .mov files.
However, these files are huge (13 GB for an hour), and so I shrinked them down by exporting them (using QT pro) into .mov file via h.264 codec.
However, when I try to convert these already shrinked .mov files into mpeg2 files via compressor 2 (so that I can made a DVD in DVD SP), the files become corrupt when I use 2-pass vbr. (Frame freezes on play back in DVD SP and QT pro). It's OK with 1 pass vbr though.
If I convert those huge .mov files via mpeg4 in QT pro rather than h.264, there is not problem with 2-pass vbr.
So my delemma is: shall I store the files using mpeg4, or h.264?
I am under the impression that h.264 gives a better quality for the same file size than mpeg4, but 2-pass vbr will give a better quality than 1-pass vbr if I want to burn it on a DVD.
Thanks in advance.

In general recompressing from VHS to your computer to H.264 (or MPEG 4) then to m2v is going to hurt quality, so if you are able to get extra Hard Drives and store that way, or even a inexpensive camera with a firewire in/out you are probably better off (though with VHS it may be hard to tell regardless)
Also if you at least go straight the first time to m2v and check to make sure it looks okay to you, you may want to make sure to do that first
That being said, H.264 and One-Pass should in all likelihood (I have not tried recently, did it a while ago just to test things) will be better than MPEG-4 2-Pass, depends on the settings. Also if you try 1-Pass H.264 it seems to work with Compressor.

Sorenson 2-pass VBR?

Can someone out there tell me why there is no option for 2-pass VBR when using the sorenson pro codec? Am i missing it somewhere?
I would love to switch from cleaner over to compressor, but this feature alone makes it a way less effective compression tool when using sorenson.
I know i can't be the only person around that still relies on the sorenson codec to take care of the bulk of their compression...
Anyone? Bueller?

Don't I wish. I've been using Squeeze as Cleaner 2 pass VBR wont play in a web browser for some strange reason. Except now Squeeze deletes both the temp VBR file AND the final file, rendering itself completely useless, and reinstalls don't help. Here's hoping Apple offers Sorenson 2 pass, because the other apps don't want to work. How hard is it to make commercial software that friggin' works properly? If you pay for it, don't you think it should function?
Anyway, the use of 2 pass VBR with the Sorenson Video 3 codec may require some kind of lisencing fee, so Apple may be hesitant to cough up. Just a theory.

2-pass VBR Best vs 2-pass

As was recently pointed out to me, 2-pass VBR seems to outperform 2p VBR Best, although I plan to do more analysis of fast motion to check. I have posted some results including an interesting comparison with a high-end software decoder CCE.
http://www.netspeed.com.au/mark/encoders/Site/encoders.html

I feel your pain Alan, and am right there with you.
HOWEVER, it has been noted her several times that if you are not happy with compressor, to opt for another encoder.
there are a few AWESOME software encoders out there, main concept, bitvice and even procoder from lacie (although hardware) is AWESOME!
will it cost some money, yes. does it warrant such a cost, YES. is it fair that you need to buy ANOTHER encoder when you spent your already hard earned money on something that SHOULD be done with what you have.. HECK NO!
remember, compressor is just a tool in your box of goodies. i know more than likely you will not loose clients, but are all the heartaches and "empty promises" from apple worth it, i think so.
to buy the above mention encoders are fairly inexpensive and worth it. i would look into it if i were you.
HOPEFULLY one day, soon, compressor will be where it was once.
till that day however, i wll use what i got
Mikey M.

Difference between CBR and 2 pass VBR...

I used to always set DVDSP 3 encoder to the same bitrate and max bitrate, usually both at 7.0 VBR 2 pass, if the max is the same as the regular bitrate, am i wasting my time doing a 2 pass?
im just wondering if i set , lets say 1hr 10min, to 1pass CBR at 7, i can save lots of time and still have high quality, or does VBR 2pass (reg and max setting 7.0) make a better quality dvd, and if so why?
the reason i ask is because dvdsp4 forces the max rate higher then the regular rate now, it never did that before

I used to always set DVDSP 3 encoder to the same bitrate and max bitrate, usually both at 7.0 VBR 2 pass, if the max is the same as the regular bitrate, am i wasting my time doing a 2 pass?
Yes. If you set both average and max bitrate to the same number, it can't vary the bitrate.
It's probably wasting time even when average and max are different but close to each other... again, it can't really vary bitrate much and thus probably makes more sense to go CBR.
You're best off using VBR when you've got to vary the bitrate a LOT. Like average of 4.0 and max of 8.0.

AAC 256 VBR vs. AAC 320 CBR/ABR

I am planning on reimporting my music as AAC and want the best quality I can get. I noticed that when I try to pick 320 kbps, it won't let me pick VBR. Does anyone know:
1) Is this going to be CBR (rock steady 320 kbps) or ABR (average bit rate)?
2) If I pick 256 with VBR, how high will itunes let the bit rate go?
3) Which is likely to sound better? (size difference between the two doesn't matter)

I suppose it is because 320 is the highest bit rate you can go so variable bit rate implies more or less than the average bit rate. At 320, you can only go lower and perhaps the VBR algorythmn can't handle one-way (down only) variability?
If you can tell the difference between 256 and 320 kbps, then you must have some pretty **** good ears on that noggin of yours.
Cheers,
Patrick

1 pass VBR vs 2 pass VBR

What's the difference? Trying to figure out some settings for this project, but not sure which one to choose. Any help is appreciated!

