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ffmpeg/libavcodec/mpeg12.c

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/*
* MPEG1 encoder / MPEG2 decoder
* Copyright (c) 2000,2001 Gerard Lantau.
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program 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 General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/
//#define DEBUG
#include "avcodec.h"
#include "dsputil.h"
#include "mpegvideo.h"
#include "mpeg12data.h"
/* Start codes. */
#define SEQ_END_CODE 0x000001b7
#define SEQ_START_CODE 0x000001b3
#define GOP_START_CODE 0x000001b8
#define PICTURE_START_CODE 0x00000100
#define SLICE_MIN_START_CODE 0x00000101
#define SLICE_MAX_START_CODE 0x000001af
#define EXT_START_CODE 0x000001b5
#define USER_START_CODE 0x000001b2
static void mpeg1_encode_block(MpegEncContext *s,
DCTELEM *block,
int component);
static void mpeg1_encode_motion(MpegEncContext *s, int val);
static void mpeg1_skip_picture(MpegEncContext *s, int pict_num);
static int mpeg1_decode_block(MpegEncContext *s,
DCTELEM *block,
int n);
static int mpeg2_decode_block_non_intra(MpegEncContext *s,
DCTELEM *block,
int n);
static int mpeg2_decode_block_intra(MpegEncContext *s,
DCTELEM *block,
int n);
static int mpeg_decode_motion(MpegEncContext *s, int fcode, int pred);
static void put_header(MpegEncContext *s, int header)
{
align_put_bits(&s->pb);
put_bits(&s->pb, 32, header);
}
/* put sequence header if needed */
static void mpeg1_encode_sequence_header(MpegEncContext *s)
{
unsigned int vbv_buffer_size;
unsigned int fps, v;
int n;
UINT64 time_code;
if ((s->picture_number % s->gop_size) == 0) {
/* mpeg1 header repeated every gop */
put_header(s, SEQ_START_CODE);
/* search closest frame rate */
{
int i, dmin, d;
s->frame_rate_index = 0;
dmin = 0x7fffffff;
for(i=1;i<9;i++) {
d = abs(s->frame_rate - frame_rate_tab[i]);
if (d < dmin) {
dmin = d;
s->frame_rate_index = i;
}
}
}
put_bits(&s->pb, 12, s->width);
put_bits(&s->pb, 12, s->height);
put_bits(&s->pb, 4, 1); /* 1/1 aspect ratio */
put_bits(&s->pb, 4, s->frame_rate_index);
v = s->bit_rate / 400;
if (v > 0x3ffff)
v = 0x3ffff;
put_bits(&s->pb, 18, v);
put_bits(&s->pb, 1, 1); /* marker */
/* vbv buffer size: slightly greater than an I frame. We add
some margin just in case */
vbv_buffer_size = (3 * s->I_frame_bits) / (2 * 8);
put_bits(&s->pb, 10, (vbv_buffer_size + 16383) / 16384);
put_bits(&s->pb, 1, 1); /* constrained parameter flag */
put_bits(&s->pb, 1, 0); /* no custom intra matrix */
put_bits(&s->pb, 1, 0); /* no custom non intra matrix */
put_header(s, GOP_START_CODE);
put_bits(&s->pb, 1, 0); /* do drop frame */
/* time code : we must convert from the real frame rate to a
fake mpeg frame rate in case of low frame rate */
fps = frame_rate_tab[s->frame_rate_index];
time_code = s->fake_picture_number * FRAME_RATE_BASE;
s->gop_picture_number = s->fake_picture_number;
put_bits(&s->pb, 5, (UINT32)((time_code / (fps * 3600)) % 24));
put_bits(&s->pb, 6, (UINT32)((time_code / (fps * 60)) % 60));
put_bits(&s->pb, 1, 1);
put_bits(&s->pb, 6, (UINT32)((time_code / fps) % 60));
put_bits(&s->pb, 6, (UINT32)((time_code % fps) / FRAME_RATE_BASE));
put_bits(&s->pb, 1, 1); /* closed gop */
put_bits(&s->pb, 1, 0); /* broken link */
}
if (s->frame_rate < (24 * FRAME_RATE_BASE) && s->picture_number > 0) {
/* insert empty P pictures to slow down to the desired
frame rate. Each fake pictures takes about 20 bytes */
fps = frame_rate_tab[s->frame_rate_index];
n = ((s->picture_number * fps) / s->frame_rate) - 1;
while (s->fake_picture_number < n) {
mpeg1_skip_picture(s, s->fake_picture_number -
s->gop_picture_number);
s->fake_picture_number++;
}
}
s->fake_picture_number++;
}
/* insert a fake P picture */
static void mpeg1_skip_picture(MpegEncContext *s, int pict_num)
{
unsigned int mb_incr;
/* mpeg1 picture header */
put_header(s, PICTURE_START_CODE);
/* temporal reference */
put_bits(&s->pb, 10, pict_num & 0x3ff);
put_bits(&s->pb, 3, P_TYPE);
put_bits(&s->pb, 16, 0xffff); /* non constant bit rate */
put_bits(&s->pb, 1, 1); /* integer coordinates */
put_bits(&s->pb, 3, 1); /* forward_f_code */
put_bits(&s->pb, 1, 0); /* extra bit picture */
/* only one slice */
put_header(s, SLICE_MIN_START_CODE);
put_bits(&s->pb, 5, 1); /* quantizer scale */
put_bits(&s->pb, 1, 0); /* slice extra information */
mb_incr = 1;
put_bits(&s->pb, mbAddrIncrTable[mb_incr - 1][1],
