shithub: opus

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ref: 87efe1df00c6f952e4121c103af787f755723b59
parent: 2ce5c63d224de2d5f7cf08363c5dbde8392a4d6d
author: Jean-Marc Valin <jean-marc.valin@usherbrooke.ca>
date: Tue Jan 18 09:44:04 EST 2011

Adds an anti-collapse mechanism for transients

This looks for bands in each short block that have no energy. For
each of these "collapsed" bands, noise is injected to have an
energy equal to the minimum of the two previous frames for that band.
The mechanism can be used whenever there are 4 or more MDCTs (otherwise
no complete collapse is possible) and is signalled with one bit just
before the final fine energy bits.