PCM, Dolby Digital, & AC3 in DVD Authoring?! at DVinfo.net

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Old May 16th, 2003, 11:28 AM   #1
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PCM, Dolby Digital, & AC3 in DVD Authoring?!

DVDit offers the ability to encode audio in Dolby Digital. Supposedly it is higher compression over PCM but at little loss of quality. I thought dolby digital is high-end sound usually associated with surround sound/home theaters?!

Also I've seen a version of Ulead's DVD Workshop that supports AC3. Now how is someone like me to take advantage of this. AC3 is 5.1 with stereo rears right? I shoot on the DVX100 with a "MONO" Senheisser ME66/k6. How are you supposed to make your video productions surround sound AC3?!
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Old May 16th, 2003, 01:11 PM   #2
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My first guess, would be ambient sounds filling the other cannels. A car skid left rear, gunshots front right, speaking center and left... Foley crews are usually the people that add this dimension to film in Hollywood.
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Old May 16th, 2003, 05:45 PM   #3
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Vegas4+DVD also features AC3 encoding, and can do full 5.1 mixing to match it. Mono sources make it more easy to position, especially in the case of dialog. Vegas makes it easy to take a mono track and place it in one channel and then pan it around as you see fit. Most surround sound productions (movies) place dialog in the center, soundtrack to the sides, and ambient or exaggerated sounds to the sides and rear. You can also send effects specifically to the LFE (subwoofer) channel, for extra rumble. Depending on the shoot, you might place an omni mic somewhere out of the main stage to pick up the ambient sounds (like traffic, or nature), then place that as a separate track in your mix to all 4 outside channels or just the rears.
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Old May 16th, 2003, 08:39 PM   #4
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Wow sounds cool- it's ashame I don't use Vegas.
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Old May 17th, 2003, 12:10 PM   #5
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brian covered most of it, but one addition is that ou can set teh LFE cutoff frequency, as well as set keyframed pans thruout the whole project.
If you have Softencode installed, u can directly export the audio as ac3 then run it thru dvd architect to finish off your DVD.

on top of that Vegas is the only video editor which allows for keyframed effects.. these come in very handy when creating the surround environment.

just remember if u sue Dolby technologies and you intend on using their logos, you must sign and pass a standardisation requirement set by Dolby Labs.
If u dont, u can get into BIG trouble...

oh and finally, dvd rchitect can convert a stereo track into 5.1 (without the need to export as ac3) but its really not worth it if your not utilising the technology in full...
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Old May 17th, 2003, 01:11 PM   #6
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<<<Now how is someone like me to take advantage of this. AC3 is 5.1 with stereo rears right? I shoot on the DVX100 with a "MONO" Senheisser ME66/k6. How are you supposed to make your video productions surround sound AC3?!>>>

A large amount of info needs to be passed in order to answer this question.
Way too much for this single post. Here is a primer.

5.1 and other surround mixes are built in a studio that has the ability
to record multiple tracks and the capability to sync and blend them all
into 6 separate mixes (usually recorded back on to another 8 track).

(skipping over a huge amount of planning, imagination and work)

Once you get and record your 6 mixes, you then save each track/mix into its
own file of exactly the same frame length. Re-import them into
the program that turns those 6 tracks into one surround file.
The last part of this process is the "easy as hell no brainer"
that FCP (and Vegas?) can do for you. Getting to that last part is the really
hard, takes lots of planning, gear and time that isn't mentioned in the
product hype.

So, if you don't have a studio with this kind of capability, I wouldn't attempt
it. You cannot make a good 5.1 mix with just one mono voice track.
A single voice is just one element that can be moved
around (or not) inside of a 5.1 mix.

Does Vegas include hardware that allows you to output 6 discreet audio mixes
was well as an internal mixer that can take any of say 24 recorded
audio tracks and mix and output each recorded track to any of these
hardware outputs at any volume? If not, I don't think that is what I would
personally call full 5.1 mixing.

BTW, I love surround sound!!!
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University of Michigan-Video Studio Manager
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Old May 18th, 2003, 04:29 AM   #7
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"Getting to that last part is the really
hard, takes lots of planning, gear and time that isn't mentioned in the product hype."

Hahaha mate, you are NOT wrong there!!! Bloody hell, Dolby configs have been a headache, but once you set up afew work templates, its smooth as silk.

Jacques, i'll try to answer your q's as precise as possible

"Once you get and record your 6 mixes, you then save each track/mix into its own file of exactly the same frame length. Re-import them into the program that turns those 6 tracks into one surround file."

Nail on the head. the differnce is that with Vegas u can create auto "sends to bus" so u can raise or lower the gain as you see fit.
With Vegas however, the is also a simpler way with the surround sound keyframing device.. this is more of a keyframing as you go along and feeds off the stereo channels, recreating the 5.1 environment in accordance with panning positions. (ill get into this a lil later)

So, if you don't have a studio with this kind of capability, I wouldn't attempt it. You cannot make a good 5.1 mix with just one mono voice track. A single voice is just one element that can be moved around (or not) inside of a 5.1 mix.