mbAddrIncrTable[mb_incr - 1][0]);
/* empty macroblock */
put_bits(&s->pb, 3, 1); /* motion only */
/* zero motion x & y */
put_bits(&s->pb, 1, 1);
put_bits(&s->pb, 1, 1);
/* output a number of empty slice */
mb_incr = s->mb_width * s->mb_height - 1;
while (mb_incr > 33) {
put_bits(&s->pb, 11, 0x008);
mb_incr -= 33;
}
put_bits(&s->pb, mbAddrIncrTable[mb_incr - 1][1],
mbAddrIncrTable[mb_incr - 1][0]);
/* empty macroblock */
put_bits(&s->pb, 3, 1); /* motion only */
/* zero motion x & y */
put_bits(&s->pb, 1, 1);
put_bits(&s->pb, 1, 1);
}
void mpeg1_encode_picture_header(MpegEncContext *s, int picture_number)
{
static int done;
if (!done) {
done = 1;
init_rl(&rl_mpeg1);
}
mpeg1_encode_sequence_header(s);
/* mpeg1 picture header */
put_header(s, PICTURE_START_CODE);
/* temporal reference */
put_bits(&s->pb, 10, (s->fake_picture_number -
s->gop_picture_number) & 0x3ff);
put_bits(&s->pb, 3, s->pict_type);
put_bits(&s->pb, 16, 0xffff); /* non constant bit rate */
if (s->pict_type == P_TYPE) {
put_bits(&s->pb, 1, 0); /* half pel coordinates */
put_bits(&s->pb, 3, s->f_code); /* forward_f_code */
}
put_bits(&s->pb, 1, 0); /* extra bit picture */
/* only one slice */
put_header(s, SLICE_MIN_START_CODE);
put_bits(&s->pb, 5, s->qscale); /* quantizer scale */
put_bits(&s->pb, 1, 0); /* slice extra information */
}
void mpeg1_encode_mb(MpegEncContext *s,
DCTELEM block[6][64],
int motion_x, int motion_y)
{
int mb_incr, i, cbp, mb_x, mb_y;
mb_x = s->mb_x;
mb_y = s->mb_y;
/* compute cbp */
cbp = 0;
for(i=0;i<6;i++) {
if (s->block_last_index[i] >= 0)
cbp |= 1 << (5 - i);
}
/* skip macroblock, except if first or last macroblock of a slice */
if ((cbp | motion_x | motion_y) == 0 &&
(!((mb_x | mb_y) == 0 ||
(mb_x == s->mb_width - 1 && mb_y == s->mb_height - 1)))) {
s->mb_incr++;
} else {
/* output mb incr */
mb_incr = s->mb_incr;
while (mb_incr > 33) {
put_bits(&s->pb, 11, 0x008);
mb_incr -= 33;
}
put_bits(&s->pb, mbAddrIncrTable[mb_incr - 1][1],
mbAddrIncrTable[mb_incr - 1][0]);
if (s->pict_type == I_TYPE) {
put_bits(&s->pb, 1, 1); /* macroblock_type : macroblock_quant = 0 */
} else {
if (s->mb_intra) {
put_bits(&s->pb, 5, 0x03);
} else {
if (cbp != 0) {
if (motion_x == 0 && motion_y == 0) {
put_bits(&s->pb, 2, 1); /* macroblock_pattern only */
put_bits(&s->pb, mbPatTable[cbp - 1][1], mbPatTable[cbp - 1][0]);
} else {
put_bits(&s->pb, 1, 1); /* motion + cbp */
mpeg1_encode_motion(s, motion_x - s->last_mv[0][0][0]);
mpeg1_encode_motion(s, motion_y - s->last_mv[0][0][1]);
put_bits(&s->pb, mbPatTable[cbp - 1][1], mbPatTable[cbp - 1][0]);
}
} else {
put_bits(&s->pb, 3, 1); /* motion only */
mpeg1_encode_motion(s, motion_x - s->last_mv[0][0][0]);
mpeg1_encode_motion(s, motion_y - s->last_mv[0][0][1]);
}
}
}
for(i=0;i<6;i++) {
if (cbp & (1 << (5 - i))) {
mpeg1_encode_block(s, block[i], i);
}
}
s->mb_incr = 1;
}
s->last_mv[0][0][0] = motion_x;
s->last_mv[0][0][1] = motion_y;
}
static void mpeg1_encode_motion(MpegEncContext *s, int val)
{
int code, bit_size, l, m, bits, range, sign;
if (val == 0) {
/* zero vector */
code = 0;
put_bits(&s->pb,
mbMotionVectorTable[0][1],
mbMotionVectorTable[0][0]);
} else {
bit_size = s->f_code - 1;
range = 1 << bit_size;
/* modulo encoding */
l = 16 * range;
m = 2 * l;
if (val < -l) {
val += m;
} else if (val >= l) {
val -= m;
}
if (val >= 0) {
val--;
code = (val >> bit_size) + 1;
bits = val & (range - 1);
sign = 0;
} else {
val = -val;
val--;
code = (val >> bit_size) + 1;
bits = val & (range - 1);
sign = 1;
}
put_bits(&s->pb,
mbMotionVectorTable[code][1],
mbMotionVectorTable[code][0]);
put_bits(&s->pb, 1, sign);
if (bit_size > 0) {
put_bits(&s->pb, bit_size, bits);
}
}
}
static inline void encode_dc(MpegEncContext *s, int diff, int component)
{
int adiff, index;
adiff = abs(diff);
index = vlc_dc_table[adiff];
if (component == 0) {
put_bits(&s->pb, vlc_dc_lum_bits[index], vlc_dc_lum_code[index]);
} else {
put_bits(&s->pb, vlc_dc_chroma_bits[index], vlc_dc_chroma_code[index]);
}
if (diff > 0) {
put_bits(&s->pb, index, (diff & ((1 << index) - 1)));
} else if (diff < 0) {
put_bits(&s->pb, index, ((diff - 1) & ((1 << index) - 1)));
}
}
static void mpeg1_encode_block(MpegEncContext *s,
DCTELEM *block,
int n)
{
int alevel, level, last_non_zero, dc, diff, i, j, run, last_index, sign;
int code, component;
RLTable *rl = &rl_mpeg1;
last_index = s->block_last_index[n];
