Some doubts about audio DELAYs (which I haven't found clearly replied)

[AsukaFan]

Hi everyone!! This is my first thread... & I've really tried not to post it, but all I've got after reading a bunch of other threads is a quite severe headache :confused: :(

Well, I'd like to know a bit more about the DELAY of an AC3 audio track ripped from a DVD; you know, I'm trying to add a new language (audio) track to a DVD (which already has audio tracks, of course), but the new audio is from a completely different source (TV captured sound... too much long to explain it), so the file hasn't got any delay info.

More specifically:

(1) Is the "delay" just the amount of time that the audio is delayed (positive, +, delay) or advanced (- delay) in relation to the video track?? Or is it something "somewhat" different??

(Even more specifically: Does a delay of -110 ms (MINUS 110) mean that the audio track begins 110 ms before the video track??)

(2) Using DVD Maestro (for example) as authoring program, how can be applied a NEGATIVE delay?? (I know the theory about frames, BTW). You know, it's impossible to drag the video to the right, or to drag the audio to the left (into the "negative zone"... only the Fantastic Four could do that ;) ).

...Or is it completely unnecessary to do anything, because DVD Maestro will use the "delay code" embedded into the AC3 file (that -110 ms) & it will do whatever has to be done??

...Or should I get rid of that -110 ms delay, trimming the AC3 files ripped from the DVD & reseting their "delay code" (BTW, how??) & put all files, video & audio, aligned at the "00:00:00.00" position??

(3) How can a WAV file be converted into a quality AC3 file AND set a delay for that new AC3 file?? My BeSweet GUI (DD&Dg's) has a "Set Delay to" option... Should I put there "-110 ms" & encode using BeSweet?? Is it SO simple??

...Remember, I'm trying to ADD a new language (audio) track to a DVD, but it's from a different (analog) source; so, of course, that audio must be in sync with the other languages tracks & the video track... so, it should have the same delay as the other track, I presume!!!

OK, I hope it's clear what I'm asking. PLEASE, if you can help me with this matter, I'd be eternally grateful to you. THANK YOU VERY MUCH in advance.

[killingspree]

i have to admit i'm not enough of an audio guru to answer these questions precisely. so just a few thoughts (or doubts)

first i somehow have doubts about your method of adding a new audio track. while i can think of the reasons why you want to add one this way, i shave the strongest doubts that this method will just get you in a lot (and i mean a huge lot) of problems. even if the digital part and the analog source have the exact same lenght (which i doubt anyway. you will never be able to capture at an analog audio precisely enough to end up with a completely similar lenght to the digital ones.
even if you did it has to be questioned a lot if the range of the audio is exactly the same (so you can definitely not tell besweet to just add or deduct 110 ms) remember you are dealing with MILLIseconds. this is one thousandst of a second. - incredibly short. so you IMHO at least dealing with a way greater delay anyway.
the only way to get this audio in sync, if it is possible, is to sync it manually - trial and error.

now to your questions: (i'm not a 100% sure about it though )
(1) afaik the delay is in relation to the video

(2)of course you can't just let the audio start before the video (filewise i mean) but you're always able to add a few black frames (remember you are usually dealing with milliseconds here) in the beginning, or cut a few videoframes.

(3) as i said i doubt very much that you'll end up with the delay you want. it's worth a try anyway (:

hope this helps
steVe
PS: oh and if i sounded a bit harsh: i didn't mean to!

[AsukaFan]

Well, firstly, THANKS A LOT, killingspree. &, about the complexity of adding a new audio track from a "completely different source"... OK, you're quite right: It IS a complex matter.

...but... call me crazy, call me a maniac, but I've done it!! Fortunately, the new audio track was only about 2 seconds shorter than the DVD one (not too bad for a 2 hours film), so it was just a matter of really HARD & LONG work at my favorite WAV-edition program. In fact, that matter is almost 100% finished now (&, IM-not so-HO, the result is really awesome), that's why I'm asking this DVD questions.

Anyway, I'm still a bit confused about my questions (2) & (3); you know:

--> whether DVD Maestro uses (or not) the "delay code" embedded into any AC3 file;

--> which is the best method to convert the WAV file into a quality AC3 file AND set a -110 ms delay for that new AC3 file;

--> whether it is the best method (or not) to just "reset" that delay code (how??), & just cut a few audio ms or add a few black video frames (BTW, how you'd add those black frames??)

Remember: I AM a maniac, perfectionist enough to spend a lot of hours getting in sync 2 audio tracks (searching tens of sounds common to both tracks, like screams & explosions, & then adding 0.027 seconds to sync them)... so I'd like the best methods & knowledge to finally accomplish this matter. I'd almost die or kill for that knowledge!!! (I'm a maniac, am I not?)

[killingspree]

Originally posted by AsukaFan

...but... call me crazy, call me a maniac, but I've done it!! Fortunately, the new audio track was only about 2 seconds shorter than the DVD one (not too bad for a 2 hours film), so it was just a matter of really HARD & LONG work at my favorite WAV-edition program. In fact, that matter is almost 100% finished now (&, IM-not so-HO, the result is really awesome), that's why I'm asking this DVD questions.


well gratulations you must have spent a huge amount of time there!!

Anyway, I'm still a bit confused about my questions (2) & (3); you know:

--> whether DVD Maestro uses (or not) the "delay code" embedded into any AC3 file;

--> which is the best method to convert the WAV file into a quality AC3 file AND set a -110 ms delay for that new AC3 file;

--> whether it is the best method (or not) to just "reset" that delay code (how??), & just cut a few audio ms or add a few black video frames (BTW, how you'd add those black frames??)

honestly, i don't do dvd authoring, since i don't have a DVD burner!so i am nor really able to answer any questions regarding DVD Maestro or encoding ac3 files. i just de- or tanscode ac3 files and i've never used DVD Maestro!
so you might want to go over to the DVD authoring forum (the basic one) and ask there! if i were a moderator i'd move you, but since i'm not just do some crossposting but please formulate your questions a little different so you won't get into trouble for doing it!

Remember: I AM a maniac, (...) (I'm a maniac, am I not?)
definitely, YES

regards
steVe