Audio Mastering for DVD,VHS, and CD

jmpatrick wrote on 11/19/2001, 1:03 PM

Here's a couple more questions:

I've got a concert video that I'm planning to release in 3 formats, DVD, VHS, and CD. These aren't going to be widely relased, just a couple dozen copies at our gigs. However, I want them to look and sound as pro as I can with the tools I have before I take people's hard-earned.

1. After mixing the multi-track audio master (8 tracks), do I need to make special considerations for the DVD and VHS? Obviously, the audio will be at 16/48 for the DVD, and 16/44.1 for the CD's...but what about the mix? Are multi-format releases such as this treated differently in the mix stage? I guess you can't assume that viewers will be playing the audio back through a stereo system...rather, it might be just the TV's internal speakers.

2. What is the best way to master the final audio? Should I bring the final mix back into Vegas and apply my multi-band dynamics...or should I do it in Soundforge? Should I convert to 16/44 for the CD before I apply multi-band, or after?

Thanks!

jp

Comments

jmpatrick wrote on 11/20/2001, 7:46 AM

Anyone?

fosko wrote on 11/20/2001, 11:40 AM

I dont know any ofthe answers, but I just didnt want you to feel ignored :-)

I will be watching this post. Those are GOOD questions.

SonyEPM wrote on 11/20/2001, 12:23 PM

"Are multi-format releases treated differently in the mix stage?"

Absolutely! ...and I'll leave it to the working pros out there to disclose some of there personal tricks. I look forward to the responses on this thread- should be interesting.

Spot|DSE wrote on 11/20/2001, 1:03 PM

Different mixes are required for various delivery methods. For instance, VHS and broadcast/NTSC require that you mash the audio significantly. If you don't, the bandwidth of audio can easily damage your video quality. Same goes with not having true NTSC color values on your video, if it's destined for VHS or NTSC spaces. The bright whites that exceed 100 IRE will play havoc with your high end, and cause distortion in the audio.
For DVD, you can get away with several audio mixes, depending on your authoring tool. If you have a good authoring tool, you can do an AC3/surround mix, a 'bit down' 2 track stereo mix for watching on a normal television or computer screen, and a foreign language, band commentary, etc track as well. You also don't need to worry anywhere near as much about bandwidth/frequency response with DVD as you do for broadcast or duplication.

ScoriaMM wrote on 11/20/2001, 3:03 PM

>>>Different mixes are required for various delivery methods. For instance, VHS and broadcast/NTSC require that you mash the audio significantly.
Can you be a little more specific as to "mash"? Are there certain frequencies that you need to be aware of? Such as bass/treble roll-offs? Or do you mean dynamic range? Such as audio can only be -6db rather than 0?

