-/**
- * 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;
- static int h261_framecounter = 0;
- uint32_t startcode;
- align_get_bits(&s->gb);
-
- startcode = (h->last_bits << (12 - (8-h->bits_left))) | get_bits(&s->gb, 20-8 - (8- h->bits_left));
-
- 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, pass the test in MPV_frame_start in mpegvideo.c
- if(h261_framecounter > 1)
- s->pict_type = P_TYPE;
- else
- s->pict_type = I_TYPE;
-
- h261_framecounter++;
-
- h->gob_number = 0;
- return 0;
-}
-
-static int h261_decode_gob(H261Context *h){
- MpegEncContext * const s = &h->s;
- int i;
-
- ff_set_qscale(s, s->qscale);
- while(h->current_mba <= MAX_MBA)
- {
- int ret;
- /* DCT & quantize */
- s->dsp.clear_blocks(s->block[0]);
- ret= h261_decode_mb(h, s->block);
- if(ret<0){
- const int xy= s->mb_x + s->mb_y*s->mb_stride;
- if(ret==SLICE_END){
- MPV_decode_mb(s, s->block);
- if(h->loop_filter){
- ff_h261_loop_filter(h);
- }
- h->loop_filter = 0;
- for(i=1; i<h->mba_diff; i++){
- s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1-i) % 11);
- s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1-i) / 11);
- ff_init_block_index(s);
- ff_update_block_index(s);
- s->dsp.clear_blocks(s->block[0]);
- ret= h261_decode_mb_skipped(h, s->block);
- MPV_decode_mb(s, s->block);
- }
-
- return 0;
- }else if(ret==SLICE_NOEND){
- av_log(s->avctx, AV_LOG_ERROR, "Slice mismatch at MB: %d\n", xy);
- return -1;
- }
- av_log(s->avctx, AV_LOG_ERROR, "Error at MB: %d\n", xy);
- return -1;
- }
- MPV_decode_mb(s, s->block);
- if(h->loop_filter){
- ff_h261_loop_filter(h);
- }
-
- h->loop_filter = 0;
- for(i=1; i<h->mba_diff; i++){
- s->mb_x= ((h->gob_number-1) % 2) * 11 + ((h->current_mba-1-i) % 11);
- s->mb_y= ((h->gob_number-1) / 2) * 3 + ((h->current_mba-1-i) / 11);
- ff_init_block_index(s);
- ff_update_block_index(s);
- s->dsp.clear_blocks(s->block[0]);
- ret= h261_decode_mb_skipped(h, s->block);
- MPV_decode_mb(s, s->block);
- }
- }
-
- 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){
- int pos= (get_bits_count(&s->gb)+7)>>3;
-
- if(s->flags&CODEC_FLAG_TRUNCATED){
- pos -= s->parse_context.last_index;
- if(pos<0) pos=0;// padding is not really read so this might be -1
- return pos;
- }else{
- if(pos==0) pos=1; //avoid infinite loops (i doubt thats 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,
- uint8_t *buf, int buf_size)