vorbis.c

ffmpeg源码分析

    vc->floors=(vorbis_floor *)av_mallocz(vc->floor_count * sizeof(vorbis_floor));

    for (i=0;i<vc->floor_count;++i) {
        vorbis_floor *floor_setup=&vc->floors[i];

        floor_setup->floor_type=get_bits(gb, 16);

        AV_DEBUG(" %d. floor type %d \n", i, floor_setup->floor_type);

        if (floor_setup->floor_type==1) {
            uint_fast8_t maximum_class=0;
            uint_fast8_t rangebits;
            uint_fast16_t floor1_values=2;

            floor_setup->decode=vorbis_floor1_decode;

            floor_setup->data.t1.partitions=get_bits(gb, 5);

            AV_DEBUG(" %d.floor: %d partitions \n", i, floor_setup->data.t1.partitions);

            for(j=0;j<floor_setup->data.t1.partitions;++j) {
                floor_setup->data.t1.partition_class[j]=get_bits(gb, 4);
                if (floor_setup->data.t1.partition_class[j]>maximum_class) maximum_class=floor_setup->data.t1.partition_class[j];

                AV_DEBUG(" %d. floor %d partition class %d \n", i, j, floor_setup->data.t1.partition_class[j]);

            }

            AV_DEBUG(" maximum class %d \n", maximum_class);

            floor_setup->data.t1.maximum_class=maximum_class;

            for(j=0;j<=maximum_class;++j) {
                floor_setup->data.t1.class_dimensions[j]=get_bits(gb, 3)+1;
                floor_setup->data.t1.class_subclasses[j]=get_bits(gb, 2);

                AV_DEBUG(" %d floor %d class dim: %d subclasses %d \n", i, j, floor_setup->data.t1.class_dimensions[j], floor_setup->data.t1.class_subclasses[j]);

                if (floor_setup->data.t1.class_subclasses[j]) {
                    floor_setup->data.t1.class_masterbook[j]=get_bits(gb, 8);

                    AV_DEBUG("   masterbook: %d \n", floor_setup->data.t1.class_masterbook[j]);
                }

                for(k=0;k<(1<<floor_setup->data.t1.class_subclasses[j]);++k) {
                    floor_setup->data.t1.subclass_books[j][k]=get_bits(gb, 8)-1;

                    AV_DEBUG("    book %d. : %d \n", k, floor_setup->data.t1.subclass_books[j][k]);
                }
            }

            floor_setup->data.t1.multiplier=get_bits(gb, 2)+1;
            floor_setup->data.t1.x_list_dim=2;

            for(j=0;j<floor_setup->data.t1.partitions;++j) {
                floor_setup->data.t1.x_list_dim+=floor_setup->data.t1.class_dimensions[floor_setup->data.t1.partition_class[j]];
            }

            floor_setup->data.t1.x_list=(uint_fast16_t *)av_mallocz(floor_setup->data.t1.x_list_dim * sizeof(uint_fast16_t));
            floor_setup->data.t1.x_list_order=(uint_fast16_t *)av_mallocz(floor_setup->data.t1.x_list_dim * sizeof(uint_fast16_t));
            floor_setup->data.t1.low_neighbour=(uint_fast16_t *)av_mallocz(floor_setup->data.t1.x_list_dim * sizeof(uint_fast16_t));
            floor_setup->data.t1.high_neighbour=(uint_fast16_t *)av_mallocz(floor_setup->data.t1.x_list_dim * sizeof(uint_fast16_t));


            rangebits=get_bits(gb, 4);
            floor_setup->data.t1.x_list[0] = 0;
            floor_setup->data.t1.x_list[1] = (1<<rangebits);

            for(j=0;j<floor_setup->data.t1.partitions;++j) {
                for(k=0;k<floor_setup->data.t1.class_dimensions[floor_setup->data.t1.partition_class[j]];++k,++floor1_values) {
                    floor_setup->data.t1.x_list[floor1_values]=get_bits(gb, rangebits);

