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

b24e5746 introduced changes to LastGainIndex which broke
 conditional coding for side frames after a mid-only frame (i.e.,
 in a 60 ms frame where the side is coded, not coded, then coded
 again).
These rules were a mess in general, however, because the side
 channel state kept a different nFramesDecoded count from the mid
 channel state, and had no way to tell if the prior side frame was
 coded.

This patch attempts to rationalize them by moving the conditional
 coding decision up to the top level, where all this information is
 available.
The first coded side frame after an uncoded side frame now always
 uses independent coding.
If such a frame is also not the first side frame in an Opus frame,
 then it doesn't include an LTP scaling parameter (because the LTP
 state is well-defined).

Only one of the two required checks in the encoder were updated. Thanks to
Tim for tracking down the actual cause of the mismatch.

These were caused by not prefilling the hybrid CELT state

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

A number of fixes and additions, including
* Ensure all usage of the word "mode" refer only to the choice of
   SILK/hybrid/CELT, not audio bandwidth, frame size, channel count,
   or anything else.
  There's still a bunch of usage of "mode" in CELT to refer to
   things in the CELTMode struct (e.g., band layout, etc.).
* Document the LSF reordering for silk_NLSF2A_find_poly().
* Document the DC response check during LSF stabilization.
* Fix the excitation scaling to give decoded SILK output in the
   range -1.0...1.0.
* Rewrite the mode-switching section.
  Ironically the title of the section still implies "mode" means
   than just SILK/hybrid/CELT, but I couldn't come up with a
   better one.
* Minor clean-ups to the acknowledgements.

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

Input that caused the problem was:
a_Q16[] = [129763 -49346 -42032 5488 28014 -1549 -2384 -8568
3154 -5104 -1605 6291 11861 -1843 -17715 7361]

The energy "sliding window" was using double accumulation with
float multiplications. This forces the multiplications to be
double as well.

The previous commit introduced some cross-talk for the case of SILK
with one channel muted.

- There was a bug where the decoder resampler was not properly initialized
when fs_kHz == API_fs_kHz. In that case the resampler would continue to
upsample, and the output was corrupt.

- The delay value in the decoder was taken from the state before it was
potentially updated. This caused the decoder to apply the new dalay value one
frame late

- The encoder and decoder states are now updated more consistently, when
the sampling rate changes (pesq liked these changes)

- Properly resetting the side channel encoder and decoder for the first
frame with side coding active again

- Faster updating the "ratio" value in the LR_to_MS() code for large
prediction values means that for certain extreme/artificial input
signals the output looks better

Move a number of files and functions which are only used by fixed point builds from silk/ to silk/fixed/.

I attempted to not break the msvc projects, but I can't test them.

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

- compile warning in opus_decoder.c
- decoder state reduced by ~3 kB (by merging buffers, as Tim suggested)
- some minor decoder optimizations (only the PLC is non-bit exact, so should be ok)

We check the DC gain before doing the full RC calculations

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

- fixes the test_opus "skip" for stereo
- fixes 6 visual studio compile warnings
- adds several header files to visual studio's include folder

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

- increases the max pitch lag by 1 (the thing Tim pointed out).  this brings the decoder in sync with the old one
- avoids that the first stereo frame is collapsed to mono

SILK now reports an "effective width" that takes into account side prediction.

Making sure not to abruptly "de-collapse" the stereo for such transitions

When SILK decided not to use the desired bandwidth, the redundancy
could be encoded at the desired bandwidth rather than at the actual
bandwidth used.

No longer encoding the redundancy flag for SILK since we can infer
redundancy from the length of the frame. Also, we skip encoding the
flag for hybrid mode when we know the decoder will not read it.

Also not fuzzing the mode when it's forced

We now make sure that side is given >0 bits when it isn't disabled.

1) averaging the output of the left and right resampling states when
   switching to mono
2) averaging the the delay buffers from left and right when switching

Adds SILK delay compensation that depends on encode and decode sampling
rate, as well as SILK internal coding rate. This ensures that the SILK
part of Opus is always in sync with the CELT part no matter what the
sampling rates are. It also increases the resampling delay to 1.15 ms
(was previously 0.48 ms).

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

This patch
 * expands sections on LPC and LTP synthesis into something that can
    actually be implemented
 * fixes an error in the excitation reconstruction
 * reverts an erroneous simplification of the subframe gain
    decoding, and
 * updates the LPC gain limiting description to reflect the new,
    more accurate approach for computing the reflection
    coefficients.
It also includes a number of general clean-ups, such as
 * correcting the description of the sample rates various pieces
    run at (e.g., we can decode directly to rates other than 48 kHz)
 * the usage of "sampling rate" vs. "sample rate"
 * capitalization consistency in TOC titles, and
 * better selection of which sections appear in the TOC.