Orban Processors OPTIMOD-TV 8685 Surround Loudness Controller builds on Orban’s 30+ years experience in television audio processing to provide audibly transparent automatic loudness control and dialog intelligibility control for one surround program (up to 7.1) and four stereo programs simultaneously. The stereo processing can operate in dual-mono mode, so it can process four subchannels in stereo or eight subchannels in mono.
The Orban Processors OPTIMOD-TV 8685 Surround Loudness Controller is Orban’s second-generation surround/2.0 processor offers standard AES3id and SD, HD-SDI (3G) input/output and audio routing capabilities that include support for optional Dolby-E encoding and decoding. Dual redundant power supplies help ensure maximum uptime where a relay provides hard-wire safety bypass from the SDI input to the SDI output in case of hardware failure. The OPTIMOD TV 8685 is dialnorm-aware. Loudness control is excellent when measured by the ITU BS.1770 standard (as specified in ATSC A/85:2013) or by the OPTIMOD TV 8685’s built-in CBS Loudness Meters.
When properly installed and set up, the OPTIMOD TV 8685 will automatically make a station compliant with the CALM Act or EBU R128. In stereo mode, the four stereo processors can be made pre-emphasis aware, allowing the OPTIMOD TV 8685 to be purchased for immediate use with analog transmitters with the assurance that it will provide no-compromise processing for digital transmissions when the need arises. A second use for the stereo processors is processing up to four different languages in DTV program streams.
Absolute Control of Loudness and Peak Modulation
The Orban Processors OPTIMOD-TV 8685 Surround Loudness Controller includes third-generation CBS Loudness Controllers for DTV applications. Separate loudness controllers are available in the multichannel and 2.0 processing chains and work with the both Two-Band and Five-Band structures. The third-generation improvements reduce annoyance more than simple loudness control alone, doing so without audible gain pumping. Attack time is fast enough to prevent audible loudness overshoots, so the control is smooth and unobtrusive
Loudness control is excellent when measured by the OPTIMOD TV 8685’s built-in ITU BS.1770 and second-generation (Jones & Torick) CBS Loudness Meters, allowing stations to comply automatically with the requirements of the CALM act. The OPTIMOD TV 8685 implements “true peak” control by oversampling the peak limiter’s sidechain at 192 kHz. This allows the OPTIMOD TV 8685 to prevent clipping in a playback device’s analog signal path by predicting and controlling the analog peak level following the playback device’s reconstruction filter to an accuracy of better than 0.5 dB.
For typical program material, accuracy is 0.2 dB. Without true peak control, analog clipping can occur even if all peak values of the digital samples are below 0 dBFS. This phenomenon has also been termed “0 dBFS+.” Thanks to true peak control, sample rate conversion, unless it removes high frequency program energy or introduces group delay distortion, cannot cause sample peaks to increase more than 0.5 dB. For example, sample rate conversion from 48 kHz to 44.1 kHz is highly unlikely to cause sample peak clipping in the 44.1 kHz audio data.