                    AV_DEBUG(" %d. floor1 Y coord. %d \n", floor1_values, floor_setup->data.t1.x_list[floor1_values]);
                }
            }

// Precalculate order of x coordinates - needed for decode

            for(k=0;k<floor_setup->data.t1.x_list_dim;++k) {
                floor_setup->data.t1.x_list_order[k]=k;
            }

            for(k=0;k<floor_setup->data.t1.x_list_dim-1;++k) {   // FIXME optimize sorting ?
                for(j=k+1;j<floor_setup->data.t1.x_list_dim;++j) {
                    if(floor_setup->data.t1.x_list[floor_setup->data.t1.x_list_order[k]]>floor_setup->data.t1.x_list[floor_setup->data.t1.x_list_order[j]]) {
                        uint_fast16_t tmp=floor_setup->data.t1.x_list_order[k];
                        floor_setup->data.t1.x_list_order[k]=floor_setup->data.t1.x_list_order[j];
                        floor_setup->data.t1.x_list_order[j]=tmp;
                    }
                }
            }

// Precalculate low and high neighbours

            for(k=2;k<floor_setup->data.t1.x_list_dim;++k) {
                floor_setup->data.t1.low_neighbour[k]=0;
                floor_setup->data.t1.high_neighbour[k]=1;  // correct according to SPEC requirements

                for (j=0;j<k;++j) {
                    if ((floor_setup->data.t1.x_list[j]<floor_setup->data.t1.x_list[k]) &&
                      (floor_setup->data.t1.x_list[j]>floor_setup->data.t1.x_list[floor_setup->data.t1.low_neighbour[k]])) {
                        floor_setup->data.t1.low_neighbour[k]=j;
                    }
                    if ((floor_setup->data.t1.x_list[j]>floor_setup->data.t1.x_list[k]) &&
                      (floor_setup->data.t1.x_list[j]<floor_setup->data.t1.x_list[floor_setup->data.t1.high_neighbour[k]])) {
                        floor_setup->data.t1.high_neighbour[k]=j;
                    }
                }
            }
        }
        else if(floor_setup->floor_type==0) {
            uint_fast8_t max_codebook_dim=0;

            floor_setup->decode=vorbis_floor0_decode;

            floor_setup->data.t0.order=get_bits(gb, 8);
            floor_setup->data.t0.rate=get_bits(gb, 16);
            floor_setup->data.t0.bark_map_size=get_bits(gb, 16);
            floor_setup->data.t0.amplitude_bits=get_bits(gb, 6);
            /* zero would result in a div by zero later *
             * 2^0 - 1 == 0                             */
            if (floor_setup->data.t0.amplitude_bits == 0) {
              av_log(vc->avccontext, AV_LOG_ERROR,
                     "Floor 0 amplitude bits is 0.\n");
              return 1;
            }
            floor_setup->data.t0.amplitude_offset=get_bits(gb, 8);
            floor_setup->data.t0.num_books=get_bits(gb, 4)+1;

            /* allocate mem for booklist */
            floor_setup->data.t0.book_list=
                av_malloc(floor_setup->data.t0.num_books);
            if(!floor_setup->data.t0.book_list) { return 1; }
            /* read book indexes */
            {
                int idx;
                uint_fast8_t book_idx;
                for (idx=0;idx<floor_setup->data.t0.num_books;++idx) {
                    book_idx=get_bits(gb, 8);
                    floor_setup->data.t0.book_list[idx]=book_idx;
                    if (vc->codebooks[book_idx].dimensions > max_codebook_dim)
                        max_codebook_dim=vc->codebooks[book_idx].dimensions;

                    if (floor_setup->data.t0.book_list[idx]>vc->codebook_count)
                        return 1;
                }
            }

            create_map( vc, i );

