One Case Study: Herbie Hancock's Butterfly in 10.2

It has already been explained that this piece was written with surround sound in mind, but when delivered as a 2-track CD mix due to the record company's demand it failed in the marketplace, probably because too much sound was crammed into too little space. Herbie Hancock has been a supporter of surround sound for many years, including writing for the medium and lending his name to the International Alliance for Multichannel Music among other things. This follows his mantra of "don't be afraid to try things." He lent us the 48-track original session files of this tune for a demonstration of 10.2-channel sound at the Consumer Electronics Show. His mixer Dave Hampton was supposed to do the work accompanied by me, but he became ill and was not available to do the work so I took it on. Ably assisted by then undergraduate Andrew Turner, we spent two very very long days

producing a mix. Having done it, Herbie came down to USC and listened to it and said one of the best things I've ever been told: "Now the engineer becomes one of the musicians." So here is what I did.

First fully one-half of the mixing time was really spent in an editing function, sorting out tracks, muting parts we didn't want to use, for crosstalk or other reasons. This is really an editorial function, not a mixing one, but nonetheless had to be done in the mixing period. In film work, this would have been done off line, in an edit room, then brought to a mix stage for balancing.

The direct/ambient approach was inappropriate for this mix as one wants to spread the sound out the most and the sound-all-round approach offered us the most amount of articulation in the mix, the opposite of why the 2-channel version failed. Here is how the various parts of the mix were treated:

• Herbie Hancock is a keyboard player, in this case of electronic keyboards. They were set to be a rather warm sound, with blurred attacks, not like a traditional piano sound. So we decided to put them in left and right wide speakers at ±60° and left and right direct radiating surround at ±110°, so that the listener is embedded in the keyboard parts.

• This is a jazz piece, with the idiom being that each solo takes the spotlight. For us, this mean front and center, so most solos were panned to center.

• The primary solo, a flute part, was put in center front, but also in center back, just as an experiment—a play on front/back confusion.

• Percussion was largely kept in front LCR because percussion in the surround we find distracting to the purpose: it spotlights the speaker positions.

• Certain effects sounding parts I would call zings were put in center back, to highlight them.

• Hand chimes were put in left and right height channels, at ±45° in plan and 45° elevated, and panned between the 2 channels as glis-sandos were played on them.

• At the end, when the orchestration thins out to be just the flute solo, the flute "takes off" and flys around the room.

One primary thought here is that while it is possible to pan everything all the time, too many things cannot be panned, as that would result in confusion and possibly dizziness. Keeping the amount of panning smaller keeps it perceptible in a good way. And with Butterfly, as it turned out, there was a good reason to pan the flute at the end: Herbie told us that it was the butterfly and it takes off at the end, something that frankly had escaped us in getting buried in mixing!

Surround Mixing for DVD Music Videos

Music videos must compete with 2-channel mixes, even though they are in surround. This is due to the comparison of the surround mix with the existing 2-channel one during postproduction of music videos. With dialnorm (see p. 154) adjusting the level to make the source more interchangeable with other sources downwards by something on the order of 7dB, the mix seems soft to producers and musicians. The comparison of a 2-channel mix recorded with flattened peak levels through limiting with a wider dynamic range mix lowered by the amount necessary so that so much limiting is not necessary and by the amount necessary to make it comparable to other sources in the system (applying dialnorm), is unfavorable to the surround mix. Thus it may wind up being even more compressed/limited than the 2-track mix, or at least as much. The bad practices that have crept into music mastering over the years are carried across to media with very wide dynamic range capacity, only a tiny fraction of which is used.

Another factor in music mixing is the use of the center channel. Since many mix engineers have a great deal of experience with stereo, and are used to its defects and have ways around them, several factors come into play. The most far out don't use the center at all. Those that do tentatively stick one toe in the water and might put the bass fundamentals there (they've been taught that to prevent "lifts" in LP production: areas where the cutting stylus might retract so far that it doesn't produce a groove—obviously of no relevance to digital media). Or only the lead solo might be put in the center, leading to paranoid reactions of the artist when they find someone on the other end can solo their performance. In the best film mixing, all three front channels are treated equally for all the elements. Music is recorded in 3-channel format for film mixes. B movies may well use needle-drop music off CD in left and right only in the interest of time and money saving, but it is bad practice that should be excoriated.

An example is in order. We built a system for 2-channel stereo reproduction that separately processed the center channel (from the center of a 5.1 input, or from a 2-channel Lt/Rt input decoded into LCRS then put back together into L/R and S).The purpose of having the center channel separate was to do special signal processing on it before re-insertion as a phantom image. A television camera was arranged on top of the corresponding picture monitor (using a direct view monitor with no room for a center speaker was the original impetus of this work), looking out at the listener. Through sophisticated face recognition, the location of the person's ears could be found. By correcting the time delay of the center separately into left and right speakers, a centered sound could

be kept centered despite the person leaning left and right. Naive listeners when this was explained to them had no problem with the concept, saw the point of it, and found it to work well. Professional listeners, on the other hand, were flummoxed, convinced there was some kind of black magic at work: they were so used to the defect of the phantom center moving around as one moves one's head that the sensation was uncanny to them! This example demonstrates that change only comes slowly since workarounds have been found for problems to the extent that they have become standard practice.

George Massenburg

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