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synced 2024-11-21 10:55:51 +02:00
Split out grouping of exponents into a separate function.
Originally committed as revision 25998 to svn://svn.ffmpeg.org/ffmpeg/trunk
This commit is contained in:
Justin Ruggles
parent
b6a1e5236e
commit
f94bacc538
@ -37,6 +37,9 @@
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#define MDCT_NBITS 9
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#define MDCT_SAMPLES (1 << MDCT_NBITS)
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/** Maximum number of exponent groups. +1 for separate DC exponent. */
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#define AC3_MAX_EXP_GROUPS 85
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/** Scale a float value by 2^bits and convert to an integer. */
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#define SCALE_FLOAT(a, bits) lrintf((a) * (float)(1 << (bits)))
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@ -569,11 +572,10 @@ static void exponent_min(uint8_t exp[AC3_MAX_COEFS], uint8_t exp1[AC3_MAX_COEFS]
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/**
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* Update the exponents so that they are the ones the decoder will decode.
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* @return the number of bits used to encode the exponents.
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*/
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static int encode_exponents_blk_ch(uint8_t encoded_exp[AC3_MAX_COEFS],
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uint8_t exp[AC3_MAX_COEFS],
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int nb_exps, int exp_strategy)
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static void encode_exponents_blk_ch(uint8_t encoded_exp[AC3_MAX_COEFS],
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uint8_t exp[AC3_MAX_COEFS],
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int nb_exps, int exp_strategy)
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{
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int group_size, nb_groups, i, j, k, exp_min;
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uint8_t exp1[AC3_MAX_COEFS];
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@ -614,8 +616,6 @@ static int encode_exponents_blk_ch(uint8_t encoded_exp[AC3_MAX_COEFS],
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encoded_exp[k+j] = exp1[i];
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k += group_size;
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}
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return 4 + (nb_groups / 3) * 7;
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}
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@ -624,17 +624,14 @@ static int encode_exponents_blk_ch(uint8_t encoded_exp[AC3_MAX_COEFS],
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* This copies and groups exponents based on exponent strategy and reduces
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* deltas between adjacent exponent groups so that they can be differentially
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* encoded.
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* @return bits needed to encode the exponents
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*/
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static int encode_exponents(AC3EncodeContext *s,
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uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
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uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
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uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS])
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static void encode_exponents(AC3EncodeContext *s,
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uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
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uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
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uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS])
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{
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int blk, blk1, blk2, ch;
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int frame_bits;
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frame_bits = 0;
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for (ch = 0; ch < s->channels; ch++) {
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/* for the EXP_REUSE case we select the min of the exponents */
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blk = 0;
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@ -644,7 +641,7 @@ static int encode_exponents(AC3EncodeContext *s,
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exponent_min(exp[blk][ch], exp[blk1][ch], s->nb_coefs[ch]);
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blk1++;
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}
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frame_bits += encode_exponents_blk_ch(encoded_exp[blk][ch],
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encode_exponents_blk_ch(encoded_exp[blk][ch],
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exp[blk][ch], s->nb_coefs[ch],
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exp_strategy[blk][ch]);
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/* copy encoded exponents for reuse case */
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@ -655,8 +652,67 @@ static int encode_exponents(AC3EncodeContext *s,
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blk = blk1;
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}
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}
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}
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return frame_bits;
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/**
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* Group exponents.
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* 3 delta-encoded exponents are in each 7-bit group. The number of groups
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* varies depending on exponent strategy and bandwidth.
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* @return bits needed to encode the exponents
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*/
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static int group_exponents(AC3EncodeContext *s,
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uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
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uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
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uint8_t num_exp_groups[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
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uint8_t grouped_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_EXP_GROUPS])
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{
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int blk, ch, i;
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int group_size, bit_count;
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uint8_t *p;
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int delta0, delta1, delta2;
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int exp0, exp1;
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bit_count = 0;
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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for (ch = 0; ch < s->channels; ch++) {
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if (exp_strategy[blk][ch] == EXP_REUSE) {
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num_exp_groups[blk][ch] = 0;
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continue;
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}
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group_size = exp_strategy[blk][ch] + (exp_strategy[blk][ch] == EXP_D45);
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num_exp_groups[blk][ch] = (s->nb_coefs[ch] + (group_size * 3) - 4) / (3 * group_size);
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bit_count += 4 + (num_exp_groups[blk][ch] * 7);
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p = encoded_exp[blk][ch];
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/* DC exponent */
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exp1 = *p++;
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grouped_exp[blk][ch][0] = exp1;
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/* remaining exponents are delta encoded */
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for (i = 1; i <= num_exp_groups[blk][ch]; i++) {
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/* merge three delta in one code */
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exp0 = exp1;
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exp1 = p[0];
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p += group_size;
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delta0 = exp1 - exp0 + 2;
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exp0 = exp1;
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exp1 = p[0];
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p += group_size;
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delta1 = exp1 - exp0 + 2;
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exp0 = exp1;
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exp1 = p[0];
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p += group_size;
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delta2 = exp1 - exp0 + 2;
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grouped_exp[blk][ch][i] = ((delta0 * 5 + delta1) * 5) + delta2;
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}
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}
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}
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return bit_count;
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}
