Delaying stereo->mono switching decisions so that SILK can do a smooth
downmix. Also, wrote proper float/fixed code for the hybrid variable
stereo collapse, including a smooth downmix for stereo<->mono switching

Gregory Maxwell authored 13 years ago and Jean-Marc Valin committed 13 years ago

As of commit 44203907 all celt bands N>1 are even, including custom modes. In light of this, remove some pointless tests.

Jean-Marc Valin authored 13 years ago and Jean-Marc Valin committed 13 years ago

LPC_inverse_pred_gain_QA() was failing to detect unstable filters
because of insufficient numerical precision. Precision was increased
to Q24 for LPC coefs and the reciprocal now uses all the precision
available (variable shift right from the start).

(Fs_kHz is always 8/12/16 in Opus and also enforced by the assert on line 112)

There's still a range coder mismatch on the first frame when using FEC.

Timothy B. Terriberry authored 13 years ago and Jean-Marc Valin committed 13 years ago

The SILK bitstream allowed coding 0 pulses in a shell block, but a
 non-zero number of LSb's, meaning some excitation coefficients
 could be non-zero, but would not have a corresponding sign.
To fix this without breaking already-encoded bitstreams, this patch
 adds a set of sign PDFs for the 0 pulses case.

This is occasionally more efficient than the normal encoding if
 there are a large number of coefficients with positive signs,
 since these cost more than 1 bit when using the > 0 pulse PDFs.
It only saves 0.33 bits per second (on average: it does better at
 high rates), but that's probably enough to justify the two
 redundant ways of coding things (and it's too late now to remove
 the second one entirely, anyway).
This patch does not include the encoder modifications required to
 check if this coding method is more efficient and switch to it.

We no longer reset the decoder predictors when switching only the
frame size and not the sampling rate. The encoder already doesn't reset.

For these transitions, we now start the left and right resamplers
from the same state.

Ben Schwartz authored 13 years ago and Jean-Marc Valin committed 13 years ago

The PLC section has been moved from under CELT to the top
level and expanded to cover both SILK and CELT.  The clock drift
text provides some advice and explanation of the new GET_PITCH API.

Result should be bit-identical on most machines/compilers, minus the undefined
behaviour

Koen Vos authored 13 years ago and Jean-Marc Valin committed 13 years ago

Also some MSVC build fixes

The base64 implementation included with MacOS 10.7 doesn't
support the -w option for wrapping lines. Using the fold
command is more portable.