VCD in Dolby Surround?

[cfraider]

I have read a lot of posts in this forum about Dolby Surround and VCD's but it seems that no one has still answered the question of how to create VCD's in Dolby Surround. Specifically: I wish to make a VCD out of my home video materials (i.e. no professional equipments involved, just my video cam and trusty computer for editing) and have its audio be encoded (?) in Dolby Surround so it can be compatible with the general Dolby Surround decoders.

Thanks!

[bugster]

Assuming you are encoding your own captures, with stereo audio then AFAIK, it can't be done.

Dolby surround would probably require multiple wav files for input, uses a hardware encoder (never heard of a SW encoder) to produce a stereo output file with surround informatiion somehow encoded into it (something to do with the phase difference between the two channels is used to carry the surround info).

So basically I don't believe it can be done, esp as VCD does NOT support multichannel sound.

You can do SVCD with multichannel mp2 sound, but very few players support it. But again, how would you get the 5 seperate channels from your stereo capture?

[kitty]

Yes true VCD spec only allows stereo - any changes to this would be some sort of xvcd and I have not read of someone grafting their own home movie encoded 5.1 onto a vcd ( doesn't mean someone hasn't done it as I can barely hear my wife nagging )

[Nelson37]

Unless you have 5 or 6 microphones what would be the point? That would be like upsampling 352x240 to 720x480, you would not gain anything.

Not to mention the fact that AC-3 (which can be created by SoftEncode from any WAVE file, but you need 6 of them to truly get the effect) is NOT compatible with SVCD.

Now, IF you had multiple microphones, AND some way to record all 5 waves at the same time, you could encode to Prologic 2, which does work on SVCD. But with plain stereo, and in fact on most camcorders it is just MONO, there is no real point to trying to convert to Surround.

[cfraider]

errr, I was actually referring to Dolby Surround and not Dolby Digital (again, I'm quite not good with these but is familiar with some -- Dolby Surround is actually stereo and can be put in a VCD; Dolby Digitial is the one you're referring to and can't really be put in a VCD)

Thanks!

[JimJohnD]

Dolby Surround (as seen or heard on tv) is simply a mixed stereo audio signal.

With a wave editing package like COOL EDIT PRO you can make a "surround sound" soundtrack.

You need 5 mono wave files at 44.1K sample rate.
1. (Left Only)
2. (Center)
3. (Right Only)
4. (Surround - Rear)
5. (Surround - Rear, COPY OF #4) "Inverted" or Phase shifted by 180 degrees.

Your final mixed stereo wave file should be mixed as follows:
Left Channel= 1 + 2 + 4
Right Channel= 3 + 2 + 5

There some other tweeks you can do like reduce the rear by 3 db but I've never had a real problem not doing it. Because the result is a STANDARD STEREO audio file you can use it in VCD, XVCD and DVD if you use 48K samples instead of 44.1K.

If you feel REAL daring you can even use ACID PRO 4.0 to mix a surround soundtrack.

1. Edit and Render your video.
2. Open the video in ACID Pro 4.0 using the 5.1 project settings.
3. Leave your camcorder audio centered and in the front. (don't forget to turn up the center channel)
4. Add whatever sound effects/music you want. You can even auto-pan sounds from one place to another in the sound field!
5. Render the 5.1 Wave files. (44.1K 16bit MONO)
6. Mix the two rear files to make one mono wave.
7. You now have a FRONT, CENTER, LEFT and SURROUND wave to use in the mixing process described above.

If you want to put the time and effort into it you can make some really kick butt videos, even using VCD/SVCD

[JimJohnD]

P.S.

You will of course have to use your video editor of choice to replace the old audio with the new mixed audio, I use Ulead Media Studio Pro, if you have any questions

[hp_lovecraft]

As mentioned above-
Dolby Surround is just a special type of 2-channel surround track, and nearly all commercial VCDs, and DVD->VCDs would already contain a surround track.

How does it work?

Basically, if the surround decoder sees the exact same signal in the left and right channel, and puts it in the center (front channe).
If it sees the same signal, except 1 side is out of phase, then it sticks it in the rear (surround) channel.

MetaTags can be inserted into the stream for added pan effects.

Anyway, you can actually make a homemade surround track with a simple stereo wav editor.

I was making a homevideo VCD and wanted to stick my daughters voice into the surround speakers, so I recorded her onto a wav, split it into a stereo track, and reversed one side, then mixed it into a music track, and BOOM, that was it.

WHen encoding, you HAVE to make sure you encode as stereo obviosly.

NIck

[cfraider]

one thing I want to tell you guys -- WOW!
perhaps two -- THANKS!

