flacenc.c

ffmpeg移植到symbian的全部源代码

        if(smp[i] != smp[0]) break;
    }
    if(i == n) {
        sub->type = sub->type_code = FLAC_SUBFRAME_CONSTANT;
        res[0] = smp[0];
        return sub->obits;
    }

    /* VERBATIM */
    if(n < 5) {
        sub->type = sub->type_code = FLAC_SUBFRAME_VERBATIM;
        encode_residual_verbatim(res, smp, n);
        return sub->obits * n;
    }

    min_order = ctx->options.min_prediction_order;
    max_order = ctx->options.max_prediction_order;
    min_porder = ctx->options.min_partition_order;
    max_porder = ctx->options.max_partition_order;
    precision = ctx->options.lpc_coeff_precision;
    omethod = ctx->options.prediction_order_method;

    /* FIXED */
    if(!ctx->options.use_lpc || max_order == 0 || (n <= max_order)) {
        uint32_t bits[MAX_FIXED_ORDER+1];
        if(max_order > MAX_FIXED_ORDER) max_order = MAX_FIXED_ORDER;
        opt_order = 0;
        bits[0] = UINT32_MAX;
        for(i=min_order; i<=max_order; i++) {
            encode_residual_fixed(res, smp, n, i);
            bits[i] = calc_rice_params_fixed(&sub->rc, min_porder, max_porder, res,
                                             n, i, sub->obits);
            if(bits[i] < bits[opt_order]) {
                opt_order = i;
            }
        }
        sub->order = opt_order;
        sub->type = FLAC_SUBFRAME_FIXED;
        sub->type_code = sub->type | sub->order;
        if(sub->order != max_order) {
            encode_residual_fixed(res, smp, n, sub->order);
            return calc_rice_params_fixed(&sub->rc, min_porder, max_porder, res, n,
                                          sub->order, sub->obits);
        }
        return bits[sub->order];
    }

    /* LPC */
    opt_order = lpc_calc_coefs(ctx, smp, n, max_order, precision, coefs, shift, ctx->options.use_lpc, omethod);

    if(omethod == ORDER_METHOD_2LEVEL ||
       omethod == ORDER_METHOD_4LEVEL ||
       omethod == ORDER_METHOD_8LEVEL) {
        int levels = 1 << omethod;
#ifdef __CW32__
        uint32_t *bits;
#else
        uint32_t bits[levels];
#endif
        int order;
        int opt_index = levels-1;
#ifdef __CW32__
        bits = av_malloc(sizeof(uint32_t)*levels);
#endif
        opt_order = max_order-1;
        bits[opt_index] = UINT32_MAX;
        for(i=levels-1; i>=0; i--) {
            order = min_order + (((max_order-min_order+1) * (i+1)) / levels)-1;
            if(order < 0) order = 0;
            encode_residual_lpc(res, smp, n, order+1, coefs[order], shift[order]);
            bits[i] = calc_rice_params_lpc(&sub->rc, min_porder, max_porder,
                                           res, n, order+1, sub->obits, precision);
            if(bits[i] < bits[opt_index]) {
                opt_index = i;
                opt_order = order;
            }
        }
        opt_order++;
#ifdef __CW32__
        av_free(bits);
#endif
    } else if(omethod == ORDER_METHOD_SEARCH) {
        // brute-force optimal order search
        uint32_t bits[MAX_LPC_ORDER];
        opt_order = 0;
        bits[0] = UINT32_MAX;
        for(i=min_order-1; i<max_order; i++) {
            encode_residual_lpc(res, smp, n, i+1, coefs[i], shift[i]);
            bits[i] = calc_rice_params_lpc(&sub->rc, min_porder, max_porder,
                                           res, n, i+1, sub->obits, precision);
            if(bits[i] < bits[opt_order]) {
                opt_order = i;
            }
        }
        opt_order++;
    } else if(omethod == ORDER_METHOD_LOG) {
        uint32_t bits[MAX_LPC_ORDER];
        int step;

        opt_order= min_order - 1 + (max_order-min_order)/3;
        memset(bits, -1, sizeof(bits));

