Need help calculating bitrate for XVCD - Not a newbie questi

[Sterling]

I have not been able to find an answer to my question on previous posts in the forums, so if you think this is a newbie question, I apologize in advance.


I am trying to convert some DivX movies that are 720x288 and 720x352 to XVCDs at 720x480 to burn onto 2 80 minute CD-R's.

When I use the calculator on this site, I put in the specs for the first movie (131 minutes, 2 80 minute CDs, 224 kb audio bitrate) and come up with 1412 kbit/sec video bitrate.

I fire up TMPGEnc beta 12j, load the VCD(NTSCfilm) and unlock.mcf templates (just like the convert guide says), then set the video output to 720x480 and CBR @ 1400 (just to be safe) and let it convert.

After converting the clip, I cut it into 2 equal size parts (65 minutes and a few seconds, around 750 megs each) and launch Nero 5.5. I do Video CD (NOT standard compliant) and when I move the first mpg clip in, Nero thinks it like 88 minutes long.

If I try to simulate a burn, it says it is 88 minutes long, 879 megs in size and it spits out my 80 minute CD.

What am I doing wrong? Why wont Nero burn a 65 minute/750 meg XVCD onto an 80 minute CD?

Also, when I convert the clips, do I need to take into account that the calculator on this site for XVCDs is only for 352x240 and WONT work for 720x480? If so, how can I calculate the proper bitrate for a 720x480 XVCD?

Many Thanks!

[davidian]

Oh I don't really know too much about this, but one thing strikes me.. should 750 megs fit on a 700 meg CD (80 mins) ? Unless it's standard comliant VCD ..

[Sterling]

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On 2001-09-08 12:29:47, davidian wrote:
Oh I don't really know too much about this, but one thing strikes me.. should 750 megs fit on a 700 meg CD (80 mins) ? Unless it's standard comliant VCD ..
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It is my understanding that an 80 minute CD-R will hold 700 megs of regular file data (with error correction) but almost 800 megs of VCD data (because there is NO error correction).

Sterling

[vivisimonvi]

I had a similar problem as well before (Nero seemed to tack on an additional 80 megs or something). You could try to remux the file in TMPGEnc as a "VideoCD" so that it'll register as a compliant 2.0 VCD file. It always works for me.

[Peter]

Same prob here. I just encoded a movie for 2 cd's, each file is 780 MB (352x288 PAL VBR 2000). If I disable standard vcd in Nero I can't burn, because it's too long according Nero.
I thought VCD can fit 800 MB on a 80min CD, also when non-compliant. Is this not true?

[Vejita-sama]

Two things:

1) Why did you use the NTSC film template? Is your source at 23.976fps?

2) Nero sucks are burning MPEGs directly. Make an image of the MPEG and use nero to burn that. VCDImager (look under the Tools link to the left) is a good choice. It's a dos program so you might want to d/load a GUI for it. VCDIMager GUI is a simple choice. I use TSCV so I can add seamless chapters, menus, etc. (www.ttool.org). TSCV isn't the most user friendly program but it's fairly easy to use. It defaults to MPEG2, to make MPEG1 bun/cue you'll need to copy the CDI folder from nero into the dir you installed TSCV (if you read the guides at ttool.org they walk your through it).

[pibble]

Sterling:

My advice to you is to encode each half of the movie as a separate project in Tmpgenc. It's really easy. If you do this and make sure you use an encoding bitrate that guarantees a certain file size per second of video, you will be sure to get an image that fits on your 80 min CDR. I've found that the mpeg cutting tool included with tmpgenc is a bit dodgy... it gives me weird effects at the cut point such as the video continuing w/o sound, and the file length is inexact for my needs.

It's easier to just encode your two/three parts as separate projects.

Basically, you get the others settings all set up all like you like, then you go into the "Advanced" tab and check Source Range. Then double-click on Source Range again and it should bring up a screen where you can set Start Frame and End Frame marks in the clip. Put the Start Frame at the beginning of the clip and your End Frame either half-way or one-third through the clip, depending if you need 2 or 3 parts. Click OK to exit the Source Range screen and make sure your output file in the main tab says "Project Foo (part 1).mpg" or similar. Save the project (ctrl-s). Then immediately change the output filename to "Project Foo (part 2).mpg" and then go into advanced tab, source range, and "move to end frame." Set that as the start frame (or just a few frames before that...) and make your new end-frame and so on. Then save your project again, and then run both the projects in Batch Mode. Works like a charm.... no using the crude mpeg cutting tools. Each part is already a complete, valid mpeg file.

Hope this helps...

pibble

PS. Why are you setting the VCD (output file) video res to 720x480? Just curious. Is it because your player happens to support higher resolutions?

