AVI to SVCD - Why split video and audio?

[sync]

I've seen several guides for doing this. Some process the audio and video separately and some don't. I haven't found any explanation of when/why the video and audio should be encoded separately.

[Bubba]

I think the process of "encoding the audio & video separately" give you a way to predict the correct size of the final video. What I meant is, if you encoded the audio first to a xx MBytes, and if you want to fit your video to have a final output of 800 MBytes, then you know you only have (800 - xx) MBytes to work with your video portion.

If you notice, DVD2SVCD also do that. DVD2SVCD extracted the audio and/or subtitle first, and do the video next.

Cheers,

[sync]

I'm using DVD2SVCD and have noticed it does that. But I didn't understand why. Are you referring to the bitrate tab?

[Bubba]

Yes... After encoding the Audio part, DVD2SVCD will know how much disk size it has left to encoded the video. So it depend on how long your movie is, it will calculate what kind of bitrate to do the video part, and so it will come up with correct final size, when combining the audio and video.

[sync]

Originally posted by Bubba
Yes... After encoding the Audio part, DVD2SVCD will know how much disk size it has left to encoded the video. So it depend on how long your movie is, it will calculate what kind of bitrate to do the video part, and so it will come up with correct final size, when combining the audio and video.
I'm confused by that. What's the point in specifying bitrates if DVD2SVCD ignores them and calculates it's own bitrate? It doesn't sound right to me.

[Abond]

@sync
DVD2SVCD uses BeSweet for audio. It is easier when the audio is separated and processed as one piece (in case of vobs). About avi I think BeSweet will not accept avi files.
It is not true that DVD2SVCD ignores bitrates you specified. If you think so, give an example.

[reihen]

another thing that can go wrong when you don't split audio/video is the audio can go out of sync. always split audio/video to avoid sync problems

[Corrado]

Originally posted by sync
I'm confused by that. What's the point in specifying bitrates if DVD2SVCD ignores them and calculates it's own bitrate? It doesn't sound right to me.

As far as I know, in DVD2SVCD you don't usually specify a fixed bitrate but, given the duration of the video, you specify how many CDs it has to fit. The bitrate must therefore be adjusted also according to the audio file size.

This is the general rule, and that's why audio and video are encoded separately in those programs.

In Gordian Knot you can do the same for DivX movies, but you can also fix the bitrate (and the audio file size will be ignored): I do this for my home DV videos, where I don't care for the file size since the movies are short, but I care for the final quality/bitrate. I guess you can do this also in DVD2SVCD.

Corrado