/* DC coef */
if (s->mb_intra) {
component = (n <= 3 ? 0 : n - 4 + 1);
dc = block[0]; /* overflow is impossible */
diff = dc - s->last_dc[component];
encode_dc(s, diff, component);
s->last_dc[component] = dc;
i = 1;
} else {
/* encode the first coefficient : needs to be done here because
it is handled slightly differently */
level = block[0];
if (abs(level) == 1) {
code = ((UINT32)level >> 31); /* the sign bit */
put_bits(&s->pb, 2, code | 0x02);
i = 1;
} else {
i = 0;
last_non_zero = -1;
goto next_coef;
}
}
/* now quantify & encode AC coefs */
last_non_zero = i - 1;
for(;i<=last_index;i++) {
j = zigzag_direct[i];
level = block[j];
next_coef:
#if 0
if (level != 0)
dprintf("level[%d]=%d\n", i, level);
#endif
/* encode using VLC */
if (level != 0) {
run = i - last_non_zero - 1;
sign = 0;
alevel = level;
if (alevel < 0) {
sign = 1;
alevel = -alevel;
}
code = get_rl_index(rl, 0, run, alevel);
put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
if (code != rl->n) {
put_bits(&s->pb, 1, sign);
} else {
/* escape: only clip in this case */
put_bits(&s->pb, 6, run);
if (alevel < 128) {
put_bits(&s->pb, 8, level & 0xff);
} else {
if (level < 0) {
put_bits(&s->pb, 16, 0x8001 + level + 255);
} else {
put_bits(&s->pb, 16, level & 0xffff);
}
}
}
last_non_zero = i;
}
}
/* end of block */
put_bits(&s->pb, 2, 0x2);
}
/******************************************/
/* decoding */
static VLC dc_lum_vlc;
static VLC dc_chroma_vlc;
static VLC mv_vlc;
static VLC mbincr_vlc;
static VLC mb_ptype_vlc;
static VLC mb_btype_vlc;
static VLC mb_pat_vlc;
void mpeg1_init_vlc(MpegEncContext *s)
{
static int done = 0;
if (!done) {
init_vlc(&dc_lum_vlc, 9, 12,
vlc_dc_lum_bits, 1, 1,
vlc_dc_lum_code, 2, 2);
init_vlc(&dc_chroma_vlc, 9, 12,
vlc_dc_chroma_bits, 1, 1,
vlc_dc_chroma_code, 2, 2);
init_vlc(&mv_vlc, 9, 17,
&mbMotionVectorTable[0][1], 2, 1,
&mbMotionVectorTable[0][0], 2, 1);
init_vlc(&mbincr_vlc, 9, 35,
&mbAddrIncrTable[0][1], 2, 1,
&mbAddrIncrTable[0][0], 2, 1);
init_vlc(&mb_pat_vlc, 9, 63,
&mbPatTable[0][1], 2, 1,
&mbPatTable[0][0], 2, 1);
init_vlc(&mb_ptype_vlc, 6, 32,
&table_mb_ptype[0][1], 2, 1,
&table_mb_ptype[0][0], 2, 1);
init_vlc(&mb_btype_vlc, 6, 32,
&table_mb_btype[0][1], 2, 1,
&table_mb_btype[0][0], 2, 1);
init_rl(&rl_mpeg1);
init_rl(&rl_mpeg2);
/* cannot use generic init because we must add the EOB code */
init_vlc(&rl_mpeg1.vlc, 9, rl_mpeg1.n + 2,
&rl_mpeg1.table_vlc[0][1], 4, 2,
&rl_mpeg1.table_vlc[0][0], 4, 2);
init_vlc(&rl_mpeg2.vlc, 9, rl_mpeg2.n + 2,
&rl_mpeg2.table_vlc[0][1], 4, 2,
&rl_mpeg2.table_vlc[0][0], 4, 2);
}
}
static inline int get_dmv(MpegEncContext *s)
{
if(get_bits1(&s->gb))
return 1 - (get_bits1(&s->gb) << 1);
else
return 0;
}
static inline int get_qscale(MpegEncContext *s)
{
int qscale;
if (s->mpeg2) {
if (s->q_scale_type) {
qscale = non_linear_qscale[get_bits(&s->gb, 5)];
} else {
qscale = get_bits(&s->gb, 5) << 1;
}
} else {
/* for mpeg1, we use the generic unquant code */
qscale = get_bits(&s->gb, 5);
}
return qscale;
}
/* motion type (for mpeg2) */
#define MT_FIELD 1
#define MT_FRAME 2
#define MT_16X8 2
#define MT_DMV 3
static int mpeg_decode_mb(MpegEncContext *s,
DCTELEM block[6][64])
{
int i, j, k, cbp, val, code, mb_type, motion_type;
/* skip mb handling */
if (s->mb_incr == 0) {
/* read again increment */
s->mb_incr = 1;
for(;;) {
code = get_vlc(&s->gb, &mbincr_vlc);
if (code < 0)
return 1; /* error = end of slice */
if (code >= 33) {
if (code == 33) {
s->mb_incr += 33;
}
/* otherwise, stuffing, nothing to do */
} else {
s->mb_incr += code;
break;
}
}
}
if (++s->mb_x >= s->mb_width) {
s->mb_x = 0;
if (s->mb_y >= (s->mb_height - 1))
return -1;
s->mb_y++;
}
dprintf("decode_mb: x=%d y=%d\n", s->mb_x, s->mb_y);
if (--s->mb_incr != 0) {
/* skip mb */
s->mb_intra = 0;
for(i=0;i<6;i++)
s->block_last_index[i] = -1;
s->mv_type = MV_TYPE_16X16;
if (s->pict_type == P_TYPE) {
/* if P type, zero motion vector is implied */
s->mv_dir = MV_DIR_FORWARD;
s->mv[0][0][0] = s->mv[0][0][1] = 0;
s->last_mv[0][0][0] = s->last_mv[0][0][1] = 0;
s->last_mv[0][1][0] = s->last_mv[0][1][1] = 0;
} else {
/* if B type, reuse previous vectors and directions */
s->mv[0][0][0] = s->last_mv[0][0][0];
s->mv[0][0][1] = s->last_mv[0][0][1];
s->mv[1][0][0] = s->last_mv[1][0][0];
s->mv[1][0][1] = s->last_mv[1][0][1];
}
s->mb_skiped = 1;
return 0;
}
switch(s->pict_type) {
default:
case I_TYPE:
if (get_bits1(&s->gb) == 0) {