Perhaps a question or two -- does it matter which editing software do I use to "mix" the video and the "new surround" audio? I'm starting to learn Adobe Premiere and I was hoping it would have a support for this. Also, does it matter if I use tmpgenc to compress the "final" video into mpeg (which settings should I use)?

Thanks again!

[hp_lovecraft]

For TMPG, make sure you DONT use "joint-stereo". It mixes high frquencies into a mono channel (which wil all be directed to the center channel). Use want to use plain "stereo".
"dual-channel" will also work, but some players consider this 2 separate mono tracks, and will default to the left channel when you start.

I havnt used the ADOBE software, but it don't see any reason why it wouldnt work unless it lowers the quality of the audio alot.

Have fun.

Nick

[vitualis]

Yes, you should reduce your centre and surround source audio by 3 dB.

Also, I believe that there is a high pass filter placed upon the centre and surround channels as well. I'm not entire sure what frequency it is at but I have a vague feeling that it is around 7-8 kHz.

The audio you make this way won't be "truly" Dolby Surround encoded but it works well enough. There will probably be some audio bleeding between the channels but it feels great getting it working at all.

Regards.

[cfraider]

WOW! Thanks guys for all your help! At last, my question has finally been answered

[JDI]

HI , I am just picking up on all this Dolby Digital and surround sound stuff.

I know everyone here has basically discussed this thing to end yet I have a few simple Questions.

1. Do I have it right that Dolby Surround is just a plain stereo track and decoded by a decoder. Also I see there is an encoding option to use to make Dolby Surround. I have Soft-Encode , but whats the point in using that if the decoder does all the work , or does a plain stereo track need to be encoded to Dolby Prologic.

2. Should I be able to hear a Dolby Prologic encoded file from Soft-Encode on my PC. I dont have Dolby Decoder. I saved a file as regular wav , not an ac3 or DD wav and I could hear it just fine. Using besweet converting from ac3 to wav makes a typical wav file as well I understand.

3. How many channels shoud Dolby Surround have? 4 or 5. I see some say 5 and others say 4 , which is it.


4. Let's say I have a Stereo wav , do I have to split the file into 2 mono or just leave as one stereo wav file to use in Soft-Encode. And last , can anything be done with just a mono , EX mono to Dolby Surround , or is that just a big waste of time.

JJ

[vitualis]

1. Do I have it right that Dolby Surround is just a plain stereo track and decoded by a decoder. Also I see there is an encoding option to use to make Dolby Surround. I have Soft-Encode , but whats the point in using that if the decoder does all the work , or does a plain stereo track need to be encoded to Dolby Prologic.

You are missing the point. "Dolby Surround" is a method of matrixing an additional TWO channels (surround and centre) into a stereo audio source. The end result is still in stereo so it can be carried by anything that uses stereo audio (e.g., CDs, FM radio, etc.)

You will need a decoder capable of decoding the "Dolby Surround" material to get the additonal channels.

2. Should I be able to hear a Dolby Prologic encoded file from Soft-Encode on my PC. I dont have Dolby Decoder. I saved a file as regular wav , not an ac3 or DD wav and I could hear it just fine. Using besweet converting from ac3 to wav makes a typical wav file as well I understand.

There is no such thing as a Dolby Pro Logic encoded file.

Dolby Pro Logic and Dolby Pro Logic II are decoding methods only. They both decode "Dolby Surround" material.

Dolby Surround can be carried by any stereo audio source. Thus, a standard WAV file can have Dolby Surround material encoded in it. If you play it back without Dolby Surround/Pro Logic/Pro Logic II decoder equipment, you will just hear the matrixed stereo. You won't get separation of the additional channels in the audio.

3. How many channels shoud Dolby Surround have? 4 or 5. I see some say 5 and others say 4 , which is it.

I think that you are confusing the terms Dolby Surround, Dolby Pro Logic and Dolby Digital. I suggest that you visit the Dolby website for clarification.

Dolby Surround itself only matrixes 4 channels. L, R, S and C.

If you decode the Dolby Surround audio with an (OLD) Dolby Surround decoder, you get L, R and S channels separated.

If you decode the Dolby Surround audio with a Pro Logic decoder, you get L, R, C and S channels separated.

If you decode the Dolby Surround audio with a Pro Logic II deocder, you get L, R, C, LS and RS channels.

Remember, however, that the matrixing itself only uses four channels of audio and none of them are discrete.

Dolby Digital is a flexible format and can have MANY channels.

4. Let's say I have a Stereo wav , do I have to split the file into 2 mono or just leave as one stereo wav file to use in Soft-Encode. And last , can anything be done with just a mono , EX mono to Dolby Surround , or is that just a big waste of time.

Don't know enough about your program to answer that. From memory, Soft Encode encoded files to Dolby Digital or DTS and that isn't what you really want if you just want to make Dolby Surround encoded clips.