            /* allocate mem for lsp coefficients */
            {
                /* codebook dim is for padding if codebook dim doesn't *
                 * divide order+1 then we need to read more data       */
                floor_setup->data.t0.lsp=
                    av_malloc((floor_setup->data.t0.order+1 + max_codebook_dim)
                              * sizeof(float));
                if(!floor_setup->data.t0.lsp) { return 1; }
            }

#ifdef V_DEBUG /* debug output parsed headers */
            AV_DEBUG("floor0 order: %u\n", floor_setup->data.t0.order);
            AV_DEBUG("floor0 rate: %u\n", floor_setup->data.t0.rate);
            AV_DEBUG("floor0 bark map size: %u\n",
              floor_setup->data.t0.bark_map_size);
            AV_DEBUG("floor0 amplitude bits: %u\n",
              floor_setup->data.t0.amplitude_bits);
            AV_DEBUG("floor0 amplitude offset: %u\n",
              floor_setup->data.t0.amplitude_offset);
            AV_DEBUG("floor0 number of books: %u\n",
              floor_setup->data.t0.num_books);
            AV_DEBUG("floor0 book list pointer: %p\n",
              floor_setup->data.t0.book_list);
            {
              int idx;
              for (idx=0;idx<floor_setup->data.t0.num_books;++idx) {
                AV_DEBUG( "  Book %d: %u\n",
                  idx+1,
                  floor_setup->data.t0.book_list[idx] );
              }
            }
#endif
        }
        else {
            av_log(vc->avccontext, AV_LOG_ERROR, "Invalid floor type!\n");
            return 1;
        }
    }
    return 0;
}

// Process residues part

static int vorbis_parse_setup_hdr_residues(vorbis_context *vc){
    GetBitContext *gb=&vc->gb;
    uint_fast8_t i, j, k;

    vc->residue_count=get_bits(gb, 6)+1;
    vc->residues=(vorbis_residue *)av_mallocz(vc->residue_count * sizeof(vorbis_residue));

    AV_DEBUG(" There are %d residues. \n", vc->residue_count);

    for(i=0;i<vc->residue_count;++i) {
        vorbis_residue *res_setup=&vc->residues[i];
        uint_fast8_t cascade[64];
        uint_fast8_t high_bits;
        uint_fast8_t low_bits;

        res_setup->type=get_bits(gb, 16);

        AV_DEBUG(" %d. residue type %d \n", i, res_setup->type);

        res_setup->begin=get_bits(gb, 24);
        res_setup->end=get_bits(gb, 24);
        res_setup->partition_size=get_bits(gb, 24)+1;
        res_setup->classifications=get_bits(gb, 6)+1;
        res_setup->classbook=get_bits(gb, 8);

        AV_DEBUG("    begin %d end %d part.size %d classif.s %d classbook %d \n", res_setup->begin, res_setup->end, res_setup->partition_size,
          res_setup->classifications, res_setup->classbook);

        for(j=0;j<res_setup->classifications;++j) {
            high_bits=0;
            low_bits=get_bits(gb, 3);
            if (get_bits1(gb)) {
                high_bits=get_bits(gb, 5);
            }
            cascade[j]=(high_bits<<3)+low_bits;

            AV_DEBUG("     %d class casscade depth: %d \n", j, ilog(cascade[j]));
        }

        res_setup->maxpass=0;
        for(j=0;j<res_setup->classifications;++j) {
            for(k=0;k<8;++k) {
                if (cascade[j]&(1<<k)) {
                        res_setup->books[j][k]=get_bits(gb, 8);

                    AV_DEBUG("     %d class casscade depth %d book: %d \n", j, k, res_setup->books[j][k]);

                    if (k>res_setup->maxpass) {
                        res_setup->maxpass=k;
                    }
                } else {
                    res_setup->books[j][k]=-1;
                }
            }
        }
    }
    return 0;
}

