large avi vs dvd

[mumadad]

ive noticed that movies compressed to 700mb avi are generally decent quality.

i'm wondering if when i back up my dvds, reencoding to a 4.7gb avi using d-vision 3 will give me a better quality copy than compressing using toast 7 or dvd2onex, but keeping the dvd format.

i'm not bothered about being able to watch them on a stand-alone player, as i have a 20" imac. and i'm led to believe that what takes up a lot of space in dvd format is uncompressed audio.

so, i'm thinking that re-encoding to avi might allow me to change audio to mp3, but keep almost the same video bitrate. any thoughts.

[DanSlagle]

You mean DivX? .AVI is not a format it is a container like a .MOV file. What encoding method are you using.

I personally feel H.264 is the best and d-vision supports it.

[mumadad]

yeah generally divx or xvid. h.264 i haven't tried as yet.

but i'm just thinking you could probably keep the video bitrate the same but reencode the audio, and therefore keep the video quality identical to the original.

would this work? i dont use a stand-alone player so i'm really not fussed about just being able to watch on my computer.

also what is h.264?

[sdm]

You don't need nearly the bitrate for divx/xvid/h264.
In my experience 1400-2000 kbps is plenty for the video (compared to 4000 - 7000 ish kbps for mpeg2).

Often dvd audio is AC3 which is a compressed format. You can 'pass thru' this audio, or compress to stero mp3.

Yes D-vision produces excellent results. Also try Handbrake or ffmpegX.

-- Good luck.

[mumadad]

just been doing a bit of research on h.264, and im going to give it a try.
thanks for the input.

[edDV]

just been doing a bit of research on h.264, and im going to give it a try.
thanks for the input.

Transcoding almost always reduces quality. Why do you need to further compress this file? If it looks good how can 700 MB be unusable?

If you want to start encoding H.264, be prepared for extremely long computation.

[mumadad]

its mostly academic at the moment, but i know there is a slight reduction in quality if you compress a big dvd such as LOTR to 4.7 (or in the case of the dvds i am using; 4.21)gb.

so my thought was that you could reencode the video, keeping the exact same quality, but a smaller size.

and, although i'm not very technical so don't understand the finer points, h.264 seems quite advanced.

[thoughton]

Mumadad, you are right on the money. If you simply encode to a 4.7gig divx or mpeg4 or h264, hell, virtually any modern format, then you can achieve better quality than a 8.5 gig DVD compressed to 4.7gig.

You should however note that h264 encoding takes forever and a day. Even divx encoding (which itself is much faster than h264 encoding) is at least 10 times slower than compressing a DVD.

The only drawback to this method is the massive increase in processing time, and the fact that you cannot playback on a normal DVD player.

[edDV]

Mumadad, you are right on the money. If you simply encode to a 4.7gig divx or mpeg4 or h264, hell, virtually any modern format, then you can achieve better quality than a 8.5 gig DVD compressed to 4.7gig.

You should however note that h264 encoding takes forever and a day. Even divx encoding (which itself is much faster than h264 encoding) is at least 10 times slower than compressing a DVD.

The only drawback to this method is the massive increase in processing time, and the fact that you cannot playback on a normal DVD player.

Although h.264 (also VC-1) is part of the new HD DVD and BluRay standards and will be playable on all next generation High Def players.

Encoding will need to move into hardware to make these formats practical.