Theoretical questions...(NEWBIE)

Hi.
I am a total newbie to DVD creation.
I have a bunch of files taking up space on my hard drive (.avi & mpeg) that I want to burn to DVD, so I can watch them on TV.

My questions relate to picture quality.

Ok for eg.
One 500 MB file is 352 x 240 @ 23.83fps (and it’s 72 mins long) 1150kbps

Another is the same quality, but it’s 50 mins long.

My question relates to quality (bitrate settings) – If I wanted to burn both to the same DVD, would the best quality still be really bad because of the space limitations of the DVD (vs. if I burned them to separate DVDs?)

-Or is a case of the quality of the original files (pretty average in this example).

I guess my question relates to decoding a lossy format. (for eg, if I took a 128 kbps .mp3 and made it 256 kbps, it’s size would go up and I could not fit as many on one disk, BUT the quality would only ever be 128 kbps!!!)

-Is this the same with my .avi example above?

If so, what is the maximum (best quality) bitrate I would need to make each file to achieve the best quality possible, given it isn’t great to start with.

-I mean, if I made it 720 x 576 @ 9000 kbps (which would take up tons of DVD space), would that look any better than 352 x 576 @ 4000 kbps, given the original file’s specs (352 x 240 @ 23.83fps @ 1150kbps)

I guess what I’m asking is what is the maximum quality I can make – is it identical to the original file’s specs (i.e., 352 x 240 @ 23.83fps, 1150kbps), or can I make it look better by giving it a higher bitrate, but thereby taking up more disk space?

-Is the answer the same for other compression techniques? (e.g., A would Divx at the same quality specs be able to be put to DVD with higher settings, and ‘look better’, because Divx is better, or is it that the maximum quality I can ever make a compressed file always identical to the original file’s specs? And, if so, what if I make a 352 x 576, a 720 x 576? Is that a bad idea / is it better to leave it as it is? How will it look on a tv at 352 x 576, vs. in 720 x 576, given it was originally 352 x 576?)

Thanks for your help / suggestions!
(Told you I was a newbie!)

Welcome to the Forum ac17 Theoretical Answer Normally what every you start of with is what you will end up with. Best thing to do is try it and you will see first hand if it will work or not.

So does that mean that there is NO POINT making a file orignially 352 x 240 a 720 x 576?

I haven’t done this much lately since I capture my own video already with the needed specs but there was a time with my slower pc when I couldn’t so here goes…

A couple of factors will influence your decision.
The quality of the original video and the total amount of time you wish to put on the DVD.
I’m in Canada so use NTSC 720x480 however there is no quality gain when your video is only 352x240 and you increase it up the max resolution. Depending on how you resize it can introduce more distortion and noise to the video. With those specs you can probably get 3 hours or more of video on a DVD depending on the chosen bitrate.( I didn’t pull out my bitrate calc here) :slight_smile:
Increasing the bitrate is not a solution of itself either but some players have problems with motion in low bitrate DVD. Also depends on whether you go with mpeg1 or mpeg2 (see my next point)

With the specs of the mpeg you describe 1150 bitrate, 352x240 and the 23.xx framerate you probably have a file originally encoded as a vcd.
If that is the case it is already in spec for dvd except for 2 things.
1- The video at 23.976 is probably an mpeg1 and that framerate as far as I recall is ok for mpeg2 dvd but not for mpeg1 so you would have to re-encode it to mpeg2 or leave it as mpeg1 but change the framerate to 29.976 (in NTSC land).
2- The VCD’s audio is likely 44.1 kHz and would need to be re-encoded at 48kHz.
That sounds simple but can sometimes result in synch issues.

If I had such files and my standalone played vcd on cd I would be tempted just to burn these to vcd.

Whatever method you choose don’t expect too much either way.

“Sync Issues”…?

-Yep!!!

I burned the two files to DVD using the original resolution specs, without paying attention to the audio sample rate (I was impatient, and you’r reply had not yet been written) and I got sync issues :frowning:

Anyway, how do I resolve this? (I.e., do I have to extract the audio and then reattach is, like .5 of a sec later?)

What prog do I use (or should I burn with audio set at 44.1 and this will aviod sync issues?)

Ed: I just checked what I did in NERO Express: there is no setting to check what is going on with AUDIO (and there’s no way of setting the AUDIO to 44.1 or 48khz)

Are there better programs I could be using that do (while still being easy to use)?

Cheers