DVD Audio level

[VRYK]

I understand it is not possible to modify the audio sound level in the whole, or part, of a DVD. However, I would be grateful for confirmation of this.

[r0lZ]

Short answer: Impossible.

However, it's possible if you demux the VOBs, edit and re-encode the audio streams, remux and re-integrate the new VOBs in the original DVD. It's long, difficult, and the quality of the new audio is less good, but it's theoretically possible.

Note that it is possible to change the volume of a MP3 audio stream without re-encoding it (but only by steps of 1.5 dB) with tools like MP3DirectCut, MP3Gain or Foobar2000. As far as I know, it's not possible with AC3 or DTS streams.

[VRYK]

Many thanks for your reply.
< It's long, difficult, and the quality of the new audio is less good...>
These seem good reasons to leave it at the theoretical level. Since the Audio is AC3, the second solution is ruled out.

I would be grateful if you could clear up what seems to have been a misunderstanding on my part – i.e. that by setting the Subtitles track to 63 only forced subtitles would be shown.

[r0lZ]

Well, I must admit that I have never totally understood what that "63 stream" is supposed to do. At least, I have never been able to display any subpics with that option set. Perhaps it is used to show the captions sometimes embedded in NTSC video streams, and is not related to real subtitle tracks. Since I live in PAL land, I can't easily test if it's the case.

Anyway, to display only the forced subpics of a regular subtitle track (those subpics that have the "forced start" flag set), it is sufficient to select the right subtitle track with the SetSTN command, but with the "OFF" parameter. The track is therefore the "current track", but should not display the regular subtitles. Only the forced ones are shown.

BTW, that means that if you have only one subpic track in your DVD and it contains forced subs, you cannot turn the forced subs off, as the track is always current. You have to create an empty subtitle track, and select it (in ON or OFF mode), to disable all subtitles. (Or perhaps it is possible to use that "63" magic number to disable completely the current track. I have never tried.)

[VRYK]

Many thanks for your reply. The video concerned has two audio and two subtitle streams (English and Spanish). Since there is a fair amount of a third language spoken, I though there would be forced subs. However, when following para 2 of your reply didn’t work I checked in DVDSubEdit and found (to my surprise) that there are no forced subtitles. [I don’t know if there is a more direct way of establishing whether or not forced subtitles exist]

The video’s first chapter opens with the title which is however barely readable (lack of contrast). While menus can be exported to an appropriate editor and re-imported as bitmap images, would I be correct in assuming that in the Titles domain this would require de- and re-muxing ?

[r0lZ]

... I checked in DVDSubEdit and found (to my surprise) that there are no forced subtitles. [I don’t know if there is a more direct way of establishing whether or not forced subtitles exist]

As far as I know, DVDSubedit is the best tool to examine them. And, BTW, you can also change the "normal start" to "forced start" for the subtiyles that should be forced.

The video’s first chapter opens with the title which is however barely readable (lack of contrast). While menus can be exported to an appropriate editor and re-imported as bitmap images, would I be correct in assuming that in the Titles domain this would require de- and re-muxing ?

You mean change the contrast of the movie? Or of the first chapter only?
Anyway, yes, you have to demux, re-encode the video, and remux. Take care: you have to encode it in a format compatible with the rest of the VTS (and with the whole DVD): same frame rate and resolution, of course, but also the same encoding parameters.
You can then remux the movie (or first chapter), and import it back in the DVD.
(If the movie is alone in its own VTS, you can import it with PgcEdit. If you have processed only the first chapter, you can use VobBlanker. For the whole movie in a VTS containing other titles, things are even more complicated, as you will have to cut the new VOB in chapters, and replace all chapters one at a time with VobBlanker.)

Again, it's a long and difficult job.

[VRYK]

Many thanks for your reply.

> And, BTW, you can also change the "normal start" to "forced start" for the subtiyles that should be forced.<
Is this a command in DVDSubEdit? I use the box “Only show forced subpics”.

>Again, it's a long and difficult job.<
A lot of cost for little benefit!

[r0lZ]

Is this a command in DVDSubEdit?

Yes. It is called "Start command", and it is in the frame "Subpic start, timing and duration".

[VRYK]

Many thanks.