libavcodec/vorbis_dec.c:1572: error: Uninitialized Value
  The value read from res_chan[_] was never initialized.

libavcodec/vorbis_dec.c:1572:9: 
1570.         float *mag, *ang;
1571. 
1572.         mag = vc->channel_residues+res_chan[mapping->magnitude[i]] * blocksize / 2;
              ^
1573.         ang = vc->channel_residues+res_chan[mapping->angle[i]]     * blocksize / 2;
1574.         vc->dsp.vorbis_inverse_coupling(mag, ang, blocksize / 2);

static int vorbis_parse_audio_packet(vorbis_context *vc)
{
    GetBitContext *gb = &vc->gb;
    uint_fast8_t previous_window = vc->previous_window;
    uint_fast8_t mode_number;
    uint_fast8_t blockflag;
    uint_fast16_t blocksize;
    int_fast32_t i,j;
    uint_fast8_t no_residue[vc->audio_channels];
    uint_fast8_t do_not_decode[vc->audio_channels];
    vorbis_mapping *mapping;
    float *ch_res_ptr   = vc->channel_residues;
    float *ch_floor_ptr = vc->channel_floors;
    uint_fast8_t res_chan[vc->audio_channels];
    uint_fast8_t res_num = 0;
    int_fast16_t retlen  = 0;
    float fadd_bias = vc->add_bias;
    if (get_bits1(gb)) {
        av_log(vc->avccontext, AV_LOG_ERROR, "Not a Vorbis I audio packet.\n");
        return -1;
    }
    if (vc->mode_count == 1) {
        mode_number = 0;
    } else {
        mode_number = get_bits(gb, ilog(vc->mode_count-1));
    }
    if (mode_number >= vc->mode_count) {
        av_log(vc->avccontext, AV_LOG_ERROR, "mode number %d out of range.\n", mode_number);
        return -1;
    }
    vc->mode_number = mode_number;
    mapping = &vc->mappings[vc->modes[mode_number].mapping];
    AV_DEBUG(" Mode number: %d , mapping: %d , blocktype %d \n", mode_number, vc->modes[mode_number].mapping, vc->modes[mode_number].blockflag);
    blockflag = vc->modes[mode_number].blockflag;
    blocksize = vc->blocksize[blockflag];
    if (blockflag)
        skip_bits(gb, 2);
    memset(ch_res_ptr,   0, sizeof(float) * vc->audio_channels * blocksize / 2);
    memset(ch_floor_ptr, 0, sizeof(float) * vc->audio_channels * blocksize / 2);
    for (i = 0; i < vc->audio_channels; ++i) {
        vorbis_floor *floor;
        if (mapping->submaps > 1) {
            floor = &vc->floors[mapping->submap_floor[mapping->mux[i]]];
        } else {
            floor = &vc->floors[mapping->submap_floor[0]];
        }
        no_residue[i] = floor->decode(vc, &floor->data, ch_floor_ptr);
        ch_floor_ptr += blocksize / 2;
    }
    for (i = mapping->coupling_steps - 1; i >= 0; --i) {
        if (!(no_residue[mapping->magnitude[i]] & no_residue[mapping->angle[i]])) {
            no_residue[mapping->magnitude[i]] = 0;
            no_residue[mapping->angle[i]]     = 0;
        }
    }
    for (i = 0; i < mapping->submaps; ++i) {
        vorbis_residue *residue;
        uint_fast8_t ch = 0;
        for (j = 0; j < vc->audio_channels; ++j) {
            if ((mapping->submaps == 1) || (i == mapping->mux[j])) {
                res_chan[j] = res_num;
                if (no_residue[j]) {
                    do_not_decode[ch] = 1;
                } else {
                    do_not_decode[ch] = 0;
                }
                ++ch;
                ++res_num;
            }
        }
        residue = &vc->residues[mapping->submap_residue[i]];
        vorbis_residue_decode(vc, residue, ch, do_not_decode, ch_res_ptr, blocksize/2);
        ch_res_ptr += ch * blocksize / 2;
    }