if (get_bits1(&s->gb) == 0)
return -1;
mb_type = MB_QUANT | MB_INTRA;
} else {
mb_type = MB_INTRA;
}
break;
case P_TYPE:
mb_type = get_vlc(&s->gb, &mb_ptype_vlc);
if (mb_type < 0)
return -1;
break;
case B_TYPE:
mb_type = get_vlc(&s->gb, &mb_btype_vlc);
if (mb_type < 0)
return -1;
break;
}
dprintf("mb_type=%x\n", mb_type);
motion_type = 0; /* avoid warning */
if (mb_type & (MB_FOR|MB_BACK)) {
/* get additionnal motion vector type */
if (s->picture_structure == PICT_FRAME && s->frame_pred_frame_dct)
motion_type = MT_FRAME;
else
motion_type = get_bits(&s->gb, 2);
}
/* compute dct type */
if (s->picture_structure == PICT_FRAME &&
!s->frame_pred_frame_dct &&
(mb_type & (MB_PAT | MB_INTRA))) {
s->interlaced_dct = get_bits1(&s->gb);
#ifdef DEBUG
if (s->interlaced_dct)
printf("interlaced_dct\n");
#endif
} else {
s->interlaced_dct = 0; /* frame based */
}
if (mb_type & MB_QUANT) {
s->qscale = get_qscale(s);
}
if (mb_type & MB_INTRA) {
if (s->concealment_motion_vectors) {
/* just parse them */
if (s->picture_structure != PICT_FRAME)
skip_bits1(&s->gb); /* field select */
mpeg_decode_motion(s, s->mpeg_f_code[0][0], 0);
mpeg_decode_motion(s, s->mpeg_f_code[0][1], 0);
}
s->mb_intra = 1;
cbp = 0x3f;
memset(s->last_mv, 0, sizeof(s->last_mv)); /* reset mv prediction */
} else {
s->mb_intra = 0;
cbp = 0;
}
/* special case of implicit zero motion vector */
if (s->pict_type == P_TYPE && !(mb_type & MB_FOR)) {
s->mv_dir = MV_DIR_FORWARD;
s->mv_type = MV_TYPE_16X16;
s->last_mv[0][0][0] = 0;
s->last_mv[0][0][1] = 0;
s->last_mv[0][1][0] = 0;
s->last_mv[0][1][1] = 0;
s->mv[0][0][0] = 0;
s->mv[0][0][1] = 0;
} else if (mb_type & (MB_FOR | MB_BACK)) {
/* motion vectors */
s->mv_dir = 0;
for(i=0;i<2;i++) {
if (mb_type & (MB_FOR >> i)) {
s->mv_dir |= (MV_DIR_FORWARD >> i);
dprintf("motion_type=%d\n", motion_type);
switch(motion_type) {
case MT_FRAME: /* or MT_16X8 */
if (s->picture_structure == PICT_FRAME) {
/* MT_FRAME */
s->mv_type = MV_TYPE_16X16;
for(k=0;k<2;k++) {
val = mpeg_decode_motion(s, s->mpeg_f_code[i][k],
s->last_mv[i][0][k]);
s->last_mv[i][0][k] = val;
s->last_mv[i][1][k] = val;
/* full_pel: only for mpeg1 */
if (s->full_pel[i])
val = val << 1;
s->mv[i][0][k] = val;
dprintf("mv%d: %d\n", k, val);
}
} else {
/* MT_16X8 */
s->mv_type = MV_TYPE_16X8;
for(j=0;j<2;j++) {
s->field_select[i][j] = get_bits1(&s->gb);
for(k=0;k<2;k++) {
val = mpeg_decode_motion(s, s->mpeg_f_code[i][k],
s->last_mv[i][j][k]);
s->last_mv[i][j][k] = val;
s->mv[i][j][k] = val;
}
}
}
break;
case MT_FIELD:
if (s->picture_structure == PICT_FRAME) {
s->mv_type = MV_TYPE_FIELD;
for(j=0;j<2;j++) {
s->field_select[i][j] = get_bits1(&s->gb);
val = mpeg_decode_motion(s, s->mpeg_f_code[i][0],
s->last_mv[i][j][0]);
s->last_mv[i][j][0] = val;
s->mv[i][j][0] = val;
dprintf("fmx=%d\n", val);
val = mpeg_decode_motion(s, s->mpeg_f_code[i][1],
s->last_mv[i][j][1] >> 1);
s->last_mv[i][j][1] = val << 1;
s->mv[i][j][1] = val;
dprintf("fmy=%d\n", val);
}
} else {
s->mv_type = MV_TYPE_16X16;
s->field_select[i][0] = get_bits1(&s->gb);
for(k=0;k<2;k++) {
val = mpeg_decode_motion(s, s->mpeg_f_code[i][k],
s->last_mv[i][0][k]);
s->last_mv[i][0][k] = val;
s->last_mv[i][1][k] = val;
s->mv[i][0][k] = val;
}
}
break;
case MT_DMV:
{
int dmx, dmy, mx, my, m;
mx = mpeg_decode_motion(s, s->mpeg_f_code[i][0],
s->last_mv[i][0][0]);
s->last_mv[i][0][0] = mx;
s->last_mv[i][1][0] = mx;
dmx = get_dmv(s);
my = mpeg_decode_motion(s, s->mpeg_f_code[i][1],
s->last_mv[i][0][1] >> 1);
dmy = get_dmv(s);
s->mv_type = MV_TYPE_DMV;
/* XXX: totally broken */
if (s->picture_structure == PICT_FRAME) {
s->last_mv[i][0][1] = my << 1;
s->last_mv[i][1][1] = my << 1;
m = s->top_field_first ? 1 : 3;
/* top -> top pred */
s->mv[i][0][0] = mx;
s->mv[i][0][1] = my << 1;
s->mv[i][1][0] = ((mx * m + (mx > 0)) >> 1) + dmx;
s->mv[i][1][1] = ((my * m + (my > 0)) >> 1) + dmy - 1;
m = 4 - m;
s->mv[i][2][0] = mx;
s->mv[i][2][1] = my << 1;
s->mv[i][3][0] = ((mx * m + (mx > 0)) >> 1) + dmx;
s->mv[i][3][1] = ((my * m + (my > 0)) >> 1) + dmy + 1;
} else {
s->last_mv[i][0][1] = my;
s->last_mv[i][1][1] = my;
s->mv[i][0][0] = mx;
s->mv[i][0][1] = my;
s->mv[i][1][0] = ((mx + (mx > 0)) >> 1) + dmx;
s->mv[i][1][1] = ((my + (my > 0)) >> 1) + dmy - 1
/* + 2 * cur_field */;
}
}
break;
}
}
}
}
if ((mb_type & MB_INTRA) && s->concealment_motion_vectors) {
skip_bits1(&s->gb); /* marker */
}
if (mb_type & MB_PAT) {
