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e55ade2c01
FFmpeg/libavcodec/mpc8.c
Andreas Rheinhardt e55ade2c01 avcodec/mpc8: Reduce the size of the length tables to initialize VLCs 
After permuting both length, code as well as symbol tables so that
the codes are ordered from left to right in the tree, it became apparent
that the length of the codes decreases from left to right. Therefore one
can run-length encode the lengths to save space. This commit implements
this.

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2020-12-08 17:51:45 +01:00

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/*
* Musepack SV8 decoder
* Copyright (c) 2007 Konstantin Shishkov
*
* This file is part of FFmpeg.
*
* FFmpeg 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.
*
* FFmpeg 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 FFmpeg; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
/**
* @file
* MPEG Audio Layer 1/2 -like codec with frames of 1152 samples
* divided into 32 subbands.
*/
#include "libavutil/channel_layout.h"
#include "libavutil/lfg.h"
#include "avcodec.h"
#include "get_bits.h"
#include "internal.h"
#include "mpegaudiodsp.h"
#include "mpc.h"
#include "mpc8data.h"
#include "mpc8huff.h"
static VLC band_vlc, scfi_vlc[2], dscf_vlc[2], res_vlc[2];
static VLC q1_vlc, q2_vlc[2], q3_vlc[2], quant_vlc[4][2], q9up_vlc;
static inline int mpc8_dec_base(GetBitContext *gb, int k, int n)
{
int len = mpc8_cnk_len[k-1][n-1] - 1;
int code = len ? get_bits_long(gb, len) : 0;
if (code >= mpc8_cnk_lost[k-1][n-1])
code = ((code << 1) | get_bits1(gb)) - mpc8_cnk_lost[k-1][n-1];
return code;
}
static inline int mpc8_dec_enum(GetBitContext *gb, int k, int n)
{
int bits = 0;
const uint32_t * C = mpc8_cnk[k-1];
int code = mpc8_dec_base(gb, k, n);
do {
n--;
if (code >= C[n]) {
bits |= 1U << n;
code -= C[n];
C -= 32;
k--;
}
} while(k > 0);
return bits;
}
static inline int mpc8_get_mod_golomb(GetBitContext *gb, int m)
{
if(mpc8_cnk_len[0][m] < 1) return 0;
return mpc8_dec_base(gb, 1, m+1);
}
static int mpc8_get_mask(GetBitContext *gb, int size, int t)
{
int mask = 0;
if(t && t != size)
mask = mpc8_dec_enum(gb, FFMIN(t, size - t), size);
if((t << 1) > size) mask = ~mask;
return mask;
}
static const uint16_t vlc_offsets[13] = {
0, 640, 1184, 1748, 2298, 2426, 2554, 3066, 3578, 4106, 4618, 5196, 5708
};
static av_cold void build_vlc(VLC *vlc, int nb_bits,
const uint8_t codes_counts[16],
const uint8_t syms[], int offset)
{
uint8_t len[MPC8_MAX_VLC_SIZE];
unsigned num = 0;
for (int i = 16; i > 0; i--)
for (unsigned tmp = num + codes_counts[i - 1]; num < tmp; num++)
len[num] = i;
ff_init_vlc_from_lengths(vlc, nb_bits, num, len, 1,
syms, 1, 1, offset, INIT_VLC_USE_NEW_STATIC, NULL);
}
static av_cold int mpc8_decode_init(AVCodecContext * avctx)
{
int i;
MPCContext *c = avctx->priv_data;
GetBitContext gb;
static int vlc_initialized = 0;
int channels;
static VLC_TYPE codes_table[5708][2];