    for (i = mapping->coupling_steps - 1; i >= 0; --i) {
        float *mag, *ang;
        mag = vc->channel_residues+res_chan[mapping->magnitude[i]] * blocksize / 2;
        ang = vc->channel_residues+res_chan[mapping->angle[i]]     * blocksize / 2;
        vc->dsp.vorbis_inverse_coupling(mag, ang, blocksize / 2);
    }
    for (j = vc->audio_channels-1;j >= 0; j--) {
        ch_floor_ptr = vc->channel_floors   + j           * blocksize / 2;
        ch_res_ptr   = vc->channel_residues + res_chan[j] * blocksize / 2;
        vc->dsp.vector_fmul(ch_floor_ptr, ch_res_ptr, blocksize / 2);
        ff_imdct_half(&vc->mdct[blockflag], ch_res_ptr, ch_floor_ptr);
    }
    retlen = (blocksize + vc->blocksize[previous_window]) / 4;
    for (j = 0; j < vc->audio_channels; j++) {
        uint_fast16_t bs0 = vc->blocksize[0];
        uint_fast16_t bs1 = vc->blocksize[1];
        float *residue    = vc->channel_residues + res_chan[j] * blocksize / 2;
        float *saved      = vc->saved + j * bs1 / 4;
        float *ret        = vc->channel_floors + j * retlen;
        float *buf        = residue;
        const float *win  = vc->win[blockflag & previous_window];
        if (blockflag == previous_window) {
            vc->dsp.vector_fmul_window(ret, saved, buf, win, fadd_bias, blocksize / 4);
        } else if (blockflag > previous_window) {
            vc->dsp.vector_fmul_window(ret, saved, buf, win, fadd_bias, bs0 / 4);
            copy_normalize(ret+bs0/2, buf+bs0/4, (bs1-bs0)/4, vc->exp_bias, fadd_bias);
        } else {
            copy_normalize(ret, saved, (bs1 - bs0) / 4, vc->exp_bias, fadd_bias);
            vc->dsp.vector_fmul_window(ret + (bs1 - bs0) / 4, saved + (bs1 - bs0) / 4, buf, win, fadd_bias, bs0 / 4);
        }
        memcpy(saved, buf + blocksize / 4, blocksize / 4 * sizeof(float));
    }
    vc->previous_window = blockflag;
    return retlen;
}
['static int vorbis_parse_audio_packet(vorbis_context *vc)\n{\n    GetBitContext *gb = &vc->gb;\n    uint_fast8_t previous_window = vc->previous_window;\n    uint_fast8_t mode_number;\n    uint_fast8_t blockflag;\n    uint_fast16_t blocksize;\n    int_fast32_t i,j;\n    uint_fast8_t no_residue[vc->audio_channels];\n    uint_fast8_t do_not_decode[vc->audio_channels];\n    vorbis_mapping *mapping;\n    float *ch_res_ptr   = vc->channel_residues;\n    float *ch_floor_ptr = vc->channel_floors;\n    uint_fast8_t res_chan[vc->audio_channels];\n    uint_fast8_t res_num = 0;\n    int_fast16_t retlen  = 0;\n    float fadd_bias = vc->add_bias;\n    if (get_bits1(gb)) {\n        av_log(vc->avccontext, AV_LOG_ERROR, "Not a Vorbis I audio packet.\\n");\n        return -1;\n    }\n    if (vc->mode_count == 1) {\n        mode_number = 0;\n    } else {\n        mode_number = get_bits(gb, ilog(vc->mode_count-1));\n    }\n    if (mode_number >= vc->mode_count) {\n        av_log(vc->avccontext, AV_LOG_ERROR, "mode number %d out of range.