TMPGEnc 2Pass VBR Confusion

[Anonymoususer]

Ok I've been making SVCD's for a while now and I have been using the Constant Bitrate Setting since I started. Lately I've been reading posts and been hearing about the 2Pass VBR Setting and how "good" it is. I was reading the TMPGEnc Options and read about this but it really didn't help me. If I use this setting and set the minimum, maximum, and average bitrate how would I determine what the file size will be, I have a 450MHZ Processor, if I enable padding how long would the entire process take..? Would it be a good idea to swicth from Constant Bitrate to 2 PAss VBR...? I was also reading about 3 & 4 Pass VBR..what softwares support that and are freeware..?

Someone explain..

[hwoodwar]

DivXerouS:

I'm sure someone else can/will give you a better definition of 2-Pass VBR, but it goes something like this: The program goes through your video trying to allocate higher bitrates, where they are needed (such as action scenes) and lower bitrates where they are not needed (areas with little motion.) The second pass then refines these setting further. Since bitrates are allocated better it can allow you to put more time on an SVCD (with the right settings) than if you create a SVCD with a CBR of 2520, and with that 2-Pass VBR you can get the same quality as the CBR.

As far as determining the filesize, if you use the project wizard built-in to TMPGenc, it does pretty good at estimating the final filesize.

Since 2-Pass VBR goes through the encoding process twice, you can expect it to take at least twice the time it takes to do you current encodes. There is no real way of determining ahead of time how much time your system will take to encode using 2-Pass VBR, there are too many variables. I would "guess" 7-10 hours for for a 352 x 480 res mpeg-2 file. That is just a guess.

TMPGenc only supports 2-Pass VBR. To get more than 2-passes you have to use Cinema Craft Encoder (and I've read that it has to be one of the versions other than the "lite" version. The next version up from the light version costs about $2,000 U.S.) The Cinema Craft Encoder reportedly runs much faster than TMPGenc.

[Anonymoususer]

Your explanation is pretty good BUT I'm still a little confised, you say

"Since bitrates are allocated better it can allow you to put more time on an SVCD (with the right settings) than if you create a SVCD with a CBR of 2520, and with that 2-Pass VBR you can get the same quality as the CBR."

Im confused about this, if it refines the video how can it be the same as the CBR setting which has the continuous bitrate throughout the movie..?




It takes me around 8 - 10 hours to convert a 40 Minute movie using the Constant Bitrate Option, and IF I use this option..it should probably take around a whole day...DAMN !

[C53248]

I use 2-pass VBR whenever I need to use the whole disc. The 2-pass method lets me use the entire disc space AND use the bitrate most effectively. Scenes with little detail can get by with a minimal bitrate, and scenes with a lot of action can use much more than average. You can use Constant Quality (CQ) VBR to do this in one pass, but then you can only guess what your file size will be, and you will likely either waste some disc space or have a file that won't fit on the disc.

For one 700MB/80min. CD, divide the seconds of video into 6553600 kilobits to get your average bitrate.

Example:
1 hour 12 minutes 32 seconds of video = 4352 seconds
6553600/4352=1506 kbps
1506 total kbps - 192 audio kbps = 1314 video kbps
so use 1314 kbps for the "average" value in 2-pass

The "maximum" value depends on your DVD player and/or the players you want the disc to be readable with. I use 2520 kbps. The "minimum" value, with the padding option, is used because at least some players will have trouble if the bitrate gets to be too low. I use 300 kbps for that.

The movie's bitrate will then vary anywhere between 300 and 2520 as needed, and this is far more effective (for quality purposes) than using a constant 1314 kbps. You have to let TMPGEnc process the movie twice, but I think it's well worth it.

file size approx. = (average bitrate + audio bitrate) x seconds of video

That's in bits. Divide by 8 to get bytes. Divide again by 1024 to get kilobytes. Divide again by 1024 to get megabytes. An 800 MB video file fits on a 700MB CD.

[hwoodwar]

DivXerouS:

This is a very off the wall example, and I'm trying to simplify it.

