This reverts commit ba0dc187 since it is
enabled by default upstream now.

Opus release 1.3

Opus 1.3 is the latest major release of Opus and brings many improvements,
including:
- The spec fixes in RFC 8251 are now enabled by default
- Improvements to the VAD and speech/music classification using an RNN
- Improvements to stereo speech coding at low bitrate
- Support for ambisonics coding using mappings 2 and 3
- Making it possible to use SILK down to bitrates around 5 kb/s
- Using wideband encoding down to 9 kb/s
- Minor quality improvement on tones
- Security improvements

Notable bug fixes include:
- Fixes to the CELT PLC
- Bandwidth detection fixes

We're adding the ambisonics API

Signed-off-by: Jean-Marc Valin <jmvalin@jmvalin.ca>

As suggested in https://github.com/xiph/opus/pull/83

or "just" 1 year and 4 months for 10-ms frames.
The overflow can eventually cause a divide-by-zero when counter == -16

Thanks to Dmitry Malinin for reporting the bug.

Without that change, a very long (> 682 ms) illegal packet could trigger
a wrap-around in the test and be accepted as valid.

Only 16-bit architectures (e.g. TI C5x) were affected.

- Switch to 'Opus' file type identification.
- Revise channel mapping to better support ambisonics.

Fixes issue #95 on GitHub.

Signed-off-by: Felicia Lim <flim@google.com>

The error was:
c:\projects\opus\celt\celt_encoder.c(1019): fatal error C1001: An internal error has occurred in the compiler. [C:\projects\opus\win32\VS2015\opus.vcxproj]
  (compiler file 'f:\dd\vctools\compiler\utc\src\p2\main.c', line 255)
   To work around this problem, try simplifying or changing the program near the locations listed above.
  Please choose the Technical Support command on the Visual C++
   Help menu, or open the Technical Support help file for more information

  Internal Compiler Error in C:\Program Files (x86)\Microsoft Visual Studio 14.0\VC\bin\x86_amd64\CL.exe.  You will be prompted to send an error report to Microsoft later.

Signed-off-by: Jean-Marc Valin <jmvalin@jmvalin.ca>

[mark.hsj: Add other missing files and update filter file]
Signed-off-by: Mark Harris <mark.hsj@gmail.com>
Fixes https://github.com/xiph/libopusenc/issues/9
Fixes https://github.com/xiph/opus-tools/issues/32

Didn't cause any problem, but still good to fix. Reported by
keithchugg on github.

clang -Wcast-align warnings with ambisonics enabled
clang -Wnull-pointer-arithmetic warnings in test_opus_api.c
gcc -Wimplicit-fallthrough warnings on arm
msvc warning C4244 in celt_encoder.c with fixed point

Causes a warning with -Wnull-pointer-arithmetic and the code wasn't doing
anything anyway (the ctl call ignores NULLs)

This gets rid of false positives in static analysis
(see https://trac.webkit.org/changeset/232236/webkit)

Fixes test_opus_projection failure under ubsan, due to clz(0).

Don't assume that frames larger than 20 ms save any overhead compared to 20 ms.

The bug was triggered because f982b84d started using prefill for
SILK bandwidth changes, which reinitialized the encoder state and
prevented the variable lowpass from working properly. To fix the problem,
we preserve the sampling rate and variable low-pass when prefilling.

Using a finer table for the rate to SNR curves in silk_control_SNR().
It's now possible to have an SNR that reaches 0, so we can lower bitrate
down to ~5 kbps for narrowband and 5.5 kbps for wideband.