        for(step=16 ;step; step>>=1){
            int last= opt_order;
            for(i=last-step; i<=last+step; i+= step){
                if(i<min_order-1 || i>=max_order || bits[i] < UINT32_MAX)
                    continue;
                encode_residual_lpc(res, smp, n, i+1, coefs[i], shift[i]);
                bits[i] = calc_rice_params_lpc(&sub->rc, min_porder, max_porder,
                                            res, n, i+1, sub->obits, precision);
                if(bits[i] < bits[opt_order])
                    opt_order= i;
            }
        }
        opt_order++;
    }

    sub->order = opt_order;
    sub->type = FLAC_SUBFRAME_LPC;
    sub->type_code = sub->type | (sub->order-1);
    sub->shift = shift[sub->order-1];
    for(i=0; i<sub->order; i++) {
        sub->coefs[i] = coefs[sub->order-1][i];
    }
    encode_residual_lpc(res, smp, n, sub->order, sub->coefs, sub->shift);
    return calc_rice_params_lpc(&sub->rc, min_porder, max_porder, res, n, sub->order,
                                sub->obits, precision);
}

static int encode_residual_v(FlacEncodeContext *ctx, int ch)
{
    int i, n;
    FlacFrame *frame;
    FlacSubframe *sub;
    int32_t *res, *smp;

    frame = &ctx->frame;
    sub = &frame->subframes[ch];
    res = sub->residual;
    smp = sub->samples;
    n = frame->blocksize;

    /* CONSTANT */
    for(i=1; i<n; i++) {
        if(smp[i] != smp[0]) break;
    }
    if(i == n) {
        sub->type = sub->type_code = FLAC_SUBFRAME_CONSTANT;
        res[0] = smp[0];
        return sub->obits;
    }

    /* VERBATIM */
    sub->type = sub->type_code = FLAC_SUBFRAME_VERBATIM;
    encode_residual_verbatim(res, smp, n);
    return sub->obits * n;
}

static int estimate_stereo_mode(int32_t *left_ch, int32_t *right_ch, int n)
{
    int i, best;
    int32_t lt, rt;
    uint64_t sum[4];
    uint64_t score[4];
    int k;

    /* calculate sum of 2nd order residual for each channel */
    sum[0] = sum[1] = sum[2] = sum[3] = 0;
    for(i=2; i<n; i++) {
        lt = left_ch[i] - 2*left_ch[i-1] + left_ch[i-2];
        rt = right_ch[i] - 2*right_ch[i-1] + right_ch[i-2];
        sum[2] += FFABS((lt + rt) >> 1);
        sum[3] += FFABS(lt - rt);
        sum[0] += FFABS(lt);
        sum[1] += FFABS(rt);
    }
    /* estimate bit counts */
    for(i=0; i<4; i++) {
        k = find_optimal_param(2*sum[i], n);
        sum[i] = rice_encode_count(2*sum[i], n, k);
    }

    /* calculate score for each mode */
    score[0] = sum[0] + sum[1];
    score[1] = sum[0] + sum[3];
    score[2] = sum[1] + sum[3];
    score[3] = sum[2] + sum[3];

    /* return mode with lowest score */
    best = 0;
    for(i=1; i<4; i++) {
        if(score[i] < score[best]) {
            best = i;
        }
    }
    if(best == 0) {
        return FLAC_CHMODE_LEFT_RIGHT;
    } else if(best == 1) {
        return FLAC_CHMODE_LEFT_SIDE;
    } else if(best == 2) {
        return FLAC_CHMODE_RIGHT_SIDE;
    } else {
        return FLAC_CHMODE_MID_SIDE;
    }
}

/**
 * Perform stereo channel decorrelation
 */
static void channel_decorrelation(FlacEncodeContext *ctx)
{
    FlacFrame *frame;
    int32_t *left, *right;
    int i, n;

    frame = &ctx->frame;
    n = frame->blocksize;
    left  = frame->subframes[0].samples;
    right = frame->subframes[1].samples;

    if(ctx->channels != 2) {
        frame->ch_mode = FLAC_CHMODE_NOT_STEREO;
        return;
    }

    frame->ch_mode = estimate_stereo_mode(left, right, n);

