ac3enc: shift coefficients to 24-bit following MDCT rather than using an exponent offset.
This makes channel coupling more accurate, increasing quality for stereocontent. It also simplifies exponent extraction and mantissa quantizationby no longer needing to apply an offset to the exponents....
ac3enc: fix bug in stereo rematrixing decision.
The rematrixing strategy reuse flags are not reset between frames, so theyneed to be initialized for all blocks, not just block 0.
Signed-off-by: Mans Rullgard <email@example.com>(cherry picked from commit 5b54d4b376fbd2c291b8a6dba7d425e28f654bcf)
ac3enc: change default floor code to 7.
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 <firstname.lastname@example.org>(cherry picked from commit 50d7140441b61809ad4ba4ea7b4ad8fe77bc6888)
ac3enc: Change EXP_DIFF_THRESHOLD to 500.
This patch changes the exponent difference threshold in the exponentstrategy decision function of the AC-3 encoder. I tested lowering inincrements of 100. From 1000 down to 500 generally increased in qualitywith each step, but 400 was generally much worse....
Add stereo rematrixing support to the AC-3 encoders.This improves the audio quality significantly for stereo source with both thefixed-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
Change the AC-3 encoder to use floating-point.Fixed-point AC-3 encoder renamed to ac3_fixed.Regression test acodec-ac3 renamed to acodec-ac3_fixed.Regression test lavf-rm changed to use ac3_fixed encoder.
Originally committed as revision 26209 to svn://svn.ffmpeg.org/ffmpeg/trunk