DVD bit rates

[mijman]

I know that the DVD format takes up to 9800 for a max bitrate,(TMPGenc's DVD template is at 9000) but by encoding MPGs at this, my files are super-huge, far larger than they should be. At these rates, I can only fit about 1:15 on a disc! They're supposed to hold, like, a whole extra hour on them!
So, What is the best rate to set your mpgs at?
What are professionally distributed movie DVD's encoded at? Is there any way to tell?

I encoded a 5 second clip (originally encoded for VCD) with the bit rate at CQ 8000 at DVD 720x480 and got a filesize of around 5.8 Mg. I took the same clip and encoded at CQ 5000, and got a size of 3.7 Mg. This is a considerable difference, especially when applied to a DVD length movie!


<font size=-1>[ This Message was edited by: mijman on 2002-01-04 22:33:20 ]</font>

[Greg12]

Are you using CBR or VBR?

DVD's use like 5-pass VBR.

u can do 2 pass vbr

[mijman]

sorry, I'm using CQ.

[poopyhead]

keep in mind the vob files on the original dvds are HUGE..but since a DVD can hold so much data, it's ok for them to encode with super high bitrates...however, since you're making a SVCD on a regular CD, you can't go up that high..

there are some things you can do to increase quality and/or lower filesize

motion search accuracy to high quality (slow)

if you using CQ_VBR (like i am) don't set the CQ to any higher than 70....any higher value will drastically increase filesize with no increase in quality...

also, you need to lower your bitrate...i set my max at 2520...and some people would say that itself is already too high (i like the quality thou)

also, fitting 1 hour / SVCD disc will result in some crappy quality..in order to do that..you will have to drastically lower the bitrate....for me..i can usually fit a max of 42-44 min / SVCD disc...

btw...resolution does NOT increase filesize..so basically you don't have to worry about your resolution being too high

[mijman]

actually, poopyhead, I AM making DVD, not SVCD.
SVCD levels are not important to me.

[Kdiddy]

9.8 mbps is usually peak bitrate...most DVDs however AVERAGE around 4.5-6 mbps...I suggest lowering your average to this..and maybe keeping you peak around 7-8

" encoded a 5 second clip (originally encoded for VCD)"

I hope this is not standard practice for you...if it is originally a VCD, its not going to be much better by double the res & giving more bitrate...maybe a slightly sharper, but it still will look much like VCD.

[KoalaBear]

Hiya Mij.

First, DVDs are most frequently coded using VBR at 2 to 4 Mb/S. The bitrate is established according to how much time is to be recorded on the disc, with quality ultimately determined by what the encoder can buy with your bit budget. Here's the formula I use:

Say you want to set VBR for a 112-minute movie with a 384Kb/S audio track:

Max = 9800 - audio bitrate == 9416
Avg = (capacity / length / 60) * .60 == 4297
Min = Avg / 2 == 2148

Or you want to archive four episodes of Buffy per DVD (180 minutes) with a 224Kb/S audio track:

Max = 9800 - 224 == 9576
Avg = (4812800000 / 180 / 60) * .60 == 2674
Min = Avg / 2 == 1337

Assuming you use Cinema Craft, you would perform pass 0 as CBR at the average bitrate. Essentially this sets the length of the file and allows the encoder to build a complexity map for additional passes. Then you would perform two or more VBR passes using the Min / Avg / Max bitrates. The size of the final product won't change all that much, but the bits will be reallocated to provide the maximum quality the average will allow.

Second, some DVD players have a display mode that will show you the encoding bitrate. Check your remote control.

<font size=-1>[ This Message was edited by: KoalaBear on 2002-01-04 22:39:08 ]</font>

[poopyhead]

mijman, you're making a DVD?...i'm assuming you're burning it to a DVD disc (DVD-R/+R)....it sounded like you were trying to burn your DVD to a regular CD-R

[mijman]

@Kdiddy
No, this is not standard practice, simply a test with what was handy. and small.

@koalabear
LOL how'd you know I wanted to do buffy episodes?
For now, though I was trying to get a 139 min. movie, but I was totalling around 7GB! (at CQ 8000)
Thanks for the equations. They will come in handy.
I don't currently use cinemacraft. I use TMPGenc, and MyDVD.
So, how much will the quality suffer from encoding at CQ 2500, compared to say 5000 or 8000? Does it matter a great deal?

@Poopyhead
Sorry, I WAS being a bit vague. my bad. I'm trying to make a DVD out of captured video.

[poopyhead]

mijman, but r u trying to burn on a regular CD-R or DVD-R/+R?

[KoalaBear]

Mij:

Remember that thread where some guy claimed to be the 'king of compression' or something because he recorded the Godfather on a single VCD? People teased him a bit by exaggerating their own compression accomplishments. You took the cake by insisting that you recorded all 100 episodes of Buffy on one side of a 360K floppy, but to be fair, you had to flip it over to have room to record the Angels.

Man, I laugh every time I think about that.

As for TMPGenc, I don't know. I don't use that encoder myself. Theoretically, in order to hold the quality constant the bitrate would be unpredictable. You'd have to test code a few segments to verify that it's giving you what you want from it. But it's the average bitrate that determines the size of the file in any case.

[poopyhead]

hrm...i dunno about u guys...but one of the may reason for these new formats (i.e. SVCD) is quality. fitting godfather on 1 CD? wut is that like...?...gotta be the worst quality shit of all time, like real media files or something. having more discs is, in my opinion, is a good price to pay for near DVD quality rips.

[Kdiddy]

Cmon now their are just some movies that are worth owning on DVD, Godfather would be one such movie...

[mijman]

ROFLAO @Koalabear

I do remember that thread. It was pretty funny. There are few things funnier (IMHO) than ludicrous (sp?) exaggeration.

"Every joke needs one thing to be waaaaayy out of porportion." - George Carlin

[Lamont Cranston]

Make sure your Authoring software does not transcode the audio to PCM. With PCM your max video bit rate is limited to 8000kbps because the PCM audio takes 1600kbps. Sonic's MyDVD and DVDIt (not PE) are examples of authoring software that transcodes the audio to PCM.

[mijman]

Well, I would use spruceup, but I can't register version 1.1 or FIND 1.0. I DO have pinnacle DVD express, but haven't played with it yet.