This IS the Avid L2: Re: [Avid-L2] True peak audio limiter

Tuesday, June 3, 2014

Re: [Avid-L2] True peak audio limiter

My understanding - as I guess is Job's - is that dBTP is a technical measurement to prevent clipping.

It has nothing to do with loudness (i.e. how a sound pressure level at a certain frequency is perceived by our brains) but rather attempts to prevent clipping e.g. when the sample rate is changed and inter-sample peaks become relevant.

This document explains it rather well (page 13) and I would recommend it to anyone who is interested in loudness measurement:

https://tech.ebu.ch/docs/tech/tech3343.pdf

Am 04.06.2014 08:23 schrieb "'Job ter Burg (L2B)' Job_L2@terburg.com [Avid-L2]" <Avid-L2@yahoogroups.com>:

Then I must misunderstand what you wrote. Not trying to play any games. My apologies.

The way I came to understand TP was by thinking about it as inter-sample peaks, whereas peak program would measure just the loudness of samples, and the actual resulting waveform when played back could very well have values that are higher than the individual samples.

Sent from my iPad

On 3 jun. 2014, at 23:59, "Mark Spano cutandcover@gmail.com [Avid-L2]" <Avid-L2@yahoogroups.com> wrote:

No what I said is true of True Peak. It is the perceived converted value of the peak (dBFs) into real world loudness (dBTP). I am not talking about LUFS/LKFS - that is a loudness measurement. I think you know that too and are playing games with semantics here. There's no reason for a "True Peak" measurement to exist unless you are talking about what happens when digital audio becomes real sonic movement in the air.

On Tue, Jun 3, 2014 at 5:33 PM, 'Job ter Burg (L2B)' Job_L2@terburg.com [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

TP is not "determined by the perceived converted value from the dBFS into real world loudness". That would be LUFS or LKFS. TP refers to inter-sample peaks.

On 3 jun. 2014, at 22:20, Mark Spano cutandcover@gmail.com [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

Job - how is what you said different from what I said?

On Tue, Jun 3, 2014 at 3:44 PM, 'Job ter Burg (L2B)' Job_L2@terburg.com [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

Mark, this is not quite accurate. A/85 and R128 both specify perceived average loudness, but measured in LUFS (EBU) or LKFS (ATSC). TP is a different thing, but is or can be part of the spec, and it is the more accurate way to measure actual peaks in the sound. In fact, a 0dBFS signal could theoretically cause peaks well over +2dB- TP when played back. This is why the new standards allow for TP measurement on top of LUFS / LKFS.

On 3 jun. 2014, at 15:34, Mark Spano cutandcover@gmail.com [Avid-L2] <Avid-L2@yahoogroups.com> wrote:

True Peak. This is a peak value that is determined by the perceived converted value from the dBFs into real world loudness. For example, a clip with audio peaking at -9 dBFs might have a True Peak value of -8.6 dB TP