ac3dec_fixed: always use the USE_FIXED=1 variant of the AC3DecodeContext

The AC3DecodeContext has a float (USE_FIXED=0) and an integer
(USE_FIXED=1) variant, both of which can be present in the same binary.
This is not only very confusing, but it also breaks horribly, when one
variant is used by code expecting the other.

This currently happens, because eac3dec.c is only compiled for the float
variant, but also used from ac3dec_fixed.c, which uses the integer
variant.

The result is memory corruption, leading to crashes.

So compile eac3dec.c once for each variant and adapt it, so that it
works with the integer variant.

A loss of precission and scaling bug has been fixed by the committer
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
(cherry picked from commit 7b05b5093e)

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/Makefile

@@ -206,7 +206,7 @@ OBJS-$(CONFIG_DVVIDEO_DECODER)         += dvdec.o dv.o dvdata.o
 OBJS-$(CONFIG_DVVIDEO_ENCODER)         += dvenc.o dv.o dvdata.o
 OBJS-$(CONFIG_DXA_DECODER)             += dxa.o
 OBJS-$(CONFIG_DXTORY_DECODER)          += dxtory.o
-OBJS-$(CONFIG_EAC3_DECODER)            += eac3dec.o eac3_data.o
+OBJS-$(CONFIG_EAC3_DECODER)            += eac3_data.o
 OBJS-$(CONFIG_EAC3_ENCODER)            += eac3enc.o eac3_data.o
 OBJS-$(CONFIG_EACMV_DECODER)           += eacmv.o
 OBJS-$(CONFIG_EAMAD_DECODER)           += eamad.o eaidct.o mpeg12.o \

libavcodec/ac3dec.h

@@ -243,19 +243,19 @@ typedef struct AC3DecodeContext {
  * Parse the E-AC-3 frame header.
  * This parses both the bit stream info and audio frame header.
  */
-int ff_eac3_parse_header(AC3DecodeContext *s);
+static int ff_eac3_parse_header(AC3DecodeContext *s);
 
 /**
  * Decode mantissas in a single channel for the entire frame.
  * This is used when AHT mode is enabled.
  */
-void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch);
+static void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch);
 
 /**
  * Apply spectral extension to each channel by copying lower frequency
  * coefficients to higher frequency bins and applying side information to
  * approximate the original high frequency signal.
  */
-void ff_eac3_apply_spectral_extension(AC3DecodeContext *s);
+static void ff_eac3_apply_spectral_extension(AC3DecodeContext *s);
 
 #endif /* AVCODEC_AC3DEC_H */

libavcodec/ac3dec_fixed.c

@@ -164,6 +164,7 @@ static void ac3_downmix_c_fixed16(int16_t **samples, int16_t (*matrix)[2],
     }
 }
 
+#include "eac3dec.c"
 #include "ac3dec.c"
 
 static const AVOption options[] = {

libavcodec/ac3dec_float.c

@@ -28,6 +28,7 @@
  * Upmix delay samples from stereo to original channel layout.
  */
 #include "ac3dec.h"
+#include "eac3dec.c"
 #include "ac3dec.c"
 
 static const AVOption options[] = {

libavcodec/eac3dec.c

@@ -63,7 +63,7 @@ typedef enum {
 
 #define EAC3_SR_CODE_REDUCED  3
 
-void ff_eac3_apply_spectral_extension(AC3DecodeContext *s)
+static void ff_eac3_apply_spectral_extension(AC3DecodeContext *s)
 {
     int bin, bnd, ch, i;
     uint8_t wrapflag[SPX_MAX_BANDS]={1,0,}, num_copy_sections, copy_sizes[SPX_MAX_BANDS];
@@ -101,7 +101,7 @@ void ff_eac3_apply_spectral_extension(AC3DecodeContext *s)
         for (i = 0; i < num_copy_sections; i++) {
             memcpy(&s->transform_coeffs[ch][bin],
                    &s->transform_coeffs[ch][s->spx_dst_start_freq],
-                   copy_sizes[i]*sizeof(float));
+                   copy_sizes[i]*sizeof(INTFLOAT));
             bin += copy_sizes[i];
         }
 
@@ -124,7 +124,7 @@ void ff_eac3_apply_spectral_extension(AC3DecodeContext *s)
             bin = s->spx_src_start_freq - 2;
             for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
                 if (wrapflag[bnd]) {
-                    float *coeffs = &s->transform_coeffs[ch][bin];
+                    INTFLOAT *coeffs = &s->transform_coeffs[ch][bin];
                     coeffs[0] *= atten_tab[0];
                     coeffs[1] *= atten_tab[1];
                     coeffs[2] *= atten_tab[2];
@@ -142,6 +142,9 @@ void ff_eac3_apply_spectral_extension(AC3DecodeContext *s)
         for (bnd = 0; bnd < s->num_spx_bands; bnd++) {
             float nscale = s->spx_noise_blend[ch][bnd] * rms_energy[bnd] * (1.0f / INT32_MIN);
             float sscale = s->spx_signal_blend[ch][bnd];
+#if USE_FIXED
+            nscale *= 1.0 / (1<<23);
+#endif
             for (i = 0; i < s->spx_band_sizes[bnd]; i++) {
                 float noise  = nscale * (int32_t)av_lfg_get(&s->dith_state);
                 s->transform_coeffs[ch][bin]   *= sscale;
@@ -195,7 +198,7 @@ static void idct6(int pre_mant[6])
     pre_mant[5] = even0 - odd0;
 }
 
-void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch)
+static void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch)
 {
     int bin, blk, gs;
     int end_bap, gaq_mode;
@@ -288,7 +291,7 @@ void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch)
     }
 }
 
-int ff_eac3_parse_header(AC3DecodeContext *s)
+static int ff_eac3_parse_header(AC3DecodeContext *s)
 {
     int i, blk, ch;
     int ac3_exponent_strategy, parse_aht_info, parse_spx_atten_data;