// Process mappings part

static int vorbis_parse_setup_hdr_mappings(vorbis_context *vc) {
    GetBitContext *gb=&vc->gb;
    uint_fast8_t i, j;

    vc->mapping_count=get_bits(gb, 6)+1;
    vc->mappings=(vorbis_mapping *)av_mallocz(vc->mapping_count * sizeof(vorbis_mapping));

    AV_DEBUG(" There are %d mappings. \n", vc->mapping_count);

    for(i=0;i<vc->mapping_count;++i) {
        vorbis_mapping *mapping_setup=&vc->mappings[i];

        if (get_bits(gb, 16)) {
            av_log(vc->avccontext, AV_LOG_ERROR, "Other mappings than type 0 are not compliant with the Vorbis I specification. \n");
            return 1;
        }
        if (get_bits1(gb)) {
            mapping_setup->submaps=get_bits(gb, 4)+1;
        } else {
            mapping_setup->submaps=1;
        }

        if (get_bits1(gb)) {
            mapping_setup->coupling_steps=get_bits(gb, 8)+1;
            mapping_setup->magnitude=(uint_fast8_t *)av_mallocz(mapping_setup->coupling_steps * sizeof(uint_fast8_t));
            mapping_setup->angle=(uint_fast8_t *)av_mallocz(mapping_setup->coupling_steps * sizeof(uint_fast8_t));
            for(j=0;j<mapping_setup->coupling_steps;++j) {
                mapping_setup->magnitude[j]=get_bits(gb, ilog(vc->audio_channels-1));
                mapping_setup->angle[j]=get_bits(gb, ilog(vc->audio_channels-1));
                // FIXME: sanity checks
            }
        } else {
            mapping_setup->coupling_steps=0;
        }

        AV_DEBUG("   %d mapping coupling steps: %d \n", i, mapping_setup->coupling_steps);

        if(get_bits(gb, 2)) {
            av_log(vc->avccontext, AV_LOG_ERROR, "%d. mapping setup data invalid. \n", i);
            return 1; // following spec.
        }

        if (mapping_setup->submaps>1) {
            mapping_setup->mux=(uint_fast8_t *)av_mallocz(vc->audio_channels * sizeof(uint_fast8_t));
            for(j=0;j<vc->audio_channels;++j) {
                mapping_setup->mux[j]=get_bits(gb, 4);
            }
        }

        for(j=0;j<mapping_setup->submaps;++j) {
            get_bits(gb, 8); // FIXME check?
            mapping_setup->submap_floor[j]=get_bits(gb, 8);
            mapping_setup->submap_residue[j]=get_bits(gb, 8);

            AV_DEBUG("   %d mapping %d submap : floor %d, residue %d \n", i, j, mapping_setup->submap_floor[j], mapping_setup->submap_residue[j]);
        }
    }
    return 0;
}

// Process modes part

static void create_map( vorbis_context * vc, uint_fast8_t floor_number )
{
    vorbis_floor * floors=vc->floors;
    vorbis_floor0 * vf;
    int idx;
    int_fast8_t blockflag;
    int_fast32_t * map;
    int_fast32_t n; //TODO: could theoretically be smaller?

    for (blockflag=0;blockflag<2;++blockflag)
    {
    n=(blockflag ? vc->blocksize_1 : vc->blocksize_0) / 2;
    floors[floor_number].data.t0.map[blockflag]=
        av_malloc((n+1) * sizeof(int_fast32_t)); // n+sentinel

    map=floors[floor_number].data.t0.map[blockflag];
    vf=&floors[floor_number].data.t0;

    for (idx=0; idx<n;++idx) {
        map[idx]=floor( BARK((vf->rate*idx)/(2.0f*n)) *
                              ((vf->bark_map_size)/
                               BARK(vf->rate/2.0f )) );
        if (vf->bark_map_size-1 < map[idx]) {
            map[idx]=vf->bark_map_size-1;
        }
    }
    map[n]=-1;
    vf->map_size[blockflag]=n;
    }

