VS10 - File Size Increasing?!

[Manzano808]

Once more into the breech . . . and once more I need the help of you Gurus. You have helped me immensly in the past.

I had worked so hard to set up a resolution that would allow me to record a certain amount of captured analog video and be able to fit it onto a single DVD without any compression. I was able to get 88 min onto a DVD @ 7250 kbps with Digital Dolby audio at 256. I was able to do this consistently for quite some time, with well over a hundred DVDs. Also, this would still allow me to setup menus and even motion thumbnails. Ah, life was good . . . until,

Just recently, I noticed that the DVD was over this amount and that the file size was quite a bit larger and would now force me to have to compress in order to fit. I went back and checked the settings and nothing appears to have changed.

What could this be? I've done a whole lot of research and testing with various resolutions and time of capture etc. Now all that gets thrown out the window and I don't know why. I find that now I must set it to 6700 kbps and it is still larger file size than what i had with 7250. Thats going down 550 kbps and I can't do the motion thumbnails or much else.

I've never touched the settings but could VS have changed something without me knowing it and if so what could it be? The only thing I could think of would be the "Speed - Quality" slider but i know this has ALWAYS been set at 80%. I've never changed it.

I hope someone can help point me in the right direction to figure this out.

Thank you very much

[2Dogs]

Can you post your video file properties?

One thing you could easily rule out would be an accidental change from 7250kbps Variable Bitrate to 7250kbps Constant Bitrate. That would result in bigger file sizes.

Looking at your project duration, it's likely that you are using variable bitrate. In that case, you can never be entirely certain about file sizes, since the amount of motion in footage will vary. In an extreme case, such as a slideshow, there will be a huge difference between 7250kbps variable bitrate and 7250kbps constant bitrate.

It may well be, however, that the implementation of variable bitrate encoding in VS10 is different from that in VS9. Some "codec people" will no doubt be able to advise on that.

You're not the first poster to mention making up dozens, or in your case, one hundred DVD's. That's a lot. What exactly are you doing? Is it just compilations of TV episodes made commercial free? (nothing to do with your problem but I'm just interested!)

I had worked so hard to set up a resolution that would allow me to record a certain amount of captured analog video and be able to fit it onto a single DVD without any compression.

I can think of lots of harder things to do!

[heinz-oz]

You have me a little confused with your remark of capturing analog video and put it on DVD without compression. You are, I suppose, capturing your analog video to mpeg2 format or you wouldn't have a DVD after, that's compressing it to mpeg2. Coming from an anlog source, I feel your intended bitrate is very high, IMHO, resulting in a larger file size than neccessary. Have you experimented with this? I have converted analog video at 8000 kbps and 6000 kbps without a noticable (to me) degradation in quality and now use a setting of around 4500 kbps which still looks as good as the original footage.

All this doesn't explain the symptoms you are having, of course, but I think you are worried about something that's not worth worrying about. For an analog source, your settings of 7250 kbps are unnecessarily high and will not give you a btter result than a lower one.

[roy wood]

Hi Heinz I too have been burning Analogue to Mpeg2 at a high bite rate (8000kbps) in the hope of improving quality but from what I've read here that's a waste of space.
What would you reccomend as the optimum for 8mm and also Hi8. My priorities would be Quality over Quantity. Thanks Roy.

[2Dogs]

Hi Heinz I too have been burning Analogue to Mpeg2 at a high bite rate (8000kbps) in the hope of improving quality but from what I've read here that's a waste of space.
What would you reccomend as the optimum for 8mm and also Hi8. My priorities would be Quality over Quantity. Thanks Roy.

Tsk tsk Roy, you're going off the topic!

Do a search of the forum - Trevor Andrew and Heinz have posted before on this. But at the end of the day, do some tests and see what you think about it, let yourself be the beholder with the eye....

[Manzano808]

Can you post your video file properties?

File format: NTSC DVD
Video type: MPEG-2 Video, Upper Field First
Attributes: 24 bits, 720x480, 4:3
Frame Rate: 29.970 frames/sec
Data rate: 7250 kbps
Audio type: Dolby Digital
Attributes: 48000 Hz
Layer: None
Bit rate: 224

One thing you could easily rule out would be an accidental change from 7250kbps Variable Bitrate to 7250kbps Constant Bitrate. That would result in bigger file sizes.

AFAIK, it's always been set at Constant. I can't remember ever changing that. I've always thought that "Constant" SHOULD be a smaller file size than "Variable". Is that generally true?

What exactly are you doing? Is it just compilations of TV episodes made commercial free?

Yes

Thank you 2Dogs!

[2Dogs]

I've always thought that "Constant" SHOULD be a smaller file size than "Variable". Is that generally true?

No, it's actually the reverse. Variable bitrate will use a high bitrate for video with lots of change from one frame to the next - i.e. movement, panning, and so on, but a lower bitrate, i.e. higher compression, for sections that have less changes. Therefore the file size of a video encoded at 7250kbps variable bitrate will be smaller than the same video encoded at 7250kbps constant bitrate.

Depending on your source material, it might appear that variable bitrate might result in a slightly better image quality if you are trying to fit 88 minutes worth onto a single 4.5Gb disk - or at the very least it would give you more "headroom" for fancier menus and audio.

Whether you have the option to select variable bitrate might depend on what capture device you are using.

[Manzano808]

Coming from an anlog source, I feel your intended bitrate is very high, IMHO, resulting in a larger file size than neccessary. Have you experimented with this?

Yes, but unlike Audio, where i can really tell the differences between quality, Video gives me trouble. Because I can't really seem to see the difference, i've always assumed that it would be better at a higher res.

