hcr.c

mpeg4 video codec mpeg4 video codec

                            /* process only sfb's that are due now */
                            ((ics->sect_start[g][i] <= sfb) && (ics->sect_end[g][i] > sfb))
                            )
                        {
                            if ((sect_cb != ZERO_HCB) &&
                                (sect_cb != NOISE_HCB) &&
                                (sect_cb != INTENSITY_HCB) &&
                                (sect_cb != INTENSITY_HCB2))
                            {
                                uint8_t inc = (sect_cb < FIRST_PAIR_HCB) ? QUAD_LEN : PAIR_LEN;
                                uint16_t k;

                                uint32_t	hw, lw;

                                for  (k=0; (k < (4/inc)*ics->window_group_length[g]) &&
                                    ( (k+w*ics->window_group_length[g]/inc) < (ics->sect_sfb_offset[g][sfb+1] - ics->sect_sfb_offset[g][sfb])); k++)
                                {
                                    uint16_t sp = sp_offset[g] + ics->sect_sfb_offset[g][sfb] + inc*(k+w*ics->window_group_length[g]/inc);

                                    if (!PCW_decoded)
                                    {
                                        /* if we haven't yet read until the end of the buffer, we can directly decode the so-called PCWs */
                                        if ((BitsRead + segmentWidth( sect_cb ))<= ics->length_of_reordered_spectral_data)
                                        {
                                            Segment[ numberOfSegments ].len = segmentWidth( sect_cb );

                                            if (segmentWidth( sect_cb ) > 32)
                                            {
                                                Segment[ numberOfSegments ].bufb = faad_showbits(ld, segmentWidth( sect_cb ) - 32);
                                                faad_flushbits(ld, segmentWidth( sect_cb) - 32);
                                                Segment[ numberOfSegments ].bufa = faad_showbits(ld, 32),
                                                    faad_flushbits(ld, 32 );

                                            } else {
                                                Segment[ numberOfSegments ].bufa = faad_showbits(ld,  segmentWidth( sect_cb ));
                                                Segment[ numberOfSegments ].bufb = 0;
                                                faad_flushbits(ld, segmentWidth( sect_cb) );
                                            }

                                            huffman_spectral_data_2(sect_cb, &Segment[ numberOfSegments ], &spectral_data[sp]);

                                            BitsRead += segmentWidth( sect_cb );

                                            /* skip to next segment, but store left bits in new buffer */
                                            rewind_bits( &Segment[ numberOfSegments ]);

                                            numberOfSegments++;
                                        } else {

                                            /* the last segment is extended until length_of_reordered_spectral_data */

                                            if (BitsRead < ics->length_of_reordered_spectral_data)
                                            {

                                                uint8_t additional_bits = (ics->length_of_reordered_spectral_data - BitsRead);

                                                if ( additional_bits > 32)
                                                {
                                                    hw = faad_showbits(ld, additional_bits - 32);
                                                    faad_flushbits(ld, additional_bits - 32);
                                                    lw = faad_showbits(ld, 32);
                                                    faad_flushbits(ld, 32 );
                                                } else {
                                                    lw = faad_showbits(ld, additional_bits);
                                                    hw = 0;
                                                    faad_flushbits(ld, additional_bits );
                                                }
                                                rewind_lword( &hw, &lw, additional_bits + Segment[ numberOfSegments-1 ].len );
                                                if (Segment[ numberOfSegments-1 ].len > 32)
                                                {
                                                    Segment[ numberOfSegments-1 ].bufb = hw + 
                                                        showbits_hcr(&Segment[ numberOfSegments-1 ], Segment[ numberOfSegments-1 ].len - 32);
                                                    Segment[ numberOfSegments-1 ].bufa = lw + 
                                                        showbits_hcr(&Segment[ numberOfSegments-1 ], 32);
                                                } else {
                                                    Segment[ numberOfSegments-1 ].bufa = lw + 
                                                        showbits_hcr(&Segment[ numberOfSegments-1 ], Segment[ numberOfSegments-1 ].len);
                                                    Segment[ numberOfSegments-1 ].bufb = hw;
                                                }
                                                Segment[ numberOfSegments-1 ].len += additional_bits;
                                            }
                                            BitsRead = ics->length_of_reordered_spectral_data;
                                            PCW_decoded = 1;

