AC3 audio problem with Nerovision Express

vbimport

#1

AC3 audio problem with Nerovision Express
I posted this a week ago in the transcoding section. It got 70 reads, but not one reply. I’m hoping that I’ll have more success in this forum.

I have a DVB Satellite card and record movies with AC3 audio. The format is limited with these Sat cards. Many times, you’re forced to record in a 544x480 resolution. I’m in NTSCland, so this makes it hard to convert the file with TMPG DVDauthor (it wants 704x480 or 720x480). TMPG Plus won’t accept the mpg file. I’ve met with limited success with Premiere, but it’s major time consumption.
Nerovision accepts the file nicely, and will convert to DVD format (720x480), or it will export to 720x480 MPEG-2. The problem is that, even though I select Dolby Digital (AC3) audio for the output, I wind up with only PCM (2 channel) out to my external AC3 receiver, even though the same receiver gets Dolby Digital 5.1 when the original MPEG-2 (recorded) file is played.
I’m hoping we might have a few digital audio experts on this forum, and that they might be able to help. (That’s why it’s important to me that I’m posted in the correct category and sub.)
I obviously have the Nero MPEG-2 plugin, and according to Ahead, it includes an AC3 plugin. I’m not sure if I have the correct AC3 plugin. Anyone know what it’s named?


#2

I have tried to search for the actual name of the plug-in and am unaware, sorry.


#3

The retail version of Nero allows AC3 2 channel encode/decode and ac3 5.1 channel decode. Nero vision is not able to encode 5.1 channels. It can do 2 channel AC3 (different then PCM stream 2 channel).


#4

That’s exactly what I’m getting, Mike. AC3 - 2 channel audio (not PCM). Does anyone know of a s/w program that will process DVB mpeg-2 stream and maintain 5.1 audio while converting to DVD format, or to an mpeg-2 file that will be accepted by a program that will convert to VOB (5.1 audio retained).


#5

Have you tried looking at the doom9 forums?

That place is the king of all things video, it should be able to help you out.

In what way TMPGenc + fail, does it fail to read to recognise the audio or video part of your mpeg?

In either case I would probably feed the file to virtualdubmod via avisynth, and demux out the audio, then turn off the audio and output the the video portion as an avi file using huffyuv, then encode the avi with TMPGenc, and import the resulting mpeg encoded file and the demuxed AC3 to a dvd authoring package like dvdlab to produce the needed VOB’s.

(yep it is pretty involved and time consuming, but I don’t know of any free AC3 5.1 transcoders.)

Anyway check out the doom9 forums for heaps of info on what you need to do.

Hope this helps


#6

I wouldn’t do any DVD authoring without the help of Doom9 or VCR/DVD Help.

TMPG doesn’t seem to like audio files with AC3 extensions. TMPG+ won’t accept them. TMPG Enc DVD Author will, but won’t accept the 544x480 res.

I’ve also tried Premiere, as well as PVAstrumento, DVR Studio, XMPEG, and ReJig (programs designed to edit mpeg streams produced by PCI satellite cards).
I can demux the 544x480 file to produce a 720x480 video file and an AC3 audio file with XMPEG 5, and I can then mux the result with TMPG Enc DVD Author, or with ReJig, and that allows me to retain the 5.1 sound, but once the original mpg has been demuxed, there’s no way to get the sound back in sync with the video, even though ReJig has the ability to allow an audio delay offset. (The audio, in fact, already trails the video. I need to set the audio ahead.)