if(avctx->extradata_size < 2){
av_log(avctx, AV_LOG_ERROR, "Too small extradata size (%i)!\n", avctx->extradata_size);
return -1;
}
memset(c->oldDSCF, 0, sizeof(c->oldDSCF));
av_lfg_init(&c->rnd, 0xDEADBEEF);
ff_mpadsp_init(&c->mpadsp);
init_get_bits(&gb, avctx->extradata, 16);
skip_bits(&gb, 3);//sample rate
c->maxbands = get_bits(&gb, 5) + 1;
if (c->maxbands >= BANDS) {
av_log(avctx,AV_LOG_ERROR, "maxbands %d too high\n", c->maxbands);
return AVERROR_INVALIDDATA;
}
channels = get_bits(&gb, 4) + 1;
if (channels > 2) {
avpriv_request_sample(avctx, "Multichannel MPC SV8");
return AVERROR_PATCHWELCOME;
}
c->MSS = get_bits1(&gb);
c->frames = 1 << (get_bits(&gb, 3) * 2);
avctx->sample_fmt = AV_SAMPLE_FMT_S16P;
avctx->channel_layout = (channels==2) ? AV_CH_LAYOUT_STEREO : AV_CH_LAYOUT_MONO;
avctx->channels = channels;
if(vlc_initialized) return 0;
av_log(avctx, AV_LOG_DEBUG, "Initing VLC\n");
#define INIT_VLC(vlc, bits, len_counts, symbols, offset, static_size) \
do { \
static VLC_TYPE table[static_size][2]; \
(vlc)->table = table; \
(vlc)->table_allocated = static_size; \
build_vlc(vlc, bits, len_counts, symbols, offset); \
} while (0)
INIT_VLC(&band_vlc, MPC8_BANDS_BITS,
mpc8_bands_len_counts, mpc8_bands_syms, 0, 542);
INIT_VLC(&q1_vlc, MPC8_Q1_BITS,
mpc8_q1_len_counts, mpc8_q1_syms, 0, 520);
INIT_VLC(&q9up_vlc, MPC8_Q9UP_BITS,
mpc8_q9up_len_counts, mpc8_q9up_syms, 0, 524);
INIT_VLC(&scfi_vlc[0], MPC8_SCFI0_BITS,
mpc8_scfi_len_counts[0], mpc8_scfi0_syms, 0, 1 << MPC8_SCFI0_BITS);
INIT_VLC(&scfi_vlc[1], MPC8_SCFI1_BITS,
mpc8_scfi_len_counts[1], mpc8_scfi1_syms, 0, 1 << MPC8_SCFI1_BITS);
INIT_VLC(&dscf_vlc[0], MPC8_DSCF0_BITS,
mpc8_dscf_len_counts[0], mpc8_dscf0_syms, 0, 560);
INIT_VLC(&dscf_vlc[1], MPC8_DSCF1_BITS,
mpc8_dscf_len_counts[1], mpc8_dscf1_syms, 0, 598);
INIT_VLC(&q3_vlc[0], MPC8_Q3_BITS,
mpc8_q3_len_counts, mpc8_q3_syms, MPC8_Q3_OFFSET, 512);
INIT_VLC(&q3_vlc[1], MPC8_Q4_BITS,
mpc8_q4_len_counts, mpc8_q4_syms, MPC8_Q4_OFFSET, 516);
for(i = 0; i < 2; i++){
res_vlc[i].table = &codes_table[vlc_offsets[0+i]];
res_vlc[i].table_allocated = vlc_offsets[1+i] - vlc_offsets[0+i];
build_vlc(&res_vlc[i], MPC8_RES_BITS,
mpc8_res_len_counts[i], mpc8_res_syms[i], 0);
q2_vlc[i].table = &codes_table[vlc_offsets[2+i]];
q2_vlc[i].table_allocated = vlc_offsets[3+i] - vlc_offsets[2+i];
build_vlc(&q2_vlc[i], MPC8_Q2_BITS,
mpc8_q2_len_counts[i], mpc8_q2_syms[i], 0);
quant_vlc[0][i].table = &codes_table[vlc_offsets[4+i]];
quant_vlc[0][i].table_allocated = vlc_offsets[5+i] - vlc_offsets[4+i];
build_vlc(&quant_vlc[0][i], MPC8_Q5_BITS,
mpc8_q5_len_counts[i], mpc8_q5_syms[i], MPC8_Q5_OFFSET);
quant_vlc[1][i].table = &codes_table[vlc_offsets[6+i]];
quant_vlc[1][i].table_allocated = vlc_offsets[7+i] - vlc_offsets[6+i];
build_vlc(&quant_vlc[1][i], MPC8_Q6_BITS,
mpc8_q6_len_counts[i], mpc8_q6_syms[i], MPC8_Q6_OFFSET);
quant_vlc[2][i].table = &codes_table[vlc_offsets[8+i]];