As for mono, I believe there are methods to create pseudo-stereo and perhaps even surroundish audio from it. That is way beyond my level of knowledge however.

Regards.

[JDI]

Ok Thanks for the info.


So what your saying is , there is no need to tamper with a stereo wav file if you have a Dolby surround decoder , the decoder will matrix the 2 channels into 4 and depending on your decoder you,ll get the corresponding channels?

No Extra work needed.

I did see a guide that shows how to make Dolby surround from stereo wav and it is as follows.

1) Create from various WAV-files an AC3-file (Soft Encode)
2) Downmix AC3 to Dolby Surround compliant stereo WAV-file (DVD2AVI)
3) Compres to MPEG1-Layer2 (CCE, TMPGE, etc)
4) Mux with MPEG2-video, Author, Burn (I-Author)

But I dont have various wav files , So I am assuming that this option is for a file which originally had Dolby 5.1 , make six waves then follow the above. So Going from 5.1 to surround using an encoding method is possible.

[vitualis]

So what your saying is , there is no need to tamper with a stereo wav file if you have a Dolby surround decoder , the decoder will matrix the 2 channels into 4 and depending on your decoder you,ll get the corresponding channels?

No Extra work needed.

I did see a guide that shows how to make Dolby surround from stereo wav and it is as follows.

1) Create from various WAV-files an AC3-file (Soft Encode)
2) Downmix AC3 to Dolby Surround compliant stereo WAV-file (DVD2AVI)
3) Compres to MPEG1-Layer2 (CCE, TMPGE, etc)
4) Mux with MPEG2-video, Author, Burn (I-Author)

I see what you are getting at now. Your ordinary "stereo" file will not have the Dolby Surround material encoded in it. Without this material, you will not get the centre and surround channels.

Perhaps it is a little bit difficult to understand, but a stereo audio source that has the Dolby Surround material is still in STEREO in so far that it is on two channels (L and R). However, buried in the stereo audio is a signal that the Dolby Pro Logic/Pro Logic II decoder can lock on to and recreate the surround and centre channels.

You still need to have the Dolby Surround material encoded into your audio to have the additional channels.

If you want to create your own Dolby Surround encoded stereo files (in WAV format), you will need to start with your original stereo file, an additional mono wav file that contains the "centre" channel, and an additional mono wav file that contains the "surround" channel.

You then create a "sort of" Dolby Surround encoded clip by doing the following:

L = L + (C + S)
R = L + (C - S)

You should reduce both C and S WAV files by 3 dB and perform a high pass filter of 7 kHz first.

The reason people have suggested you create an AC3 file first and then downmix it to a Dolby Surround compatible stereo WAV file is because there is no good software out there that will create a Dolby Surround encoded WAV file de novo from your source.

There is, however, very good quality software for downmixing AC3 to Dolby Surround compatible stereo...

Regards.

[JDI]

OK Thanks , this is great!

I am using Soft-Encode for this , and am using the following scheme.

3/1 = Left, Center, Right, Surround

-3db for C and -3 for S.

There is an option for high pass filter as follows.

DC High pass filter. There is no option to set the 7 Khz.

I assume the above is correct according to your scheme of:

L = L + (C + S)
R = L + (C - S)

You should reduce both C and S WAV files by 3 dB and perform a high pass filter of 7 kHz first.


Or is it wrong , when you say L = L + (C + S) what exactly does this mean? or L + (C - S) or do I not need to both myself with it as long as I supply the tracks as stereo-wav , mono-C , mono-S. As to this scheme I assume the mono files are exact copies of the stereo source just given different channels , C & S. Correct me on this if i,m off-base. As that's all I have a Stereo-wav. I understand true Dolby Surround has different sound in the files, but would making copies of the stereo just be a waste of time or would I get some sort of effect because of the -3db for C,S along with L + (C + S) and L + (C - S).

Having said all that , Do I need to use another program to create the channel scheme or is Soft-Encode ok. I use besweet to convert the AC3 to wav selecting Surround , 2/0 and not using the -3db for S or C cause it was already done in Soft-Encode. Do you have the scheme for Dolby Prologic ? My goal is to have the sound play back through a Prologic decoder.

This is really helping me out.
Thanks for all the info.

JJ

[vitualis]

L = original left channel of stereo audio
R = original right channel of stereo audio
C = centre channel
S = surround channel

With an audio editor (e.g., CoolEdit), create two new wav files of the following:
C - S and C + S

To create C + S, use "add merge" function.

To create C - S, use "add merge" but invert the S track first.

Now reduce both of these by 3 dB and do a highpass at 7 kHz.

For the new stereo audio file with the Dolby data (sort of):

new Left channel = L + (C + S) [i.e., original left "add merge" the C+S audio after the 3 dB reduction and highpass filter]

new Right channel = R + (C - S) [as above]

This audio track should "sort of" be detected and played back by a Pro Logic decoder as separate channels.

