Mark Spano
Forum Replies Created
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Concur. OMF or bust. No professional (or even semi-pro) audio facility wants AIFF track stems when they could have an OMF. The difference is that with AIFF track stems, the audio editor only has access to the audio in your timeline (no handles) and it’s consolidated to one big chunk. OMF preserves the individual edits and offers the ability to include handles for every clip.
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Create a new preset and choose either MPEG-4 (for mp4) or H.264 for Apple Devices (for m4v). Both will make H.264/AAC files, you can customize from there…
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[Joachim Freitag] “searching for a way to edit the presets given in the pull-down-menu”
You can’t. It’s buried in code, and not saved in prefs or anywhere you can edit.
You are better off creating droplets in Compressor if you have it. Compressor can export any kind of file that Quicktime Pro can, usually with nicer results.
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[Matt Gorecki] “That’s about how I thought it worked. I must be doing something wrong then during recording because the rear channels never show up.”
When you record with this microphone, you get an already encoded signal, which is two-channel stereo Lt/Rt. You’ll only hear the rear channels when that signal is played through a Pro Logic decoder.
[Matt Gorecki] “Can audio compression affect the Dolby encoding? Say a bad mp3 encode?”
Two types of audio compression you might be referring to: one is dynamics control, the other is lossy perceptual coding compression. Dynamics control is what you’d use when you want to control the overall level of a track – bringing peak levels closer to average levels. That can sometimes adversely affect an encoded track, but usually not too bad. Lossy perceptual coding compression is what you’d use to shrink the bandwidth/file size of an audio file (like MP3). That will probably completely destroy Pro Logic encoding. MP3 encoding basically throws information away that it thinks your brain won’t miss – this is precisely the information that the Dolby people have harvested to use to encode more ‘channels’ into a stereo pair. MP3 encoding often messes up phase relationships on a sample level and Pro Logic encoding requires precise phase relationships in order to direct the subsequent decoder to put certain information in the rear and center channels.
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[Matt Gorecki] “how do I work with this audio?”
Pro Logic encoded audio is LCRS (left, center, right, surround, aka 4.0) encoded to two channel Lt/Rt (Left total, right total) stereo-compatible audio. What that means is that you can use it just like regular stereo audio in your edit. If this audio is played through a Pro Logic decoder, it will decode back into LCRS.
[Matt Gorecki] “Does the Blu-ray player and/or receiver automatically figure out that the audio stream is Dolby encoded?”
Most likely it would be the receiver with a Dolby Pro Logic decoder built-in. As long as the end-user’s receiver is set up to decode Pro Logic, the material will play out LCRS. If not, it’ll play in stereo.
[Matt Gorecki] “Would I theoretically be able to drop other audio samples onto these two tracks without affecting the Dolby encoding?”
You could add audio into the mix, but it would make it less likely that a decoder would play back LCRS. It would still sound like you want it to in stereo, though, and many music tracks and other source materials are used this way.
[Matt Gorecki] “I realize that they would only play on the primary left and right channels, but would the other channels be affected?”
Yes. The way Pro Logic encoding works has to do with summing and phase relationships between the channels. Once you add something into this mix that isn’t encoded, the decoder might not work correctly. The only real way to find out is to try it out – play your mixed audio back through a Pro Logic decoding receiver in a surround monitoring setup. Other than that, you might have to give up hoping it’ll play in LCRS and concentrate on making it still sound good in stereo.
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[Bill Ravens] “Avid MC 5, soon to be released, has announced support for the matrox MXO2 Mini box. It will do hd and SD.”
Please be careful about the language here – the MXO2 Mini is supported for monitoring ONLY on MC5. No “I”, no “O”.
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A normal stereo mix has some elements in the left and right channel that are common and elements that are different, creating the separation that makes stereo sound different from mono. Phase relationships between the channels can be slightly off, but not too far, otherwise it sounds weird and if you collapse the stereo mix into mono, elements will cancel out and disappear. This is probably what they are referring to – out of phase audio means that something in the left channel is 180Ëš out of phase with the right channel and therefore will cancel out and be silent when summed together. Most likely you won’t be able to change this if your audio came to you this way, but it may have something to do with the way you layed it to tape. If you are laying back analog, you’ll need to check the wiring to make sure phase isn’t being flipped somewhere down the chain. Do you have any scopes? A modern video scope like the Tektronix WFM7000 has a built-in audio metering section with a phase meter display. That would help as well. A quick and dirty way to check phase coherency is by exporting a section of your mix and bringing it into iTunes and installing the ancient TechRTA visualizer plugin for iTunes. This thing is old and buggy and you have to do a lot of clicking to get the phase scope up, but it can come in handy.
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[Michael Hancock] “Then write Apple and tell them to release a ProRes decoder for Macs and PCs.”
I assume this was a typo and so this post is a correction (informational only). The decoder for ProRes is built in to the latest versions of Quicktime for Mac. If you have an earlier version, or Quicktime for PC, you can download the decoder separately from Apple here (PC). It is correct however that the only way to encode ProRes is with an FCP install on Mac.
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[Jason Rodriguez] “I am trying to figure out the correct audio levels for broadcast.”
Correct answer? Figure out where you’re delivering to and ask them what they want. Too many variables to sort out if you’re guessing or researching online.
[Jason Rodriguez] “imported it into FCP and it is hitting 0”
Lots of music and source footage will not be “broadcast level” – they’re intended to be mixed, so they’re likely taking advantage of the full dynamic range offered by digital audio recording. If you’re mixing, it’s your job to bring all of your audio elements into balance at the required output level.
[Jason Rodriguez] “It sounds awfully low for my taste.”
This one gets me every time. Volume is relative. dBFs is not. -10dBFs is an exact digital value – if this sounds too low to you, turn up your monitors.
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Should be in the menu. Look at the super out on a monitor and open the on screen menu (shift+menu) – operational hours are in the first section.