cbp = get_vlc(&s->gb, &mb_pat_vlc);
if (cbp < 0)
return -1;
cbp++;
}
dprintf("cbp=%x\n", cbp);
if (s->mpeg2) {
if (s->mb_intra) {
for(i=0;i<6;i++) {
if (cbp & (1 << (5 - i))) {
if (mpeg2_decode_block_intra(s, block[i], i) < 0)
return -1;
}
}
} else {
for(i=0;i<6;i++) {
if (cbp & (1 << (5 - i))) {
if (mpeg2_decode_block_non_intra(s, block[i], i) < 0)
return -1;
}
}
}
} else {
for(i=0;i<6;i++) {
if (cbp & (1 << (5 - i))) {
if (mpeg1_decode_block(s, block[i], i) < 0)
return -1;
}
}
}
return 0;
}
/* as h263, but only 17 codes */
static int mpeg_decode_motion(MpegEncContext *s, int fcode, int pred)
{
int code, sign, val, m, l, shift;
code = get_vlc(&s->gb, &mv_vlc);
if (code < 0) {
return 0xffff;
}
if (code == 0) {
return pred;
}
sign = get_bits1(&s->gb);
shift = fcode - 1;
val = (code - 1) << shift;
if (shift > 0)
val |= get_bits(&s->gb, shift);
val++;
if (sign)
val = -val;
val += pred;
/* modulo decoding */
l = (1 << shift) * 16;
m = 2 * l;
if (val < -l) {
val += m;
} else if (val >= l) {
val -= m;
}
return val;
}
static inline int decode_dc(MpegEncContext *s, int component)
{
int code, diff;
if (component == 0) {
code = get_vlc(&s->gb, &dc_lum_vlc);
} else {
code = get_vlc(&s->gb, &dc_chroma_vlc);
}
if (code < 0)
return 0xffff;
if (code == 0) {
diff = 0;
} else {
diff = get_bits(&s->gb, code);
if ((diff & (1 << (code - 1))) == 0)
diff = (-1 << code) | (diff + 1);
}
return diff;
}
static int mpeg1_decode_block(MpegEncContext *s,
DCTELEM *block,
int n)
{
int level, dc, diff, i, j, run;
int code, component;
RLTable *rl = &rl_mpeg1;
if (s->mb_intra) {
/* DC coef */
component = (n <= 3 ? 0 : n - 4 + 1);
diff = decode_dc(s, component);
if (diff >= 0xffff)
return -1;
dc = s->last_dc[component];
dc += diff;
s->last_dc[component] = dc;
block[0] = dc;
dprintf("dc=%d diff=%d\n", dc, diff);
i = 1;
} else {
int bit_cnt, v;
UINT32 bit_buf;
UINT8 *buf_ptr;
i = 0;
/* special case for the first coef. no need to add a second vlc table */
SAVE_BITS(&s->gb);
SHOW_BITS(&s->gb, v, 2);
if (v & 2) {
run = 0;
level = 1 - ((v & 1) << 1);
FLUSH_BITS(2);
RESTORE_BITS(&s->gb);
goto add_coef;
}
RESTORE_BITS(&s->gb);
}
/* now quantify & encode AC coefs */
for(;;) {
code = get_vlc(&s->gb, &rl->vlc);
if (code < 0) {
return -1;
}
if (code == 112) {
break;
} else if (code == 111) {
/* escape */
run = get_bits(&s->gb, 6);
level = get_bits(&s->gb, 8);
level = (level << 24) >> 24;
if (level == -128) {
level = get_bits(&s->gb, 8) - 256;
} else if (level == 0) {
level = get_bits(&s->gb, 8);
}
} else {
run = rl->table_run[code];
level = rl->table_level[code];
if (get_bits1(&s->gb))
level = -level;
}
i += run;
if (i >= 64)
return -1;
add_coef:
dprintf("%d: run=%d level=%d\n", n, run, level);
j = zigzag_direct[i];
block[j] = level;
i++;
}
s->block_last_index[n] = i;
return 0;
}
/* Also does unquantization here, since I will never support mpeg2
encoding */
static int mpeg2_decode_block_non_intra(MpegEncContext *s,
DCTELEM *block,
int n)
{
int level, i, j, run;
int code;
RLTable *rl = &rl_mpeg1;
const UINT8 *scan_table;
const UINT16 *matrix;
int mismatch;
if (s->alternate_scan)
scan_table = ff_alternate_vertical_scan;
else
scan_table = zigzag_direct;
mismatch = 1;
{
int bit_cnt, v;
UINT32 bit_buf;
UINT8 *buf_ptr;
i = 0;
if (n < 4)
matrix = s->non_intra_matrix;
else
matrix = s->chroma_non_intra_matrix;
/* special case for the first coef. no need to add a second vlc table */
SAVE_BITS(&s->gb);
SHOW_BITS(&s->gb, v, 2);
if (v & 2) {
run = 0;
level = 1 - ((v & 1) << 1);
FLUSH_BITS(2);
RESTORE_BITS(&s->gb);
goto add_coef;
}
RESTORE_BITS(&s->gb);
}
/* now quantify & encode AC coefs */
for(;;) {
code = get_vlc(&s->gb, &rl->vlc);
if (code < 0)
return -1;
if (code == 112) {
break;
} else if (code == 111) {
/* escape */
run = get_bits(&s->gb, 6);
level = get_bits(&s->gb, 12);
level = (level << 20) >> 20;
} else {
run = rl->table_run[code];
level = rl->table_level[code];
if (get_bits1(&s->gb))
level = -level;
}
i += run;
if (i >= 64)
return -1;
add_coef:
j = scan_table[i];
dprintf("%d: run=%d level=%d\n", n, run, level);
/* XXX: optimize */
if (level > 0) {
level = ((level * 2 + 1) * s->qscale * matrix[j]) >> 5;
} else {
level = ((-level * 2 + 1) * s->qscale * matrix[j]) >> 5;
level = -level;
}
/* XXX: is it really necessary to saturate since the encoder
knows whats going on ? */
mismatch ^= level;
block[j] = level;
i++;
}
block[63] ^= (mismatch & 1);
