Is the bitrate calculator on this site wrong?

[Robbins1940]

I been using the new bitrate calulator on this site to capture in real time mpeg2 from broadcast tv.

For example i been using a bitrate for 44minutes svcd, usualy the file size before burning is around 750mb but now its 795mb and thats for 43min and 38 secs. When you add on the files nero adds to the disc it goes over 800mb and i have to overburn. And yes the bitrate is for 1 80m disc at 224 audio rate. Video bitrate is 2245 kbps.

So sefy is the calculator wrong?

David

[adam]

In order to have a perfect bitrate calculator you would need a perfect mpeg encoder. Since neither exists, your calculations will always be off by at least a few MB's. That is why you should always be conservative and shave off a little bitrate from what the calculator says.

Overhead for a svcd can be up to 10MB's. If your file is 795MB's than your only off by about 5MB's, which is definitely within the expected margin of error for any bitrate calcultor. In the future just lower the bitrate a little, otherwise continue to overburn.

[shochan]

if you want to do it yourself and get pretty close use this equation
v=video bitrate
a=audio bitrate
f=file size in kilobytes divide by 1024 to get MB
t=time in seconds

(v+a)*(2048/201*t/8=f

The (2048/201should be worked before solving this problem it just is a huge decimle number that I dont feel like typing.

[shochan]

Oh and no the calc is fine a cdr holds vcd and svcd differnt from normal data hince the 80min on the cd, but tat is only for vcds tho and it comes out to about 811mb you can fit on there if it is standard. I think the vcd is the same and you can fit 811 on it. I only solve for 798mb myself just so I have a little slack.

[Robbins1940]

Ok thanks just wondering.

So if the calculated video bitrate is 1964kbps for 50 minutes, how much should i reduce so the file comes out 790mb?

I am using variable bitrate if that makes any difference.

And when you overburn is it normal for the burn process to fail when the lead out is about to be burned?

David

[Sefy]

Robbins1940, i'm in the same dilema as you are at the moment, i've decided to give SVCD a try, now I used the Calculator on VCDhelp and it gave me 1964 average and 2492 maximum

but the downloadable calculator gave me 1642 bitrate, so now i'm stumped, cause I don't know what i'm supposed to use, cause as far as I read 1642 is not enough bitrate for SVCD, its barely 500k over VCD bitrate.

So, can anyone give an approximate bitrate for a 50min movie that will use 224k Audio and the target is 80min CDR, how much Bitrate would I need for the Video Maximum ?

[thefuzion]

cant give you approx. bitrate
but qualitywise i would say that fullscreen svcd´s (4:3) should have a minimum bitrate of 1800kbps and widescreen (16:9) should have a bitrate of atleast 1600kbps.

that, in my opinion is the lowest acceptable bitrate, below that you might as well go for (x)vcd´s as the quality would suck either way.

[Truman]

I use to calculate the bitrate with FitCD. It is very accurate, I always substract 3 kbps anyway. Until now it never failed for me.

[Sefy]

thefuzion, isn't 1600/1800kbps a bit low for SVCD ? the movie i'm doing (which I gave up on SVCD) is Swordfish, which I found a great spot to cut the movie exactly at 50min mark using the TMPGEnc Source Range.

If VCD has 352x240 and 1150kbps, wouldn't 480x480 require alot more bitrate to look half as decent ? having higher resolution and not enough bitrate to support it, well, might as well have XVCD instead

[omoses]

[quote]
On 2001-11-23 02:03:32, Sefy wrote:
isn't 1600/1800kbps a bit low for SVCD ? the movie i'm
[/qoute]
I do a lot of SVCDs with about 1600-1700kbps, and they look fine. It's ok with a lot of movies, if you use VBR. I only convert the first of 2 or 3 CDs, and then have a look. If the artefacts in high-motion-scenes are too bad I use the "reduce artefacts" in tmpg, but it's only for very few movies until now.
<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
If VCD has 352x240 and 1150kbps, wouldn't 480x480 require alot more bitrate to look half as decent ?
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>
Because the resolution of a SVCD is higher than vcd, the artefacts are much less prominent, and the movie will look better than VCD in most cases. And MPEG2 normaly is better for compressing than MPEG1, if you have at least 1500kbps. If I want to do a really nice movie that is too long for 1 VCD, I use kind of S-XVCD with MEPG2/VBR and resolution of 352*288(PAL) or 352*240(NTSC). The whole movie fits on 1 CD and it looks really nice. Tested this with up to 2 hrs on 1 CD with 90 Minutes.