[pibble]

I should add that you should use either a CBR (constant bit rate) or a 2pass VBR (two pass variable bit rate... takes longer but produces excellent results with exact length.) 2pass VBR should (probably) only be used on SVCDs because MPEG-1 VCD's are supposed to be CBR always.

Do NOT use the CQ (Constant Quality) or single pass VBR because these can produce inexact file sizes that may be too large to burn.

I always make 2pass VBR SVCD's with "High Quality (slower)" motion search. I usually use bitrates of at least 1800 kbps. This combined with some tweaks to the GOP Structure and Quantize Matrix settings, and I make standards-compliant SVCD's that to me seem to be about 80-90% of the visual quality of a DVD on a standard television. (IE, virtually indistinguishable except to hard core videophiles.)

[Peter]

Vejita-sama:
I tried VCDImager to make image file from a 784MB MPEG-1 file (non-standard). If I add the file to the cd layout VCDImager is telling me in red: 'approximate CD Size 825 MB'

[Sterling]

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On 2001-09-08 15:45:25, pibble wrote:
I should add that you should use either a CBR (constant bit rate) or a 2pass VBR (two pass variable bit rate... takes longer but produces excellent results with exact length.) 2pass VBR should (probably) only be used on SVCDs because MPEG-1 VCD's are supposed to be CBR always.

Do NOT use the CQ (Constant Quality) or single pass VBR because these can produce inexact file sizes that may be too large to burn.

I always make 2pass VBR SVCD's with "High Quality (slower)" motion search. I usually use bitrates of at least 1800 kbps. This combined with some tweaks to the GOP Structure and Quantize Matrix settings, and I make standards-compliant SVCD's that to me seem to be about 80-90% of the visual quality of a DVD on a standard television. (IE, virtually indistinguishable except to hard core videophiles.)

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Yes, my Sony DVP-S560D will play 720x480 and since the sources are 720x280/352, I wanted to try to keep it as close to the source as possible.

I did not know about Source Range - I tried it last night and it works great! I will be using that feature more often!

All of the S/XVCDs I have made so far have always been CBR, using the bitrate from the online calculator, but these last 2 clips have really given me hell.

I will keep you posted on my success (or lack thereof).

Thanks!

Sterling

[Randytronic]

I had the exact same problem when I made an XSVCD of Starship Troopers (2 cd's, 60 minutes each at 720x480). Both files were less than 800 megs, but Nero reported them as being much larger. I solved the problem by remuxing with BBenc, choosing the SVCD option under program stream settings. I should add that this did not make them SVCD compliant, because of the 720x480 resolution, but it did make Nero report the file size correctly and I was able to do a successful burn as a non-compliant SVCD.

So, my advice would be to demux with TMPenc, then remux with BBenc. (instructions on how to do that are on this web site) Since it's an XVCD (mpeg1), I assume you would use the VCD option under program stream settings, and burn as a non-compliant vcd...

Hope this helps.

[vivisimonvi]

I found that burning as a non-compliant VCD, files can only go as high as 700 Megs (Nero will "think" this is actually a 100 Megs more making it 800).

However if you use TMPGEnc to remux your non-VCD compliant MPEG as a "Video-CD" stream, you can fool Nero in thinking the files is actually VCD 2.0 compliant (this works for video streams over 1150 kbps). That way you can use the full 800 Megs and burn as a compliant VCD. Actually, it's better to keep MPEGs under 795 Megs so the other VCD files can fit.

I haven't tried Randytronics method, although this is for regular VCD. (My player seems to do fine whether my MPEG XVCD's are compliant or not)

[vivisimonvi]

On my previous post, the actual amount of "extra" data Nero interprets depends on how big the MPEG file is. The bigger the MPEG, the more "extra" data is added on.

[Sterling]

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On 2001-09-09 22:17:35, vivisimonvi wrote:
I found that burning as a non-compliant VCD, files can only go as high as 700 Megs (Nero will "think" this is actually a 100 Megs more making it 800).

However if you use TMPGEnc to remux your non-VCD compliant MPEG as a "Video-CD" stream, you can fool Nero in thinking the files is actually VCD 2.0 compliant (this works for video streams over 1150 kbps). That way you can use the full 800 Megs and burn as a compliant VCD. Actually, it's better to keep MPEGs under 795 Megs so the other VCD files can fit.

I haven't tried Randytronics method, although this is for regular VCD. (My player seems to do fine whether my MPEG XVCD's are compliant or not)
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Instead of remuxing my clips, I went ahead and converted them at 1400 CBR to make a 1.5 GB MPG and then used TMPGEnc's MPEG Tools to Cut them into equal pieces.

Before, though, when cutting, I set the Type to "MPEG-1 Automatic" and this time I did "MPEG-1 Video CD" and after the cutting, Nero said they were ad big as they really were; only a few megs were added to the total size.

Thanks for all the help guys!

Now onto my next questions!

Sterling