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# Date Author Comment
e05a3ac7 04/04/2011 12:59 AM Justin Ruggles

ac3enc: select bandwidth based on bit rate, sample rate, and number of
full-bandwidth channels.

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

79997def 04/03/2011 06:01 PM Mans Rullgard

ac3enc: use generic fixed-point mdct

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 <>

e6e98234 03/23/2011 01:08 AM Justin Ruggles

Add apply_window_int16() to DSPContext with x86-optimized versions and use it
in the ac3_fixed encoder.

323e6fea 03/14/2011 12:45 PM Justin

ac3enc: do not right-shift fixed-point coefficients in the final MDCT stage.

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...

50d71404 02/15/2011 09:40 PM Justin Ruggles

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 <>

c3beafa0 02/02/2011 08:00 PM Justin Ruggles

ac3enc: Change EXP_DIFF_THRESHOLD to 500.

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....

ec44dd5f 12/29/2010 07:17 PM Justin Ruggles

Change the default dB-per-bit code from 2 to 3.
This gives slightly better quality in PEAQ tests.
Code 3 gives a dBpb value of 2816 = -132dB (128 psd units = -6dB), which
corresponds to 22 bits. Since the exponents have an offset applied, the
16-bit source looks like 24-bit source to the bit allocation routine....

295ab2af 12/21/2010 09:18 PM Justin Ruggles

Change FIX15 back to clipping to -32767..32767.
This avoids a 16-bit overflow in mdct512() due to a -32768 value in costab.
References updated for acodec-ac3, lavf-rm, and seek-ac3_rm tests.
Thanks to Måns Rullgård for finding the bug.

Originally committed as revision 26071 to svn://

8c634b70 12/14/2010 04:14 PM Justin Ruggles

Update the test references for lavf-rm and seek-ac3_rm.
The references changed due to r25956.

Originally committed as revision 26004 to svn://

cc3e2472 03/02/2010 09:41 PM Måns Rullgård

Place regression test output files in subdirs per family

Originally committed as revision 22155 to svn://

eca478c3 01/16/2010 08:18 PM Måns Rullgård

regtest: split reference files allowing tests to run individually

With this change, the output is checked immediately after each test
has run. This means commands like "make regtest-mpeg2" can now be
used to run a single test and get meaningful results....