How accurate is the bit rate calculator embedded in TEMPGEnc

[jeremymiller]

itself? I reduced the average bit rate to fit 60min of SVCD onto one disk based on TMPGEnc's own calculator in the Wizard. But when the file is encoded, it is larger than one disk can hold. I did VBR-2pass. Don't know if I did something wrong. Any pointers would be appreciated. Thanks,

Jeremy

[theboywonder]

What bitrate did you use? (FitCD is the best, although its a separate program - still, download it!)

For 60 mins exactly, you should have an average of 1600kbps (recommended max: 2516, min: 1145).

I dont know about anyone else, but I never use the TMPGenc wizard... I'm assuming that most people don't either. Its easier to see whats happening when you load and modify the template yourself!

1) Disable the wizard, open your source file, and then click the little 'LOAD' button in the bottom right corner of TMPGEnc.

2) You want to open an SVCD template. They're located inside the TMPGenc folder in a sub-folder called 'templates' funnily enough.
You'll see various ones... you'll need something like: SuperVideoCD (PAL).mcf ....... or if your source is NTSC, use the NTSC one instead!

3) Once that is opened, click the 'SETTING' button next to the 'LOAD' button.
Change the 'Rate Control Mode' from
'Constant Bitrate (CBR)' -----------> '2-pass VBR (VBR)'.

4) To the right of that, there is a setting button again. Click it.

5) Enter the appropriate bitrates, and ignore all the rest. Click OK.

6) If you want the the best quality to time to encode ratio, at the botton change the 'Motion Search Precision' from
'Motion Estimate Seach' -----------> 'High'

_____________________________

Good luck!
Robin

[jeremymiller]

thanks for the info. I tried according using FitCD to get the numbers and run it through TMPGEnc and the file is still over the size limit by quite a bit. Wondering why.

[theboywonder]

post your exact method and i'll try and help best i can...

[guitar_george_skank]

Just wondering...What frequency is the audio at? 44.1Khz or 48Khz? I did basically the same thing as yourself but because i tried it with 48k sound the file was too big for the CD. When i converted to 44.1 it fitted perfectly. The calulator does not seem to take into account the higher rate of 48k. Hope this helps, but if i'm talking rubbish, please let me know! I'm still fairly new to this but learning fast.

[theboywonder]

lol guitar_george_skank,

there is no difference between the size of the audio, whether its encoded at 48Khz or 44.1Khz. The only importance here is the bitrate (kBit/sec).

or in otherwords, 224kBit/sec audio uses 28 kilobytes per second whether it's frequency is 44.1Khz or 48Khz!

Jeremy, audio for both vcd and svcd should be 224kbit/sec.
Aswell as your method, gimme the length of your movie and I'll work out the exact bitrate in FITcd (just incase you're using it wrong?!).

[jeremymiller]

Appreciate the help. The movie length is 95m23' and I loaded the .d2v file into FitCD and these are the numbers: on 2 74m CDs, Max 2565 Min 1195 and Aver. 1947. I used the SVCD-NTSCfilm and selected VBR-2pass and changed the average to 1947 and Min to 1195 and the resulted mpg2 file is 1.75G, which is much larger than what two 74m CD-R can hold. Each holds about 750MB. Thanks for the helpl

Jeremy

[theboywonder]

Hmmmm.

How were you planning to split that mpg?

The bitrates I get are:
Average: 1898
Max: 2516
Min: 1145.

Try loading the template, then loading 'unlock.mcf' (located inside a folder called 'extra' which is in the templates folder).

Then modify the bitrate.... (although you shouldn't have to do this.... )

Its got me a little stumped! Anyone else?!!!

[d5i5s5c5o5]

ok, i regged on these boards just to answer this one...the problem is likely that the stream is being padded with extra data...

i myself had this problem two days ago while making my first full length vcd (everything else had been short episodes and music videos)... i encoded it four times and kept ending up at 904MB no matter what bitrate i encoded with (and the movie was 90:39 so that should be the standard vcd's size)... i also tried converting both the origional 640x480 DIVXMPG4 V3 file i had and a 320x240 divx 5.02 file i converted for use with dcdivx and both came out the same... i was thinking that the settings just werent making a differance, but after reviewing the encoded clips there definately was a differance in quality, but the size was the same...

my eventual solution was to run the .mpg through tmpgs mpeg tools and take out the audio and video streams then put them back together without the padding stream (youll see it in the stream selction area).... if you havent deleted your mpg then this should work, if you have, when you re-encode, make sure to unlock the settings and go to the system tab and make sure you are selecting "svcd non-standard" and you wont have that problem any more...

[jeremymiller]

I still have the oversized mpg file and did a de-multiplex and separate the video and audio streams and then multiplex them again, with no change in size at all. I also unlock the setting and put in all the data, i.e. max, min and ave bitrate, but it seems the system is igoring these settings and produces larger than desired settings. Wonder what's wrong here.

Jeremy

[adam]

Are you sure you are using the exact settings that FitCD tells you...for both video AND audio?

You say fitcd calculated an avg of 1947kbits but with your source that would only happen if you had the audio set to about 160kbits.

So in TMPGenc did you use 160kbits? Because in your method you say you simply loaded the template and adjusted the video bitrate, but the default audio bitrate is 224kbits, which would give you a total filesize of about 1.75G. So unless my detective work is incorrect I think you just didn't calculate your audio bitrate correctly.

As theboywonder said you should have used an avg of about 1898kbits if you used the default 224kbits for audio.

If you are happy with 160kbits for audio then simply re-encode your original audio stream to 160kbits and multiplex it with your current video stream and it should fit on 2 74 min cdrs.

Is there any reason why you are using a min bitrate of 1195kbits? There is no advantage to using a higher min bitrate, actually it is a disadvantage. Your min bitrate should be 0-300, or the lowest bitrate you think you will ever need in any given scene in your movie, for example the end credits. The only reason to use a higher min bitrate setting is if for some reason your dvd player cannot handle low bitrates and skips or freezes during low bitrate scenes.

[jeremymiller]

Thanks you for your help, Adam. It's working now.