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@ -671,13 +727,17 @@ static int process_exponents(AC3EncodeContext *s,
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int8_t exp_shift[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
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uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
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uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
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uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS])
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uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
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uint8_t num_exp_groups[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
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uint8_t grouped_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_EXP_GROUPS])
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{
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extract_exponents(s, mdct_coef, exp_shift, exp);
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compute_exp_strategy(s, exp_strategy, exp);
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return encode_exponents(s, exp, exp_strategy, encoded_exp);
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encode_exponents(s, exp, exp_strategy, encoded_exp);
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return group_exponents(s, encoded_exp, exp_strategy, num_exp_groups, grouped_exp);
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}
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@ -1125,15 +1185,13 @@ static void output_frame_header(AC3EncodeContext *s)
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*/
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static void output_audio_block(AC3EncodeContext *s,
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uint8_t exp_strategy[AC3_MAX_CHANNELS],
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uint8_t encoded_exp[AC3_MAX_CHANNELS][AC3_MAX_COEFS],
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uint8_t num_exp_groups[AC3_MAX_CHANNELS],
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uint8_t grouped_exp[AC3_MAX_CHANNELS][AC3_MAX_EXP_GROUPS],
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uint8_t bap[AC3_MAX_CHANNELS][AC3_MAX_COEFS],
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uint16_t qmant[AC3_MAX_CHANNELS][AC3_MAX_COEFS],
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int block_num)
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{
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int ch, nb_groups, group_size, i, baie, rbnd;
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uint8_t *p;
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int exp0, exp1;
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int delta0, delta1, delta2;
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int ch, i, baie, rbnd;
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for (ch = 0; ch < s->fbw_channels; ch++)
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put_bits(&s->pb, 1, 0); /* no block switching */
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@ -1178,34 +1236,13 @@ static void output_audio_block(AC3EncodeContext *s,
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for (ch = 0; ch < s->channels; ch++) {
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if (exp_strategy[ch] == EXP_REUSE)
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continue;
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group_size = exp_strategy[ch] + (exp_strategy[ch] == EXP_D45);
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nb_groups = (s->nb_coefs[ch] + (group_size * 3) - 4) / (3 * group_size);
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p = encoded_exp[ch];
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/* first exponent */
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exp1 = *p++;
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put_bits(&s->pb, 4, exp1);
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put_bits(&s->pb, 4, grouped_exp[ch][0]);
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/* next ones are delta encoded */
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for (i = 0; i < nb_groups; i++) {
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/* merge three delta in one code */
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exp0 = exp1;
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exp1 = p[0];
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p += group_size;
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delta0 = exp1 - exp0 + 2;
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exp0 = exp1;
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exp1 = p[0];
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p += group_size;
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delta1 = exp1 - exp0 + 2;
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exp0 = exp1;
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exp1 = p[0];
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p += group_size;
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delta2 = exp1 - exp0 + 2;
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put_bits(&s->pb, 7, ((delta0 * 5 + delta1) * 5) + delta2);
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}
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/* next ones are delta-encoded and grouped */
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for (i = 1; i <= num_exp_groups[ch]; i++)
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put_bits(&s->pb, 7, grouped_exp[ch][i]);
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if (ch != s->lfe_channel)
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put_bits(&s->pb, 2, 0); /* no gain range info */
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@ -1335,7 +1372,8 @@ static void output_frame_end(AC3EncodeContext *s)
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static void output_frame(AC3EncodeContext *s,
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unsigned char *frame,
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uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
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uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
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uint8_t num_exp_groups[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS],
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uint8_t grouped_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_EXP_GROUPS],
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uint8_t bap[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS],
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uint16_t qmant[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS])
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{
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@ -1346,8 +1384,8 @@ static void output_frame(AC3EncodeContext *s,
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output_frame_header(s);
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for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
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output_audio_block(s, exp_strategy[blk], encoded_exp[blk],
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bap[blk], qmant[blk], blk);
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output_audio_block(s, exp_strategy[blk], num_exp_groups[blk],
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grouped_exp[blk], bap[blk], qmant[blk], blk);
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}
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output_frame_end(s);
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@ -1367,6 +1405,8 @@ static int ac3_encode_frame(AVCodecContext *avctx,
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uint8_t exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
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uint8_t exp_strategy[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS];
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uint8_t encoded_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
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uint8_t num_exp_groups[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS];
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uint8_t grouped_exp[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_EXP_GROUPS];
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uint8_t bap[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
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int8_t exp_shift[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS];
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uint16_t qmant[AC3_MAX_BLOCKS][AC3_MAX_CHANNELS][AC3_MAX_COEFS];
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@ -1379,13 +1419,14 @@ static int ac3_encode_frame(AVCodecContext *avctx,
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apply_mdct(s, planar_samples, exp_shift, mdct_coef);
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frame_bits = process_exponents(s, mdct_coef, exp_shift, exp, exp_strategy, encoded_exp);
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frame_bits = process_exponents(s, mdct_coef, exp_shift, exp, exp_strategy,
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encoded_exp, num_exp_groups, grouped_exp);
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compute_bit_allocation(s, bap, encoded_exp, exp_strategy, frame_bits);
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quantize_mantissas(s, mdct_coef, exp_shift, encoded_exp, bap, qmant);
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output_frame(s, frame, exp_strategy, encoded_exp, bap, qmant);
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output_frame(s, frame, exp_strategy, num_exp_groups, grouped_exp, bap, qmant);
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return s->frame_size;
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}
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