You start with an avi file that you want to encode to SVCD compliance and it's 50 minutes long, 25 minutes of it are normal to little action scenes and 25 minutes of it are fast-action scenes.

In the 25 minutes of normal to little action scenes a high bitrate is not required to maintain quality, so for the sake of this example lets say these scenes only require 1200kbits/sec bitrate. In affect 50 percent of the movie only really requires a 1200kbits/sec video bitrate.

Again, for the sake of this example lets say the fast action scenes require 2520kbits/sec to maintain the quality level.

For the target file you decide to use 128kbit/sec audio

For your CBR mode to fit 50 minutes the video bitrate would be approx 2040kbits/sec (this is the only video bitrate I actually calculated, the others are guesses, or just for illustration purposes to try to explain this)

For my 2-Pass VBR I set a min video bitrate of 1100, average of 1800 and a max of 2520. So about 50 percent of the video will be encoded approx 600 lower and about 50 percent will be encoded a higher (because of the 1800 average.) It can give you the same, or better quality than the CBR and it might allow for 5-10 minutes additional on an 800mb CD.

There is a chance this might be describing CQ_VBR, if so, anyone feel free to jump in and correct me. I don't feel real confident about trying to explain this.

As far as your current system currently taking "around 8 - 10 hours to convert a 40 Minute movie using the Constant Bitrate Option" there are plenty of people out there taking 18-24 hours or more for an entire movie. My DVD ripping I actually do on a much less powerful system then the one listed in my profile, and it takes me 18-24 hours, or more (using DVD2SVCD, 2-Pass VBR and high quality motion search precision.)

[Anonymoususer]

Thanks to these explanations I now exactly what it is and how it works. Thanks Hwoodwar and C53248. You guys have been doing your homework.

I still have one more question for

C53248

You gave me the formula for calculating the average bitrate and told me what you set as the maximum bitrate, but for the minimum bitrate you said that you just enable padding so it won't go lower then the minimum bitrate because some DVD PLayers can't handle lower then 300. Let's say my average bitrate it is 2000 and my maximum bitrate is 2520 then if my minimum bitrate is 300, won't that degrade the quality ? or will it still look sharp ?


P.S:- This information should be posted in the TMPGEnc Settings area to clarify a little bit more for people who are new to using this option like me.

[Anonymoususer]

To begin with my math is terrible..seriously it's very terrible...BUT I tried out some calculations for finding out the Average Bitrate and I think they look pretty good. Here goes.

Fatal Fury The Motion Picture Broken In 2 [Part-1]

46Minutes & 13 Seconds.

46*60= 2760+13= 2773 <This is the Seconds of Video.

6553600/2773 = 2363.360980 = 2363.

2363 - 192 = 2171<-- So this is my Average Bitrate.

Now Im gonna try to see how big the file size is.

(2171 + 192) * 2773 = 6552599/8 = 819074.875/1024 = 799.87<--Mb's.
For the minimum Bitrate Im gonna raise it from 300 to 1000. Would that cause any change ? Make my file bigger, etc ?

I think this looks pretty good. Anyone find some problems please tell me.

DAMN I hate math....!

[puertorican138]

Let's say my average bitrate it is 2000 and my maximum bitrate is 2520 then if my minimum bitrate is 300, won't that degrade the quality ? or will it still look sharp ?

P.S:- This information should be posted in the TMPGEnc Settings area to clarify a little bit more for people who are new to using this option like me.

No, it won't degrade quality. Your video will still be OK.

For vcds and svcds you should never use a min bitrate higher than 500 or so unless you have specific playback problems on your dvd player with low bitrates. Raising the min bitrate decreases quality, it doesnt increase it. Besides, your encoder needs that range (Ex. 300 to 2520).

Hope That Helps!!! :P

[Anonymoususer]

So raising the Minimum bitrate will DECREASE the quality, but in my opinion it doesn't seem to make sense..If your my MAX is 2520 and my Average is 2171, wouldn't that be a drastic jump downwards..? or I guess specific scenes will look better at 300..weird

Well things seem a lot clearer now. Thanks to everyone for the help and the clarification, again this info should be included in the TMPGEnc Settings Explained section, considering many people use TMPGEnc to encode movies.