quant_vlc[2][i].table_allocated = vlc_offsets[9+i] - vlc_offsets[8+i];
build_vlc(&quant_vlc[2][i], MPC8_Q7_BITS,
mpc8_q7_len_counts[i], mpc8_q7_syms[i], MPC8_Q7_OFFSET);
quant_vlc[3][i].table = &codes_table[vlc_offsets[10+i]];
quant_vlc[3][i].table_allocated = vlc_offsets[11+i] - vlc_offsets[10+i];
build_vlc(&quant_vlc[3][i], MPC8_Q8_BITS,
mpc8_q8_len_counts[i], mpc8_q8_syms[i], MPC8_Q8_OFFSET);
}
vlc_initialized = 1;
ff_mpa_synth_init_fixed();
return 0;
}
static int mpc8_decode_frame(AVCodecContext * avctx, void *data,
int *got_frame_ptr, AVPacket *avpkt)
{
AVFrame *frame = data;
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
MPCContext *c = avctx->priv_data;
GetBitContext gb2, *gb = &gb2;
int i, j, k, ch, cnt, res, t;
Band *bands = c->bands;
int off;
int maxband, keyframe;
int last[2];
keyframe = c->cur_frame == 0;
if(keyframe){
memset(c->Q, 0, sizeof(c->Q));
c->last_bits_used = 0;
}
if ((res = init_get_bits8(gb, buf, buf_size)) < 0)
return res;
skip_bits(gb, c->last_bits_used & 7);
if(keyframe)
maxband = mpc8_get_mod_golomb(gb, c->maxbands + 1);
else{
maxband = c->last_max_band + get_vlc2(gb, band_vlc.table, MPC8_BANDS_BITS, 2);
if(maxband > 32) maxband -= 33;
}
if (get_bits_left(gb) < 0) {
*got_frame_ptr = 0;
return buf_size;
}
if(maxband > c->maxbands + 1) {
av_log(avctx, AV_LOG_ERROR, "maxband %d too large\n",maxband);
return AVERROR_INVALIDDATA;
}
c->last_max_band = maxband;
/* read subband indexes */
if(maxband){
last[0] = last[1] = 0;
for(i = maxband - 1; i >= 0; i--){
for(ch = 0; ch < 2; ch++){
last[ch] = get_vlc2(gb, res_vlc[last[ch] > 2].table, MPC8_RES_BITS, 2) + last[ch];
if(last[ch] > 15) last[ch] -= 17;
bands[i].res[ch] = last[ch];
}
}
if(c->MSS){
int mask;
cnt = 0;
for(i = 0; i < maxband; i++)
if(bands[i].res[0] || bands[i].res[1])
cnt++;
t = mpc8_get_mod_golomb(gb, cnt);
mask = mpc8_get_mask(gb, cnt, t);
for(i = maxband - 1; i >= 0; i--)
if(bands[i].res[0] || bands[i].res[1]){
bands[i].msf = mask & 1;
mask >>= 1;
}
}
}
for(i = maxband; i < c->maxbands; i++)
bands[i].res[0] = bands[i].res[1] = 0;
if(keyframe){
for(i = 0; i < 32; i++)
c->oldDSCF[0][i] = c->oldDSCF[1][i] = 1;
}
for(i = 0; i < maxband; i++){
if(bands[i].res[0] || bands[i].res[1]){
cnt = !!bands[i].res[0] + !!bands[i].res[1] - 1;
if(cnt >= 0){
t = get_vlc2(gb, scfi_vlc[cnt].table, scfi_vlc[cnt].bits, 1);
if(bands[i].res[0]) bands[i].scfi[0] = t >> (2 * cnt);
if(bands[i].res[1]) bands[i].scfi[1] = t & 3;
}
}
}
for(i = 0; i < maxband; i++){
for(ch = 0; ch < 2; ch++){
if(!bands[i].res[ch]) continue;
if(c->oldDSCF[ch][i]){
bands[i].scf_idx[ch][0] = get_bits(gb, 7) - 6;
c->oldDSCF[ch][i] = 0;
}else{
t = get_vlc2(gb, dscf_vlc[1].table, MPC8_DSCF1_BITS, 2);
if(t == 64)
t += get_bits(gb, 6);
bands[i].scf_idx[ch][0] = ((bands[i].scf_idx[ch][2] + t - 25) & 0x7F) - 6;
}
for(j = 0; j < 2; j++){
if((bands[i].scfi[ch] << j) & 2)
bands[i].scf_idx[ch][j + 1] = bands[i].scf_idx[ch][j];
else{
t = get_vlc2(gb, dscf_vlc[0].table, MPC8_DSCF0_BITS, 2);