Regards.

[Nelson37]

EXCELLENT Discussion!

I have one question, the description of PL-2 agrees with what I had heard, basically there are TWO surround channels and they are seperate, and also of a higher volume than PL-1 (?). But the question involves the original Dolby Surround Encoding, it would seem that it would have to be different for PL-2 to get two - Distinct as opposed to Discrete - seperate channels, rather than one for PL-1.

I understand the way the files are combined and such, I had thought there must be an improved Dolby Surround Encoding for PL-2 to work.
Has the Surround channel always contained two seperate sound streams or does this mean that the LS and RS are not really different, just faked somehow?

[JDI]

Thanks

Can I use Cool Edit 2000 to merge the Center and Surround files or Do I need Cool Edit Pro?

Also , where is the -3 db option and high pass filter 7Khz located?
I have Cool Edit 2000.

Maybe the same can be acomplished with C-E 2000.


Thanks again.

JJ

[JDI]

In regards to my last question on Cool Edit.

You mention the add merge function , which I cannot find within cool edit.
Do you mean Paste or Mix (super-impose) the C channel over the S channel? If I paste of course it just over writes the audio that was in place origianlly. I assume you mean Mix the C an S channels , then save as Mono wav file.

I think I can do the same with GoldWave , correct me if I am wrong.

[vitualis]

With CoolEdit 2000 (that's the version I have):

Edit --> Mix Paste --> Overlap

On that dialog window, you can select "Invert" as well.

To invert a wave file you have opened: Transform --> Invert.

To reduce by 3 dB: Transform --> Amplitude --> Amplify --> Choose the "3 dB cut" preset option.

Actually, I mean "low-pass" filter.

Transform --> Filters --> FFT filters
Choose one of the low pass filters and adjust the graph thing to 7 kHz. You probably want to save this as a preset so you don't have to manually do it again next time.

Best regards.

[vitualis]

EXCELLENT Discussion!

I have one question, the description of PL-2 agrees with what I had heard, basically there are TWO surround channels and they are seperate, and also of a higher volume than PL-1 (?). But the question involves the original Dolby Surround Encoding, it would seem that it would have to be different for PL-2 to get two - Distinct as opposed to Discrete - seperate channels, rather than one for PL-1.

I understand the way the files are combined and such, I had thought there must be an improved Dolby Surround Encoding for PL-2 to work.
Has the Surround channel always contained two seperate sound streams or does this mean that the LS and RS are not really different, just faked somehow?

I think they are faked. I have not read any DOLBY documentation on a new matrixing method especially for PL-II. I think it is still standard Dolby Surround.

The freeware 5.1 --> Dolby Surround downmixer (can't remember the name for some reason... Head...something) has an option that seems to work better for PL-II. However, in another thread, it seems that the author of the proggy arrived at those settings by trial and error... Does it work as well for PL-I deocders? Who knows...

Regards.

[JDI]

OK , Great thanks!

So I assume if I want to just simulate surround for a typical 2 speaker
system I would just take a stereo-wav and invert one channel , no need to ow pass or reduce by 3db , correct?

JJ

[vitualis]

Um... if you only have a two speaker system, then you can't really get surround audio... Or perhaps I'm misunderstanding you?

Regards.

[flaninacupboard]

Thought i'd add my experience with Pro logic 2. With old material, using P2 to decode just seems to produce one surround channel. newer material does have two rear channels, so i think some jiggery pokery has gone on that dolby hasn't told us about. a good example is the nintendo gamecube, it's output is definitely pro logic2, if you run audio tests it hits each speaker seperately, or at least the difference is enough for me to think it's seperate. it's great playing rogue leader and hearing tie fighters swoop in from behind. always makes me shout "they came from behin.....ARGHHHH!"

[vitualis]

...so i think some jiggery pokery has gone on that dolby hasn't told us about.

Figures...

Regards.

[JDI]

Here's a snip I got from Goldwave.

Invert

Reflects the selection about the x (time) axis. This produces no noticeable effect in mono sounds and has a slight effect in stereo sounds. Inverting a single channel of a stereo sound will produce a simulated surround-sound effect.

JJ

[vitualis]

I've done it before... Inverting a one of the channels on a stereo source makes the audio sound a little bit weird (you get phase interference between the left and right channels) but that's about it. It's a hard call to say you get "surround" effects though.

Regards.

[JDI]

Alright , Thanks for the tip.

I guess that's all you,ll get from a 2 channel stereo file.

Do you know of a way to record AC3 or dolby digital 5.1 from ....let's say a standalone dvd player? I have a Sound Blaster live (CT 4830).

Thanks again.

JJ