lowest bitrate for DVD spec?

[sdsumike619]

Hi, does anyone know what the lowest bitrate for DVD is? I know the max is 9800 kbps but is there a minimum as well? Thanks

[adam]

I don't believe there is any minimum requirement.

[sacajaweeda]

Whatever your particular player will accept, basicly.

[sdsumike619]

Oh I see... so I could put say 2.5 or 3 hours of MPEG2 video onto a DVD and it would play ok? I was under the impression that there was a 2 hour time limit for DVD-5 (seems like I read it somewhere)

[Cornucopia]

No such time limit. At all.

The equation is:

Bitrate = Size / Time

and can be re-organized as:

Time = Size / Bitrate

or

Size = Bitrate * Time

So, you can see how you would put in 4.37GB for the total size, and can fiddle with the Time and Bitrates (inversely) to get what you need.

Of course Bitrate (and visual complexity & resolution) determines quality, so there are some "practical" limits.

Scott

[sdsumike619]

gotcha, thanks!

[jman98]

I have some low resolution QuickTime Star Trek fan films that I downloaded and converted to DVD, but used standard VCD bit rates (1150 Kbps) for the video and MPEG-1 video. They played fine. You can go even lower if you want as there is no minimum bit rate, but of course quality will get even worse at lower bit rates.

3 hours of MPEG-2 could be done at a constant bit rate of 3170 Kpbs according to my calculator. With the right encoder and good quality source, you could do it. That's higher than SVCD bit rates for video. Of course, each person's idea of what is acceptible video quality varies, so try it and see if you like it. The "2 hour limit" is not a real limit for DVD-5, but something manufacturers use to explain concepts to people. It's just too complicated to say "Well, at 2 hours you could record at an average bit rate of 4800 and have very good quality DVD video, but 3 hours would require a bit rate of 3100 and the quality may suffer". It just depends on what you find acceptible in terms of quality.

[kush]

The reason there's SP/LP/EP, 2/4/8 hour, whatever marking on products in the brick and mortar stores is the idiot factor... The average Joe Schmoe consumer that walks into Worst Buy looking for DVD-/+R/RW is going to give you a deer in the headlights look if you mention anything about bitrates and sampling rates and VBR/CBR, and so on.

[edit] ps 3 hours is about max quality wise (IMO only you might accept more) that you really should go. Also, you should consider even going to 352x480 (1/2 D1) reolution if you want 3+ hrs on a SL disc (some even say so when over 1-1.5 hrs its all relative to your own wants/needs). It will tend to soften the image a bit (how badly dependent partially on source quality too), but will allow you to keep a lower average br without getting totally pixelated.

[Cornucopia]

It's just too complicated to say "Well, at 2 hours you could record at an average bit rate of 4800 and have very good quality DVD video, but 3 hours would require a bit rate of 3100 and the quality may suffer". It just depends on what you find acceptible in terms of quality.

It must not be that complicated--You just said it! :P

Scott

[Cornucopia]

Give them the Sponge Box analogy:

You got a box full of sponges (all same size).

How many can you get in there?

Well, if they're wet (and fully puffed up), you can get a dozen.

But if you squeeze the water out a little, you can get 18.

If you squeeze out a little more, you can get 20.

A little more, 22. A little more 23. A little more 24. You might be able to get a tiny bit more, but you're really having to squeeze hard.


So, what does the box look like?

Wet, it looks like a box of normal sponges.
Squeezed, it looks like more and more wrinkled/convoluted versions of sponges.

Scott

[kush]

It's is "complicated" in the sense that there's all the variables involved...Personal qulaity perceptions, what bitrates you're willing to accept, 1/2 or full D1 (or even 1/4), what encoders used, if/what filters to process the video, how the end product will be used (ie: 20" pos average TV or big-screen HDTV/projector/etc), and so on...

[Wile_E]

Here are some bitrate graphs from lordsmurf's website. It shows the bitrates needed for each resolution, to maintain quality. After a certain amount, it may become overkill to use more bitrate on certain sources.

http://www.digitalfaq.com/dvdguides/capture/intro.htm#mpegbitrate

[vhelp]

In addition..

Its not just the bitrate that you have to consider as the final straw.
You also have to consider the MPEG encoder in use. This is your actual
and final desiding factor.

Now first of all, there are so many MPEG encoder out there, we just scratch
the surface during our google searches and what-nots.

And, even if you find that *right* MPEG encoder, you must also be a skilled
craftmen at the usage of this tool, not to mention that your source also
has a play as well. And the more original your source is, the better.

So, considering to a point what I have just mentioned, it is possible to use
a lower than usual bitrate*, but that it is more or less critical that your
MPEG encoder be highly optimized to handle most potential problems seen in
the video source.. noise; motion; interlace; fps; etc. etc.

* There is also another level or side to MPEG encoders. What I speak on
is the "hackable" inclenations of the encoder and the user behind it. Some
MPEG encoders are equipted to go above the law -- so to speak. And these
areas can and do include, such as GOP; and their attributes that follow it
as well as motion compensation techniques; and other built-in filter-like
functions that ack like enhancers or optimizers or bitrate reducers, etc.

In fact, I am testing an MPEG encoder as we speak. Its a command-line ver,
and it does a pretty decent job, but there are little glitches in the final
mpeg that disturbs me. But, regarding the usage of bitrate, I have been able
to use a lower than usual (that I tipically use) on this encoder and seen
good results..

( I believe that this encoder is included in the freeware ver of the dvdauthor
or dvdauthor gui tool, though freeware, the source code to it was not available,
speaking on the ver that I have which did not come from the dvdauthor tool. )

..I've been coding up a GUI for it, since there seems to have been none developed
for it. I guess its because people only use it for short things like mpeg stills
for menus and things. Anyway. I thought I would share that bit with you all here,
because it served its purpose of demonstrating as an example of what I was talking
about in terms of lower bitrates; and/or hackability; etc. in an MPEG encoder.

And last, try not to missinterpret the dvd media space limitation thing.

I mean. Tipical Commercial DVD movies are on DL (doul or double layer) dvd
discs and they hold aprox 8gig of video (or the disc can hold aprox 8gig) but,
the store-bought dvd-r/rw disks are single layer and only 4.3g of video storage.

So, when thinking about pushing video onto these tipicle 4.3g discs, its wise
to realize that your 2hr movie is not going to serve you as well as those done
commercially, though 8gig size discs, in terms of video quality, etc. Its my
personal observations that this is what has been confusing most users when try-
ing to fit their (movies) videos onto store-bought dvd r/rw discs and at a loss
as to why the quality is not the same (or comparitable) to those Commercially
produced.

-vhelp 4098

[David K]

I've run into situations where the DVD authoring program will not accept files below a certain bitrate. For example, DVD Maestro will not accept audio files below 60 kbps. (I was trying to load a voice-only commentary track and I didn't mind going real low.) but since I've never tried to load anything lower than a VCD bitrate, I don't know if there's a certain minimum bitrate for this or other DVD authoring programs.

[adam]

David there are minimum audio bitrate requirements, but none for video. I believe that Dolby Digital requires a minimum of 32kbps per channel. For commentary tracks I often encode them at 32kbps mono.