wavpack.c

来自「linux下的MPEG1」· C语言 代码 · 共 557 行 · 第 1/2 页

                R = R2;
                s->decorr[i].samplesA[0] = R;
            }else{
                R2 = R + ((s->decorr[i].weightB * s->decorr[i].samplesB[0] + 512) >> 10);
                UPDATE_WEIGHT_CLIP(s->decorr[i].weightB, s->decorr[i].delta, s->decorr[i].samplesB[0], R);
                R = R2;

                if(t == -3){
                    R2 = s->decorr[i].samplesA[0];
                    s->decorr[i].samplesA[0] = R;
                }

                L2 = L + ((s->decorr[i].weightA * R2 + 512) >> 10);
                UPDATE_WEIGHT_CLIP(s->decorr[i].weightA, s->decorr[i].delta, R2, L);
                L = L2;
                s->decorr[i].samplesB[0] = L;
            }
        }
        pos = (pos + 1) & 7;
        if(s->joint)
            L += (R -= (L >> 1));
        crc = (crc * 3 + L) * 3 + R;
        *dst++ = L;
        *dst++ = R;

        count++;
    }while(!last && count < s->samples);

    if(crc != s->CRC){
        av_log(s->avctx, AV_LOG_ERROR, "CRC error\n");
        return -1;
    }
    return count * 2;
}

static int wv_unpack_mono(WavpackContext *s, GetBitContext *gb, int16_t *dst)
{
    int i, j, count = 0;
    int last, t;
    int A, S, T;
    int pos = 0;
    uint32_t crc = 0xFFFFFFFF;

    s->one = s->zero = s->zeroes = 0;
    do{
        T = wv_get_value(s, gb, s->median, &last);
        S = 0;
        if(last) break;
        for(i = 0; i < s->terms; i++){
            t = s->decorr[i].value;
            if(t > 8){
                if(t & 1)
                    A = 2 * s->decorr[i].samplesA[0] - s->decorr[i].samplesA[1];
                else
                    A = (3 * s->decorr[i].samplesA[0] - s->decorr[i].samplesA[1]) >> 1;
                s->decorr[i].samplesA[1] = s->decorr[i].samplesA[0];
                j = 0;
            }else{
                A = s->decorr[i].samplesA[pos];
                j = (pos + t) & 7;
            }
            S = T + ((s->decorr[i].weightA * A + 512) >> 10);
            if(A && T) s->decorr[i].weightA -= ((((T ^ A) >> 30) & 2) - 1) * s->decorr[i].delta;
            s->decorr[i].samplesA[j] = T = S;
        }
        pos = (pos + 1) & 7;
        crc = crc * 3 + S;
        *dst++ = S;
        count++;
    }while(!last && count < s->samples);

    if(crc != s->CRC){
        av_log(s->avctx, AV_LOG_ERROR, "CRC error\n");
        return -1;
    }
    return count;
}

static int wavpack_decode_init(AVCodecContext *avctx)
{
    WavpackContext *s = avctx->priv_data;

    s->avctx = avctx;
    s->stereo = (avctx->channels == 2);

    return 0;
}

static int wavpack_decode_close(AVCodecContext *avctx)
{
//    WavpackContext *s = avctx->priv_data;

    return 0;
}

static int wavpack_decode_frame(AVCodecContext *avctx,
                            void *data, int *data_size,
                            uint8_t *buf, int buf_size)
{
    WavpackContext *s = avctx->priv_data;
    int16_t *samples = data;
    int samplecount;
    int got_terms = 0, got_weights = 0, got_samples = 0, got_entropy = 0, got_bs = 0;
    uint8_t* buf_end = buf + buf_size;
    int i, j, id, size, ssize, weights, t;

    if (buf_size == 0) return 0;

    memset(s->decorr, 0, MAX_TERMS * sizeof(Decorr));

