- 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);
- s->dsp.clear_blocks(s->block[0]);
-
- 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_skiped = 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);
- s->dsp.clear_blocks(s->block[0]);
-
- // 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)){
- for (i = 0; i < 6; i++) {
- if (h261_decode_block(h, s->block[i], i, cbp&32) < 0){
- return SLICE_ERROR;
- }
- cbp+=cbp;
- }
- }
-
- MPV_decode_mb(s, s->block);
-
- return SLICE_OK;
-}
-
-/**
- * decodes a macroblock
- * @return <0 if an error occured
- */
-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
- */
-int h261_decode_picture_header(H261Context *h){
- MpegEncContext * const s = &h->s;
- int format, i;
- uint32_t startcode= 0;
-
- for(i= s->gb.size_in_bits - get_bits_count(&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 */
- s->picture_number = get_bits(&s->gb, 5); /* picture timestamp */
-
- /* 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 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 = 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;
-}
-
-static int h261_find_frame_end(ParseContext *pc, AVCodecContext* avctx, const uint8_t *buf, int buf_size){
- int vop_found, i, j, bits_left, last_bits;
- uint32_t state;
-
- H261Context *h = avctx->priv_data;
-
- if(h){
- bits_left = h->bits_left;
- last_bits = h->last_bits;
- }
- else{
- bits_left = 0;
- last_bits = 0;
- }
-
- vop_found= pc->frame_start_found;
- state= pc->state;
- if(bits_left!=0 && !vop_found)
- state = state << (8-bits_left) | last_bits;
- i=0;
- if(!vop_found){
- for(i=0; i<buf_size; i++){
- state= (state<<8) | buf[i];
- for(j=0; j<8; j++){
- if(( ( (state<<j) | (buf[i]>>(8-j)) )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
- i++;
- vop_found=1;
- break;
- }
- }
- if(vop_found)
- break;
- }
- }
- if(vop_found){
- for(; i<buf_size; i++){
- if(avctx->flags & CODEC_FLAG_TRUNCATED)//XXX ffplay workaround, someone a better solution?
- state= (state<<8) | buf[i];
- for(j=0; j<8; j++){
- if(( ( (state<<j) | (buf[i]>>(8-j)) )>>(32-20) == 0x10 )&&(((state >> (17-j)) & 0x4000) == 0x0)){
- pc->frame_start_found=0;
- pc->state=-1;
- return i-3;
- }
- }
- }
- }
-
- pc->frame_start_found= vop_found;
- pc->state= state;
- return END_NOT_FOUND;
-}
-
-static int h261_parse(AVCodecParserContext *s,
- AVCodecContext *avctx,
- uint8_t **poutbuf, int *poutbuf_size,
- const uint8_t *buf, int buf_size)
-{
- ParseContext *pc = s->priv_data;
- int next;
-
- next= h261_find_frame_end(pc,avctx, buf, buf_size);
- if (ff_combine_frame(pc, next, (uint8_t **)&buf, &buf_size) < 0) {
- *poutbuf = NULL;
- *poutbuf_size = 0;
- return buf_size;
- }
- *poutbuf = (uint8_t *)buf;
- *poutbuf_size = buf_size;
- return next;
-}
-
-/**
- * returns the number of bytes consumed for building the current frame
- */
-static int get_consumed_bytes(MpegEncContext *s, int buf_size){
- if(s->flags&CODEC_FLAG_TRUNCATED){
- int pos= (get_bits_count(&s->gb)+7)>>3;
- pos -= s->parse_context.last_index;
- if(pos<0) pos=0;// padding is not really read so this might be -1
- return pos;
- }else{
- int pos= get_bits_count(&s->gb)>>3;
- if(pos==0) pos=1; //avoid infinite loops (i doubt thats needed but ...)
- if(pos+10>buf_size) pos=buf_size; // oops ;)