    /* perform decorrelation and adjust bits-per-sample */
    if(frame->ch_mode == FLAC_CHMODE_LEFT_RIGHT) {
        return;
    }
    if(frame->ch_mode == FLAC_CHMODE_MID_SIDE) {
        int32_t tmp;
        for(i=0; i<n; i++) {
            tmp = left[i];
            left[i] = (tmp + right[i]) >> 1;
            right[i] = tmp - right[i];
        }
        frame->subframes[1].obits++;
    } else if(frame->ch_mode == FLAC_CHMODE_LEFT_SIDE) {
        for(i=0; i<n; i++) {
            right[i] = left[i] - right[i];
        }
        frame->subframes[1].obits++;
    } else {
        for(i=0; i<n; i++) {
            left[i] -= right[i];
        }
        frame->subframes[0].obits++;
    }
}

static void write_utf8(PutBitContext *pb, uint32_t val)
{
    uint8_t tmp;
    PUT_UTF8(val, tmp, put_bits(pb, 8, tmp);)
}

static void output_frame_header(FlacEncodeContext *s)
{
    FlacFrame *frame;
    int crc;

    frame = &s->frame;

    put_bits(&s->pb, 16, 0xFFF8);
    put_bits(&s->pb, 4, frame->bs_code[0]);
    put_bits(&s->pb, 4, s->sr_code[0]);
    if(frame->ch_mode == FLAC_CHMODE_NOT_STEREO) {
        put_bits(&s->pb, 4, s->ch_code);
    } else {
        put_bits(&s->pb, 4, frame->ch_mode);
    }
    put_bits(&s->pb, 3, 4); /* bits-per-sample code */
    put_bits(&s->pb, 1, 0);
    write_utf8(&s->pb, s->frame_count);
    if(frame->bs_code[0] == 6) {
        put_bits(&s->pb, 8, frame->bs_code[1]);
    } else if(frame->bs_code[0] == 7) {
        put_bits(&s->pb, 16, frame->bs_code[1]);
    }
    if(s->sr_code[0] == 12) {
        put_bits(&s->pb, 8, s->sr_code[1]);
    } else if(s->sr_code[0] > 12) {
        put_bits(&s->pb, 16, s->sr_code[1]);
    }
    flush_put_bits(&s->pb);
    crc = av_crc(av_crc_get_table(AV_CRC_8_ATM), 0,
                 s->pb.buf, put_bits_count(&s->pb)>>3);
    put_bits(&s->pb, 8, crc);
}

static void output_subframe_constant(FlacEncodeContext *s, int ch)
{
    FlacSubframe *sub;
    int32_t res;

    sub = &s->frame.subframes[ch];
    res = sub->residual[0];
    put_sbits(&s->pb, sub->obits, res);
}

static void output_subframe_verbatim(FlacEncodeContext *s, int ch)
{
    int i;
    FlacFrame *frame;
    FlacSubframe *sub;
    int32_t res;

    frame = &s->frame;
    sub = &frame->subframes[ch];

    for(i=0; i<frame->blocksize; i++) {
        res = sub->residual[i];
        put_sbits(&s->pb, sub->obits, res);
    }
}

static void output_residual(FlacEncodeContext *ctx, int ch)
{
    int i, j, p, n, parts;
    int k, porder, psize, res_cnt;
    FlacFrame *frame;
    FlacSubframe *sub;
    int32_t *res;

    frame = &ctx->frame;
    sub = &frame->subframes[ch];
    res = sub->residual;
    n = frame->blocksize;

    /* rice-encoded block */
    put_bits(&ctx->pb, 2, 0);

    /* partition order */
    porder = sub->rc.porder;
    psize = n >> porder;
    parts = (1 << porder);
    put_bits(&ctx->pb, 4, porder);
    res_cnt = psize - sub->order;

    /* residual */
    j = sub->order;
    for(p=0; p<parts; p++) {
        k = sub->rc.params[p];
        put_bits(&ctx->pb, 4, k);
        if(p == 1) res_cnt = psize;
        for(i=0; i<res_cnt && j<n; i++, j++) {
            set_sr_golomb_flac(&ctx->pb, res[j], k, INT32_MAX, 0);
        }
    }
}

static void output_subframe_fixed(FlacEncodeContext *ctx, int ch)
{
    int i;
    FlacFrame *frame;
    FlacSubframe *sub;

    frame = &ctx->frame;
    sub = &frame->subframes[ch];

    /* warm-up samples */
    for(i=0; i<sub->order; i++) {
        put_sbits(&ctx->pb, sub->obits, sub->residual[i]);
    }