-Matt

Spot|DSE wrote on 11/20/2001, 11:36 PM

>Are there certain frequencies that you need to be aware of? Such as bass/treble roll-offs? Or do you mean dynamic range? Such as audio can only be -6db rather than 0?
By 'mash,' I mean both. You must limit the dynamic range of audio AND limit the frequency range.
First off, I don't understand where you get the "6dB is really 0dB" as it's not so. General practice is that digital tones are set at -12dB to -18dB for a '0' analog setting/duping. In our house, we set tone at -12dB, with a limiter set to -3dB for dupe-oriented projects. Critical that digital never crosses zero. Equally critical is that dynamic range be limited to not more than 20dB. In fact, in the real, calibrated world, 0dB analog is the same as -20dB digital. Or you could look at it by saying that 0dB digital equals +20dB analog, take your pick. Currently, SOFO's setting in Vegas is non-adjustable and too hot at output by 6dB when matched to a standard Digibeta or mirror mother machine's VU meters.
That being said, be sure you don't have audio going beyond 10K, as it's just going to get lost in broadcast compression. Same with audio below 120hz. this is what I mean by 'mashed.'
Worse, if you send off a digital project that hasn't been prepped for NTSC standards (vegas has a video-only clamping plug for this) then you'll see the results of audio messing up picture, or worse, non-legal picture messing up audio. If you don't believe that picture or audio can screw with each other, try rendering a 10 second stream of color bar with a 1Ktone set to +12dB. Then take the same render, impose a series of titles over top of it. (using Vegas title tool) watch the picture. Notice that the titles appear to be jiggling, aliased? that's the audio breaking up the video signal.
Now, go into photoshop or some other graphic edit app. Build a title that is non-legal in color. Make sure the blacks are absolute zero, and that the whites are 255/255/255. Insert the title into Vegas, without the color clamp on. Take your favorite piece of music that you know very well, place it on the timeline. print to tape, preferably VHS, as this is more like broadcast tape, and listen to the audio. Notice how it's distorted, even though it was clean when previewing? For a better example, take the same non-legal graphic and fade it in and out over a picture that is legal in Vegas. You'll 'hear' the video fades in your audio.
I know I've strayed a bit from your question, but with so many people getting into the video field with dreams of being the next Steven Spielberg, it's critical to understand video. Learn what legal colors and audio mean. Learn what IRE means, learn how to compose external graphics like jpg's, bmp's, gif's png's, etc. You'll be amazed at what a difference a small amount of knowledge can make in your picture.
Hope this small amount of info helps. My fingers are tired now.

ScoriaMM wrote on 11/21/2001, 10:48 AM

>>>First off, I don't understand where you get the "6dB is really 0dB" as it's not so.
It was an example.. I wasnt trying to quote actual settings.

Thanks for the post.

kkolbo wrote on 11/21/2001, 1:48 PM

Thanks for the info. I am so used to sending my final output through an engineer who "mashes" it for me that I wasn't sure what all he was doing. I personally will be paying more attention to it and making his life easier in the future.

K

kkolbo wrote on 11/21/2001, 2:20 PM

SPOT has posted some excellent information on the technical limtations of the video environment. I would suggest you review those.

Beyond the technical issues there are many creative issues that are involved. (I am a producer not an Engineer Jim)

I advocate seperate mixes for each type of delivery. Here is the breakdown that I use.

First pass is a premix to stems. I often work from a stem set of 8-16 stems. The music is set up on 8 of thoses. The remaning are dialog stems, background stems and effects stems. This is assuming a 5.1 feature delivery. For a LCR or Stereo feature delivery you can reduce the stems.

Now I break out to finals. It is important to mix for each environmet.

Use a mix stage or a theater to mix your 5.1, LCR or stereo feature release. That will help with the creative on the feature release. There are some small studios that are set up for feature release mix without a stage. Key elements are be gentle with the two rear channels. Notice the difference in the EQ settings for a real theater instead of a studio. Take advantage of the bass reproduction. Keep dialog in the Center Channel. Be careful not to get too wet in the dialog. Widen the strings. Have a pro do the foley panning. Don't try it at home :) Also, do a different mix for 5.1, LCR and Stereo. They do not fold down well. Sometimes an LCR can be folded to stereo, but don't waste your time trying to fold down a 5.1.

For the CD mix use a good studio environment or I have even done it by headset. Make it rich. Add room presence such as a good reverb chamber to it. Much wetter than a TV or a feature mix. Watch your peaks though, don't get carried away. Let the composer have some fun.

For TV, there are two types. DVD and Tape. I have found DVD to provide a bit more range. You may consider doing a seperate mix for it, but most don't. The theater 5.1 can sometimes be used for a DVD (the producer assumes that someone with a 5.1 system will have a controled viewing environmet) but most of the time a remix is reccomended. For Tape and DVD release, the key element is that you do not have control over the playback environment. I do these in a studio on standard studio monitors rather than the big boys. I then listen over junk stuff too. Assume the room will be more live than a theater. Be careful with the reverb. TV systems do not reproduce that well. Small speakers such as home thater or TV speakers have a limited freq response. Pay attention to speech or vocal intelligibility. Make the key effects clearer or cleaner than the theater mix. Music solos need more clearence around them than on the CD.

OK I could go on and on, but I love what I do.

Good Luck