#   ifdef V_DEBUG
    for(idx=0;idx<=n;++idx) {
        AV_DEBUG("floor0 map: map at pos %d is %d\n",
                 idx, map[idx]);
    }
#   endif
}

static int vorbis_parse_setup_hdr_modes(vorbis_context *vc) {
    GetBitContext *gb=&vc->gb;
    uint_fast8_t i;

    vc->mode_count=get_bits(gb, 6)+1;
    vc->modes=(vorbis_mode *)av_mallocz(vc->mode_count * sizeof(vorbis_mode));

    AV_DEBUG(" There are %d modes.\n", vc->mode_count);

    for(i=0;i<vc->mode_count;++i) {
        vorbis_mode *mode_setup=&vc->modes[i];

        mode_setup->blockflag=get_bits(gb, 1);
        mode_setup->windowtype=get_bits(gb, 16); //FIXME check
        mode_setup->transformtype=get_bits(gb, 16); //FIXME check
        mode_setup->mapping=get_bits(gb, 8); //FIXME check

        AV_DEBUG(" %d mode: blockflag %d, windowtype %d, transformtype %d, mapping %d \n", i, mode_setup->blockflag, mode_setup->windowtype, mode_setup->transformtype, mode_setup->mapping);
    }
    return 0;
}

// Process the whole setup header using the functions above

static int vorbis_parse_setup_hdr(vorbis_context *vc) {
    GetBitContext *gb=&vc->gb;

    if ((get_bits(gb, 8)!='v') || (get_bits(gb, 8)!='o') ||
    (get_bits(gb, 8)!='r') || (get_bits(gb, 8)!='b') ||
    (get_bits(gb, 8)!='i') || (get_bits(gb, 8)!='s')) {
        av_log(vc->avccontext, AV_LOG_ERROR, " Vorbis setup header packet corrupt (no vorbis signature). \n");
        return 1;
    }

    if (vorbis_parse_setup_hdr_codebooks(vc)) {
        av_log(vc->avccontext, AV_LOG_ERROR, " Vorbis setup header packet corrupt (codebooks). \n");
        return 2;
    }
    if (vorbis_parse_setup_hdr_tdtransforms(vc)) {
        av_log(vc->avccontext, AV_LOG_ERROR, " Vorbis setup header packet corrupt (time domain transforms). \n");
        return 3;
    }
    if (vorbis_parse_setup_hdr_floors(vc)) {
        av_log(vc->avccontext, AV_LOG_ERROR, " Vorbis setup header packet corrupt (floors). \n");
        return 4;
    }
    if (vorbis_parse_setup_hdr_residues(vc)) {
        av_log(vc->avccontext, AV_LOG_ERROR, " Vorbis setup header packet corrupt (residues). \n");
        return 5;
    }
    if (vorbis_parse_setup_hdr_mappings(vc)) {
        av_log(vc->avccontext, AV_LOG_ERROR, " Vorbis setup header packet corrupt (mappings). \n");
        return 6;
    }
    if (vorbis_parse_setup_hdr_modes(vc)) {
        av_log(vc->avccontext, AV_LOG_ERROR, " Vorbis setup header packet corrupt (modes). \n");
        return 7;
    }
    if (!get_bits1(gb)) {
        av_log(vc->avccontext, AV_LOG_ERROR, " Vorbis setup header packet corrupt (framing flag). \n");
        return 8; // framing flag bit unset error
    }

    return 0;
}

// Process the identification header

static int vorbis_parse_id_hdr(vorbis_context *vc){
    GetBitContext *gb=&vc->gb;
    uint_fast8_t bl0, bl1;
    const float *vwin[8]={ vwin64, vwin128, vwin256, vwin512, vwin1024, vwin2048, vwin4096, vwin8192 };

    if ((get_bits(gb, 8)!='v') || (get_bits(gb, 8)!='o') ||