DVD Encoding bitrate

[duexbeer]

Hi All,

I have video files in various formats (dvd avi divx mov real nero) and I intend on settling down all content in DVD. My question is regarding the bitrate to use for transconding (hope I used the correct lingo). For example, if my divx movie is 554bps then what should be the target bitrate for the converted DVD movie file. Are there any formulas/table showing
X bitrate of A format is equivalent to Y bitrate of B format

OR

Since decoding and encoding results in lower quality, I should consider sticking to the highest possible bitrate for DVD (~8000bps).

Since the source content is about 300GB, the decision is crucial. Although i have been going through the guides on this website, please bear with the stupidity of assumptions.

Why I am doing this?
I know that the best possible storage of the video content is that of the source format, but I want to play media from a PC instead of shuttling though the CD/DVD in the players. Something similar to Media Center.

Thank you friends!
Vivek

[mats.hogberg]

A rule of thumb, is to use 3-4 times DivX/XviD bitrate when encoding to DVD specs mpg.
For full D1, never lower than 4000 kbps
1/2 D1, down to 2500, perhaps.

/Mats

[julitomg]

Open each file in its respective player (Quicktime, Real Player, WMP, divx player, etc..), find the duration (hours/mins/secs) and use one of the bitrate calculators you can easily find in the tools section of this site. That´s what I do. Good luck

[jagabo]

Or use constant quality encoding. The encoder will use whatever bitrate is needed to get that quality you specify. Then put as much as you can on each DVD.

[duexbeer]

yup the bitrate calculator. I found it after posting the message. But it doesn't have calculations for real media rm rmvb files

Secondly, auto calculation of bitrate in encoding softs are more focussed on how much (minutes) can be put in the Disc. They do not answer (the ones I have checked yet) this question.

For example 554kbps of DivX or Real should be encoded with a bitrate of 2200kbps of DVD. It only says that if the length is say 94 minutes , then encoding it in X bitrate fills the disc. Seems no software can suggest that. Thus I ask you what bitrate did you choose for your DivX movie of X kbps, Real movie of Y bitrate, ... to maintain the same quality.

thank you all & Mats

[mats.hogberg]

I've already given you an answer for DivX/XviD. It's true that bitrate calcs only calculates against a given file/disc size - but all other calculations are purely subjective.
But regardless of source (be it RM or DivX or whatever) my subjective calculations apply:

For full D1, never lower than 4000 kbps
1/2 D1, down to 2500, perhaps.

I can add: <2500 kbps - resize to VCD resolution.
There is no hard (if any at all) connection/relation between bitrate using codec A (DivX or RM or DivX or...), and the bitrate for the same video encoded using codec B (mpg2 in this case)

/Mats

[Alex_ander]

Some encoders like CCE2.70 or TMPGEncXpress directly show you file sizes for just selected video bitrate.
If you are not much limited in space on DVDR, CBR at maximum bitrate value (depending on selected audio format it varies 8000 to 9200 kbps) gives the fastest encoding (1pass) with maximum quality (it can't be better for any VBR setting due to limited max value).

[mats.hogberg]

If I read the OP right, what he/she wants, is a formula for "If I have a video encoded with codec X at bitrate Y, what bitrate should I use when encoding it to DVD compliant MPG to keep the quality while not wasting bitrate", nothing about finding file sizes and stuff. And If that's the question, there is no answer, because A) There will always be some quality loss when encoding to mpg, and B) all recommendations are just that: recommendations, purely subjective.

/Mats

[jagabo]

There is a simple answer to the question: use constant quality encoding. You pick the quality you want, the encoder uses exactly the right bitrate (at every frame) to deliver that quality. It's just as fast as CBR encoding since it takes only one pass. And typically, with Divx/Xvid sources and "good" quality encoding the resulting MPEG2 file will have 2 to 4 times the source's bitrate.

Quality in this sense is how closely the output resembles the source. Obviously, you won't get better quality than the source video. You don't have to worry about frame size, frame rate, letterboxing vs anamorphic, how much or little action is in the video, etc. Two MPEG2 encoders that I know support this are TMPGEnc Plus and CCE.

[duexbeer]

Thank you all for the replies. I think I can start work now.

thanks again, V

[Nelson37]

And what will you do when the calculated, "correct" answer does not work for a particular film? You will look at it, decide the quality is too low, and raise the bitrate.

The real question is, if you are going to play these files from a PC as you stated, why are you converting them to other formats, taking a quality hit when the intended player can already play the files, which are already in their most space-efficient and best-quality format?

[duexbeer]

And what will you do when the calculated, "correct" answer does not work for a particular film? You will look at it, decide the quality is too low, and raise the bitrate.

I do not want to do this that is why I asked you guys but you are correct, this may still happen.

... if you are going to play these files from a PC as you stated, why are you converting them ...

I'm playing this from PC, but would like to use a remote control to select movie(s). I also do not have chapters on the movies in real format. Anyway re-encoding needs to be done. This project will result similar to Media Center. If everything goes well, the PC will be away from living room, just select and watch using remote control. If you have other pointers, pitfalls to avoid, please do let me know.

thank you