slice.c

网络MPEG4IP流媒体开发源代码

      		/*fprintf(stderr, "mpeg3_decode_slice: too many macroblocks in picture\n"); */
      		return 1;
    	}

/* not skipped */
    	if(mba_inc == 1)
		{
			mpeg3video_macroblock_modes(slice, 
				video, 
				&mb_type, 
				&stwtype, 
				&stwclass,
        		&motion_type, 
				&mv_count, 
				&mv_format, 
				&dmv, 
				&mvscale, 
				&dct_type);

			if(slice->fault) return 1;

      		if(mb_type & MB_QUANT)
			{
        		qs = mpeg3slice_getbits(slice_buffer, 5);

        		if(video->mpeg2)
            	 	slice->quant_scale = video->qscale_type ? mpeg3_non_linear_mquant_table[qs] : (qs << 1);
        		else 
					slice->quant_scale = qs;

        		if(video->scalable_mode == SC_DP)
/* make sure quant_scale is valid */
          			slice->quant_scale = slice->quant_scale;
      		}

/* motion vectors */


/* decode forward motion vectors */
      		if((mb_type & MB_FORWARD) || ((mb_type & MB_INTRA) && video->conceal_mv))
			{
        		if(video->mpeg2)
        			mpeg3video_motion_vectors(slice, 
						video, 
						pmv, 
						dmvector, 
						mv_field_sel, 
            			0, 
						mv_count, 
						mv_format, 
						video->h_forw_r_size, 
						video->v_forw_r_size, 
						dmv, 
						mvscale);
        		else
        		  	mpeg3video_motion_vector(slice, 
						video, 
						pmv[0][0], 
						dmvector, 
            			video->forw_r_size, 
						video->forw_r_size, 
						0, 
						0, 
						video->full_forw);
    		}
      		if(slice->fault) return 1;

/* decode backward motion vectors */
    		if(mb_type & MB_BACKWARD)
			{
        		if(video->mpeg2)
        		  	mpeg3video_motion_vectors(slice, 
						video, 
						pmv, 
						dmvector, 
						mv_field_sel, 
            			1, 
						mv_count, 
						mv_format, 
						video->h_back_r_size, 
						video->v_back_r_size, 
						0, 
						mvscale);
        		else
        		  	mpeg3video_motion_vector(slice, 
						video, 
						pmv[0][1], 
						dmvector, 
            			video->back_r_size, 
						video->back_r_size, 
						0, 
						0, 
						video->full_back);
    		}

      		if(slice->fault) return 1;

/* remove marker_bit */
      		if((mb_type & MB_INTRA) && video->conceal_mv)
        		mpeg3slice_flushbit(slice_buffer);

/* macroblock_pattern */
      		if(mb_type & MB_PATTERN)
			{
        		cbp = mpeg3video_get_cbp(slice);
        		if(video->chroma_format == CHROMA422)
				{
/* coded_block_pattern_1 */
        		  	cbp = (cbp << 2) | mpeg3slice_getbits2(slice_buffer); 
        		}
        		else
				if(video->chroma_format == CHROMA444)
				{
/* coded_block_pattern_2 */
        		  	cbp = (cbp << 6) | mpeg3slice_getbits(slice_buffer, 6); 
        		}
    		}
    		else
        	  	cbp = (mb_type & MB_INTRA) ? ((1 << video->blk_cnt) - 1) : 0;

      		if(slice->fault) return 1;
/* decode blocks */
      		mpeg3video_clearblock(slice, 0, video->blk_cnt);
      		for(comp = 0; comp < video->blk_cnt; comp++)
			{
        		if(cbp & (1 << (video->blk_cnt - comp - 1)))
				{
          			if(mb_type & MB_INTRA)
					{
            			if(video->mpeg2)
							mpeg3video_getmpg2intrablock(slice, video, comp, dc_dct_pred);
            			else
							mpeg3video_getintrablock(slice, video, comp, dc_dct_pred);
          			}
        			else 
					{
            		  	if(video->mpeg2) 
					  		mpeg3video_getmpg2interblock(slice, video, comp);
            		  	else           
					  		mpeg3video_getinterblock(slice, video, comp);
        			}
        			if(slice->fault) return 1;
        		}
      		}

/* reset intra_dc predictors */
			if(!(mb_type & MB_INTRA))
        	  	dc_dct_pred[0] = dc_dct_pred[1] = dc_dct_pred[2] = 0;

/* reset motion vector predictors */
    		if((mb_type & MB_INTRA) && !video->conceal_mv)
			{
/* intra mb without concealment motion vectors */
        		pmv[0][0][0] = pmv[0][0][1] = pmv[1][0][0] = pmv[1][0][1] = 0;
        		pmv[0][1][0] = pmv[0][1][1] = pmv[1][1][0] = pmv[1][1][1] = 0;
    		}

    		if((video->pict_type == P_TYPE) && !(mb_type & (MB_FORWARD | MB_INTRA)))
			{
/* non-intra mb without forward mv in a P picture */
        		pmv[0][0][0] = pmv[0][0][1] = pmv[1][0][0] = pmv[1][0][1] = 0;

/* derive motion_type */
        		if(video->pict_struct == FRAME_PICTURE) 
					motion_type = MC_FRAME;
        		else
        		{
        			motion_type = MC_FIELD;
/* predict from field of same parity */
        			mv_field_sel[0][0] = (video->pict_struct == BOTTOM_FIELD);
        		}
      		}

    		if(stwclass == 4)
    		{
/* purely spatially predicted macroblock */
        		pmv[0][0][0] = pmv[0][0][1] = pmv[1][0][0] = pmv[1][0][1] = 0;
        		pmv[0][1][0] = pmv[0][1][1] = pmv[1][1][0] = pmv[1][1][1] = 0;
    		}
    	}
    	else 
		{
/* mba_inc!=1: skipped macroblock */
      		mpeg3video_clearblock(slice, 0, video->blk_cnt);