                                            Codewords[ 0 ].sp_offset = sp;
                                            Codewords[ 0 ].cb = sect_cb;
                                            Codewords[ 0 ].decoded = 0;
                                            Codewords[ 0 ].bits.len = 0;
                                        }
                                    } else {
                                        Codewords[ NrCodeWords - numberOfSegments ].sp_offset = sp;
                                        Codewords[ NrCodeWords - numberOfSegments ].cb = sect_cb;
                                        Codewords[ NrCodeWords - numberOfSegments ].decoded = 0;
                                        Codewords[ NrCodeWords - numberOfSegments ].bits.len = 0;

                                    } /* PCW decoded */
                                    NrCodeWords++;
                                } /* of k */
                            }
                        }
                    } /* of i */
                 } /* of g */
             } /* of w */
         } /* of sfb */
    } /* of presort */

    /* Avoid divide by zero */
    if (numberOfSegments == 0)
        return 10; /* this is not good... */

    numberOfSets = NrCodeWords / numberOfSegments;     

    /* second step: decode nonPCWs */

    for (set = 1; set <= numberOfSets; set++)
    {
        uint16_t trial;

        for (trial = 0; trial < numberOfSegments; trial++)
        {
            uint16_t codewordBase;
            uint16_t set_decoded=numberOfSegments;

            if (set == numberOfSets)
                set_decoded = NrCodeWords - set*numberOfSegments;	/* last set is shorter than the rest */

            for (codewordBase = 0; codewordBase < numberOfSegments; codewordBase++)
            {
                uint16_t segment_index = (trial + codewordBase) % numberOfSegments;
                uint16_t codeword_index = codewordBase + set*numberOfSegments - numberOfSegments;

                if ((codeword_index + numberOfSegments) >= NrCodeWords)
                    break;
                if (!Codewords[ codeword_index ].decoded)
                {
                    if ( Segment[ segment_index ].len > 0)
                    {
                        uint8_t tmplen;

                        if (Codewords[ codeword_index ].bits.len != 0)
                        {
                            /* on the first trial the data is only stored in Segment[], not in Codewords[]. 
                               On next trials first collect the data stored for this codeword and
                               concatenate the new data from Segment[] */

                            concat_bits( &Codewords[ codeword_index ].bits, &Segment[ segment_index ]);                            
                            /* Now everthing is stored in Segment[] */
                        }
                        tmplen = Segment[ segment_index ].len;
                        if ( huffman_spectral_data_2(Codewords[ codeword_index ].cb, &Segment[ segment_index ],
                            &spectral_data[ Codewords[ codeword_index ].sp_offset ]) >=0)
                        {
                            /* CW did fit into segment */

                            Codewords[ codeword_index ].decoded = 1;
                            set_decoded--;
                        } else {

                            /* CW did not fit, so store for later use */

                            Codewords[ codeword_index ].bits.len = tmplen;
                            Codewords[ codeword_index ].bits.bufa = Segment[ segment_index ].bufa;
                            Codewords[ codeword_index ].bits.bufb = Segment[ segment_index ].bufb;
                        }
                    }                        
                }
            } /* of codewordBase */

            if (set_decoded == 0) break;	/* no undecoded codewords left in this set */

        } /* of trial */

        /* rewind all bits in remaining segments with len>0 */
        for (i=0; i < numberOfSegments; i++)
            rewind_bits( &Segment[ i ] );
    }

#if 0
    {
        int i, r=0, c=0;
        for (i=0; i< numberOfSegments; i++)
            r += Segment[ i ].len;
        if (r != 0)
        {
            printf("reordered_spectral_data: %d bits remaining!\n", r);
        }
        for (i=0; i< NrCodeWords - numberOfSegments; i++)
        {
            if (Codewords[ i ].decoded == 0)
            {
                c++;
            }
        }
        if (c != 0)
        {
            printf("reordered_spectral_data: %d Undecoded Codewords remaining!\n",c );
        }
        if ((r !=0) || (c!=0))	return 10;
    }
#endif

    return 0;
}
#endif