avi to mpeg2 bitrate

[rudeboymcc]

hi. i've got a few avi's which i'd like to convert back to mpeg2 and then put them on a dvd-r disk.

they are small files (30 minutes max) and not great quality (from a digicam).

one thing i've noticed in many guides is that they set the average bitrate of the video to 5000 or more.

my avi files are only 800kbps roughly, but they are half the resolution (352x280 roughly).

if i convert to mpeg2 at 5000kbps and 720x480 (don't know the exact reolution but i mean the dvd one) won't they be very over-sized for what they are? if i set it to 800kbps will the quality be reduced? (does the 720x480 part make any difference at such low quality?)

[r6d2]

Originally posted by rudeboymcc
my avi files are only 800kbps roughly, but they are half the resolution (352x280 roughly).

if i convert to mpeg2 at 5000kbps and 720x480
It probably will not look better if resized bigger. You can keep the original size and use CVD, which is a DVD compliant frame size.

As for the BR issue, it is useless too to increase it artificially, quality-wise. The best, IMHO, would be to let the encoder decide how much BR is needed and then allocated. Try using a quality based encoding, like TMPGEnc CQ mode.

[jojo15]

Are you gonna make one file or are you gonna leave them seperate?
I suggest to just encode using 5000kb/s and 720x480
if the total filesize is to great, you can always make the mpeg2's smaller using ReJig

[rudeboymcc]

i'm not making one file. i'm making many files and then making a menu with tmpeg dvd auth to point to each one.

how does constant quality (CQ) actually work? it doesn't mention anything about automatic quality. it says maximum and minimum, and then quality (from 1 to 100). shall i leave the max at 8000 but reduce the minimum from 2000 to say 500?? this is in tmpegenc btw.

[r6d2]

Originally posted by rudeboymcc
how does constant quality (CQ) actually work? it doesn't mention anything about automatic quality. it says maximum and minimum, and then quality (from 1 to 100). shall i leave the max at 8000 but reduce the minimum from 2000 to say 500?? this is in tmpegenc btw.
The TMPGEnc manual is a good starting point. You can :search: on this forum or google about "tmpgenc quality mode guide". You'll find lots of them.

[rudeboymcc]

thanks. quite a good guide. one thing though.

mpeg1 and mpeg2, do they use the same bitrate? ie say a vcd is mpeg1 and is soething like 1750kbps. this gives you 80 minutes on one cd-r.

can i use 1750 on mpeg2 and expect the output file to be roughly 700mb? would it be the same quality as the VCD or better?

[r6d2]

Originally posted by rudeboymcc
can i use 1750 on mpeg2 and expect the output file to be roughly 700mb?
This depends on the movie duration.
would it be the same quality as the VCD or better?
If you use the same quality with MPEG-1 and MPEG-2, they will have different output bitrates but it will depend on the frame size you choose and not on being MPEG-1 or MPEG-2.

Read the guide on my signature if you want to understand better the relationship between BR and quality.

If I were you I would not worry about BR and let the encoder in quality mode do the work.

[rudeboymcc]

thanks. sorry about the 700mb thing, i forgot to mention if a movie is 80 minutes long and i used all the same settings as VCD but mpeg2 (including the framesize) will it come out to be 700mb?

[jojo15]

Probably,
the best way to find out is trying it..