ac3enc: initialize all coefficients to zero.

Uninitialized coefficients were being used to generate exponents, some
of which actually ended up in the final stream.  Even though, they were
just extra exponents that are not used by any decoder, it is still
better to have consistent output for testing. This also fixes valgrind
errors.

libavcodec/ac3enc.c

@@ -583,8 +583,8 @@ static inline float calc_cpl_coord(float energy_ch, float energy_cpl)
 static void apply_channel_coupling(AC3EncodeContext *s)
 {
 #if CONFIG_AC3ENC_FLOAT
-    DECLARE_ALIGNED(16, float,   cpl_coords)      [AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16];
-    DECLARE_ALIGNED(16, int32_t, fixed_cpl_coords)[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16];
+    DECLARE_ALIGNED(16, float,   cpl_coords)      [AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
+    DECLARE_ALIGNED(16, int32_t, fixed_cpl_coords)[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
     int blk, ch, bnd, i, j;
     CoefSumType energy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][16] = {{{0}}};
     int num_cpl_coefs = s->num_cpl_subbands * 12;
@@ -2658,8 +2658,8 @@ static av_cold int allocate_buffers(AVCodecContext *avctx)
                      AC3_MAX_COEFS * sizeof(*s->bap_buffer),  alloc_fail);
     FF_ALLOC_OR_GOTO(avctx, s->bap1_buffer, AC3_MAX_BLOCKS * channels *
                      AC3_MAX_COEFS * sizeof(*s->bap1_buffer), alloc_fail);
-    FF_ALLOC_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * channels *
-                     AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
+    FF_ALLOCZ_OR_GOTO(avctx, s->mdct_coef_buffer, AC3_MAX_BLOCKS * channels *
+                      AC3_MAX_COEFS * sizeof(*s->mdct_coef_buffer), alloc_fail);
     FF_ALLOC_OR_GOTO(avctx, s->exp_buffer, AC3_MAX_BLOCKS * channels *
                      AC3_MAX_COEFS * sizeof(*s->exp_buffer), alloc_fail);
     FF_ALLOC_OR_GOTO(avctx, s->grouped_exp_buffer, AC3_MAX_BLOCKS * channels *
@@ -2723,8 +2723,8 @@ static av_cold int allocate_buffers(AVCodecContext *avctx)
     }
 
     if (CONFIG_AC3ENC_FLOAT) {
-        FF_ALLOC_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * channels *
-                         AC3_MAX_COEFS * sizeof(*s->fixed_coef_buffer), alloc_fail);
+        FF_ALLOCZ_OR_GOTO(avctx, s->fixed_coef_buffer, AC3_MAX_BLOCKS * channels *
+                          AC3_MAX_COEFS * sizeof(*s->fixed_coef_buffer), alloc_fail);
         for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
             AC3Block *block = &s->blocks[blk];
             FF_ALLOCZ_OR_GOTO(avctx, block->fixed_coef, channels *