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FFmpeg/libavcodec/h261dec.c
Stefano Sabatini 72415b2adb Define AVMediaType enum, and use it instead of enum CodecType, which 
is deprecated and will be dropped at the next major bump.

Originally committed as revision 22735 to svn://svn.ffmpeg.org/ffmpeg/trunk
2010-03-30 23:30:55 +00:00

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/*
* H261 decoder
* 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 libavcodec/h261dec.c
* H.261 decoder.
*/
#include "dsputil.h"
#include "avcodec.h"
#include "mpegvideo.h"
#include "h263.h"
#include "h261.h"
#include "h261data.h"
#define H261_MBA_VLC_BITS 9
#define H261_MTYPE_VLC_BITS 6
#define H261_MV_VLC_BITS 7
#define H261_CBP_VLC_BITS 9
#define TCOEFF_VLC_BITS 9
#define MBA_STUFFING 33
#define MBA_STARTCODE 34
extern uint8_t ff_h261_rl_table_store[2][2*MAX_RUN + MAX_LEVEL + 3];
static VLC h261_mba_vlc;
static VLC h261_mtype_vlc;
static VLC h261_mv_vlc;
static VLC h261_cbp_vlc;
static int h261_decode_block(H261Context * h, DCTELEM * block, int n, int coded);
static av_cold void h261_decode_init_vlc(H261Context *h){
static int done = 0;
if(!done){
done = 1;
INIT_VLC_STATIC(&h261_mba_vlc, H261_MBA_VLC_BITS, 35,
h261_mba_bits, 1, 1,
h261_mba_code, 1, 1, 662);
INIT_VLC_STATIC(&h261_mtype_vlc, H261_MTYPE_VLC_BITS, 10,
h261_mtype_bits, 1, 1,
h261_mtype_code, 1, 1, 80);
INIT_VLC_STATIC(&h261_mv_vlc, H261_MV_VLC_BITS, 17,
&h261_mv_tab[0][1], 2, 1,
&h261_mv_tab[0][0], 2, 1, 144);
INIT_VLC_STATIC(&h261_cbp_vlc, H261_CBP_VLC_BITS, 63,
&h261_cbp_tab[0][1], 2, 1,
&h261_cbp_tab[0][0], 2, 1, 512);
init_rl(&h261_rl_tcoeff, ff_h261_rl_table_store);
INIT_VLC_RL(h261_rl_tcoeff, 552);
}
}
static av_cold int h261_decode_init(AVCodecContext *avctx){
H261Context *h= avctx->priv_data;
MpegEncContext * const s = &h->s;
// set defaults
MPV_decode_defaults(s);
s->avctx = avctx;
s->width = s->avctx->coded_width;
s->height = s->avctx->coded_height;
s->codec_id = s->avctx->codec->id;
s->out_format = FMT_H261;
s->low_delay= 1;
avctx->pix_fmt= PIX_FMT_YUV420P;
s->codec_id= avctx->codec->id;
h261_decode_init_vlc(h);
h->gob_start_code_skipped = 0;
return 0;
}
/**
* decodes the group of blocks header or slice header.
* @return <0 if an error occurred
*/
static int h261_decode_gob_header(H261Context *h){
unsigned int val;
MpegEncContext * const s = &h->s;
if ( !h->gob_start_code_skipped ){
/* Check for GOB Start Code */
val = show_bits(&s->gb, 15);
if(val)
return -1;
/* We have a GBSC */
skip_bits(&s->gb, 16);
}
h->gob_start_code_skipped = 0;
h->gob_number = get_bits(&s->gb, 4); /* GN */
s->qscale = get_bits(&s->gb, 5); /* GQUANT */
/* Check if gob_number is valid */
if (s->mb_height==18){ //cif
if ((h->gob_number<=0) || (h->gob_number>12))
return -1;
}
else{ //qcif
if ((h->gob_number!=1) && (h->gob_number!=3) && (h->gob_number!=5))
return -1;
}
/* GEI */
while (get_bits1(&s->gb) != 0) {
skip_bits(&s->gb, 8);
}
if(s->qscale==0) {
av_log(s->avctx, AV_LOG_ERROR, "qscale has forbidden 0 value\n");
if (s->avctx->error_recognition >= FF_ER_COMPLIANT)
return -1;
}
// For the first transmitted macroblock in a GOB, MBA is the absolute address. For
// subsequent macroblocks, MBA is the difference between the absolute addresses of
// the macroblock and the last transmitted macroblock.
h->current_mba = 0;
h->mba_diff = 0;
return 0;
}
/**
* decodes the group of blocks / video packet header.
