mpeg1 audio/system question

[Tasslehoff]

Hi guys,
I'm working with MPEG-1, and I'd like to know if it is possible to have more than 1 audio stream. I know u can divide an audio stream into two mono channels, but is it also possible to have more than 1 stream for the audio?
Thanks for answering.

[guns1inger]

Just mepg-1, or ultimately VCD or DVD ?

[redwudz]

In the MPEG-1 format, no, AFAIK, just two channels or one stereo channel. You could go to SVCD and have two stereo channels, but that would be MPEG-2.

From a MPEG audio webpage: http://www.tnt.uni-hannover.de/project/mpeg/audio/

MPEG-1 Audio (ISO/IEC 11172-3) provides

single-channel ('mono') and two-channel ('stereo' or 'dual mono') coding at 32, 44.1, and 48 kHz sampling rate. The predefined bit rates range from 32 to 448 kbit/s for Layer I, from 32 to 384 kbit/s for Layer II, and from 32 to 320 kbit/s for Layer III.

And welcome to our forums.

[Cornucopia]

To clarify,

MPEG 1 (layers 1, 2, & 3) and MPEG 2 (but not 2.5) provide for only 4 channel types per stream:

• Mono (1 channel)
  Dual Mono (2 ch)
  Joint Stereo (2 ch)
  Stereo (2 ch)

MPEG 2.5 (backward-compatible) and MPEG 4/2NBC(AAC) allow for more channels--up to 7.1, IIRC.

But MPEG does allow for multiple audio streams (muxed together in the program/transport/system stream). Note--this is MPEG in general, not the VCD, SVCD, or DVD specs. These are much more constricted.

What is your ultimate destination format?

Scott

[Tasslehoff]

Thanks for your answers.

The ultimate format is MPEG-1. Trying to get it clearer: What I need to know is if I can encode a video with more than one audio stream (like a stream for voice, a stream for soundtrack and a stream for other sounds, for example, all of them stereo), and read on the .mpeg generated file the different streams separately.

The channel types per stream are pretty clear.

[Cornucopia]

Yes, but you still didn't tell us how it was going to be used...

VCD? (1 audio stream max)
SVCD? (2-4 audio streams max--depending on configuration)
DVD? (8 audio streams max)
MPEG on Computer? (whatever MPEG limit is...15? 32?, also depends on "player/stream switcher" plugin--read Morgan Stream switcher)
Some other embedded system? (no idea, but probably 1 only)
Broadcast? (no idea, but probably 1, 2 or 4 --greatly depending on available bitrate, IMHO)

Scott

[jman98]

Tasselhoff - People here ARE trying to help you, but you aren't cooperating. How many times do we have to ask what you are making? VCD, DVD, etc. If you can only answer "MPEG-1" then we will go away and stop wasting our time with you.

[Tasslehoff]

Jeez, there is no need to be rude - I just didn't get what exactly was the question.
The end file is an .mpeg file to be read on the computer. To be read by another computer program, I mean.
That is why I was asking if it could be encoded (and not specifying the end result) - because if it can be encoded respecting the standard, then it can also be read.
Hope it is clearer.
Thanks again.

[guns1inger]

I assume you have a specific playback program in mind, as not all software will playback multiple audio tracks correctly. WMP, for example, will probably play them all back simultaneously.

[Tasslehoff]

Actually, I don't mind if its played simultaneously. What I need is to be able to read it separately - and there comes the specific program.
I'm assuming that means yes, I can have multiple audio streams on mpeg-1.

That solved, do you know of an encoding program that can do that? It would be of great help.

Thanks a lot

[mats.hogberg]

It's not so much an encoder as a multiplexer you're looking for. Not that I know of any capable of what you're looking for (but then again, maybe mplex can do it - I've never had a reason to look for it!)

/Mats

[Cornucopia]

Just about ALL standalone multiplexers can do that.

I usually use TMPGEnc for stuff like that. Imago Mux is good too.

Scott

[Tasslehoff]

Sorry about the delayed answer - been quite busy.
Thanks for you help guys, I got all answers I needed