\\n", mode_number);\n        return -1;\n    }\n    vc->mode_number = mode_number;\n    mapping = &vc->mappings[vc->modes[mode_number].mapping];\n    AV_DEBUG(" Mode number: %d , mapping: %d , blocktype %d \\n", mode_number, vc->modes[mode_number].mapping, vc->modes[mode_number].blockflag);\n    blockflag = vc->modes[mode_number].blockflag;\n    blocksize = vc->blocksize[blockflag];\n    if (blockflag)\n        skip_bits(gb, 2);\n    memset(ch_res_ptr,   0, sizeof(float) * vc->audio_channels * blocksize / 2);\n    memset(ch_floor_ptr, 0, sizeof(float) * vc->audio_channels * blocksize / 2);\n    for (i = 0; i < vc->audio_channels; ++i) {\n        vorbis_floor *floor;\n        if (mapping->submaps > 1) {\n            floor = &vc->floors[mapping->submap_floor[mapping->mux[i]]];\n        } else {\n            floor = &vc->floors[mapping->submap_floor[0]];\n        }\n        no_residue[i] = floor->decode(vc, &floor->data, ch_floor_ptr);\n        ch_floor_ptr += blocksize / 2;\n    }\n    for (i = mapping->coupling_steps - 1; i >= 0; --i) {\n        if (!(no_residue[mapping->magnitude[i]] & no_residue[mapping->angle[i]])) {\n            no_residue[mapping->magnitude[i]] = 0;\n            no_residue[mapping->angle[i]]     = 0;\n        }\n    }\n    for (i = 0; i < mapping->submaps; ++i) {\n        vorbis_residue *residue;\n        uint_fast8_t ch = 0;\n        for (j = 0; j < vc->audio_channels; ++j) {\n            if ((mapping->submaps == 1) || (i == mapping->mux[j])) {\n                res_chan[j] = res_num;\n                if (no_residue[j]) {\n                    do_not_decode[ch] = 1;\n                } else {\n                    do_not_decode[ch] = 0;\n                }\n                ++ch;\n                ++res_num;\n            }\n        }\n        residue = &vc->residues[mapping->submap_residue[i]];\n        vorbis_residue_decode(vc, residue, ch, do_not_decode, ch_res_ptr, blocksize/2);\n        ch_res_ptr += ch * blocksize / 2;\n    }\n    for (i = mapping->coupling_steps - 1; i >= 0; --i) {\n        float *mag, *ang;\n        mag = vc->channel_residues+res_chan[mapping->magnitude[i]] * blocksize / 2;\n        ang = vc->channel_residues+res_chan[mapping->angle[i]]     * blocksize / 2;\n        vc->dsp.vorbis_inverse_coupling(mag, ang, blocksize / 2);\n    }\n    for (j = vc->audio_channels-1;j >= 0; j--) {\n        ch_floor_ptr = vc->channel_floors   + j           * blocksize / 2;\n        ch_res_ptr   = vc->channel_residues + res_chan[j] * blocksize / 2;\n        vc->dsp.vector_fmul(ch_floor_ptr, ch_res_ptr, blocksize / 2);\n        ff_imdct_half(&vc->mdct[blockflag], ch_res_ptr, ch_floor_ptr);\n    }\n    retlen = (blocksize + vc->blocksize[previous_window]) / 4;\n    for (j = 0; j < vc->audio_channels; j++) {\n        uint_fast16_t bs0 = vc->blocksize[0];\n        uint_fast16_t bs1 = vc->blocksize[1];\n        float *residue    = vc->channel_residues + res_chan[j] * blocksize / 2;\n        float *saved      = vc->saved + j * bs1 / 4;\n        float *ret        = vc->channel_floors + j * retlen;\n        float *buf        = residue;\n        const float *win  = vc->win[blockflag & previous_window];\n        if (blockflag == previous_window) {\n            vc->dsp.vector_fmul_window(ret, saved, buf, win, fadd_bias, blocksize / 4);\n        } else if (blockflag > previous_window) {\n            vc->dsp.vector_fmul_window(ret, saved, buf, win, fadd_bias, bs0 / 4);\n            copy_normalize(ret+bs0/2, buf+bs0/4, (bs1-bs0)/4, vc->exp_bias, fadd_bias);\n        } else {\n            copy_normalize(ret, saved, (bs1 - bs0) / 4, vc->exp_bias, fadd_bias);\n            vc->dsp.vector_fmul_window(ret + (bs1 - bs0) / 4, saved + (bs1 - bs0) / 4, buf, win, fadd_bias, bs0 / 4);\n        }\n        memcpy(saved, buf + blocksize / 4, blocksize / 4 * sizeof(float));\n    }\n    vc->previous_window = blockflag;\n    return retlen;\n}']