* @return <0 if no resync found
*/
static int ff_h261_resync(H261Context *h){
MpegEncContext * const s = &h->s;
int left, ret;
if ( h->gob_start_code_skipped ){
ret= h261_decode_gob_header(h);
if(ret>=0)
return 0;
}
else{
if(show_bits(&s->gb, 15)==0){
ret= h261_decode_gob_header(h);
if(ret>=0)
return 0;
}
//OK, it is not where it is supposed to be ...
s->gb= s->last_resync_gb;
align_get_bits(&s->gb);
left= get_bits_left(&s->gb);
for(;left>15+1+4+5; left-=8){
if(show_bits(&s->gb, 15)==0){
GetBitContext bak= s->gb;
ret= h261_decode_gob_header(h);
if(ret>=0)
return 0;
s->gb= bak;
}
skip_bits(&s->gb, 8);
}
}
return -1;
}
/**
* decodes skipped macroblocks
* @return 0
*/
static int h261_decode_mb_skipped(H261Context *h, int mba1, int mba2 )
{
MpegEncContext * const s = &h->s;
int i;
s->mb_intra = 0;
for(i=mba1; i<mba2; i++){
int j, xy;
s->mb_x= ((h->gob_number-1) % 2) * 11 + i % 11;
s->mb_y= ((h->gob_number-1) / 2) * 3 + i / 11;
xy = s->mb_x + s->mb_y * s->mb_stride;
ff_init_block_index(s);
ff_update_block_index(s);
for(j=0;j<6;j++)
s->block_last_index[j] = -1;
s->mv_dir = MV_DIR_FORWARD;
s->mv_type = MV_TYPE_16X16;
s->current_picture.mb_type[xy]= MB_TYPE_SKIP | MB_TYPE_16x16 | MB_TYPE_L0;
s->mv[0][0][0] = 0;
s->mv[0][0][1] = 0;
s->mb_skipped = 1;
h->mtype &= ~MB_TYPE_H261_FIL;
MPV_decode_mb(s, s->block);
}
return 0;
}
static int decode_mv_component(GetBitContext *gb, int v){
int mv_diff = get_vlc2(gb, h261_mv_vlc.table, H261_MV_VLC_BITS, 2);
/* check if mv_diff is valid */
if ( mv_diff < 0 )
return v;
mv_diff = mvmap[mv_diff];
if(mv_diff && !get_bits1(gb))
mv_diff= -mv_diff;
v += mv_diff;
if (v <=-16) v+= 32;
else if(v >= 16) v-= 32;
return v;
}
static int h261_decode_mb(H261Context *h){
MpegEncContext * const s = &h->s;
int i, cbp, xy;
cbp = 63;
// Read mba
do{
h->mba_diff = get_vlc2(&s->gb, h261_mba_vlc.table, H261_MBA_VLC_BITS, 2);
/* Check for slice end */
/* NOTE: GOB can be empty (no MB data) or exist only of MBA_stuffing */
if (h->mba_diff == MBA_STARTCODE){ // start code
h->gob_start_code_skipped = 1;
return SLICE_END;
}
}
while( h->mba_diff == MBA_STUFFING ); // stuffing
if ( h->mba_diff < 0 ){
if ( get_bits_count(&s->gb) + 7 >= s->gb.size_in_bits )
return SLICE_END;
av_log(s->avctx, AV_LOG_ERROR, "illegal mba at %d %d\n", s->mb_x, s->mb_y);
return SLICE_ERROR;
}
h->mba_diff += 1;
h->current_mba += h->mba_diff;
if ( h->current_mba > MBA_STUFFING )
return SLICE_ERROR;
s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1) % 11);
s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1) / 11);
xy = s->mb_x + s->mb_y * s->mb_stride;
ff_init_block_index(s);
ff_update_block_index(s);
// Read mtype
h->mtype = get_vlc2(&s->gb, h261_mtype_vlc.table, H261_MTYPE_VLC_BITS, 2);
h->mtype = h261_mtype_map[h->mtype];
// Read mquant
if ( IS_QUANT ( h->mtype ) ){
ff_set_qscale(s, get_bits(&s->gb, 5));
}
s->mb_intra = IS_INTRA4x4(h->mtype);
// Read mv
if ( IS_16X16 ( h->mtype ) ){
// Motion vector data is included for all MC macroblocks. MVD is obtained from the macroblock vector by subtracting the
// vector of the preceding macroblock. For this calculation the vector of the preceding macroblock is regarded as zero in the
// following three situations:
// 1) evaluating MVD for macroblocks 1, 12 and 23;
// 2) evaluating MVD for macroblocks in which MBA does not represent a difference of 1;
// 3) MTYPE of the previous macroblock was not MC.
