diff options
| author | Lynne <dev@lynne.ee> | 2020-02-08 23:13:28 +0000 |
|---|---|---|
| committer | Lynne <dev@lynne.ee> | 2020-02-13 17:10:34 +0000 |
| commit | e8f054b095baa194623b3852f06fc507ae697503 (patch) | |
| tree | 32fc6a24fb5747e5a11ee74fb8aaf6d62a517882 /libavutil/tx_int32.c | |
| parent | e007059d6617ca966380810fe03c571566ecd9c3 (diff) | |
lavu/tx: implement 32 bit fixed point FFT and MDCT
Required minimal changes to the code so made sense to implement.
FFT and MDCT tested, the output of both was properly rounded.
Fun fact: the non-power-of-two fixed-point FFT and MDCT are the fastest ever
non-power-of-two fixed-point FFT and MDCT written.
This can replace the power of two integer MDCTs in aac and ac3 if the
MIPS optimizations are ported across.
Unfortunately the ac3 encoder uses a 16-bit fixed point forward transform,
unlike the encoder which uses a 32bit inverse transform, so some modifications
might be required there.
The 3-point FFT is somewhat less accurate than it otherwise could be,
having minor rounding errors with bigger transforms. However, this
could be improved later, and the way its currently written is the way one
would write assembly for it.
Similar rounding errors can also be found throughout the power of two FFTs
as well, though those are more difficult to correct.
Despite this, the integer transforms are more than accurate enough.
Diffstat (limited to 'libavutil/tx_int32.c')
| -rw-r--r-- | libavutil/tx_int32.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/libavutil/tx_int32.c b/libavutil/tx_int32.c new file mode 100644 index 0000000000..9261013bf6 --- /dev/null +++ b/libavutil/tx_int32.c @@ -0,0 +1,21 @@ +/* + * This file is part of FFmpeg. + * + * FFmpeg is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * FFmpeg is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with FFmpeg; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#define TX_INT32 +#include "tx_priv.h" +#include "tx_template.c" |