s->block_last_index[n] = i;
return 0;
}
static int mpeg2_decode_block_intra(MpegEncContext *s,
DCTELEM *block,
int n)
{
int level, dc, diff, i, j, run;
int code, component;
RLTable *rl;
const UINT8 *scan_table;
const UINT16 *matrix;
int mismatch;
if (s->alternate_scan)
scan_table = ff_alternate_vertical_scan;
else
scan_table = zigzag_direct;
/* DC coef */
component = (n <= 3 ? 0 : n - 4 + 1);
diff = decode_dc(s, component);
if (diff >= 0xffff)
return -1;
dc = s->last_dc[component];
dc += diff;
s->last_dc[component] = dc;
block[0] = dc << (3 - s->intra_dc_precision);
dprintf("dc=%d\n", block[0]);
mismatch = block[0] ^ 1;
i = 1;
if (s->intra_vlc_format)
rl = &rl_mpeg2;
else
rl = &rl_mpeg1;
if (n < 4)
matrix = s->intra_matrix;
else
matrix = s->chroma_intra_matrix;
/* now quantify & encode AC coefs */
for(;;) {
code = get_vlc(&s->gb, &rl->vlc);
if (code < 0)
return -1;
if (code == 112) {
break;
} else if (code == 111) {
/* escape */
run = get_bits(&s->gb, 6);
level = get_bits(&s->gb, 12);
level = (level << 20) >> 20;
} else {
run = rl->table_run[code];
level = rl->table_level[code];
if (get_bits1(&s->gb))
level = -level;
}
i += run;
if (i >= 64)
return -1;
j = scan_table[i];
dprintf("%d: run=%d level=%d\n", n, run, level);
level = (level * s->qscale * matrix[j]) / 16;
/* XXX: is it really necessary to saturate since the encoder
knows whats going on ? */
mismatch ^= level;
block[j] = level;
i++;
}
block[63] ^= (mismatch & 1);
s->block_last_index[n] = i;
return 0;
}
/* compressed picture size */
#define PICTURE_BUFFER_SIZE 100000
typedef struct Mpeg1Context {
MpegEncContext mpeg_enc_ctx;
UINT32 header_state;
int start_code; /* current start code */
UINT8 buffer[PICTURE_BUFFER_SIZE];
UINT8 *buf_ptr;
int buffer_size;
int mpeg_enc_ctx_allocated; /* true if decoding context allocated */
} Mpeg1Context;
static int mpeg_decode_init(AVCodecContext *avctx)
{
Mpeg1Context *s = avctx->priv_data;
s->header_state = 0xff;
s->mpeg_enc_ctx_allocated = 0;
s->buffer_size = PICTURE_BUFFER_SIZE;
s->start_code = -1;
s->buf_ptr = s->buffer;
s->mpeg_enc_ctx.picture_number = 0;
return 0;
}
/* return the 8 bit start code value and update the search
state. Return -1 if no start code found */
static int find_start_code(UINT8 **pbuf_ptr, UINT8 *buf_end,
UINT32 *header_state)
{
UINT8 *buf_ptr;
unsigned int state, v;
int val;
state = *header_state;
buf_ptr = *pbuf_ptr;
while (buf_ptr < buf_end) {
v = *buf_ptr++;
if (state == 0x000001) {
state = ((state << 8) | v) & 0xffffff;
val = state;
goto found;
}
state = ((state << 8) | v) & 0xffffff;
}
val = -1;
found:
*pbuf_ptr = buf_ptr;
*header_state = state;
return val;
}
static int mpeg1_decode_picture(AVCodecContext *avctx,
UINT8 *buf, int buf_size)
{
Mpeg1Context *s1 = avctx->priv_data;
MpegEncContext *s = &s1->mpeg_enc_ctx;
int ref, f_code;
init_get_bits(&s->gb, buf, buf_size);
ref = get_bits(&s->gb, 10); /* temporal ref */
s->pict_type = get_bits(&s->gb, 3);
dprintf("pict_type=%d number=%d\n", s->pict_type, s->picture_number);
skip_bits(&s->gb, 16);
if (s->pict_type == P_TYPE || s->pict_type == B_TYPE) {
s->full_pel[0] = get_bits1(&s->gb);
f_code = get_bits(&s->gb, 3);
if (f_code == 0)
return -1;
s->mpeg_f_code[0][0] = f_code;
s->mpeg_f_code[0][1] = f_code;
}
if (s->pict_type == B_TYPE) {
s->full_pel[1] = get_bits1(&s->gb);
f_code = get_bits(&s->gb, 3);
if (f_code == 0)
return -1;
s->mpeg_f_code[1][0] = f_code;
s->mpeg_f_code[1][1] = f_code;
}
s->y_dc_scale = 8;
s->c_dc_scale = 8;
s->first_slice = 1;
return 0;
}
static void mpeg_decode_sequence_extension(MpegEncContext *s)
{
int horiz_size_ext, vert_size_ext;
int bit_rate_ext, vbv_buf_ext, low_delay;
int frame_rate_ext_n, frame_rate_ext_d;
skip_bits(&s->gb, 8); /* profil and level */
skip_bits(&s->gb, 1); /* progressive_sequence */
skip_bits(&s->gb, 2); /* chroma_format */
horiz_size_ext = get_bits(&s->gb, 2);
vert_size_ext = get_bits(&s->gb, 2);
s->width |= (horiz_size_ext << 12);
s->height |= (vert_size_ext << 12);
bit_rate_ext = get_bits(&s->gb, 12); /* XXX: handle it */
s->bit_rate = ((s->bit_rate / 400) | (bit_rate_ext << 12)) * 400;
skip_bits1(&s->gb); /* marker */
vbv_buf_ext = get_bits(&s->gb, 8);
low_delay = get_bits1(&s->gb);
frame_rate_ext_n = get_bits(&s->gb, 2);
frame_rate_ext_d = get_bits(&s->gb, 5);
if (frame_rate_ext_d >= 1)
s->frame_rate = (s->frame_rate * frame_rate_ext_n) / frame_rate_ext_d;
