ac3enc: modify mantissa bit counting to keep bap counts for all values of bap

instead of just 0 to 4.

This does all the actual bit counting as a final step.

libavcodec/ac3dsp.c

@@ -128,24 +128,33 @@ static void ac3_bit_alloc_calc_bap_c(int16_t *mask, int16_t *psd,
     } while (end > ff_ac3_band_start_tab[band++]);
 }
 
-static int ac3_compute_mantissa_size_c(int mant_cnt[5], uint8_t *bap,
-                                       int nb_coefs)
+static void ac3_update_bap_counts_c(uint16_t mant_cnt[16], uint8_t *bap,
+                                    int len)
 {
-    int bits, b, i;
+    while (len-- >= 0)
+        mant_cnt[bap[len]]++;
+}
 
-    bits = 0;
-    for (i = 0; i < nb_coefs; i++) {
-        b = bap[i];
-        if (b <= 4) {
-            // bap=1 to bap=4 will be counted in compute_mantissa_size_final
-            mant_cnt[b]++;
-        } else if (b <= 13) {
-            // bap=5 to bap=13 use (bap-1) bits
-            bits += b - 1;
-        } else {
-            // bap=14 uses 14 bits and bap=15 uses 16 bits
-            bits += (b == 14) ? 14 : 16;
-        }
+DECLARE_ALIGNED(16, const uint16_t, ff_ac3_bap_bits)[16] = {
+    0,  0,  0,  3,  0,  4,  5,  6,  7,  8,  9, 10, 11, 12, 14, 16
+};
+
+static int ac3_compute_mantissa_size_c(uint16_t mant_cnt[6][16])
+{
+    int blk, bap;
+    int bits = 0;
+
+    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+        // bap=1 : 3 mantissas in 5 bits
+        bits += (mant_cnt[blk][1] / 3) * 5;
+        // bap=2 : 3 mantissas in 7 bits
+        // bap=4 : 2 mantissas in 7 bits
+        bits += ((mant_cnt[blk][2] / 3) + (mant_cnt[blk][4] >> 1)) * 7;
+        // bap=3 : 1 mantissa in 3 bits
+        bits += mant_cnt[blk][3] * 3;
+        // bap=5 to 15 : get bits per mantissa from table
+        for (bap = 5; bap < 16; bap++)
+            bits += mant_cnt[blk][bap] * ff_ac3_bap_bits[bap];
     }
     return bits;
 }
@@ -181,6 +190,7 @@ av_cold void ff_ac3dsp_init(AC3DSPContext *c, int bit_exact)
     c->ac3_rshift_int32 = ac3_rshift_int32_c;
     c->float_to_fixed24 = float_to_fixed24_c;
     c->bit_alloc_calc_bap = ac3_bit_alloc_calc_bap_c;
+    c->update_bap_counts = ac3_update_bap_counts_c;
     c->compute_mantissa_size = ac3_compute_mantissa_size_c;
     c->extract_exponents = ac3_extract_exponents_c;
 

libavcodec/ac3dsp.h

@@ -24,6 +24,12 @@
 
 #include <stdint.h>
 
+/**
+ * Number of mantissa bits written for each bap value.
+ * bap values with fractional bits are set to 0 and are calculated separately.
+ */
+extern const uint16_t ff_ac3_bap_bits[16];
+
 typedef struct AC3DSPContext {
     /**
      * Set each encoded exponent in a block to the minimum of itself and the
@@ -101,10 +107,22 @@ typedef struct AC3DSPContext {
                                int snr_offset, int floor,
                                const uint8_t *bap_tab, uint8_t *bap);
 
+    /**
+     * Update bap counts using the supplied array of bap.
+     *
+     * @param[out] mant_cnt   bap counts for 1 block
+     * @param[in]  bap        array of bap, pointing to start coef bin
+     * @param[in]  len        number of elements to process
+     */
+    void (*update_bap_counts)(uint16_t mant_cnt[16], uint8_t *bap, int len);
+
     /**
      * Calculate the number of bits needed to encode a set of mantissas.
+     *
+     * @param[in] mant_cnt    bap counts for all blocks
+     * @return                mantissa bit count
      */
-    int (*compute_mantissa_size)(int mant_cnt[5], uint8_t *bap, int nb_coefs);
+    int (*compute_mantissa_size)(uint16_t mant_cnt[6][16]);
 
     void (*extract_exponents)(uint8_t *exp, int32_t *coef, int nb_coefs);
 } AC3DSPContext;

libavcodec/ac3enc.c

@@ -1423,22 +1423,6 @@ static void count_frame_bits(AC3EncodeContext *s)
 }
 
 
-/**
- * Finalize the mantissa bit count by adding in the grouped mantissas.
- */
-static int compute_mantissa_size_final(int mant_cnt[5])
-{
-    // bap=1 : 3 mantissas in 5 bits
-    int bits = (mant_cnt[1] / 3) * 5;
-    // bap=2 : 3 mantissas in 7 bits
-    // bap=4 : 2 mantissas in 7 bits
-    bits += ((mant_cnt[2] / 3) + (mant_cnt[4] >> 1)) * 7;
-    // bap=3 : each mantissa is 3 bits
-    bits += mant_cnt[3] * 3;
-    return bits;
-}
-
-
 /**
  * Calculate masking curve based on the final exponents.
  * Also calculate the power spectral densities to use in future calculations.
@@ -1491,38 +1475,60 @@ static void reset_block_bap(AC3EncodeContext *s)
 }
 