[Sefy]

The resolution is only prominent when watching on the PC, on the TV, it's not that visible, unless you got a Projector or a 40"+ TV of the highest quality, and lets face it, not everyone does.

I've got Original VCD's of the last 3 James Bond movies, the quality is amazing! and it's just a VCD, some people thought I was using a DVD when they saw it.

As for your SxVCD, I can't see how you can fit a 2 hours movie on a 90min CDR using 1500kbps! that doesn't make sense even using VBR compression, you got something mixed up there.

[Just G]

Sefy,
Based on an NTSC film source:

• 50 minutes of Swordfish (or any 24fps 16:9 AR source)
• 80-minute CD-R
• TMPGEnc MVBR

You should be able to do audio at 224kbps and video at a maximum bitrate of 2050kbps - don't hold me to it, though
(You might be able to squeeze in a bit more video: ~2060-2070kbps, but 2050kbps should be safe.)

The problem that everyone is seeing with the various bitrate calculators can be differences between what each considers a "Megabyte" or the "size of an 80-minute CD", etc. That aside, each should give similar results. I've found Bitrate Finder on the Tools page to be rather good.

The differences between the values you enter into the bitrate calculators and your resultant MPEGs is due to the VBR aspect and letterboxed video.

You have to play around a bit with the numbers, but IME, setting Bitrate Finder to an 835Mo CD size, a 24fps 16:9AR source encoded with VBR will give you a bitrate that should fit nicely on an 80-minute CD-R.

Encoding my 29.97fps 4:3AR capped video to VBR MPEG-2 in TMPGEnc doing inverse 3:2 pulldown, I set Bitrate Finder to an 805Mo CD size.

But, like I said, you gotta play around with the numbers a bit and my figures are based on NTSC, PAL will differ.

Start yourself a log - jot down: source run time, FPs, AR, bitrate - from a calc, the resulting MPEG size, the resulting MPEG CD play-time.

50 minutes into Swordfish - the entry into the coffee shop?

David,
When you give data, are you talking about capturing RT or using an offline encoder? Your first post mentioned RT, but your latter, sounded offline. The methods are, of course, completely different beasts.

Overburning should not fail anywhere, otherwise, the burn failed. You may have an operational CD, nonetheless. You can always verify your burn.
Get VCDGear 1.4d - I've had problems with other versions; Drop to a command prompt; do:
vcdgear -dat2mpg -fix X:\mpeg2\avseq01.mpg C:\MPEG2.mpg
(where X:\ is your CD drive letter and C:\ is where you want to put it)
Then compare this with your source MPEG:
FC /b /lb1 C:\MPEG2.mpg C:\Source.mpg
If you used TMPGEnc, they should be the same.

HTH,
G

[TPW]

There is a better way to find the bitrate that finds exactly how much you need

(AudioLength(AudioBitrate))+(VideoLength(VideoBitr ate))=(Size in MB x 137.4)

simple algebra
(137.4 is just the factor to convert MB into kilobits)

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Code:</font><HR ></TD></TR><TR><TD><FONT SIZE=-1><PRE>((Size in MB desired x 137.4)-(Length x AudioBitrate))
____________________DIVIDDED BY__________________________
(Length of Movie)
= Video Bitrate
</PRE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

I am 100% sure this worked i have made my own birate calculator on my graphing calculator.

And always remember to have at least 4-5 MB extra for VCDs and 5-10 MB extra for SVCDs

[Sefy]

Just G, my movie is NTSC, I didn't use NTSCFilm, now I tried using TPW equation (if i made a mistake don't shoot me, i'm BAD at math! real bad!)

