is ac3 reencode possible

[dvd_maniac]

I am using the latest dvd2svcd 1.2.1 build 2 and I was wondering if it is possible to reencode the audio Back to ac3? I am using scenarist 2.6 with ac3enc.exe. When I reencode the audio I get stuck with mpeg audio. Is there something in the program I am missing? If not is this something under consideration?

Also would like to take a bow to dvd2svcd for a moment of silence. This program has definitely made my life easier...

[DDogg]

Is there something in the program I am missing? I don't know. I thought if you checked "Do not convert Audio" the AC3 was just time adjusted by Besweet and then muxed by scenarist. Frankly, I do svcds except for some light testing so it might be me that is confused. Maybe mrbass will see your question.

I know you can elect to use mp2 to save a ton of bits when needed, but I don't think you are forced to do so. Er, darn, you are not talking Avi2sdvd, are you? 'Cause if you are I am gonna bite you for not mentioning it clearly. Well, not really :)

[dvd_maniac]

Hey DDogg,

No I am using the dvd2dvd method, and dvd specs require that at least one track be either dts or ac3. I am not as worried about audio as I am more into video quality and I am looking to put a couple movies onto one dvd-r using dvd2svcd then dvd2one to join them. This way the video quality is SUPERIOR and I can still use the new join function of dvd2one without it transcoding the video. However, squeezing two or even three movies (I did the Rambo trilogy as a test), onto one dvd-r is tricky. So I would really like to make a little extra room for the video by squeezing the audio down a bit. When I do, I get a mp2 audio stream instead of ac3 and I was wondering if I could get an ac3 instead. I know I could just use softencode or besweet after, but that kinda defeats the purpose of this wonderful, awesome, time saving, god of a program.

[DDogg]

So I think you are saying you want to *re-encode the AC3* to a lower bitrate? (I'm learning something here so bear with me). You said "I was wondering if it is possible to re-encode the audio Back to ac3?". It wasn't clear to me what you were saying. (Your topic was clear however. I need to read better :) )

Btw, I have done a lot of research on using RoBa to put multiple encodes on 1 dvd while ensuring each is of a similar quality no matter what the compression characteristics are of each source. Maybe I could assist there. I did a two long winded exercises that touch on that topic here, but it is more theory than actual practice: http://forum.doom9.org/showthread.php?s=&threadid=59850

/ADD: I looked at the new BeSweet gui wizard (awesome!) just to check what was involved in the command line for re-encoding the ac3 to another bitrate. It seems easy enough if I didn't miss anything.

Since d2s is already invoking BeSweet to trim the ac3 it would seem reasonable to ask him to check in to also changing bitrate at the same time. That certainly would make the setup much more flexible with those encodes you need to squeak out that little bit of extra BR for the video. I'll bring it up although the messenger may get shot. :)

[ralphthedog]

I think the only alternative for a lower bitrate AC3 stream is to re-encode the original AC3 later (and of course try to guess all the correct filesizes/discsizes to fit everything on a DVD-R) with AC3 machine and beesweet

I wonder what type of filesize similarity(or not) there is between say a 224kbit .mp2 and a re-encoded 224kbit 5.1 ac3 from the same source? Maybe there could be some fairly easy size prediction/comparison math to help with re-encoding the AC3 to a lower bitrate later.

I have renamed the re-encoded .mp2 audio to .mpa and used it as the only DVD audio stream without incident in the past, when I'm trying to maximise space (.mpa for extras etc.), but I have no Idea how compliant or not it really is.

Have seen PCM only DVD's, so I guess there's always exeptions to rules.

[DDogg]

OT and just fyi, I just drug the ac3 from lotr2t into danni D's new gui wizard, chose ac3 with a 224 29.97 > 25.00 preset as the output and away BeSweet went doing its thing making the new 5.1 ac3.

I don't know much about ac3 stuff, but if you have not tried danni's wizard gui you should. I tried to help test a bit way back from the standpoint of somebody who rarely needs this stuff and just wants to do it without having to know anything. Well, I think he has done it. It took me all of ten seconds to get it going.

[dvd_maniac]

ac3 to ac3 is very easy and I've been doing it with besweet and softencode for years now. I would just like to know if it IS or will be part of d2s. When I was doing movie only backups in the past using MaestroDVD, when the movie is just a little over the dvd-r size, I would cut out credits, and lower the bitrate of ac3 and most of the time I would get down to dvd-r size. This was not only WAYYYY faster but also allowed me to skip encoding the video. And since I care more for the video than audio quality, I would love to be able to do this in d2s.
Also I typed a boo boo
and dvd specs require that at least one track be either dts or ac3.

Either ac3 or PCM is dvd compliant.

I can play the results of mp2 audio on my dvd players, but would like to keep them in spec if possible.

[jsoto]

Not sure if it is a good idea to jump into this thread, but..

Ac3 to ac3 reencode is a nice and very simple (using BeSweet) feature. I am sure dvd2svcd will take it into account.

But, in the meantime, mdvdauth plugin does it. But it uses IfoEdit for DVD/mDVD authoring and I have read something about it has any problem with NTSC (with no attention from my side, because I am a PAL user).

Cheers.