surround formats question?

[vcd4me]

I did a search for this question: Can I have surround sound on my vcd? Now I am more confused! Also I read on a site somewhere that original vcd's only have pro-logic. So what is the possible surround modes you can put on a vcd? Some of the threads said yes some say no. I really could use some help because don't forget a movie is half picture half sound! So to basically put it my receiver can play all formats, I would even settle for pro-logic. Back in 1994 when I first set-up my home theater that's all there was. Even the vhs tapes sounded good!

[BerrantRyke]

To the best of my knowledge, Pro-Logic is the only surround sound format that VCD supports.

[vcd4me]

WOW, Nice job on your site very informative. I'm confused as to what a dv2 is? Also do you know of away to convert a divx file with ac3 to a pro-logic mode?Is that even possible? Is there a guide somewhere on this site I may have overlooked? Like I said in the begining I'm cofused!Thanks in advance VCD4ME

[BerrantRyke]

a .d2v file is what TMPEGnc looks at to reference the .vob files to get the picture information. Thats why you have to KEEP the .vob files untill you finish encoding. the .d2v is ONLY a reference for the encoder.

I dont know about getting Pro-Logic from a Divx file however. if I had to guess I would say NO, unless is was encoded that way to begin with.

Good luck out there!

[vcd4me]

Thanks again

[dvddarren]

A prologic soundtrack is decoded from just a 2channel stereo sound track.

If you extract the AC3 sound, then convert it 2 stereo (I think BeSweet can do this), then use this 2 channel sound in your vcd, im pretty sure its just a case of hitting pro-logic on your Amp/Decoder and that does all the work.

[vcd4me]

Thanks DVDDARREN, I'm going to give it a try. Now I'll just have to get a avi with ac3 and then try it. I always thought that pro-logic had to be put on the video because I have old movies with stereo sound and those don't play in surround. Can anyone elaborate on what DVDDARREN said about the receiver doing the work

[dvddarren]

I think an AC3 5.1 sound track has Pro-Logic encoded into the front left and right channels anyway. So people who dont have a Dolby Digital setup can still listen in Pro-Logic using just the left and right stereo tracks

[vcd4me]

I don't think so. pro-logic and 5.1 are diffrent as is 5.1 to dts

[dvddarren]

i know pro-logic and 5.1 are different.

AC3 5.1 or Dolby Digital is 5 pure channels of sound.

Dolby Pro-Logic is 4 channels of sound made up from 2 channels. The 2 channels of sound (left & right) are decoded using your decoder to extract 1 channel for centre and 1 channel for rear.

Now, surely your decoder can do the same decoding on the same 2 channels from the AC3 audio, it would just use the left & right audio to extract centre and rear.

[vitualis]

"Dolby Pro Logic" refers to the decoding method only.

The encoding method of matrixing the additional centre and surround channels into a stereo audio source is called "Dolby Surround".

Yes, it's confusing. 8)

That is, audio content can be encoded in "Dolby Surround" (e.g., FM radio, audio CDs, etc.)

The "Dolby Surround" encoded audio can be DECODED a number of ways including "Dolby Surround", "Dolby ProLogic" and "Dolby ProLogic II". Thus, the symbol for "Dolby ProLogic" should only appear on DECODING hardware (e.g., speakers).

AC3 5.1 audio has 5 completely discreet channels of audio and one low frequency channel (the .1). It does not contain Dolby Surround encoded information. An AC3 decoder, however, must be able to downmix the 5.1 audio channels to a Dolby Surround compatible stereo signal -- which is how you can get Dolby Surround/ProLogic audio from a DVD with only an AC3 5.1 soundtrack.

I suggest you go to the Dolby website to read their technical documents for more specific information.

All the common methods for ripping a DVD (e.g., DVD2AVI and FlaskMPEG) will decode AC3 5.1 audio (otherwise you would get no audio at all!) and will downmix the 5.1 channels into Dolby Surround compatible stereo audio.

Regards.[/b]

[vcd4me]

Tahnk you guys for your posts

Michael-- I went to the site and read alot of info. Thanks for the suggestion it cleared some things up.I also went to doom9

So are these statements right :

VCDS can have surround sound but only pro-logic.

Svcds can have ac3 on them (I read on doom9 its been tested-but really no conclusions yet)

I've got another question If I have a avi with ac3 and use virtual dub will my final product have surround sound on it? or do I have to use besweet or the other one (I can't remember the name right now)

[Kdiddy]

Svcds can have ac3 on them

No they can not. SVCDs can have multichannel mpeg2 audio, but not ac3, there is a difference. However, there are very very few receivers that will decode a multichannel mpeg2 audio stream correctly.

[vcd4me]

Ok I GIVE UP

The more I read the more confused I get !

I do understand the diffrences in the formats.

I Just don't get it about surround sound on VCDS

[dvddarren]

your best just using 2 channels of sound unless your making dvdr's then you can use AC3.

I have never seen a decoder that can decode MPEG Multichannel audio, but I know you can get them.

[vitualis]

I Just don't get it about surround sound on VCDS

VCDs only support STEREO or DUAL MONO soundtracks. That is, it only supports TWO DISCRETE CHANNELS of audio.

This is where "Dolby Surround" comes in. Dolby Surround is a method of encoding an additional centre and surround channel into stereo audio. That is, these are not discrete tracks. They are mixed in with an ordinary stereo signal. Thus, Dolby Surround encoded stereo can be used on ANY audio source that supports stereo audio (e.g., audio CDs, FM radio, etc). This obviously includes VCDs as well and is the ONLY way you can put surround sound on a VCD with any hope of it being played back properly.

Such a VCD played back on a standard stereo system (i.e., without a Dolby ProLogic decoder) will sound pretty much just like standard stereo. Such a VCD played back WITH a Dolby ProLogic decoder will lead to additional centre and surround channels being apparent.

Now, SVCDs have a few tricks up its sleeve...

Apart from (like VCDs) just supporting MPEG-1 Layer 2 stereo audio, it also supports 5.1 multichannel MPEG-2 audio.

This is 5 full discrete channels (plus one low frequency channel) encoded as MPEG-2 audio and multiplexed together.

Thus, apart from the ability to use Dolby Surround encoded stereo, it can have TRUE discrete 5.1 multichannel surround sound. Unfortunately, as others have mentioned, there are few players or receivers that support this.

AC3 5.1 = Dolby Digital 5.1. This is commonly used on DVDs. It CANNOT be used on a SVCD (if you want it to have a chance of working).

Any more questions?

Regards.