[TVPostSound]

Here are the HD specs for DCI


HIGH DEFINITION AUDIO REQUIREMENTS:

Audio program material shall be produced using industry standard and accepted
norms for good practice and workmanship. The audio portion of the master and
source audio and videotapes must be produced so that no noise, static, dropouts
or extraneous distortion is recorded in the audio.

Audio channels - Stereo audio must be fully mono compatible. The audio channels
must be in the proper phase. NOTE: Full Mono Compatibility means that when the
left and right stereo channels are actively combined to mono there is no
discernible change in audio level or fidelity. Full mix and split audio tracks
should be phase coherent (synchronized) to prevent difficulty editing between
these tracks, as necessary.

Audio Levels: Program audio must reflect reference tone level. Audio levels must
be consistent throughout the program.. Transmission limiters clip at +8 dB. FOR
BROADCAST "FULL MIX" TRACKS, TRANSIENT AUDIO PEAKS MUST NOT EXCEED +10 dB ABOVE
REFERENCE TONE WHEN MEASURED ON AN AUDIO METER USING THE "TRUE PEAK" BALLISTIC
SET (0 MS RISE, 200 MS FALL). FOR SECONDARY AUDIO TRACKS AND 5.1 SURROUND MIXES,
PEAK LEVELS MUST NOT RISE ABOVE +17 dB (-3 dbfs). When mastering to a digital
format and/or using an full scale or peak meter, where "0" is at the top of the
scale and reference tone is at -20 dBfs, audio for the "full mix" tracks should
peak at no more than -10 dBfs.

When using an analog meter, though the ballistics of analog VU meters vary
greatly, the average program audio level of -2 to -5 dB will roughly equal 10 dB
of headroom and not exceed specifications for peak limits. However, all shows
should be evaluated using a peak sensitive meter to assure adherence with
transmission specifications.

Pre-emphasis: FM transmission modulators (USA) use the 75 microsecond
pre-emphasis curve. All signal processing must take into account the
pre-emphasis curve. Improper "Sweetening", i.e. excessive equalization in the
higher frequencies, can cause sibilance and severe distortion and should be
avoided.

Audio compression: Program audio should have good dynamic range, but not be
overly dynamic. While some compression may be needed to control the dynamic
range of the program audio, excessive audio compression of the final mix should
be avoided as this reduces the perception of audio quality by the listener.
Audio signal peaks should be approximately 8 to 10 db above program reference
levels, and average loudness measurements should be comparable to reference
levels.