 
-static int count_mantissa_bits(AC3EncodeContext *s)
+/**
+ * Initialize mantissa counts.
+ * These are set so that they are padded to the next whole group size when bits
+ * are counted in compute_mantissa_size.
+ */
+static void count_mantissa_bits_init(uint16_t mant_cnt[AC3_MAX_BLOCKS][16])
 {
-    int blk, ch;
-    int mantissa_bits;
-    int mant_cnt[5];
+    int blk;
+
+    for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
+        memset(mant_cnt[blk], 0, sizeof(mant_cnt[blk]));
+        mant_cnt[blk][1] = mant_cnt[blk][2] = 2;
+        mant_cnt[blk][4] = 1;
+    }
+}
+
+
+/**
+ * Update mantissa bit counts for all blocks in 1 channel in a given bandwidth
+ * range.
+ */
+static void count_mantissa_bits_update_ch(AC3EncodeContext *s, int ch,
+                                          uint16_t mant_cnt[AC3_MAX_BLOCKS][16],
+                                          int start, int end)
+{
+    int blk;
 
-    mantissa_bits = 0;
     for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
         AC3Block *block = &s->blocks[blk];
-        int av_uninit(ch0);
-        int got_cpl = !block->cpl_in_use;
-        // initialize grouped mantissa counts. these are set so that they are
-        // padded to the next whole group size when bits are counted in
-        // compute_mantissa_size_final
-        mant_cnt[0] = mant_cnt[3] = 0;
-        mant_cnt[1] = mant_cnt[2] = 2;
-        mant_cnt[4] = 1;
-        for (ch = 1; ch <= s->channels; ch++) {
-            if (!got_cpl && ch > 1 && block->channel_in_cpl[ch-1]) {
-                ch0     = ch - 1;
-                ch      = CPL_CH;
-                got_cpl = 1;
-            }
-            mantissa_bits += s->ac3dsp.compute_mantissa_size(mant_cnt,
-                                                             s->ref_bap[ch][blk]+s->start_freq[ch],
-                                                             block->end_freq[ch]-s->start_freq[ch]);
-            if (ch == CPL_CH)
-                ch = ch0;
-        }
-        mantissa_bits += compute_mantissa_size_final(mant_cnt);
+        if (ch == CPL_CH && !block->cpl_in_use)
+            continue;
+        s->ac3dsp.update_bap_counts(mant_cnt[blk],
+                                    s->ref_bap[ch][blk] + start,
+                                    FFMIN(end, block->end_freq[ch]) - start);
     }
-    return mantissa_bits;
+}
+
+
+/**
+ * Count the number of mantissa bits in the frame based on the bap values.
+ */
+static int count_mantissa_bits(AC3EncodeContext *s)
+{
+    int ch, max_end_freq;
+    LOCAL_ALIGNED_16(uint16_t, mant_cnt,[AC3_MAX_BLOCKS][16]);
+
+    count_mantissa_bits_init(mant_cnt);
+
+    max_end_freq = s->bandwidth_code * 3 + 73;
+    for (ch = !s->cpl_enabled; ch <= s->channels; ch++)
+        count_mantissa_bits_update_ch(s, ch, mant_cnt, s->start_freq[ch],
+                                      max_end_freq);
+
+    return s->ac3dsp.compute_mantissa_size(mant_cnt);
 }
 
 

libavcodec/arm/ac3dsp_arm.S

-/*
- * Copyright (c) 2011 Mans Rullgard <mans@mansr.com>
- *
- * This file is part of Libav.
- *
- * Libav 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.
- *
- * Libav 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 Libav; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include "asm.S"
-
-function ff_ac3_compute_mantissa_size_arm, export=1
-        push            {r4-r8,lr}
-        ldm             r0,  {r4-r8}
-        mov             r3,  r0
-        mov             r0,  #0
-1:
-        ldrb            lr,  [r1], #1
-        subs            r2,  r2,  #1
-        blt             2f
-        cmp             lr,  #4
-        bgt             3f
-        subs            lr,  lr,  #1
-        addlt           r4,  r4,  #1
-        addeq           r5,  r5,  #1
-        ble             1b
-        subs            lr,  lr,  #2
-        addlt           r6,  r6,  #1
-        addeq           r7,  r7,  #1
-        addgt           r8,  r8,  #1
-        b               1b
-3:
-        cmp             lr,  #14
-        sublt           lr,  lr,  #1
-        addgt           r0,  r0,  #16
-        addle           r0,  r0,  lr
-        b               1b
-2:
-        stm             r3,  {r4-r8}
-        pop             {r4-r8,pc}
-endfunc

