TMPEGEnc and AC3

[Chaoji3791]

Hey ho,

I'm new at DVD authoring and have discovered that TMPEGEnc can multiplex an MPEG2 video stream with an AC3 file. How does it do this? Does it decode the AC3 file and then downmix it to stereo MPEG layer 2 audio? (And if so, how does it do so without an onboard decoder? I thought you needed SoftEncode or similar to decode AC3 files.) Or does it simply "attach" the AC3 file somehow to the video stream?

C h a o j i

[leebo]

I can't answer for sure, but I can tell you about something I noticed.

When I take an mpeg file that TMPEGEnc mixed w/an AC3 file and import it into VP5, it shows up as mpeg2 with AC3 audio.

So my guess is that TMPEG just marries them together.

[Chaoji3791]

I should know this ... but it's late and my brain is foggy. What's VP5?

C h a o j i

[Baldrick]

videopack 5

[Truman]

When you multiplex a MPEG-2 video file with a ac3 audio file, you will end with a MPEG-2 system stream, that contains MPEG-2 video and ac3 audio, what else? This has nothing to do with decoding or encoding. This file is not supported by SVCD but by DVD. If you want SVCD you have to transcode ac3 to MPEG-1 Layer-2 or MPEG-2 multichannel.

[Chaoji3791]

Thanks, but I never mentioned SVCD. I simply wanted to know what happened to the AC3 file when you multiplex it to the MPEG2 video stream and obviously the answer is that it doesn't get altered, it just becomes part of the MPEG2 system stream.

It's all so clear to me now.

C h a o j i