if ( ( h->current_mba == 1 ) || ( h->current_mba == 12 ) || ( h->current_mba == 23 ) ||
( h->mba_diff != 1))
{
h->current_mv_x = 0;
h->current_mv_y = 0;
}
h->current_mv_x= decode_mv_component(&s->gb, h->current_mv_x);
h->current_mv_y= decode_mv_component(&s->gb, h->current_mv_y);
}else{
h->current_mv_x = 0;
h->current_mv_y = 0;
}
// Read cbp
if ( HAS_CBP( h->mtype ) ){
cbp = get_vlc2(&s->gb, h261_cbp_vlc.table, H261_CBP_VLC_BITS, 2) + 1;
}
if(s->mb_intra){
s->current_picture.mb_type[xy]= MB_TYPE_INTRA;
goto intra;
}
//set motion vectors
s->mv_dir = MV_DIR_FORWARD;
s->mv_type = MV_TYPE_16X16;
s->current_picture.mb_type[xy]= MB_TYPE_16x16 | MB_TYPE_L0;
s->mv[0][0][0] = h->current_mv_x * 2;//gets divided by 2 in motion compensation
s->mv[0][0][1] = h->current_mv_y * 2;
intra:
/* decode each block */
if(s->mb_intra || HAS_CBP(h->mtype)){
s->dsp.clear_blocks(s->block[0]);
for (i = 0; i < 6; i++) {
if (h261_decode_block(h, s->block[i], i, cbp&32) < 0){
return SLICE_ERROR;
}
cbp+=cbp;
}
}else{
for (i = 0; i < 6; i++)
s->block_last_index[i]= -1;
}
MPV_decode_mb(s, s->block);
return SLICE_OK;
}
/**
* decodes a macroblock
* @return <0 if an error occurred
*/
static int h261_decode_block(H261Context * h, DCTELEM * block,
int n, int coded)
{
MpegEncContext * const s = &h->s;
int code, level, i, j, run;
RLTable *rl = &h261_rl_tcoeff;
const uint8_t *scan_table;
// For the variable length encoding there are two code tables, one being used for
// the first transmitted LEVEL in INTER, INTER+MC and INTER+MC+FIL blocks, the second
// for all other LEVELs except the first one in INTRA blocks which is fixed length
// coded with 8 bits.
