aacdec: convert to lavu/tx and support fixed-point 960-sample decoding

This patch replaces the transform used in AAC with lavu/tx and removes
the limitation on only being able to decode 960-sample files
with the float decoder.
This commit also removes a whole bunch of unnecessary and slow
lifting steps the decoder did to compensate for the poor accuracy
of the old integer transformation code.

Overall float decoder speedup on Zen 3 for 64kbps: 32%

1 files changed, 16 insertions, 11 deletions

diff --git a/libavcodec/aac.h b/libavcodec/aac.h
index c8d6b17710..285d3b7482 100644
--- a/libavcodec/aac.h
+++ b/libavcodec/aac.h
@@ -36,11 +36,8 @@
 #include "libavutil/float_dsp.h"
 #include "libavutil/fixed_dsp.h"
 #include "libavutil/mem_internal.h"
+#include "libavutil/tx.h"
 #include "avcodec.h"
-#if !USE_FIXED
-#include "mdct15.h"
-#endif
-#include "fft.h"
 #include "mpeg4audio.h"
 #include "sbr.h"
 
@@ -326,16 +323,24 @@ struct AACContext {
      * @name Computed / set up during initialization
      * @{
      */
-    FFTContext mdct;
-    FFTContext mdct_small;
-    FFTContext mdct_ld;
-    FFTContext mdct_ltp;
+    AVTXContext *mdct120;
+    AVTXContext *mdct128;
+    AVTXContext *mdct480;
+    AVTXContext *mdct512;
+    AVTXContext *mdct960;
+    AVTXContext *mdct1024;
+    AVTXContext *mdct_ltp;
+
+    av_tx_fn mdct120_fn;
+    av_tx_fn mdct128_fn;
+    av_tx_fn mdct480_fn;
+    av_tx_fn mdct512_fn;
+    av_tx_fn mdct960_fn;
+    av_tx_fn mdct1024_fn;
+    av_tx_fn mdct_ltp_fn;
 #if USE_FIXED
     AVFixedDSPContext *fdsp;
 #else
-    MDCT15Context *mdct120;
-    MDCT15Context *mdct480;
-    MDCT15Context *mdct960;
     AVFloatDSPContext *fdsp;
 #endif /* USE_FIXED */
     int random_state;