Hmm.. I looked up a few definitions of "glib".. well.. Thanks, I guess?

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I do have a bit of experience with TV audio and metadata, from designing the software for the OctiMax and Aeromax line of products for Linear Acoustic, from the ground up.
The AGC in AC3 (Dolby Digital) I mentioned is part of the metadata, and is not actually applied to the audio but sent along as a control value (1 value every 256 samples, applied through windowing in the decoder), but that doesn't make it any less of an AGC. There are actually three different gain values: DIALNORM, which is constant for each program, DYNRNG which is meant to provide reasonable dynamic compression for home viewing, and finally COMPR which is heavy compression/limiting, meant to prevent overloading of RF modulators downstream.
Here's how the audio chain is supposed to work according to dolby:
- Program comes in from network, has metadata with proper DIALNORM value set.
- Program AND metadata gets sent to encoder (let's use the old Dolby 562 as an example)
- Encoder analyzes audio with respect to DIALNORM and creates DYNRNG and COMPR metadata (i.e. runs a compressor/agc)
- Encoder outputs an AC3 bitstream
(snip)
- AC3 bitstream gets decoded inside consumer set-top box, DYNRNG or COMPR applied, and audio is output.
However, metadata usually gets lots at one or several steps, and even if it didn't, Dolby's compressor doesn't work all that well. Thus, I have a job in TV audio processing

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They don't like to call it an AGC, because hollywood wouldn't like that, and it can be defeated (by digging through menus in the receiver).. But, a system that analyzes the audio (in realtime as it's encoded!), creates gain values to reduce the dynamic range, and finally applies the gain value further downstream.. Well, if it looks like an AGC, and smells like an AGC, what could it be?
Dolby Volume is another story altogether. That IS a wideband compressor, and a marketing department. Imagine how good that wideband compressor would sound if they had Vorsis' marketing department :-D.
Reducing the audio to 14 bits?
Sure, why not!
It should have been 14 bits to begin with. I listen to plenty of classic rock and other well mastered recordings that average -12dB or less, and even extremely dynamic classical music, all in 16-bit format. Never once (in otherwise well recorded cuts) have I heard a bit of quantization noise!
Worrying about the bits at the lower end of the scale, in a smashed clipped 16-bit recording, is worrying about the WRONG bits!
Let's play with the numbers. Assume we're clipping just 1% off the top of the waveform.. That's essentially an error of 1%, affecting the MSB.
How many LSBs would we have to discard to come up with the same voltage error?
I believe the answer is 9. Starting with 16 bits, removing 9 bits, we have 7-bit audio -- 128 different voltage levels. Roughly as accurate as 1% of clipping.
Yes, this is an apples to oranges comparison, but it paints a colourful picture, doesn't it?
I would *much* rather listen to a well mastered and properly dithered 14-bit track (or even 12-bit!) than a smashed 16-bit track.
I've found the true noise floor of most recordings (even 24-bit DVD-A's) to be about -70 to -80dB. 16-bit gives you 96dB SNR, whereas 12-bit gives you 72dB. 12-bit is cutting it awfully close (especially if you want to AGC afterwards), but 14 is fine. Older digital recordings, which were not pushing for maximum recordings, essentially had this resolution anyway, and sounded great -- much better than modern smashed recordings.
Looking forward to seeing you this weekend! This will be a lot of fun. I accept, but make it Belgian beer

. Man, I haven't had Chimay for so long.. Not available here.
I'm looking forward to hear / play with the Ariane too, I actually haven't had a chance to play with one yet.
///Leif