But I believe you are correct Heinz. Perhaps I've never noticed the difference because there was NO difference duhhhhh. The only time i've noticed a degradation in quality with bad pixelization is when I have to compress so much. So you believe this is true with say, TCM movies and also Discovery Channel stuff? I have really wondered if it was true that after a certain res, it wouldn't improve. After your helpful response, i'm going back and test more. Just wish I was as good at seeing video quality as i am with audio quality. One thing's for sure, it would sure save me a lot of dvd's if i could go lower on the res! That would be nice.

For TCM movies, i try to choose settings whereby the entire movie will fit without any compression. But now with this weird increasing size, my settings will no longer be accurate.

Thanks Heinz!

[heinz-oz]

...

One thing you could easily rule out would be an accidental change from 7250kbps Variable Bitrate to 7250kbps Constant Bitrate. That would result in bigger file sizes.

AFAIK, it's always been set at Constant. I can't remember ever changing that. I've always thought that "Constant" SHOULD be a smaller file size than "Variable". Is that generally true?
...............

Certainly not. You will not find a significant difference between VBR and CBR if you only run one pass and/or your video does not have much movement variation in it.

If you use VBR with dual pass encoding on a video that has a lot of movement and also quiet scenes, you will find you can get better quality at a smaller file size. The first pass is going to evaluate the video and set a higher bit rate in sections where this improves the quality while in sections where it is not needed, the bit rate will be lower. With CBR, you would have to set the bit rate at the max settings of your VBR to have the same quality. Since areas which do not need it will also be encoded at the high bitrate, the file size will be bigger.

[heinz-oz]

Jeeeshhh, you guys are quick today By the time I post my response, everything had been said by others already

[Manzano808]

No, it's actually the reverse. Depending on your source material, it might appear that variable bitrate might result in a slightly better image quality

Well, maybe i did change that. But it seemed i always had it set to Constant. Now you have me wondering. I'll change it and test again. Using the AIW 9800 Pro to capture. Could it be the Lower/Upper field setting?

You know, this is so weird that I actually went back and made sure it wasn't my Editing program that was doing this. Because I had upgraded the Womble to their new DVD Version for another choice for putting the disks together. I had discoverd that VS10 wouldn't handle anything over 9800 kbps. I found that even if it was 9801, it would revert back (most of the time to 7000). I was able to isolate the problem to VS. Womble version change didn't do anything.

Thanks again 2Dogs.

[heinz-oz]

Coming from an anlog source, I feel your intended bitrate is very high, IMHO, resulting in a larger file size than neccessary. Have you experimented with this?

Yes, but unlike Audio, where i can really tell the differences between quality, Video gives me trouble. Because I can't really seem to see the difference, i've always assumed that it would be better at a higher res.

But I believe you are correct Heinz. Perhaps I've never noticed the difference because there was NO difference duhhhhh. The only time i've noticed a degradation in quality with bad pixelization is when I have to compress so much. So you believe this is true with say, TCM movies and also Discovery Channel stuff? I have really wondered if it was true that after a certain res, it wouldn't improve. After your helpful response, i'm going back and test more. Just wish I was as good at seeing video quality as i am with audio quality. One thing's for sure, it would sure save me a lot of dvd's if i could go lower on the res! That would be nice.

For TCM movies, i try to choose settings whereby the entire movie will fit without any compression. But now with this weird increasing size, my settings will no longer be accurate.

Thanks Heinz!

I think you have a few things misunderstood. Compression is needed in order to fit a video on a DVD. TV broadcasts or Web streaming have other criteria applied. If you record/capture a web video, it will have very heavy compression applied, usually DiVX, Xvid or mpeg4 to get to the small file sizes required.

In order to put that on DVD in mpeg2, you need to convert this compression to a different one, mpeg2. Invariably, after this process, your quality will have suffered while the file size has gone up.

As long as the source file is DVD compliant mpeg2, you can put this on a DVD without further processing (compression/transcoding) if it is not mpeg2 or non compliant mpeg2, it doesn't matter what you think you are doing, the file will be recoded to make it compliant.

[2Dogs]

I had discoverd that VS10 wouldn't handle anything over 9800 kbps. I found that even if it was 9801, it would revert back (most of the time to 7000). I was able to isolate the problem to VS. Womble version change didn't do anything.

That's because to comply with the DVD standard, the maximum allowable video data rate is 9800kbps. The total data rate, including audio and subs (subtitles, optional narration etc) If you use a non-compressed audio format, the maximum allowable video data rate will be 8264kbps.

For most analogue video sources, your field order should be upper field first.

I'm assuming that your main aim is to fit about 90 minutes of video, with your menus, onto a single disk at the maximum quality. You could therefore try a test project, and do it twice. First using constant bitrate, you might need to use 6700kbps as you mentioned previously, and then also using variable bitrate. You might be able to go up to perhaps 8000kbps with that, both with compressed audio (which you already were using) Then make your choice depending on your perception of the finished image quality. Just about all movies are VBR, so there must be something to it!

I would slightly differ from Heinz's summary of the benefits of variable bitrate. Your best workflow will be to capture the video at the given bitrate, and then to smart render your project. That way, there will be no re-encoding, apart from around transitions, cuts and so on, and a minimal loss of quality. The smart render process is also many times quicker than re-encoding the video too.

If you've captured your video using variable bitrate, you will still want to take advantage of smart render - so you won't opt for two pass rendering - otherwise, it will not smart render. Now in my experience, single pass VBR will still give a smaller file size than CBR. I think that the two pass process, rather than reducing the file size further, just refines the allocation of the higher bitrates more effectively, giving a slight improvement in image quality for about the same file size as single pass. It's a while since I carried out my tests on VBR vs CBR, and if I'm having a "senior moment" on that, I'm sure that someone will jump in to correct me!

I think you should have enough to be getting on with now!