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ffmpeg/libavcodec/h261enc.c

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/*
* H261 encoder
* Copyright (c) 2002-2004 Michael Niedermayer <michaelni@gmx.at>
* Copyright (c) 2004 Maarten Daniels
*
* 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
* H.261 encoder.
*/
#include "dsputil.h"
#include "avcodec.h"
#include "mpegvideo.h"
#include "h263.h"
#include "h261.h"
#include "h261data.h"
extern uint8_t ff_h261_rl_table_store[2][2*MAX_RUN + MAX_LEVEL + 3];
static void h261_encode_block(H261Context * h, DCTELEM * block,
int n);
int ff_h261_get_picture_format(int width, int height){
// QCIF
if (width == 176 && height == 144)
return 0;
// CIF
else if (width == 352 && height == 288)
return 1;
// ERROR
else
return -1;
}
void ff_h261_encode_picture_header(MpegEncContext * s, int picture_number){
H261Context * h = (H261Context *) s;
int format, temp_ref;
align_put_bits(&s->pb);
/* Update the pointer to last GOB */
s->ptr_lastgob = put_bits_ptr(&s->pb);
put_bits(&s->pb, 20, 0x10); /* PSC */
temp_ref= s->picture_number * (int64_t)30000 * s->avctx->time_base.num /
(1001 * (int64_t)s->avctx->time_base.den); //FIXME maybe this should use a timestamp
put_sbits(&s->pb, 5, temp_ref); /* TemporalReference */
put_bits(&s->pb, 1, 0); /* split screen off */
put_bits(&s->pb, 1, 0); /* camera off */
put_bits(&s->pb, 1, 0); /* freeze picture release off */
format = ff_h261_get_picture_format(s->width, s->height);
put_bits(&s->pb, 1, format); /* 0 == QCIF, 1 == CIF */
put_bits(&s->pb, 1, 0); /* still image mode */
put_bits(&s->pb, 1, 0); /* reserved */
put_bits(&s->pb, 1, 0); /* no PEI */
if(format == 0)
h->gob_number = -1;
else
h->gob_number = 0;
h->current_mba = 0;
}
/**
* Encode a group of blocks header.
*/
static void h261_encode_gob_header(MpegEncContext * s, int mb_line){
H261Context * h = (H261Context *)s;
if(ff_h261_get_picture_format(s->width, s->height) == 0){
h->gob_number+=2; // QCIF
}
else{
h->gob_number++; // CIF
}
put_bits(&s->pb, 16, 1); /* GBSC */
put_bits(&s->pb, 4, h->gob_number); /* GN */
put_bits(&s->pb, 5, s->qscale); /* GQUANT */
put_bits(&s->pb, 1, 0); /* no GEI */
h->current_mba = 0;
h->previous_mba = 0;
h->current_mv_x=0;
h->current_mv_y=0;
}
void ff_h261_reorder_mb_index(MpegEncContext* s){
int index= s->mb_x + s->mb_y*s->mb_width;
if(index % 33 == 0)
h261_encode_gob_header(s,0);
/* for CIF the GOB's are fragmented in the middle of a scanline
that's why we need to adjust the x and y index of the macroblocks */
if(ff_h261_get_picture_format(s->width,s->height) == 1){ // CIF
s->mb_x = index % 11 ; index /= 11;
s->mb_y = index % 3 ; index /= 3;
s->mb_x+= 11*(index % 2); index /= 2;
s->mb_y+= 3*index;
ff_init_block_index(s);
ff_update_block_index(s);
}
}
static void h261_encode_motion(H261Context * h, int val){
MpegEncContext * const s = &h->s;
int sign, code;
if(val==0){
code = 0;
put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
}
else{
if(val > 15)
val -=32;
if(val < -16)
val+=32;
sign = val < 0;
code = sign ? -val : val;
put_bits(&s->pb,h261_mv_tab[code][1],h261_mv_tab[code][0]);
put_bits(&s->pb,1,sign);
}
}
static inline int get_cbp(MpegEncContext * s,
DCTELEM block[6][64])
{
int i, cbp;
cbp= 0;
for (i = 0; i < 6; i++) {
if (s->block_last_index[i] >= 0)
cbp |= 1 << (5 - i);
}
return cbp;
}
void ff_h261_encode_mb(MpegEncContext * s,
DCTELEM block[6][64],
int motion_x, int motion_y)
{
H261Context * h = (H261Context *)s;
int mvd, mv_diff_x, mv_diff_y, i, cbp;
cbp = 63; // avoid warning
mvd = 0;
h->current_mba++;
h->mtype = 0;
if (!s->mb_intra){
/* compute cbp */