dprintf("sequence extension\n");
s->mpeg2 = 1;
}
static void mpeg_decode_quant_matrix_extension(MpegEncContext *s)
{
int i, v, j;
dprintf("matrix extension\n");
if (get_bits1(&s->gb)) {
for(i=0;i<64;i++) {
v = get_bits(&s->gb, 8);
j = zigzag_direct[i];
s->intra_matrix[j] = v;
s->chroma_intra_matrix[j] = v;
}
}
if (get_bits1(&s->gb)) {
for(i=0;i<64;i++) {
v = get_bits(&s->gb, 8);
j = zigzag_direct[i];
s->non_intra_matrix[j] = v;
s->chroma_non_intra_matrix[j] = v;
}
}
if (get_bits1(&s->gb)) {
for(i=0;i<64;i++) {
v = get_bits(&s->gb, 8);
j = zigzag_direct[i];
s->chroma_intra_matrix[j] = v;
}
}
if (get_bits1(&s->gb)) {
for(i=0;i<64;i++) {
v = get_bits(&s->gb, 8);
j = zigzag_direct[i];
s->chroma_non_intra_matrix[j] = v;
}
}
}
static void mpeg_decode_picture_coding_extension(MpegEncContext *s)
{
s->full_pel[0] = s->full_pel[1] = 0;
s->mpeg_f_code[0][0] = get_bits(&s->gb, 4);
s->mpeg_f_code[0][1] = get_bits(&s->gb, 4);
s->mpeg_f_code[1][0] = get_bits(&s->gb, 4);
s->mpeg_f_code[1][1] = get_bits(&s->gb, 4);
s->intra_dc_precision = get_bits(&s->gb, 2);
s->picture_structure = get_bits(&s->gb, 2);
s->top_field_first = get_bits1(&s->gb);
s->frame_pred_frame_dct = get_bits1(&s->gb);
s->concealment_motion_vectors = get_bits1(&s->gb);
s->q_scale_type = get_bits1(&s->gb);
s->intra_vlc_format = get_bits1(&s->gb);
s->alternate_scan = get_bits1(&s->gb);
s->repeat_first_field = get_bits1(&s->gb);
s->chroma_420_type = get_bits1(&s->gb);
s->progressive_frame = get_bits1(&s->gb);
/* composite display not parsed */
dprintf("intra_dc_precion=%d\n", s->intra_dc_precision);
dprintf("picture_structure=%d\n", s->picture_structure);
dprintf("conceal=%d\n", s->concealment_motion_vectors);
dprintf("intra_vlc_format=%d\n", s->intra_vlc_format);
dprintf("alternate_scan=%d\n", s->alternate_scan);
dprintf("frame_pred_frame_dct=%d\n", s->frame_pred_frame_dct);
}
static void mpeg_decode_extension(AVCodecContext *avctx,
UINT8 *buf, int buf_size)
{
Mpeg1Context *s1 = avctx->priv_data;
MpegEncContext *s = &s1->mpeg_enc_ctx;
int ext_type;
init_get_bits(&s->gb, buf, buf_size);
ext_type = get_bits(&s->gb, 4);
switch(ext_type) {
case 0x1:
/* sequence ext */
mpeg_decode_sequence_extension(s);
break;
case 0x3:
/* quant matrix extension */
mpeg_decode_quant_matrix_extension(s);
break;
case 0x8:
/* picture extension */
mpeg_decode_picture_coding_extension(s);
break;
}
}
/* return 1 if end of frame */
static int mpeg_decode_slice(AVCodecContext *avctx,
AVPicture *pict,
int start_code,
UINT8 *buf, int buf_size)
{
Mpeg1Context *s1 = avctx->priv_data;
MpegEncContext *s = &s1->mpeg_enc_ctx;
int ret;
start_code = (start_code - 1) & 0xff;
if (start_code >= s->mb_height)
return -1;
s->last_dc[0] = 1 << (7 + s->intra_dc_precision);
s->last_dc[1] = s->last_dc[0];
s->last_dc[2] = s->last_dc[0];
memset(s->last_mv, 0, sizeof(s->last_mv));
s->mb_x = -1;
s->mb_y = start_code;
s->mb_incr = 0;
/* start frame decoding */
if (s->first_slice) {
s->first_slice = 0;
MPV_frame_start(s);
}
init_get_bits(&s->gb, buf, buf_size);
s->qscale = get_qscale(s);
/* extra slice info */
while (get_bits1(&s->gb) != 0) {
skip_bits(&s->gb, 8);
}
for(;;) {
memset(s->block, 0, sizeof(s->block));
ret = mpeg_decode_mb(s, s->block);
dprintf("ret=%d\n", ret);
if (ret < 0)
return -1;
if (ret == 1)
break;
MPV_decode_mb(s, s->block);
}
/* end of slice reached */
if (s->mb_x == (s->mb_width - 1) &&
s->mb_y == (s->mb_height - 1)) {
/* end of image */
UINT8 **picture;
MPV_frame_end(s);
/* XXX: incorrect reported qscale for mpeg2 */
if (s->pict_type == B_TYPE) {
picture = s->current_picture;
avctx->quality = s->qscale;
} else {
/* latency of 1 frame for I and P frames */
/* XXX: use another variable than picture_number */
if (s->picture_number == 0) {
picture = NULL;
} else {
picture = s->last_picture;
avctx->quality = s->last_qscale;
}
s->last_qscale = s->qscale;
s->picture_number++;
}
if (picture) {
pict->data[0] = picture[0];
pict->data[1] = picture[1];
pict->data[2] = picture[2];
pict->linesize[0] = s->linesize;
pict->linesize[1] = s->linesize / 2;
pict->linesize[2] = s->linesize / 2;
return 1;
} else {
return 0;
}
} else {
return 0;
}
}
static int mpeg1_decode_sequence(AVCodecContext *avctx,
UINT8 *buf, int buf_size)
{
Mpeg1Context *s1 = avctx->priv_data;
MpegEncContext *s = &s1->mpeg_enc_ctx;
int width, height, i, v, j;
init_get_bits(&s->gb, buf, buf_size);
width = get_bits(&s->gb, 12);
