Key Features - OPTIMOD 6300 Audio Processor
An LCD and full-time LED meters make setup, adjustment and programming of the 6300 easy you can always see the metering while you are adjusting the processor. Navigation is by dedicated buttons, soft buttons (whose function is context-sensitive), and a large rotary knob. The LEDs show all metering functions of the processing structure (Two-Band or Five-Band) in use.
Push one of the dedicated buttons to "Recall" a preset, to "Modify" processing, or to access the system's Setup controls.
Absolute Control of Peak Modulation
The 6300 precisely controls peak levels to prevent clipping or overmodulation in transmission media. The maximum level of the digital samples is controlled to better than 2%.
The 6300 implements "true peak" control by oversampling the peak limiter's sidechain at 192 kHz. This allows the 6300 to prevent clipping in a playback device's analog signal path by predicting and controlling the analog peak level following the playback device's recon-struction 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 con-version from 48 kHz to 44.1 kHz is highly unlikely to cause sample peak clipping in the 44.1 kHz audio data.
While primarily oriented toward "flat" media, the 6300 can also provide pre-emphasis limiting for the two standard preemphasis curves of 50µs and 75µs. This allows it to protect pre-emphasized satellite uplinks and similar channels where protection limiting or light processing is required.
The 6300 includes analog and dual AES3 digital inputs and outputs. The digital input and digital outputs have sample-rate converters and can operate at 32 kHz, 44.1 kHz, 48, 88.2, and 96 kHz sample rates. The pre-emphasis status and output levels are separately adjustable for the analog and digital outputs. Note that the 6300 cannot provide simultaneous, independent audio processing for flat and pre-emphasized channels. Even though one output may be pre-emphasized while other is flat, the only difference between the outputs is that the "flat" output has de-emphasis applied to it after the processing while the pre-emphasized output does not.
OPTIMOD-DAB's outputs can be independently configured to emit the output of the AGC or the output of the multiband compressor/limiter, all configurable to use or bypass look-ahead limiting.
THE 6300 controls the audio bandwidth as necessary to accommodate the transmitted sample frequency. OPTIMOD-DAB's high frequency bandwidth can be switched instantly (typically in 1 kHz increments) between 10 kHz and 20 kHz. 20 kHz is used for highest-quality systems. 15 kHz meets the requirements of any system that uses 32 kHz sample frequency, while 10 kHz is appropriate for 24 kHz sample frequency.
The 6300's dual-mono mode allows entirely separate mono programs to be processed, facilitating dual-language operation. In this mode, both processing channels operate using the same processing parameters (like release time); you cannot adjust the two channels to provide different processing textures.
Adaptability through Multiple Audio Processing Structures
A processing structure is a program that operates as a complete audio processing system. Only one processing structure can be on-air at a time. The 6300 realizes its processing structures as a series of high-speed mathematical computations made by Digital Signal Processing (DSP) chips.
The 6300 features two processing structures: Five-Band for a spectrally consistent sound with good loudness control, and Two-Band for a transparent sound that preserves the frequency balance of the original program material while also effectively controlling subjective loudness.
In the Five-Band structure, Orban's PreCode™ technology manipulates several aspects of the audio to minimize artifacts caused by low bitrate codecs, ensuring consistent loudness and texture from one source to the next. PreCode includes special audio band detection algorithms that are energy and spectrum aware. This can improve codec performance on some codecs by reducing audio processing induced codec artifacts, even with program material that has been preprocessed by other processing than Optimod. There are several factory presets tuned specifically for low bitrate codecs.
A special Two-Band preset creates a no-compromise "Protect" function that is functionally similar to the "Protect" structures in earlier Orban digital processors. The Five-Band and the Two-Band structures can be switched via a mute-free crossfade.
OPTIMOD-DAB's Two-Band structure includes a CBS Loudness Controller™ for DTV applications. The CBS algorithm has proven its effectiveness by processing millions of hours of on-air programming since the early 1980s. It smoothly limits subjectively perceived loudness to a broadcaster-set threshold, preventing audience irritation. The controller measures subjective loudness (as perceived by an average listener) and then closes a feedback loop to limit loudness to a preset level. It effectively controls loud commercials, which are the primary irritant in sound-for-picture applications. Third generation improvements reduce annoyance more than simple loudness control alone, doing so without audible gain pumping. New in version 2.0 software is the ability to adjust the attack time, trading off short-term loudness control against transient punch.
The subjective loudness meter, labeled Loudness Level in the 6300's GUI, uses the CBS Technology Center algorithm developed by Jones and Torick. When used to drive a transmission channel using the Dolby Digital® codec, the Loudness Level meters (one for stereo processing or two for dual-mono processing) can be aligned to the Dialnorm metadata value in the Dolby Digital bitstream conveying the 6300's output signal to the consumer's receiver. When this is done, the loudness level at the receiver will be correct when the 6300's processing is adjusted to make dialog peak at "0 dB" on the 6300's Loudness Level meter. This processing fully complies with the loudness control requirements in ATSC A/85:2011 and EBU R 128.
The Loudness Level meter is also useful for mastering because it can help ensure consistent loudness from one track to the next on CD, DVD, or Blu-ray media. The CBS Loudness Controller is not needed with the Five-Band processing because the Five-Band processing's spectral consistency creates consistent loudness as a desirable byproduct.
The 6300's AGC rides gain over an adjustable range of up to 25dB, compressing dynamic range and compensating for both operator gain-riding errors and gain inconsistencies in automated systems. The AGC output is available to drive STLs, so the 6300 can be used as a studio AGC.
The 6300's processing structures are all phase-linear to maximize audible transparency.
All compressors in the Two-Band and Five-Band structures have compression ratio and knee shape controls for each band's compressor, making the 6300 perfect for applying subtle compression in mastering applications.
The 6300 can be remote-controlled by 5-12V pulses applied to eight programmable, optically isolated "general-purpose interface" (GPI) ports.
6300 PC Remote software is a graphical application that runs under Windows 2000 and XP, Vista,7 and 8. It communicates with a given 6300 via TCP/IP over modem, direct serial, and Ethernet connections. You can configure PC Remote to switch between many 6300s via a convenient organizer that supports giving any 6300 an alias and supports grouping multiple 6300s into folders. Clicking a 6300's icon causes PC Remote to connect to that 6300 through an Ethernet network or initiates a Windows Dial-Up or Direct Cable Connection if appropriate. The PC Remote software allows the user to access all 6300 features (including advanced controls not available from the 6300's front panel) and allows the user to archive and restore presets, automation lists, and system setups (containing I/O levels, digital word lengths, GPI functional assignments, etc.).
The 6300 contains a versatile real-time clock, which allows automation of various events (including recalling presets) at pre-programmed times. To ensure accuracy, the clock can be synchronized to an Internet timeserver.
A Bypass Test Mode can be invoked locally, by remote control (from either the 6300's GPI port or the 6300 PC Remote application), or by automation to permit broadcast system test and alignment or "proof of performance" tests.
The 6300 contains a built-in line-up tone generator, facilitating quick and accurate level setting in any system.
The 6300's software can be upgraded by running Orban-supplied downloadable upgrade software on a PC. The upgrade can occur remotely through the 6300's Ethernet port or serial port (connected to an external modem), or locally (by connecting a Windows® computer to the 6300's serial port through the supplied null modem cable).