GitLab

on exponent group sizes.

Signed-off-by: Reinhard Tartler <siretart@tauware.de>

Signed-off-by: Mans Rullgard <mans@mansr.com>

full-bandwidth channels.

This reduces high-frequency artifacts and improves the quality of the lower
frequency audio at low bit rates.

This makes the AC3 encoder use the shared fixed-point MDCT rather
than its own implementation.  The checksum changes are due to
different rounding in the MDCT.
Signed-off-by: Mans Rullgard <mans@mansr.com>

These expressions are equivalent since levels is always odd, and
overflow is impossible due to the constraints set by the assert().
Signed-off-by: Mans Rullgard <mans@mansr.com>

Signed-off-by: Mans Rullgard <mans@mansr.com>

These fields are only used in quantize_mantissas() and reset
on each call, no need to store them in the main context.
Signed-off-by: Mans Rullgard <mans@mansr.com>

Signed-off-by: Mans Rullgard <mans@mansr.com>

exponent reference blocks.

and decoder, and vice-versa for the AC-3 encoder.

in the ac3_fixed encoder.

Signed-off-by: Mans Rullgard <mans@mansr.com>

and use in scale_coefficients() for the floating-point AC-3 encoder.

This increases the accuracy of coefficients, leading to improved quality.
Rescaling of the coefficients to full 25-bit accuracy is done rather than
offsetting the exponent values. This requires coefficient scaling to be done
before determining the rematrixing strategy. Also, the rematrixing strategy
calculation must use 64-bit math to prevent overflow due to the higher
precision coefficients.

Currently it is always 4, but this change will allow it to be adjusted when
bandwidth-related features are added such as channel coupling, enhanced
channel coupling, and spectral extension.

The rematrixing strategy reuse flags are not reset between frames, so they
need to be initialized for all blocks, not just block 0.
Signed-off-by: Mans Rullgard <mans@mansr.com>

This is to match the value in every (E-)AC-3 file from commercial sources.
It has a negligible effect on audio quality.
Signed-off-by: Mans Rullgard <mans@mansr.com>

It is pretty hopeless that other considerable projects will adopt
libavutil alone in other projects. Projects that need small footprint
are better off with more specialized libraries such as gnulib or rather
just copy the necessary parts that they need. With this in mind, nobody
is helped by having libavutil and libavcore split. In order to ease
maintenance inside and around FFmpeg and to reduce confusion where to
put common code, avcore's functionality is merged (back) to avutil.
Signed-off-by: Reinhard Tartler <siretart@tauware.de>

Signed-off-by: Ronald S. Bultje <rsbultje@gmail.com>

This patch changes the exponent difference threshold in the exponent
strategy decision function of the AC-3 encoder.  I tested lowering in
increments of 100.  From 1000 down to 500 generally increased in quality
with each step, but 400 was generally much worse.
Signed-off-by: Mans Rullgard <mans@mansr.com>

Signed-off-by: Mans Rullgard <mans@mansr.com>

Signed-off-by: Mans Rullgard <mans@mansr.com>

Originally committed as revision 26359 to svn://svn.ffmpeg.org/ffmpeg/trunk

43% faster in function encode_exponents().

Originally committed as revision 26358 to svn://svn.ffmpeg.org/ffmpeg/trunk

simplify and speed up encode_exponents().
8% faster in function.

Originally committed as revision 26357 to svn://svn.ffmpeg.org/ffmpeg/trunk

exponent strategies for a single channel to compute_exp_strategy_ch().
This allows for removal of the temporary pointer arrays.

Originally committed as revision 26356 to svn://svn.ffmpeg.org/ffmpeg/trunk

code.

Originally committed as revision 26355 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26354 to svn://svn.ffmpeg.org/ffmpeg/trunk

Originally committed as revision 26353 to svn://svn.ffmpeg.org/ffmpeg/trunk

channel first, then by block.

Originally committed as revision 26352 to svn://svn.ffmpeg.org/ffmpeg/trunk

This will allow for faster and simpler processing of all blocks at once.

Originally committed as revision 26351 to svn://svn.ffmpeg.org/ffmpeg/trunk

This improves the audio quality significantly for stereo source with both the
fixed-point and floating-point AC-3 encoders.
Update acodec-ac3_fixed and seek-ac3_rm test references.

Originally committed as revision 26271 to svn://svn.ffmpeg.org/ffmpeg/trunk

instead of doing it separately in 2 different functions.
This makes float AC-3 encoding approx. 3-7% faster overall.
Also, the coefficient conversion can now be easily SIMD-optimized.

Originally committed as revision 26232 to svn://svn.ffmpeg.org/ffmpeg/trunk