if(t == 31)
t = 64 + get_bits(gb, 6);
bands[i].scf_idx[ch][j + 1] = ((bands[i].scf_idx[ch][j] + t - 25) & 0x7F) - 6;
}
}
}
}
for(i = 0, off = 0; i < maxband; i++, off += SAMPLES_PER_BAND){
for(ch = 0; ch < 2; ch++){
res = bands[i].res[ch];
switch(res){
case -1:
for(j = 0; j < SAMPLES_PER_BAND; j++)
c->Q[ch][off + j] = (av_lfg_get(&c->rnd) & 0x3FC) - 510;
break;
case 0:
break;
case 1:
for(j = 0; j < SAMPLES_PER_BAND; j += SAMPLES_PER_BAND / 2){
cnt = get_vlc2(gb, q1_vlc.table, MPC8_Q1_BITS, 2);
t = mpc8_get_mask(gb, 18, cnt);
for(k = 0; k < SAMPLES_PER_BAND / 2; k++)
c->Q[ch][off + j + k] = t & (1 << (SAMPLES_PER_BAND / 2 - k - 1))
? (get_bits1(gb) << 1) - 1 : 0;
}
break;
case 2:
cnt = 6;//2*mpc8_thres[res]
for(j = 0; j < SAMPLES_PER_BAND; j += 3){
t = get_vlc2(gb, q2_vlc[cnt > 3].table, MPC8_Q2_BITS, 2);
c->Q[ch][off + j + 0] = mpc8_idx50[t];
c->Q[ch][off + j + 1] = mpc8_idx51[t];
c->Q[ch][off + j + 2] = mpc8_idx52[t];
cnt = (cnt >> 1) + mpc8_huffq2[t];
}
break;
case 3:
case 4:
for(j = 0; j < SAMPLES_PER_BAND; j += 2){
t = get_vlc2(gb, q3_vlc[res - 3].table, MPC8_Q3_BITS, 2);
c->Q[ch][off + j + 1] = t >> 4;
c->Q[ch][off + j + 0] = sign_extend(t, 4);
}
break;
case 5:
case 6:
case 7:
case 8:
cnt = 2 * mpc8_thres[res];
for(j = 0; j < SAMPLES_PER_BAND; j++){
const VLC *vlc = &quant_vlc[res - 5][cnt > mpc8_thres[res]];
c->Q[ch][off + j] = get_vlc2(gb, vlc->table, vlc->bits, 2);
cnt = (cnt >> 1) + FFABS(c->Q[ch][off + j]);
}
break;
default:
for(j = 0; j < SAMPLES_PER_BAND; j++){
c->Q[ch][off + j] = get_vlc2(gb, q9up_vlc.table, MPC8_Q9UP_BITS, 2);
if(res != 9){
c->Q[ch][off + j] <<= res - 9;
c->Q[ch][off + j] |= get_bits(gb, res - 9);
}
c->Q[ch][off + j] -= (1 << (res - 2)) - 1;
}
}
}
}
frame->nb_samples = MPC_FRAME_SIZE;
if ((res = ff_get_buffer(avctx, frame, 0)) < 0)
return res;
ff_mpc_dequantize_and_synth(c, maxband - 1,
(int16_t **)frame->extended_data,
avctx->channels);
c->cur_frame++;
c->last_bits_used = get_bits_count(gb);
if(c->cur_frame >= c->frames)
c->cur_frame = 0;
if (get_bits_left(gb) < 0) {
av_log(avctx, AV_LOG_ERROR, "Overread %d\n", -get_bits_left(gb));
c->last_bits_used = buf_size << 3;
} else if (c->cur_frame == 0 && get_bits_left(gb) < 8) {// we have only padding left
c->last_bits_used = buf_size << 3;
}
*got_frame_ptr = 1;
return c->cur_frame ? c->last_bits_used >> 3 : buf_size;
}
static av_cold void mpc8_decode_flush(AVCodecContext *avctx)
{
MPCContext *c = avctx->priv_data;
c->cur_frame = 0;
}
AVCodec ff_mpc8_decoder = {
.name = "mpc8",
.long_name = NULL_IF_CONFIG_SMALL("Musepack SV8"),
.type = AVMEDIA_TYPE_AUDIO,
.id = AV_CODEC_ID_MUSEPACK8,
.priv_data_size = sizeof(MPCContext),
.init = mpc8_decode_init,
.decode = mpc8_decode_frame,
.flush = mpc8_decode_flush,
.capabilities = AV_CODEC_CAP_DR1,
.sample_fmts = (const enum AVSampleFormat[]) { AV_SAMPLE_FMT_S16P,
AV_SAMPLE_FMT_NONE },
};
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