Thanks again for the info everyone, Im gonna start my first movie today using 2 Pass VBR, hope it looks better then expected.

Will post results tommorrow, or day after tommorrow, whenever it gets done..

[banjazzer]

If you think the parts allocated a lower bitrate are of insufficient quality, try a higher minimum bitrate. For VCD I go as low as 300 kbps. For SVCD I go no lower than 1100 kbps. This works for me. 8)

And to gauge your average bitrate, why not use TMPG's project wizard? If you want a stand-alone bitrate calculator, I recommend Bearson's Bitrate Calculator. It was designed for DivX, but works very well for (S)VCD.

[Anonymoususer]

Well after letting TMPGEnc run for 15 hours straight my annoying sister wanted to use it, and after I told her not right now, she goes and snitches.

Well I decided that the best thing to do would be to break the movie in 4 parts, 20 Minutes for each part.

Banjazzer, Im making an SVCD and thanks for telling me the minimum bitrate setting. I was thinking as to why would 300 be a normal SVCD bitrate I guess I was right. Thanks for clearing that up. Will post results WHEN I finish.

One question came to mind, If I break the movie into 4 parts, and encode each of them using the same settings, would I be able to merge them together, considering the bitrate would vary from scene to scene.?

[banjazzer]

One question came to mind, If I break the movie into 4 parts, and encode each of them using the same settings, would I be able to merge them together, considering the bitrate would vary from scene to scene.?

Yes.

[AngusMacGyver]

Hi! I have noticed that 2 pass VBR in TMPGEnc isn't so good. Try using CQ (Constant Quality) method. There is a guide here to help you know how big your file will be.
Or, if you have access, you will obtain a better quality by using CCE 2 pass. I've tried its trial version. You will be surprised with the quality of CCE, at least with MPEG2.
Good luck.

[sjm817]

I always use 2 pass VBR when making an SVCD. I use the following settings for 1 Hr of video:
2 pass
High quality motion search precision
2620 max
1675 Ave
300 min
padding enabled
96K audio
These settings were used for home movies from an 8mm camcorder. Since the source audio quality was not very good, I kept the audio bitrate low to increase video bitrate. The results are very good. The video quality of the SVCD is great. With my rig (P4 @ 2.4 GHz, 512 meg ram), I can encode it in ~ 3.5 Hrs.

[LPDad]

Just some time info.

On my wife's PII 350 it takes about 20 hrs to convert a 90 min movie using 2 pass VBR with Quality set to High. (great results)

On my Athlon XP 2000+ it takes 6 hrs. (with quality set to Highest)

Using CinemaCraft Encoder it takes roughly 4.5 hrs using 4 pass.

Just an FYI.

[DJRumpy]

Just as an FYI, the first pass on a multi-pass VBR run, actually records what the file would look like, using your 'Average' setting and CBR. If you set your average to 1500, then it will use that value as CBR during the first run, and record the bitrate demands. I found this digging around on the internet for specs on the new versions of CCE.

I haven't spent alot of time thinking about this, but I found it interesting. It makes me curious as to how the encoder responds to a movie, requiring much more bitrate than the average setting. In un unrealistic world, consider a movie that has exactly 2300 kb/s demands through the entire movie. It would seem that the first pass, using the settings above, would show a movie starving for bitrate. I have to wonder how the encoder responds to a situation like this, where the average cannot be met with good results, while the max will meet the needs. Does the encoder discard the AVG setting, going for a new avg which does meet the needs according to the first pass results? I do not know if this VBR method applies to TMPGenc. This article related to CCE only.

It also makes me think that maybe Multipass VBR is essentially treated like CQ VBR on the additional passes, and it uses the AVG setting for the first pass only. Using the Min/Max values to balance the movie on any additional passes. If not this, then why isn't there a Multi-pass VBR mode, which does not require an AVG setting?