109233 - 11200
(795x137.4)-(50x224)= 98033 / 50 = 1960.66

So according to this, I should use 1960kbps for the Video ? and is that really enough for a SuperVCD movie ? cause it defenetly sounds better then 1642 which Bitrate Calculator gave me. BUT, i've encoded the movie in XVCD using:

1762kbps for Video (MPEG1 CBR) at 352x240
384kbps/48khz for Audio
and the movie was 793mb file size

Now are you guys sure that 1960kbps for Video (MPEG2 VBR/CBR) at 480x480 and Audio 224/44.1 is enough for smooth quality ?
_________________
Email me for faster replies!

Best Regards,
Sefy Levy,
Certified Computer Technician.

<font size=-1>[ This Message was edited by: Sefy on 2001-11-23 07:22:03 ]</font>

[Lamont Cranston]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
On 2001-11-23 06:29:04, TPW wrote:
simple algebra
(137.4 is just the factor to convert MB into kilobits)
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

TPW, this may be obvious to most but.. could you please expand your conversion factor to convert MB to Kbits? I don't come up with the same value.

[Thom001]

So let me get this straight: When I'm done converting my movie and the properties tell me that its just a little over 700MB (per disc). then it will still fit on a 700MB disc?

[sean madison]

ShiZZZoN-
I dont know what to say

I posted the CatX equation on ehre a week ago and no one seen it?
it gives you the vid bitrate, file size, or audio bitrate.
I did it myself and is 100% accurate.
here it is one more time-
C- cd size 80min cd- 819,200 kb
A- audio bitrate
T- time of vid in sec
X- vid bitrate

To find vid bitrate, use this equation-

TX = C - AT

[Sefy]

Thom001, an 80min CD (700mb as you call it) will give you 800mb when doing a VCD/SVCD movie.

Ok, i've used 1960kbps and 224k audio and my file size came out at 734mb which is nice cause that means I can put more Bitrate which i'm trying now (2100kbps) and i'm hoping to hit the near 800mb mark.
So where did I go wrong with the equation ? i'm using MPEG2 CQ_CBR compression, so the Bitrate is Constant, shouldn't have been that far off from the 800mb, any ideas anyone ?

[Robbins1940]

Hello Sefy,

I am capturing real time in variable mpeg2 video bitrate 2245 and audio 224. According to the calculator that is for 44 minutes on a 80min cdr. I am using the wintv pvr to capture then i use the editor to crop the video.

The cdrs burned with nero play fine on my computer, i don't have a standalone dvd player so i don't know if they play ok.

I have windows xp pro installed now but when i had windows 98se and a previous version of nero burned the discs ok without errors. With the new version it burns lead in first then track. When track is finished the burning stops with errors.

INVALID FIELD IN COMMAND
COULD NOT PERFORM END OF DISC AT ONCE
INVALID WRITESTATE
COULD NOT PERFORM END OF DISC AT ONCE

But the disc do play ok on my computer.

Is it a bug with the new nero under windows xp?

Thanks,

David

[Robbins1940]

The other thing i mentioned was a realtime capture from vhs.

David

[Sefy]

If you never had that problem before, then it could be a bug in Nero when used under XP, god knows Microsoft are not known for their compatibility.

Just to be on the safe side, try using a diffrent program to burn your movie and see if it does the same thing, I would recommand you try a CDRW so you don't waste any CD's.

[randallc]

Sefy, CQ is not at all a constant!!!

"So where did I go wrong with the equation ? i'm using MPEG2 CQ_CBR compression, so the Bitrate is Constant, shouldn't have been that far off from the 800mb, any ideas anyone ? "

You should know this in your position. CBR is a constant bit rate, CQ is a constant quantization (or some may say a constant quality)

The only way to really have a good grasp on what size the outputted file will be (with TMPGEnc) is either to use CBR or 2Pass VBR. Even though it takes twice as long, I highly recomment 2Pass VBR.

And no need to worry about the bitrate. I've found that 1450 average bitrate on 2Pass VBR encoding gives me nearly indistinguishable results from the original DVD (with letterbox movies - need to bump it up to around 1600 - 1700 for a pan and scan pix.)