// NOTE: the two code tables only differ in one VLC so we handle that manually.
scan_table = s->intra_scantable.permutated;
if (s->mb_intra){
/* DC coef */
level = get_bits(&s->gb, 8);
// 0 (00000000b) and -128 (10000000b) are FORBIDDEN
if((level&0x7F) == 0){
av_log(s->avctx, AV_LOG_ERROR, "illegal dc %d at %d %d\n", level, s->mb_x, s->mb_y);
return -1;
}
// The code 1000 0000 is not used, the reconstruction level of 1024 being coded as 1111 1111.
if (level == 255)
level = 128;
block[0] = level;
i = 1;
}else if(coded){
// Run Level Code
// EOB Not possible for first level when cbp is available (that's why the table is different)
// 0 1 1s
// * * 0*
int check = show_bits(&s->gb, 2);
i = 0;
if ( check & 0x2 ){
skip_bits(&s->gb, 2);
block[0] = ( check & 0x1 ) ? -1 : 1;
i = 1;
}
}else{
i = 0;
}
if(!coded){
s->block_last_index[n] = i - 1;
return 0;
}
for(;;){
code = get_vlc2(&s->gb, rl->vlc.table, TCOEFF_VLC_BITS, 2);
if (code < 0){
av_log(s->avctx, AV_LOG_ERROR, "illegal ac vlc code at %dx%d\n", s->mb_x, s->mb_y);
return -1;
}
if (code == rl->n) {
/* escape */
// The remaining combinations of (run, level) are encoded with a 20-bit word consisting of 6 bits escape, 6 bits run and 8 bits level.
run = get_bits(&s->gb, 6);
level = get_sbits(&s->gb, 8);
}else if(code == 0){
break;
}else{
run = rl->table_run[code];
level = rl->table_level[code];
if (get_bits1(&s->gb))
level = -level;
}
i += run;
if (i >= 64){
av_log(s->avctx, AV_LOG_ERROR, "run overflow at %dx%d\n", s->mb_x, s->mb_y);
return -1;
}
j = scan_table[i];
block[j] = level;
i++;
}
s->block_last_index[n] = i-1;
return 0;
}
/**
* decodes the H261 picture header.
* @return <0 if no startcode found
*/
static int h261_decode_picture_header(H261Context *h){
MpegEncContext * const s = &h->s;
int format, i;
uint32_t startcode= 0;
for(i= get_bits_left(&s->gb); i>24; i-=1){
startcode = ((startcode << 1) | get_bits(&s->gb, 1)) & 0x000FFFFF;
if(startcode == 0x10)
break;
}
if (startcode != 0x10){
av_log(s->avctx, AV_LOG_ERROR, "Bad picture start code\n");
return -1;
}
/* temporal reference */
i= get_bits(&s->gb, 5); /* picture timestamp */
if(i < (s->picture_number&31))
i += 32;
s->picture_number = (s->picture_number&~31) + i;
s->avctx->time_base= (AVRational){1001, 30000};
s->current_picture.pts= s->picture_number;
/* PTYPE starts here */
skip_bits1(&s->gb); /* split screen off */
skip_bits1(&s->gb); /* camera off */
skip_bits1(&s->gb); /* freeze picture release off */
format = get_bits1(&s->gb);
//only 2 formats possible
if (format == 0){//QCIF
s->width = 176;
s->height = 144;
s->mb_width = 11;
s->mb_height = 9;
}else{//CIF
s->width = 352;
s->height = 288;
s->mb_width = 22;
s->mb_height = 18;
}
s->mb_num = s->mb_width * s->mb_height;
skip_bits1(&s->gb); /* still image mode off */
skip_bits1(&s->gb); /* Reserved */
/* PEI */
while (get_bits1(&s->gb) != 0){
skip_bits(&s->gb, 8);
}
// h261 has no I-FRAMES, but if we pass FF_I_TYPE for the first frame, the codec crashes if it does
// not contain all I-blocks (e.g. when a packet is lost)
s->pict_type = FF_P_TYPE;
h->gob_number = 0;
return 0;
}
static int h261_decode_gob(H261Context *h){
MpegEncContext * const s = &h->s;
ff_set_qscale(s, s->qscale);
/* decode mb's */
while(h->current_mba <= MBA_STUFFING)
{
int ret;
/* DCT & quantize */
ret= h261_decode_mb(h);
if(ret<0){
if(ret==SLICE_END){
h261_decode_mb_skipped(h, h->current_mba, 33);
return 0;
}
av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", s->mb_x + s->mb_y*s->mb_stride);
return -1;
}
h261_decode_mb_skipped(h, h->current_mba-h->mba_diff, h->current_mba-1);
}
return -1;
}
/**
* returns the number of bytes consumed for building the current frame
*/
static int get_consumed_bytes(MpegEncContext *s, int buf_size){
int pos= get_bits_count(&s->gb)>>3;
if(pos==0) pos=1; //avoid infinite loops (i doubt that is needed but ...)
