Harmonic’s Rhozet® Carbon Coder Loudness Normalizer
and True Peak Limiter
It is well known that one fundamental problem that occurs in audio broadcasting is the loudness level oscillations of the audio materials. In a perfect world, where all the programs have an equal, universal loudness level, the listener can set his level and leave it in that position as long as he wants, without worrying that the next program or commercial break will pump his ears. In order to achieve this goal, it is required that all the mixes be done according to the loudness standards and so, to have the same audio loudness perception for all the programs that will be broadcasted.
As we all know, this is something hard to achieve in the real world, due to the diversity of programs. For solving this problem we created a plugin for Harmonic’s Rhozet® Carbon Coder that automatically measures the loudness and true peak values of the materials and normalize them according to a specified target.
Loudness Normalization does not mean constant loudness!
Using the loudness normalization doesn’t mean that the loudness will be constant during the whole program, but in this way, the average loudness will be the same for all the programs. So, you can change your loudness level according to your artistic needs, using (in most cases) a greater dynamic range than with the classic peak normalization. That means you don’t have to worry about the listener being disturbed, because the average loudness of the whole program will be equal with the target value that you choose. This is useful in all the stages of the broadcasting: production, distribution and transmission.
The measurements can be done for up to 32 channels. C-Normalizer is fully compliant with loudness measurement standards : ITU-R BS.1770-3 (with the relative gate of -10 LU) and EBU R-128. The normalization is done according to the desired value of Program Loudness or Max Short Term Loudness. In most cases, in order to maintain the original program dynamics, the normalization consist in a simply linear gain modification. Besides, C-Normalizer is capable of creating two log files of the program material, for evaluation and quality control of the descriptors (Program Loudness, Max. Short Term Loudness, Max. Momentary Loudness, Loudness Range and Max. True Peak) with their time code position for both source and target. It also contains a True Peak Limiter, which assures you that when you make the normalization of the audio program, the value of Max True Peak doesn’t exceed the desired value.
- Audio Loudness and True Peak Normalization
- Channel Formats: up to 32 audio channels available for processing
- Fully compliance with Loudness standards: BS-1770(rev.3) and EBU R128 specifications
- Complete loudness measurements using universal descriptors: Program Loudness, Max. Short Term Loudness, Max. Momentary Loudness, Loudness Range and Max. True Peak
- Normalization Parameter: Program Loudness or Maximum Short Term Loudness
- In order to maintain the original program dynamics, the normalization resumes when is possible, at a linear gain modification
- Fast brick wall True Peak Limiting with variable threshold and release time, that acts only when necessary
- Logging of : Program Loudness, Max. Short Term Loudness, Max. Momentary Loudness, Loudness Range and Max. True Peak with their time code position for both source and target
- Up to 32 audio channels available for processing
- Channels are organized in 4 groups, with 8 channels per group
- The possibility to select the number of audio groups you want to process
- Configurable channel layout for each audio group
- Channels layouts (1, 2, 2+2, 2+2+2, 2+2+2+2, 5.1, 5.1+2, 2+5.1)
- Channels which are not covered in groups will be passed unprocessed
- The channels order is important, so for custom channel routings, please use Carbon Coder channels mixer
- Program Loudness – describes the long-term integrated loudness of a program
- Max Momentary Loudness – the maximum value of the Momentary Loudness of the entire program calculated with a time window of 400 ms
- Max Short Term Loudness – the maximum value of the Short Term Loudness of the entire program calculated with a time window of 3 s
- Loudness Range – the loudness dynamic range of the entire program that helps you decide if dynamic compression is necessary
- Max True Peak Level– indicates the maximum value of the signal waveform in the continuous time domain (this value is calculated using inter-sample peaks that can be missed in quantization)
The normalization can be done either by Program Loudness or Max Short Term Loudness. If the normalization mode is set to:
- Program Loudness then the processing will be done so the Program Loudness to be equal with the desired target value
- Max Short Term Loudness” then the processing will be done so the Short Time Loudness to be lower than the Max Short Term Loudness desired value
The C-Normalizer plugin also contains a True Peak Limiter, which assures you that when you make the normalization of the audio program, the value of Max True Peak doesn’t exceed the target value.
This plugin is capable of creating a daily log file of the program material, for evaluation and quality control of the main descriptors (Program Loudness, Max. SL, Max. ML, LRA and Max. True Peak). The file contains for each process the values of descriptors and their time code position. The time code positions are generated according with the frame rate selected by the user. If the frame rate is not specified, the descriptors are written with the time position of the event.