Randy

[Sefy]

Don't worry about it, I gave up completly and officialy on SVCD, quality sucks, too much trouble, the result SVCD i got which took twice as long to make and using 2100kbps and the DVD Player playd it jerky and with hurrible quality.

I don't care if it's how TMPGEnc does it or not, and no, i'm not going to use CCE, it's an annoying program, and yes, i'm very stubborn person.

This is the reason why I prefer VCD, they are easier to make, faster to make, and work everytime for me, and i've never had a VCD that has a jerky playback.

So instead of doing SVCD at 2100kbps, I did a VCD with 1768kbps and Audio at 48k and 384kbps, and playback was great! and it took me just a one time encoding for it to work

[kinneera]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
On 2001-11-25 00:04:24, Sefy wrote:
Don't worry about it, I gave up completly and officialy on SVCD, quality sucks, too much trouble, the result SVCD i got which took twice as long to make and using 2100kbps and the DVD Player playd it jerky and with hurrible quality.
</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

Interesting that you say it was jerky on playback - this is typical of the data rate exceeding the spin speed capability of the drive (try something like 4000kbps in any format on virtually any DVD-player, you'll see what I mean). I tested one of my SVCDs in my brother's Panasonic DVD player and it did the exact same thing, but quite happily played a VCD encoded using exactly the same parameters but in MPEG1 instead of MPEG2. My Pioneer on the other hand will play both but has terrible A/V sync problems with XVCD, whereas it is perfectly happy with SVCD/XSVCD. Perhaps your troubles with SVCD aren't due to the format, but rather your equipment.

My SVCD average bitrates for movies seem to regularly fall somewhere between 1400-1800 according to the bitrate viewer, but they look great on my 20" Trinitron TV. (I use TMPGEnc's CQ mode, with max set to the SVCD max). This typically fits 50-60 min to a disc.

[thefuzion]

sefy:

i just made an svcd from the "Exit Wounds" dvd.

ntsc/480x480/1900kbps CBR (didnt have time for vbr)
The movie is in 2,35:1 and it looks absolutely great.
For even better quality a 2 or 3 pass vbr would have done it.

Ofcourse i could have used a higher bitrate., but it would also mean that i would have to use 3 cd´s instead of one. The quality would be better, but then i would have to get up from my chair 3 times during the movie to change disc.. and im lazy

[Sefy]

kinneera, i've got a Pioneer 525, I admit it's rather old, but it never gave me problems playing back anything untill now, it could be the lens is dirty as i've lately had problems playing discs over 90min, but at either way, making an SVCD is a very long, troublesome process, requires too much settings, and may eventually not even work, so i've decided to stick to VCD, as it takes less then half the time, I can put it on a single CD in about 90% of the movies so far, and as far as i'm concerned, quality is amazing for me.

thefuzion, i'm extremly curious how you can put a whole SVCD movie on even a 90min CDR, using 1900cbr, it doesnt calculate in my head, I started with 1900 as well for only a 50min movie, and it still wouldn't fit on a 80min CDR, so forgive me for being a little suspicous, it's my nature

[Lamont Cranston]

<TABLE BORDER=0 ALIGN=CENTER WIDTH=85%><TR><TD><font size=-1>Quote:</font><HR size=1 color=black></TD></TR><TR><TD><FONT SIZE=-1><BLOCKQUOTE>
On 2001-11-25 05:45:43, thefuzion wrote:
sefy:

i just made an svcd from the "Exit Wounds" dvd.

ntsc/480x480/1900kbps CBR (didnt have time for vbr)
The movie is in 2,35:1 and it looks absolutely great.
For even better quality a 2 or 3 pass vbr would have done it.

Ofcourse i could have used a higher bitrate., but it would also mean that i would have to use 3 cd´s instead of one. The quality would be better, but then i would have to get up from my chair 3 times during the movie to change disc.. and im lazy

</BLOCKQUOTE></FONT></TD></TR><TR><TD><HR size=1 color=black></TD></TR></TABLE>

I believe Exit Wounds is about 102 minutes. With a CBR of 1900 @ 480 x 480 how did you fit it on one cdr? No audio?