cbp= get_cbp(s, block);
/* mvd indicates if this block is motion compensated */
mvd = motion_x | motion_y;
if((cbp | mvd | s->dquant ) == 0) {
/* skip macroblock */
s->skip_count++;
h->current_mv_x=0;
h->current_mv_y=0;
return;
}
}
/* MB is not skipped, encode MBA */
put_bits(&s->pb, h261_mba_bits[(h->current_mba-h->previous_mba)-1], h261_mba_code[(h->current_mba-h->previous_mba)-1]);
/* calculate MTYPE */
if(!s->mb_intra){
h->mtype++;
if(mvd || s->loop_filter)
h->mtype+=3;
if(s->loop_filter)
h->mtype+=3;
if(cbp || s->dquant)
h->mtype++;
assert(h->mtype > 1);
}
if(s->dquant)
h->mtype++;
put_bits(&s->pb, h261_mtype_bits[h->mtype], h261_mtype_code[h->mtype]);
h->mtype = h261_mtype_map[h->mtype];
if(IS_QUANT(h->mtype)){
ff_set_qscale(s,s->qscale+s->dquant);
put_bits(&s->pb, 5, s->qscale);
}
if(IS_16X16(h->mtype)){
mv_diff_x = (motion_x >> 1) - h->current_mv_x;
mv_diff_y = (motion_y >> 1) - h->current_mv_y;
h->current_mv_x = (motion_x >> 1);
h->current_mv_y = (motion_y >> 1);
h261_encode_motion(h,mv_diff_x);
h261_encode_motion(h,mv_diff_y);
}
h->previous_mba = h->current_mba;
if(HAS_CBP(h->mtype)){
assert(cbp>0);
put_bits(&s->pb,h261_cbp_tab[cbp-1][1],h261_cbp_tab[cbp-1][0]);
}
for(i=0; i<6; i++) {
/* encode each block */
h261_encode_block(h, block[i], i);
}
if ( ( h->current_mba == 11 ) || ( h->current_mba == 22 ) || ( h->current_mba == 33 ) || ( !IS_16X16 ( h->mtype ) )){
h->current_mv_x=0;
h->current_mv_y=0;
}
}
void ff_h261_encode_init(MpegEncContext *s){
static int done = 0;
if (!done) {
done = 1;
init_rl(&h261_rl_tcoeff, ff_h261_rl_table_store);
}
s->min_qcoeff= -127;
s->max_qcoeff= 127;
s->y_dc_scale_table=
s->c_dc_scale_table= ff_mpeg1_dc_scale_table;
}
/**
* encodes a 8x8 block.
* @param block the 8x8 block
* @param n block index (0-3 are luma, 4-5 are chroma)
*/
static void h261_encode_block(H261Context * h, DCTELEM * block, int n){
MpegEncContext * const s = &h->s;
int level, run, i, j, last_index, last_non_zero, sign, slevel, code;
RLTable *rl;
rl = &h261_rl_tcoeff;
if (s->mb_intra) {
/* DC coef */
level = block[0];
/* 255 cannot be represented, so we clamp */
if (level > 254) {
level = 254;
block[0] = 254;
}
/* 0 cannot be represented also */
else if (level < 1) {
level = 1;
block[0] = 1;
}
if (level == 128)
put_bits(&s->pb, 8, 0xff);
else
put_bits(&s->pb, 8, level);
i = 1;
} else if((block[0]==1 || block[0] == -1) && (s->block_last_index[n] > -1)){
//special case
put_bits(&s->pb,2,block[0]>0 ? 2 : 3 );
i = 1;
} else {
i = 0;
}
/* AC coefs */
last_index = s->block_last_index[n];
last_non_zero = i - 1;
for (; i <= last_index; i++) {
j = s->intra_scantable.permutated[i];
level = block[j];
if (level) {
run = i - last_non_zero - 1;
sign = 0;
slevel = level;
if (level < 0) {
sign = 1;
level = -level;
}
code = get_rl_index(rl, 0 /*no last in H.261, EOB is used*/, run, level);
if(run==0 && level < 16)
code+=1;
put_bits(&s->pb, rl->table_vlc[code][1], rl->table_vlc[code][0]);
if (code == rl->n) {
put_bits(&s->pb, 6, run);
assert(slevel != 0);
assert(level <= 127);
put_sbits(&s->pb, 8, slevel);
} else {
put_bits(&s->pb, 1, sign);
}
last_non_zero = i;
}
}
if(last_index > -1){
put_bits(&s->pb, rl->table_vlc[0][1], rl->table_vlc[0][0]);// END OF BLOCK
}
}
AVCodec ff_h261_encoder = {
.name = "h261",
.type = AVMEDIA_TYPE_VIDEO,
.id = CODEC_ID_H261,
.priv_data_size = sizeof(H261Context),
.init = MPV_encode_init,
.encode = MPV_encode_picture,
.close = MPV_encode_end,
.pix_fmts= (const enum PixelFormat[]){PIX_FMT_YUV420P, PIX_FMT_NONE},
.long_name= NULL_IF_CONFIG_SMALL("H.261"),
};
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