libavcodec/arm/ac3dsp_init_arm.c

@@ -39,8 +39,6 @@ int ff_ac3_compute_mantissa_size_arm(int cnt[5], uint8_t *bap, int nb_coefs);
 
 av_cold void ff_ac3dsp_init_arm(AC3DSPContext *c, int bit_exact)
 {
-    c->compute_mantissa_size     = ff_ac3_compute_mantissa_size_arm;
-
     if (HAVE_ARMV6) {
         c->bit_alloc_calc_bap    = ff_ac3_bit_alloc_calc_bap_armv6;
     }

libavcodec/x86/ac3dsp.asm

@@ -27,6 +27,11 @@ SECTION_RODATA
 ; 16777216.0f - used in ff_float_to_fixed24()
 pf_1_24: times 4 dd 0x4B800000
 
+; used in ff_ac3_compute_mantissa_size()
+cextern ac3_bap_bits
+pw_bap_mul1: dw 21846, 21846, 0, 32768, 21846, 21846, 0, 32768
+pw_bap_mul2: dw 5, 7, 0, 7, 5, 7, 0, 7
+
 SECTION .text
 
 ;-----------------------------------------------------------------------------
@@ -293,3 +298,51 @@ cglobal float_to_fixed24_sse2, 3,3,9, dst, src, len
 %endif
     ja .loop
     REP_RET
+
+;------------------------------------------------------------------------------
+; int ff_ac3_compute_mantissa_size(uint16_t mant_cnt[6][16])
+;------------------------------------------------------------------------------
+
+%macro PHADDD4 2 ; xmm src, xmm tmp
+    movhlps  %2, %1
+    paddd    %1, %2
+    pshufd   %2, %1, 0x1
+    paddd    %1, %2
+%endmacro
+
+INIT_XMM
+cglobal ac3_compute_mantissa_size_sse2, 1,2,4, mant_cnt, sum
+    movdqa      m0, [mant_cntq      ]
+    movdqa      m1, [mant_cntq+ 1*16]
+    paddw       m0, [mant_cntq+ 2*16]
+    paddw       m1, [mant_cntq+ 3*16]
+    paddw       m0, [mant_cntq+ 4*16]
+    paddw       m1, [mant_cntq+ 5*16]
+    paddw       m0, [mant_cntq+ 6*16]
+    paddw       m1, [mant_cntq+ 7*16]
+    paddw       m0, [mant_cntq+ 8*16]
+    paddw       m1, [mant_cntq+ 9*16]
+    paddw       m0, [mant_cntq+10*16]
+    paddw       m1, [mant_cntq+11*16]
+    pmaddwd     m0, [ff_ac3_bap_bits   ]
+    pmaddwd     m1, [ff_ac3_bap_bits+16]
+    paddd       m0, m1
+    PHADDD4     m0, m1
+    movd      sumd, m0
+    movdqa      m3, [pw_bap_mul1]
+    movhpd      m0, [mant_cntq     +2]
+    movlpd      m0, [mant_cntq+1*32+2]
+    movhpd      m1, [mant_cntq+2*32+2]
+    movlpd      m1, [mant_cntq+3*32+2]
+    movhpd      m2, [mant_cntq+4*32+2]
+    movlpd      m2, [mant_cntq+5*32+2]
+    pmulhuw     m0, m3
+    pmulhuw     m1, m3
+    pmulhuw     m2, m3
+    paddusw     m0, m1
+    paddusw     m0, m2
+    pmaddwd     m0, [pw_bap_mul2]
+    PHADDD4     m0, m1
+    movd       eax, m0
+    add        eax, sumd
+    RET

libavcodec/x86/ac3dsp_mmx.c

@@ -42,6 +42,8 @@ extern void ff_float_to_fixed24_3dnow(int32_t *dst, const float *src, unsigned i
 extern void ff_float_to_fixed24_sse  (int32_t *dst, const float *src, unsigned int len);
 extern void ff_float_to_fixed24_sse2 (int32_t *dst, const float *src, unsigned int len);
 
+extern int ff_ac3_compute_mantissa_size_sse2(uint16_t mant_cnt[6][16]);
+
 av_cold void ff_ac3dsp_init_x86(AC3DSPContext *c, int bit_exact)
 {
     int mm_flags = av_get_cpu_flags();
@@ -69,6 +71,7 @@ av_cold void ff_ac3dsp_init_x86(AC3DSPContext *c, int bit_exact)
         c->ac3_exponent_min = ff_ac3_exponent_min_sse2;
         c->ac3_max_msb_abs_int16 = ff_ac3_max_msb_abs_int16_sse2;
         c->float_to_fixed24 = ff_float_to_fixed24_sse2;
+        c->compute_mantissa_size = ff_ac3_compute_mantissa_size_sse2;
         if (!(mm_flags & AV_CPU_FLAG_SSE2SLOW)) {
             c->ac3_lshift_int16 = ff_ac3_lshift_int16_sse2;
             c->ac3_rshift_int32 = ff_ac3_rshift_int32_sse2;