/* reset intra_dc predictors */
      		dc_dct_pred[0] = dc_dct_pred[1] = dc_dct_pred[2] = 0;

/* reset motion vector predictors */
      		if(video->pict_type == P_TYPE)
        		pmv[0][0][0] = pmv[0][0][1] = pmv[1][0][0] = pmv[1][0][1] = 0;

/* derive motion_type */
      		if(video->pict_struct == FRAME_PICTURE)
        		motion_type = MC_FRAME;
    		else
    		{
        		motion_type = MC_FIELD;
/* predict from field of same parity */
        		mv_field_sel[0][0] = mv_field_sel[0][1] = (video->pict_struct == BOTTOM_FIELD);
    		}

/* skipped I are spatial-only predicted, */
/* skipped P and B are temporal-only predicted */
      		stwtype = (video->pict_type == I_TYPE) ? 8 : 0;

/* clear MB_INTRA */
      		mb_type &= ~MB_INTRA;

/* no block data */
      		cbp = 0; 
    	}

    	snr_cbp = 0;

/* pixel coordinates of top left corner of current macroblock */
    	bx = 16 * (macroblock_address % video->mb_width);
    	by = 16 * (macroblock_address / video->mb_width);

/* motion compensation */
    	if(!(mb_type & MB_INTRA))
    	  	mpeg3video_reconstruct(video, 
				bx, 
				by, 
				mb_type, 
				motion_type, 
				pmv, 
				mv_field_sel, 
				dmvector, 
				stwtype);

/* copy or add block data into picture */
    	for(comp = 0; comp < video->blk_cnt; comp++)
		{
      		if((cbp | snr_cbp) & (1 << (video->blk_cnt - 1 - comp)))
			{
#ifdef HAVE_MMX
				if(video->have_mmx)
	  	  			IDCT_mmx(slice->block[comp]);
				else
#endif
          			mpeg3video_idct_conversion(slice->block[comp]);

        		mpeg3video_addblock(slice, 
					video, 
					comp, 
					bx, 
					by, 
					dct_type, 
					(mb_type & MB_INTRA) == 0);
      		}
    	}

/* advance to next macroblock */
    	macroblock_address++;
    	mba_inc--;
  	}

	return 0;
}

void mpeg3_slice_loop(mpeg3_slice_t *slice)
{
  mpeg3video_t *video = slice->video;
  int result = 1;
  int cont = 0;

  while(!slice->done)
    {
      if (cont == 0) {
	// only wait if we're done...
	SDL_SemWait(slice->input_sem);
	cont = 1;
      }
      if(!slice->done)
	{
	  /* Get a buffer to decode */
	  result = 1;
	  SDL_LockMutex(video->slice_lock);
	  if(slice->buffer_step > 0)
	    {
	      while(slice->current_buffer <= slice->last_buffer)
		{
		  if(!video->slice_buffers[slice->current_buffer].done &&
		     slice->current_buffer <= slice->last_buffer)
		    {
		      result = 0;
		      break;
		    }
		  slice->current_buffer += slice->buffer_step;
		}
	    }
	  else
	    {
	      while(slice->current_buffer >= slice->last_buffer)
		{
		  if(!video->slice_buffers[slice->current_buffer].done &&
		     slice->current_buffer >= slice->last_buffer)
		    {
		      result = 0;
		      break;
		    }
		  slice->current_buffer += slice->buffer_step;
		}
	    }

	  /* Got one */
	  if (!result && 
	      slice->current_buffer >= 0 && 
	      slice->current_buffer < video->total_slice_buffers)
	    {
	      slice->slice_buffer = &(video->slice_buffers[slice->current_buffer]);
	      SDL_LockMutex(slice->slice_buffer->buffer_completion_lock);
	      slice->slice_buffer->done = 1;
	      SDL_UnlockMutex(video->slice_lock);
	      mpeg3_decode_slice(slice);
	      SDL_UnlockMutex(slice->slice_buffer->buffer_completion_lock);
	    }
	  else
	    /* Finished with all */
	    {
	      cont = 0; // back to waiting
	      SDL_UnlockMutex(video->slice_lock);
	      SDL_SemPost(video->slice_complete_sem);
	    }
	}

    }
}

int mpeg3_new_slice_decoder(void *video, mpeg3_slice_t *slice)
{
#ifndef SDL_THREADS
	pthread_attr_t  attr;
#endif

	slice->video = video;
	slice->done = 0;
	slice->input_sem = SDL_CreateSemaphore(0);
#ifndef SDL_THREADS
	pthread_attr_init(&attr);
	pthread_create(&(slice->tid), &attr, (void*)mpeg3_slice_loop, slice);
#else
	slice->tid = SDL_CreateThread((void*)mpeg3_slice_loop, slice);
#endif

	return 0;
}

int mpeg3_delete_slice_decoder(mpeg3_slice_t *slice)
{
	slice->done = 1;
	SDL_SemPost(slice->input_sem);
#ifndef SDL_THREADS
	pthread_join(slice->tid, 0);
#else
	SDL_WaitThread(slice->tid, NULL);
#endif
	SDL_DestroySemaphore(slice->input_sem);
	return 0;
}