I would be very interested in two test runs, one using a low AVG setting, and one using a high AVG setting, both for an average movie clip (say 1 minute long). If no one else wants to run them, let me know, and I'll set aside some time to do them. It would be preferable to see the tests using full DVD resolutions to see a more obvious result (more bit-range so to speak than VCD/SVCD).

[Gazorgan]

The biggest advantage of 2-pass VBR over high bitrate CBR is number of disks. What would take 4 Disks in CBR can often be put on 3 disks with VBR ( and even 2 disks on occasion ).

The second big advantage is non-standard players. My player will take bitrates above 3500, so I can keep my average, but go for higher peaks

[banjazzer]

It makes me curious as to how the encoder responds to a movie, requiring much more bitrate than the average setting. In un unrealistic world, consider a movie that has exactly 2300 kb/s demands through the entire movie.

At the risk of open warfare, this was my argument as to why CQ mode is theoretically superior to n-pass VBR, if the average bitrate were to be chosen incorrectly. Now, duck down into the trench before some of the mods arrive. 8)

[Anonymoususer]

Well took 15 hours to convert the first 20 minutes of the movie....after reading some of the posts, " I CAN'T AFFORD CINEMA CRAFT ENCODER PEOPLE" I'm not a millionare, BUT I managed to get a copy from my friend. I know most of the settings already BUT does CCE take AVI's directly, everytime I try to open it says it needs a file with a .ECL extension..? someone explain... if you can or point in some direction. I have the 2.50.01.00 version.

[banjazzer]

BUT does CCE take AVI's directly, everytime I try to open it says it needs a file with a .ECL extension..?

Yes it does, but it won't yield a VCD or SVCD-compatible mpeg. FitCD will create a compliant .avs file to load into CCE.

If you try to open a file, it will look for the .ecl file. The way to encode a file is to right-click in the main window, but take note of what I already said. CCE does not come with ready-made templates.

[AngusMacGyver]

I would be very interested in two test runs, one using a low AVG setting, and one using a high AVG setting, both for an average movie clip (say 1 minute long). If no one else wants to run them, let me know, and I'll set aside some time to do them. It would be preferable to see the tests using full DVD resolutions to see a more obvious result (more bit-range so to speak than VCD/SVCD).

I think an 1 minute sample isn't a good test because there is few scene changes in that time period.
Multi pass makes a good job when there is a mix of simple and complicated sequences, where it saves bitrate at simple sequences to use it at the complicated ones.

Believe in me. I've tried TMPEGENC 2 pass, TMPEGENC CQ and CCE 2 pass (In fact, 1 pass) and I can say in order of quality with the same filesize (the best to the worst):
1) 2 pass CCE
2) CQ TMPEG
3) 2 pass TMPEG

Why is it good using TMPEG? Because it's free.
Why is it good using 2 pass? Because we can predict the final filesize.
Why is it good using CCE? Because it is faster and the quality is better than TMPEG.
Why isn't it good using CCE? Because it's not free. I don't know how, but it's expensive.

I'd like you try and see with your own eyes.

[Anonymoususer]

Ok how many MultiPasses should I run it through...what would be a good pass...also this is a widescreen movie, I need to understand SOME settings, is their a settings explanation somewhere...I was looking at the guide in the convertings section and I haven't extracted the audio, I'm just gonna encode directly in CCE....anyone have ANY, I mean ANY suggestions please tell me, some pointers, explanations, anything. Im gonna use CCE because of all the paraises I've been hearing about it lately, someone giude me through some of the settings they use to make an XSVCD, [Non Standard SVCD] - I hope it's better and faster then TMPGEnc as people say it is. Also someone said that a logo appears when your done encoding the movie...what the hell is up with that ? and how can you check to see if a logo WILL appear when your done converting..?