The difference, in essence, is speed and accuracy.
With one pass encodes, the encoder will move through the material just once examining the motion and estimating the best encode rate for each particular section, and for the settings you have put in place. It estimates, encodes and moves on.
With two pass encoding, the first pass is used to analyse the motion and the second is the encoding - this is why the second pass takes so much longer. It is largely more accurate as it establishes the best encode for each section and then applies that on the second pass.
Cinemacraft does multi-pass encoding, with each sweep refining the analysis made on the previous pass. Such a technique realy helps get the very best from the footage and this is why Cinemacraft is so highly thought of.
However, the draw back is the time it takes... 2 pass takes longer than one pass, although the quality you get for the same (or similar) resulting file size, is better.

Quality less than par

i know thee are many topis on quality, but everyone i read has a slightly different need than me.--
I have a dv video that was created in FCP 5 and when i export it and burn it, it looks horrible on my tv. the text is pixelated and parts of the images are too at some points.
here is some info
length 4 minutes
dv ntsc 48
i export> quicktime> reference.
then i let dvdsp compress it with bitrates of 4-8 at best quality...
and i need it to look better.
Any suggestions on output, compression settings, or dvdsp settings. anything will help.
thanks in advance.
tony

the text was made in motion.
How did you export it, as DV also? Usually Motion does a niccer job than FCP with text even in DV, but you can adjust the output alsoo. For me, H.264 does a real nice job from text in Motion and FCP
fcp are dv/dvcpro ntsc , 100 percent render
fcp > export> quicktime> self con/ no recompress..
If the text is looking really bad, you may want to try exporting as --> using Quicktime Conversion and another setting (H.264 or Animation) Mark in and out point around small section with text and Pop it open using various settings and see if there are differences, usuallly text alot sharper than DV Also you can add compression markers for problem areas
compress to mpeg2 -bit rate between 6.4 and 8- motion best- 1 pass non vbr...with audio as DOLBY 2..
On this I would use either CBR (for text or slow Motion) or 2-Pass VBR, never really use 1 Pass VBR. Borad stroke here CBR allocates the same rate across all frames, VBR allocates more bits to the frames where they need them and less where they do not. 2 Pass puts the bits where they are needed also in the areas of the frame.
Example - Picture a Red Circle on a Black background, not moving, for 20 seconds of a clip. Then the next 20 seconds is a tree blowing in the wind in front of a wall (Yeah kind of strange movie, isn't it?)
CBR (lets say setting of 5) would allocate 5 to every frame, the Circle and the trees, which really does not make alot of sense since the Circle is not moving and stays the same across all 20 seconds and the trees are moving.
If the Circle for the most part would look the same at 3, using VBR will take more bits from the Circle and allocate it to the tree section. (Remember the Compressor in VBR is looking for an average target rate.)
1 Pass VBR will take the bits not needed for the Circle and move them to the tree clip, spread evenly acrosss the frame. Which again has an issue - the wall is not moving, the trunk of the tree is not moving. Two Pass will take more of the bits away from the stationary part of the frame (the wall and trunk) and move more of them to where the leaves are moving.
Anyway also note that there is a cap on how much data is DVD Spec, audio and video is 10.08 Mbps (9.8 for video), I usually budget for less though, sometimes higher rates on burned DVD-Rs can cause stuttering//glitching, and also discs full to the brim also have issues on some players. I usually aim for the least rate that looks the best.

Anybody know about VBR and CBR?

Hi,
I'm using PPro CS3 at the moment since I can't get CS4 to work very well on my computer.
On exporting.
I would like to export- adobe media encoder -to Flash video and to quicktime.
I'm sure I used to be able to set VBR 2 pass etc etc with different mbps.
Have I lost these? Can you point me in the right direction?
I only seem to have CBR settings?
I am using CS3 v 3.0 (I don't want to install update to 3.2 as when I did this all audio sync went out by about twelve frames- the ability to batch capture vanished too)
Thanks
scott mackenzie

