Recording AC3 bitstream

[Quilty]

Hi there,

I am trying to record the AC3 bitstream from a LaserDisc to put it on (ultimately) a DVD as the soundtrack to the footage captured from the LD. I have got as far as stage 1, in that I can record the bitstream using the digital IN on my soundcard, store it as a 44.1 WAV file, and then burn that to a CD and play it back through my DD Amp and it works fine.

What I do not know how to do is convert the WAV into a .ac3 file ready to mux with the MP2 video stream. Can anyone advise me?

Also is there a good pure bitstream editor for AC3?

Cheers,

Quilty

[nathan118]

This might help....

http://www.doom9.org/index.html?/ac3machine.htm

[furball6969]

If you cannot get that to work for you you can transcode the WAV file to a mpeg1-layer2 audio file. 48khz, 16bit, stereo. or you can use the wav file but it will also have to be resampled to 48khz.

The fact that the file is now a 44.1khz wav file pretty much tells me that you've lost the AC3 encoding anyway.

[Quilty]

No it works fine ....

I guess the question is this: how do you convert an AC3-WAV to an AC3 file without transcoding or recompressing it.

Essentially it is a AC3-WAV I have made by recording it from the SPDIF, and though it is 44.1khz it works fine. The WAV file is just a wrapper .. I need to get at the data within!



Quilty

[BJ_M]

convert it to raw, motorola endian .. but as for converting it to 48 from 44.1 , i don't know if it will hold up (no idea) .. i used to record ac3 stream with a tascam dat recorder , but last one i did I used a mackie HDR-24/96

[Quilty]

Did you record in 48khz mode? I only recorded 44 as I wanted to burn it to cd to test

Cheers,

Quilty

[BJ_M]

yes - 48k

[Quilty]

Thanks.

Out of interest did the ones you did go into DVD? If so is there any other advice you can give me? Like about cutting the streams to sync with the video etc. or pasting the streams from the different sides of the Laserdisc?

Cheers again,

Quilty

[BJ_M]

best results i got was to convert to analog and re-encode with time stamps , laser disk video is interlaced and i performed my own inverse teli on it - and re-sync the audio up by hand on a DAW ..

[BJ_M]

most of the laser disks i have are DTS disks -- for the DTS disks i could go two routes .. one is i can pull off the DTS tracks off the original film cd's for the dts 6D player (off the digital output) and sync that to the video (when i was able to get hold of the disks) .. or i recorded in real time off a ADA DTS convertor onto a ADAT or hard disk recorder .. the film and laser dts (same with film and dvd dolby digital ac3) are totally different technologies (in fact home/consumeer AC3 and DTS vs. theatre ac3 and DTS , well the home version is higher quality) ...