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ffmpeg/libavcodec/mpc8.c
Andreas Rheinhardt 83ff99adc4 avcodec/mpc8: Avoid code duplication when initializing VLCs 
Up until now, VLCs that were part of an array of VLCs were often not
initialized in a loop, but separately. The probable reason for this
was that these VLCs differed slightly in the parameters to be used for
them (i.e. the number of codes or the number of bits to be used
differs), so that one would have to provide these parameters e.g. via
arrays.

Yet these problems have actually largely been solved by now: The length
information is contained in a run-length encoded form that is the same
for all VLCs and both the number of codes as well as the number of bits
to use for each VLC can be easily derived from them.

There is just one problem to be solved: When the underlying tables have
a different number of elements, putting them into an array of arrays
would be wasteful; using an array of pointers to the arrays would
also be wasteful. Therefore this commit combines the tables into bigger
tables. (Given that all the length tables have the same layout this
applies only to the symbols tables.)

Finally, the array containing the offset of the VLC's buffer in the big
buffer has also been removed.

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 av_cold void build_vlc(VLC *vlc, unsigned *buf_offset,
const uint8_t codes_counts[16],
const uint8_t **syms, int offset)
{
static VLC_TYPE vlc_buf[9296][2];
uint8_t len[MPC8_MAX_VLC_SIZE];
unsigned num = 0;
vlc->table = &vlc_buf[*buf_offset];
vlc->table_allocated = FF_ARRAY_ELEMS(vlc_buf) - *buf_offset;
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, FFMIN(len[0], 9), num, len, 1,
*syms, 1, 1, offset, INIT_VLC_STATIC_OVERLONG, NULL);
*buf_offset += vlc->table_size;
*syms += num;
}
static av_cold int mpc8_decode_init(AVCodecContext * avctx)
{
int i, offset = 0;
MPCContext *c = avctx->priv_data;
GetBitContext gb;
static int vlc_initialized = 0;
const uint8_t *q_syms = mpc8_q_syms, *bands_syms = mpc8_bands_syms;
const uint8_t *res_syms = mpc8_res_syms, *scfi_syms = mpc8_scfi_syms;
const uint8_t *dscf_syms = mpc8_dscf_syms;
int channels;
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");
build_vlc(&band_vlc, &offset, mpc8_bands_len_counts, &bands_syms, 0);
build_vlc(&q1_vlc, &offset, mpc8_q1_len_counts, &q_syms, 0);
build_vlc(&q9up_vlc, &offset, mpc8_q9up_len_counts, &q_syms, 0);
for(i = 0; i < 2; i++){
build_vlc(&scfi_vlc[i], &offset, mpc8_scfi_len_counts[i], &scfi_syms, 0);
build_vlc(&dscf_vlc[i], &offset, mpc8_dscf_len_counts[i], &dscf_syms, 0);
build_vlc(&res_vlc[i], &offset, mpc8_res_len_counts[i], &res_syms, 0);
build_vlc(&q2_vlc[i], &offset, mpc8_q2_len_counts[i], &q_syms, 0);
build_vlc(&q3_vlc[i], &offset, mpc8_q34_len_counts[i],
&q_syms, -48 - 16 * i);
for (int j = 0; j < 4; j++)
build_vlc(&quant_vlc[j][i], &offset, mpc8_q5_8_len_counts[i][j],
&q_syms, -((8 << j) - 1));
}
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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