Adobe 22011292 User Guide - Page 356

342 CHAPTER 20 Multichannel Encoder Export options The WMA format utilizes a perceptual compression scheme and allows you to select from several different quality settings, including Constant Bit Rate (CBR), Variable Bit Rate (VBR) and Lossless. Just as with stereo WMA files, the higher quality setting you select, the larger the file size, and vice-versa. The Lossless option will compress to a smaller file size than wav, but will result in no fidelity loss whatsoever. To encode your project as WMA, select the WMA option and then the desired quality setting in the Format Options drop-down menu. The checkbox option Show codec formats that most closely match the session's sample rate will limit the list of selectable WMA kbps option to those that are only the same sample and bit rate as the multitrack session's files. If you uncheck this box, the complete list of WMA options will be presented. Note: As mentioned above, if your project is to be sent out to a mastering, duplication or other outside service with the intention of being encoded into other specific surround or media formats, you should inquire with the recipient as to the format specifics. Channel ordering differs between surround formats. Also, the crossover frequency points vary among different formats as well. For example, DTS typically employs a crossover of 80 Hz, meaning that all frequency content of your channels lower than 80 Hz can be routed to a sub woofer, and all frequency content greater than 80 sent to mains. This differs from the Dolby Digital system that utilizes a crossover point of 120 Hz. Some systems also employ a boost of 10 dB for the LFE channel, automatically assuming your LFE content will be approximately this much lower in power than the main channels. Therefore, these components should be accounted for in your mix before you deliver your master files to the recipient. It is best to inquire with the recipient about all such requirements to ensure that the audience will hear your project the same as you are hearing it on your monitoring system! • Fold-Down to Stereo options: If the 6-channel WMA file is played back on a non-Windows XP system, or on a system that does not have a 5.1 playback setup, Windows Media Player 9 will automatically perform a "fold down" or "downmix" of the 6-channel playback to a stereo playback. The Windows Media Player 9 does this by accessing channel attenuation instructions that Adobe Audition's WMA encoder writes into the file. These attenuation parameters allow you to control how the levels of the Center, Surround and LFE channels get mixed down with the front stereo channels and played back on a stereo output system.