if(pos+10>buf_size) pos=buf_size; // oops ;)
return pos;
}
static int h261_decode_frame(AVCodecContext *avctx,
void *data, int *data_size,
AVPacket *avpkt)
{
const uint8_t *buf = avpkt->data;
int buf_size = avpkt->size;
H261Context *h= avctx->priv_data;
MpegEncContext *s = &h->s;
int ret;
AVFrame *pict = data;
dprintf(avctx, "*****frame %d size=%d\n", avctx->frame_number, buf_size);
dprintf(avctx, "bytes=%x %x %x %x\n", buf[0], buf[1], buf[2], buf[3]);
s->flags= avctx->flags;
s->flags2= avctx->flags2;
h->gob_start_code_skipped=0;
retry:
init_get_bits(&s->gb, buf, buf_size*8);
if(!s->context_initialized){
if (MPV_common_init(s) < 0) //we need the idct permutaton for reading a custom matrix
return -1;
}
//we need to set current_picture_ptr before reading the header, otherwise we cannot store anyting im there
if(s->current_picture_ptr==NULL || s->current_picture_ptr->data[0]){
int i= ff_find_unused_picture(s, 0);
s->current_picture_ptr= &s->picture[i];
}
ret = h261_decode_picture_header(h);
/* skip if the header was thrashed */
if (ret < 0){
av_log(s->avctx, AV_LOG_ERROR, "header damaged\n");
return -1;
}
if (s->width != avctx->coded_width || s->height != avctx->coded_height){
ParseContext pc= s->parse_context; //FIXME move this demuxing hack to libavformat
s->parse_context.buffer=0;
MPV_common_end(s);
s->parse_context= pc;
}
if (!s->context_initialized) {
avcodec_set_dimensions(avctx, s->width, s->height);
goto retry;
}
// for hurry_up==5
s->current_picture.pict_type= s->pict_type;
s->current_picture.key_frame= s->pict_type == FF_I_TYPE;
/* skip everything if we are in a hurry>=5 */
if(avctx->hurry_up>=5) return get_consumed_bytes(s, buf_size);
if( (avctx->skip_frame >= AVDISCARD_NONREF && s->pict_type==FF_B_TYPE)
||(avctx->skip_frame >= AVDISCARD_NONKEY && s->pict_type!=FF_I_TYPE)
|| avctx->skip_frame >= AVDISCARD_ALL)
return get_consumed_bytes(s, buf_size);
if(MPV_frame_start(s, avctx) < 0)
return -1;
ff_er_frame_start(s);
/* decode each macroblock */
s->mb_x=0;
s->mb_y=0;
while(h->gob_number < (s->mb_height==18 ? 12 : 5)){
if(ff_h261_resync(h)<0)
break;
h261_decode_gob(h);
}
MPV_frame_end(s);
assert(s->current_picture.pict_type == s->current_picture_ptr->pict_type);
assert(s->current_picture.pict_type == s->pict_type);
*pict= *(AVFrame*)s->current_picture_ptr;
ff_print_debug_info(s, pict);
*data_size = sizeof(AVFrame);
return get_consumed_bytes(s, buf_size);
}
static av_cold int h261_decode_end(AVCodecContext *avctx)
{
H261Context *h= avctx->priv_data;
MpegEncContext *s = &h->s;
MPV_common_end(s);
return 0;
}
AVCodec h261_decoder = {
"h261",
AVMEDIA_TYPE_VIDEO,
CODEC_ID_H261,
sizeof(H261Context),
h261_decode_init,
NULL,
h261_decode_end,
h261_decode_frame,
CODEC_CAP_DR1,
.long_name = NULL_IF_CONFIG_SMALL("H.261"),
};
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