Scott,
That particular video was encoded using VP6 2-pass VBR, 650kbps, 480x352, from Sorenson Squeeze for Flash v5.0.4.10. I use the VP6-E profile--the VP6-S profile is more if you're exporting HD-sized videos, but since this is originated from SD there's no need to incur extra decoding cycle. I turn on auto keyframes, and generally leave it around the Squeeze default; you may need to edit this setting depending on the footage you're encoding. Leave compression speed set to "best"--this is a counter-intuitive setting that actually should be labeled "compression quality" or have options ranging from "slow" to "faster". "Best" means the encoding runs slower, but results in a higher quality output. Strange, but true.
I crank the minimum quality slider up to about 70-75; this keeps the compressor from getting a little too overzealous. I find that it prevents some blockiness when transitioning from one scene to the next--and in my experience, the added file weight is pretty minimal for the quality gained. If you have fairly static footage with few transitions, you can gain better compression ratios by leaving the minimum quality slider set to a lower threshold. It's these settings that let VBR do its thing.
I never, or at least I haven't yet, enabled the "drop frames" setting. Unless you're trying to compress and distribute HD-sized videos, I think the prevalence and speed of high-bandwidth Internet connections negates this. On the other hand, if you need to stay within a certain bitrate threshold, like for some sort of hardware playout device, you'll probably have to experiment with this in order to produce files that meet the requirements of the hardware. For general web distribution, I've never found the need for this.
For sharpness and noise pre-processing, you'll again have to experiment. There's no magic number for these: it's going to depend on your footage and your tastes. They will both slow down encoding, and can have either a positive or negative effect on your video. I will sometimes use noise pre-processing if I'm encoding from DV or the like, to try to eliminate some of the noise and grain. This makes for a more efficient encode, because the compressor isn't trying to preserve details you don't want to see. These two settings sort of need to work in concert with each other, because one is going to blur the footage to remove noise, and the other is going to sharpen it and bring it back to a certain extent. I suggest experimenting with a short section of video, going with the extremes and then a couple settings in the middle--you'll quickly see the difference. I probably had sharpness set to 5-7, and noise pre-processing set to about 1-2, for this particular video. I think the result is quite clean.
Finally, I leave the minimum/maximum VBR and undershoot settings where they are--haven't needed to tweak these yet. These get pretty technical, and are again really the crux of VBR 2-pass encoding. They are what allow the compressor to "bit budget" an allocated bitrate for a given passage of video, and make sure that the final output stays as close as possible to that allocated bitrate. So far, the defaults have done the trick for me.
One note that I should probably explain, and that's to do with frame size. You might notice above that my output dimensions are 480x352, and not 480x360, as you might expect for a 4:3 video. This is because On2 VP6 (and many other codecs, like H.264) operate optimally in what is called mod16. What this means is that a mod16 codec will first break an input stream into 16x16 blocks, then 8x8 blocks, and then other sizes like 8x4 and 4x4. If you use a dimension that is evenly divisible by 16 (like 352 pixels high) you maximize the efficiency of the codec. I suggest doing this by cropping, and then scaling--not by scaling alone. I typically leave the "Maintain Aspect Ratio" radio button selected in the options, set one dimension (height or width, whichever), and then experiment with the crop filters until you get the other dimension evenly divisible by 16. Once you find the magic number, save the crop filter as a preset and save yourself some headache later! The crop filter will have to change depending on your export size--sometimes you'll crop vertically, and sometimes you'll crop horizontally. And it will also change if you're exporting to a 16x9 file. Sadly, that math stuff we all got into video to avoid will rear its ugly head yet again ;)
Good luck, and let me know if you need any other assistance. The biggest thing to remember is that there is NO magic formula to encoding, regardless of the source footage, the destination, or the codec used. Experimentation is really the only way.

CS4 Media Encoder- Two Pass CBR settings?

I have come across something strange in the stand alone Adobe Media Encoder CS4 (Windows and Mac) when attempting to encode an FLV with on2vp6.
There is an option under CBR that allows for a two pass, however it also has the minimum bitrate, maximum bitrate and bitrate variability options. This makes sense for VBR, but why are they there for in CBR? Are they inactive for CBR? Shouldn't they be dimmed? Are you supposed to set to 100% and leave it? Is it a bug? I know H.264 only has one pass, and it acts the same way as FLV/on2vp6 One Pass.
One of the whole points CBR is that you have a defined bitrate with no variation, used predominantly for HTTP Pseudo Streaming or Streaming. I have a bitrate limit imposed on a server, so I add video and audio bitrates together and get the total bitrate and I want a steady stream. With minimum and maximum settings it would vary depending on your content hence the term VBR which seems contradictory to CBR...
Can anyone please shed some light on this?
Thanks in advance.
Jon

Thanks again for the reply. The next question would be, is One Pass CBR then the only true CBR (or best for streaming/pseudo streaming)?
Adobe's Docs skipped right over that (2 Pass and CBR)...seems pretty important, maybe they figure most will just use One Pass for CBR.
The funny thing is you can't find any real references on the web to Two Pass CBR either. Even Google wants me to change it to VBR Two Pass in my searches :-)
The reason I ask is that when we ran Two Pass CBR, it flagged an error on the HTTP Psuedo Stream server (similar to Xmoov PHP) because it exceeded the bitrate limit at a portion of the video (evidentially) and stopped it in its tracks... Unless maybe it was a coincidence but it was tried several times supposedly. I didn't witness this, because we don't have access to the client's Intranet/VPN (long story). I built a JWPlayer/Xmoov PHP setup at our site to replicate, but it doesn't have the bandwidth throttling enabled to test that theory. I will try to run some more tests and post back here if I find the anomaly.
I much prefer VBR 2-Pass anyway for quality but you can't really stream it effectively.
-Jon

2-Pass VBR behaving close to a CBR approach

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