((two very valid points, however with clever processing, u can create the 5.1 from mono in post.
lets say u have a seminar, and youd like to extend the voice and reverb of the room, plus the rooms crowds ambience

In post, you would have your original source normalised as normal.. and place in the centre sound field.
Now this is where the work comes in.
You get that same source and run a 100% wet Room reverb and chorus (i also like to use vocal harmonisers and mic modellers/correctors to get teh pitch right) now save this file.
Being wet only.. it should jsut sound like a mush of reverberations...
This is then placed in your rear output bus tracks. As the files all share the same properties, theres no need to worry about frames...

now for your left and right...
this really depends on your personal preference, but i prefer to get the mono source and split in. Then i add a high frequency boost and stereo spreader using hyperprisms audio plugins.
finally, i get the rear source file and lower the gain on the reverb, and mix that with the stereo track.. giving a slight reverb boost but a more "stereo" source...
this is then placed in the LF/RF bus track and set to a minimal.. depending on the "size" of the room your recreating.
now in your project, as the crowd responds raise the gain, then lower it when the speaker begins again..
Vegas is VERY VERY comprehensive, but i use soundforge6 as well, and have about 400 plugins which also help... I also use the effects and compressors within vegas as it gives me a more "visual" feel for the sound im creating.. for close ups, i use a higher compression value as opposed to a reverb filled long shot.

Once the tracks are set and panning is all smooth and clean, you can then export a ac3 file.
What your doin with vegas is multitracking, and the ac3 is the final product.
problem with ac3 is that noone wants to pay for Dolby Licenses so as an audio file on its own its pretty useless. Mind you you can embed a Dolby Stereo EX downmix, so even if you only have a stereo output, you can still get the Dolby surround effect, obviously not as comprehensive as 5.1, but effective nonetheless.
Stereo is much easier to work with by the way, but it works along the same theories...
Phew.. next one.. ))

Does Vegas include hardware that allows you to output 6 discreet audio mixes was well as an internal mixer that can take any of say 24 recorded audio tracks and mix and output each recorded track to any of these hardware outputs at any volume?
((yes, it does..
u can have unlimited audio tracks, as well as numerous stereo bus tracks (LFE and FRONT are set as a stereo track with the only difference between cutoff frequency, send and EQ. This doesnt detract, and is actually an easier way of working... the Master Mixer actaully splits them.. ) You have your main/bus mixer, then your master which is your final output.

You can then solo any particular track you wish and export if thats what u need. (ie, for a AudioCD version of the seminar)
U can also set various inputs (which is what i do) for external audio sources as well as set sceens to trigger from SMTPE or trigger sound using SMTPE from teh timeline.. so minidisc/DAT and MIDI devices can blend seemslessly (if ur external recorder supports SMTPE)
All are monitorable, and there is no need for any extra hardware apart form a Dolby 5.1 Compatible sound card. I would suggest ASIO compatible cards as these offer lower latency. Also the SBLive cards are using EMU processors and they have an effects engine built in from EMU/Ensonique, which can be set to any particualr channels and controlled thru MIDI.. but im probably gettin ahead of myself... thing is u need a card which natively encodes in 48k to save hassles.. DV is 48k and SB cards are native 48k... saves excessive processing)

But the short answer to your question is YES... u can import, export, process and even edit the waveform (with SoundForge) within any channel as many times as you like, as theyre trated as seperate elements.))

If not, I don't think that is what I would
personally call full 5.1 mixing.
((IMO 5.1 mixing can be considered to be the bane of all producers existance.. u can understand why not many people implement it, as to get the most out of it, you ned to know the acoustic values and basic physics of each acoustic value for what your filming. If not, your end product sounds like crud which will ruin the look of the whole package... 6.1 and 7.1 are another story.. as they feed of the same values as 5.1, the only difference being that the decoder actually sends an additional mono signal to the rear centre.. 7.1 feeds a mix of the FL/FR and RL/RR to the centre speakers... DTS is another one, but i honesty dont wanan get into that too much.. basically it runs a variable bitrate, with higher values thatn 5.1 similar, with a little more definition, but for the average Jo, it wont make that much of a difference...))

BTW, I love surround sound

((hehhee so do i!!!))

PS- sorry if the thread is a lil messy...
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Old May 18th, 2003, 04:40 AM   #8
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"which can be set to any particualr channels and controlled thru MIDI"

a little note on this..
basically from my usage with this config, i can only get the Soundcards HW to feed a reverb from a direct wave source NOT set to a bus track... mind you you can mix a bus and main send...
as for midi, you will need a SW sequencer like Logic5 connected, but ASIO will not like this as its tryin to drive 2 audio devices when it can only handle one at a time...
ASIO2 drivers should be out soon thou..
basically letting us run multiple ASIO devices at once...

phew ok ill shut up now
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