[AngusMacGyver]

Ok how many MultiPasses should I run it through...what would be a good pass...also this is a widescreen movie, I need to understand SOME settings, is their a settings explanation somewhere...I was looking at the guide in the convertings section and I haven't extracted the audio, I'm just gonna encode directly in CCE....anyone have ANY, I mean ANY suggestions please tell me, some pointers, explanations, anything. Im gonna use CCE because of all the paraises I've been hearing about it lately, someone giude me through some of the settings they use to make an XSVCD, [Non Standard SVCD] - I hope it's better and faster then TMPGEnc as people say it is. Also someone said that a logo appears when your done encoding the movie...what the hell is up with that ? and how can you check to see if a logo WILL appear when your done converting..?

Hi!
That logo appears only with trial version. If you get the full version, there won't be any logo.
My suggestion is following the guides at vcdhelp.
Try this one: http://www.vcdhelp.com/sefy/

[DJRumpy]

DivXerouS, you should be able to drop your AVI directly onto CCE, or right click in the main window and select ADD. It should only prompt you to save the ECL file just after clicking ENCODE. Saving your encode settings in an ECL file is completely optional, and disabled on the preview versions. Just select No. It should then start encoding.

As for CQ being better than multipass, I'd have to say no. If your average is set at an optimal level, then the quality from MPVBR should surpass CQ. CQ does fine until the motion prediction routines make a bad guess. The quality will rapidly degrade until the next keyframe.

I still need to run some tests to see exactly what happens to the average setting after the first pass results are gathered. I can't imagine that the setting is discarded, or they could have simply pre-generated optimal fixed 'avg' values for you. With that in mind, I'm guessing at this point that the average is then treated like a variable quantization scale, depending on the bitrate demands at the moment, where CQ has a fixed quantization setting regardless of bitrate.

[banjazzer]

you should be able to drop your AVI directly onto CCE, or right click in the main window and select ADD

Yes, you should be able to create an mpeg, but it won't be VCD/SVCD/DVD compliant unless the resolution of your avi fits the spec. to start with! Which is why you invariably need another process before inputting your avi to CCE.

As for CQ being better than multipass, I'd have to say no. If your average is set at an optimal level, then the quality from MPVBR should surpass CQ.

It's a moot point (and for some an article of faith ) whether n-pass VBR is any better than CQ, provided both are done properly. The point is, you don't need to guess the optimal level for your average with CQ. 8)

[DJRumpy]

Yes, you should be able to create an mpeg, but it won't be VCD/SVCD/DVD compliant unless the resolution of your avi fits the spec. to start with! Which is why you invariably need another process before inputting your avi to CCE

This is a given, regardless of which encoder your using. You can use TMPGenc to peform the resize, VirtualDub, ect. I use AVISynth to resize on the fly during the encode. None of which has much, if anything to do with the ECL file used in CCE. The ECL contains only the encoding settings for any particular AVI/AVS file. I'm not sure what your driving at Banj...

[banjazzer]

None of which has much, if anything to do with the ECL file used in CCE.

I never said it had anything to do with the .ECL file. I was commenting on the statement"you should be able to drop your AVI directly onto CCE".
You can't. And it is completely different to TMPG, where you can load in any resolution avi, and provided you load the correct template, the resizing will be done automatically. CCE has no templates, so you have to take account of the resizing before dropping the file into CCE.

Maybe this was not what you intended to say?

[Anonymoususer]

ok that link you provided me really doesn't have the guide to using CCE...it tells you how to use the PLUGINS with other programs and not directly....thanks for the link though...still searching for the right guide...

[banjazzer]

www.doom9.org You will find plenty of information about CCE there. Look in the CCE forum for the FAQ, and you will find specific links.

[DJRumpy]

Actually, you can simply click the DVD compliant. In conjunction with any of the 'half' options you can get a resized output, and it will matt the avi to a standard resolution if you don't mind the black borders. If your AVI is already to spec, than yes, you could simply drag it into CCE. I know when I started, I did all of my pre-processing outside of TMPGenc, simply because it takes too long to do anything. Any additional work like resizing, is best done outside of it. Yes, you can resize using TMPGenc, but I would never suggest it, unless the person is simply too PC challenged to figure out VirtualDub, or AVISynth.

Divxerous, let me know if your still having difficulty. I can mail you the manual for version 2.66