    /* residual */
    output_residual(ctx, ch);
}

static void output_subframe_lpc(FlacEncodeContext *ctx, int ch)
{
    int i, cbits;
    FlacFrame *frame;
    FlacSubframe *sub;

    frame = &ctx->frame;
    sub = &frame->subframes[ch];

    /* warm-up samples */
    for(i=0; i<sub->order; i++) {
        put_sbits(&ctx->pb, sub->obits, sub->residual[i]);
    }

    /* LPC coefficients */
    cbits = ctx->options.lpc_coeff_precision;
    put_bits(&ctx->pb, 4, cbits-1);
    put_sbits(&ctx->pb, 5, sub->shift);
    for(i=0; i<sub->order; i++) {
        put_sbits(&ctx->pb, cbits, sub->coefs[i]);
    }

    /* residual */
    output_residual(ctx, ch);
}

static void output_subframes(FlacEncodeContext *s)
{
    FlacFrame *frame;
    FlacSubframe *sub;
    int ch;

    frame = &s->frame;

    for(ch=0; ch<s->channels; ch++) {
        sub = &frame->subframes[ch];

        /* subframe header */
        put_bits(&s->pb, 1, 0);
        put_bits(&s->pb, 6, sub->type_code);
        put_bits(&s->pb, 1, 0); /* no wasted bits */

        /* subframe */
        if(sub->type == FLAC_SUBFRAME_CONSTANT) {
            output_subframe_constant(s, ch);
        } else if(sub->type == FLAC_SUBFRAME_VERBATIM) {
            output_subframe_verbatim(s, ch);
        } else if(sub->type == FLAC_SUBFRAME_FIXED) {
            output_subframe_fixed(s, ch);
        } else if(sub->type == FLAC_SUBFRAME_LPC) {
            output_subframe_lpc(s, ch);
        }
    }
}

static void output_frame_footer(FlacEncodeContext *s)
{
    int crc;
    flush_put_bits(&s->pb);
    crc = bswap_16(av_crc(av_crc_get_table(AV_CRC_16_ANSI), 0,
                          s->pb.buf, put_bits_count(&s->pb)>>3));
    put_bits(&s->pb, 16, crc);
    flush_put_bits(&s->pb);
}

static int flac_encode_frame(AVCodecContext *avctx, uint8_t *frame,
                             int buf_size, void *data)
{
    int ch;
    FlacEncodeContext *s;
    int16_t *samples = data;
    int out_bytes;

    s = avctx->priv_data;

    init_frame(s);

    copy_samples(s, samples);

    channel_decorrelation(s);

    for(ch=0; ch<s->channels; ch++) {
        encode_residual(s, ch);
    }
    init_put_bits(&s->pb, frame, buf_size);
    output_frame_header(s);
    output_subframes(s);
    output_frame_footer(s);
    out_bytes = put_bits_count(&s->pb) >> 3;

    if(out_bytes > s->max_framesize || out_bytes >= buf_size) {
        /* frame too large. use verbatim mode */
        for(ch=0; ch<s->channels; ch++) {
            encode_residual_v(s, ch);
        }
        init_put_bits(&s->pb, frame, buf_size);
        output_frame_header(s);
        output_subframes(s);
        output_frame_footer(s);
        out_bytes = put_bits_count(&s->pb) >> 3;

        if(out_bytes > s->max_framesize || out_bytes >= buf_size) {
            /* still too large. must be an error. */
            av_log(avctx, AV_LOG_ERROR, "error encoding frame\n");
            return -1;
        }
    }

    s->frame_count++;
    return out_bytes;
}

static av_cold int flac_encode_close(AVCodecContext *avctx)
{
    av_freep(&avctx->extradata);
    avctx->extradata_size = 0;
    av_freep(&avctx->coded_frame);
    return 0;
}

AVCodec flac_encoder = {
    "flac",
    CODEC_TYPE_AUDIO,
    CODEC_ID_FLAC,
    sizeof(FlacEncodeContext),
    flac_encode_init,
    flac_encode_frame,
    flac_encode_close,
    NULL,
#ifdef __CW32__
    CODEC_CAP_SMALL_LAST_FRAME,
    0,
    0,
    0,
    0,
    NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
#else
    .capabilities = CODEC_CAP_SMALL_LAST_FRAME,
    .long_name = NULL_IF_CONFIG_SMALL("FLAC (Free Lossless Audio Codec)"),
#endif
};