height = get_bits(&s->gb, 12);
skip_bits(&s->gb, 4);
s->frame_rate_index = get_bits(&s->gb, 4);
if (s->frame_rate_index == 0)
return -1;
s->bit_rate = get_bits(&s->gb, 18) * 400;
if (get_bits1(&s->gb) == 0) /* marker */
return -1;
if (width <= 0 || height <= 0 ||
(width % 2) != 0 || (height % 2) != 0)
return -1;
if (width != s->width ||
height != s->height) {
/* start new mpeg1 context decoding */
s->out_format = FMT_MPEG1;
if (s1->mpeg_enc_ctx_allocated) {
MPV_common_end(s);
}
s->width = width;
s->height = height;
s->has_b_frames = 1;
s->avctx = avctx;
avctx->width = width;
avctx->height = height;
avctx->frame_rate = frame_rate_tab[s->frame_rate_index];
avctx->bit_rate = s->bit_rate;
if (MPV_common_init(s) < 0)
return -1;
mpeg1_init_vlc(s);
s1->mpeg_enc_ctx_allocated = 1;
}
skip_bits(&s->gb, 10); /* vbv_buffer_size */
skip_bits(&s->gb, 1);
/* get matrix */
if (get_bits1(&s->gb)) {
for(i=0;i<64;i++) {
v = get_bits(&s->gb, 8);
j = zigzag_direct[i];
s->intra_matrix[j] = v;
s->chroma_intra_matrix[j] = v;
}
#ifdef DEBUG
dprintf("intra matrix present\n");
for(i=0;i<64;i++)
dprintf(" %d", s->intra_matrix[zigzag_direct[i]]);
printf("\n");
#endif
} else {
for(i=0;i<64;i++) {
v = default_intra_matrix[i];
s->intra_matrix[i] = v;
s->chroma_intra_matrix[i] = v;
}
}
if (get_bits1(&s->gb)) {
for(i=0;i<64;i++) {
v = get_bits(&s->gb, 8);
j = zigzag_direct[i];
s->non_intra_matrix[j] = v;
s->chroma_non_intra_matrix[j] = v;
}
#ifdef DEBUG
dprintf("non intra matrix present\n");
for(i=0;i<64;i++)
dprintf(" %d", s->non_intra_matrix[zigzag_direct[i]]);
printf("\n");
#endif
} else {
for(i=0;i<64;i++) {
v = default_non_intra_matrix[i];
s->non_intra_matrix[i] = v;
s->chroma_non_intra_matrix[i] = v;
}
}
/* we set mpeg2 parameters so that it emulates mpeg1 */
s->progressive_sequence = 1;
s->progressive_frame = 1;
s->picture_structure = PICT_FRAME;
s->frame_pred_frame_dct = 1;
s->mpeg2 = 0;
return 0;
}
/* handle buffering and image synchronisation */
static int mpeg_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
UINT8 *buf, int buf_size)
{
Mpeg1Context *s = avctx->priv_data;
UINT8 *buf_end, *buf_ptr, *buf_start;
int len, start_code_found, ret, code, start_code, input_size;
AVPicture *picture = data;
dprintf("fill_buffer\n");
*data_size = 0;
/* special case for last picture */
if (buf_size == 0) {
MpegEncContext *s2 = &s->mpeg_enc_ctx;
if (s2->picture_number > 0) {
picture->data[0] = s2->next_picture[0];
picture->data[1] = s2->next_picture[1];
picture->data[2] = s2->next_picture[2];
picture->linesize[0] = s2->linesize;
picture->linesize[1] = s2->linesize / 2;
picture->linesize[2] = s2->linesize / 2;
*data_size = sizeof(AVPicture);
}
return 0;
}
buf_ptr = buf;
buf_end = buf + buf_size;
while (buf_ptr < buf_end) {
buf_start = buf_ptr;
/* find start next code */
code = find_start_code(&buf_ptr, buf_end, &s->header_state);
if (code >= 0) {
start_code_found = 1;
} else {
start_code_found = 0;
}
/* copy to buffer */
len = buf_ptr - buf_start;
if (len + (s->buf_ptr - s->buffer) > s->buffer_size) {
/* data too big : flush */
s->buf_ptr = s->buffer;
if (start_code_found)
s->start_code = code;
} else {
memcpy(s->buf_ptr, buf_start, len);
s->buf_ptr += len;
if (start_code_found) {
/* prepare data for next start code */
input_size = s->buf_ptr - s->buffer;
start_code = s->start_code;
s->buf_ptr = s->buffer;
s->start_code = code;
switch(start_code) {
case SEQ_START_CODE:
mpeg1_decode_sequence(avctx, s->buffer,
input_size);
break;
case PICTURE_START_CODE:
/* we have a complete image : we try to decompress it */
mpeg1_decode_picture(avctx,
s->buffer, input_size);
break;
case EXT_START_CODE:
mpeg_decode_extension(avctx,
s->buffer, input_size);
break;
default:
if (start_code >= SLICE_MIN_START_CODE &&
start_code <= SLICE_MAX_START_CODE) {
ret = mpeg_decode_slice(avctx, picture,
start_code, s->buffer, input_size);
if (ret == 1) {
/* got a picture: exit */
*data_size = sizeof(AVPicture);
goto the_end;
}
}
break;
}
}
}
}
the_end:
return buf_ptr - buf;
}
static int mpeg_decode_end(AVCodecContext *avctx)
{
Mpeg1Context *s = avctx->priv_data;
if (s->mpeg_enc_ctx_allocated)
MPV_common_end(&s->mpeg_enc_ctx);
return 0;
}
AVCodec mpeg_decoder = {
"mpegvideo",
CODEC_TYPE_VIDEO,
CODEC_ID_MPEG1VIDEO,
sizeof(Mpeg1Context),
mpeg_decode_init,
NULL,
mpeg_decode_end,
mpeg_decode_frame,
};
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