    s->samples = AV_RL32(buf); buf += 4;
    if(!s->samples) return buf_size;
    /* should not happen but who knows */
    if(s->samples * 2 * avctx->channels > AVCODEC_MAX_AUDIO_FRAME_SIZE){
        av_log(avctx, AV_LOG_ERROR, "Packet size is too big to be handled in lavc!\n");
        return -1;
    }
    s->joint = AV_RL32(buf) & WV_JOINT; buf += 4;
    s->CRC = AV_RL32(buf); buf += 4;
    // parse metadata blocks
    while(buf < buf_end){
        id = *buf++;
        size = *buf++;
        if(id & WP_IDF_LONG) {
            size |= (*buf++) << 8;
            size |= (*buf++) << 16;
        }
        size <<= 1; // size is specified in words
        ssize = size;
        if(id & WP_IDF_ODD) size--;
        if(size < 0){
            av_log(avctx, AV_LOG_ERROR, "Got incorrect block %02X with size %i\n", id, size);
            break;
        }
        if(buf + ssize > buf_end){
            av_log(avctx, AV_LOG_ERROR, "Block size %i is out of bounds\n", size);
            break;
        }
        if(id & WP_IDF_IGNORE){
            buf += ssize;
            continue;
        }
        switch(id & WP_IDF_MASK){
        case WP_ID_DECTERMS:
            s->terms = size;
            if(s->terms > MAX_TERMS){
                av_log(avctx, AV_LOG_ERROR, "Too many decorrelation terms\n");
                buf += ssize;
                continue;
            }
            for(i = 0; i < s->terms; i++) {
                s->decorr[s->terms - i - 1].value = (*buf & 0x1F) - 5;
                s->decorr[s->terms - i - 1].delta = *buf >> 5;
                buf++;
            }
            got_terms = 1;
            break;
        case WP_ID_DECWEIGHTS:
            if(!got_terms){
                av_log(avctx, AV_LOG_ERROR, "No decorrelation terms met\n");
                continue;
            }
            weights = size >> s->stereo;
            if(weights > MAX_TERMS || weights > s->terms){
                av_log(avctx, AV_LOG_ERROR, "Too many decorrelation weights\n");
                buf += ssize;
                continue;
            }
            for(i = 0; i < weights; i++) {
                t = (int8_t)(*buf++);
                s->decorr[s->terms - i - 1].weightA = t << 3;
                if(s->decorr[s->terms - i - 1].weightA > 0)
                    s->decorr[s->terms - i - 1].weightA += (s->decorr[s->terms - i - 1].weightA + 64) >> 7;
                if(s->stereo){
                    t = (int8_t)(*buf++);
                    s->decorr[s->terms - i - 1].weightB = t << 3;
                    if(s->decorr[s->terms - i - 1].weightB > 0)
                        s->decorr[s->terms - i - 1].weightB += (s->decorr[s->terms - i - 1].weightB + 64) >> 7;
                }
            }
            got_weights = 1;
            break;
        case WP_ID_DECSAMPLES:
            if(!got_terms){
                av_log(avctx, AV_LOG_ERROR, "No decorrelation terms met\n");
                continue;
            }
            t = 0;
            for(i = s->terms - 1; (i >= 0) && (t < size); i--) {
                if(s->decorr[i].value > 8){
                    s->decorr[i].samplesA[0] = wp_exp2(AV_RL16(buf)); buf += 2;
                    s->decorr[i].samplesA[1] = wp_exp2(AV_RL16(buf)); buf += 2;
                    if(s->stereo){
                        s->decorr[i].samplesB[0] = wp_exp2(AV_RL16(buf)); buf += 2;
                        s->decorr[i].samplesB[1] = wp_exp2(AV_RL16(buf)); buf += 2;
                        t += 4;
                    }
                    t += 4;
                }else if(s->decorr[i].value < 0){
                    s->decorr[i].samplesA[0] = wp_exp2(AV_RL16(buf)); buf += 2;
                    s->decorr[i].samplesB[0] = wp_exp2(AV_RL16(buf)); buf += 2;
                    t += 4;
                }else{
                    for(j = 0; j < s->decorr[i].value; j++){
                        s->decorr[i].samplesA[j] = wp_exp2(AV_RL16(buf)); buf += 2;
                        if(s->stereo){
                            s->decorr[i].samplesB[j] = wp_exp2(AV_RL16(buf)); buf += 2;
                        }
                    }
                    t += s->decorr[i].value * 2 * avctx->channels;
                }
            }
            got_samples = 1;
            break;
        case WP_ID_ENTROPY:
            if(size != 6 * avctx->channels){
                av_log(avctx, AV_LOG_ERROR, "Entropy vars size should be %i, got %i", 6 * avctx->channels, size);
                buf += ssize;
                continue;
            }
            for(i = 0; i < 3 * avctx->channels; i++){
                s->median[i] = wp_exp2(AV_RL16(buf));
                buf += 2;
            }
            got_entropy = 1;
            break;
        case WP_ID_DATA:
            init_get_bits(&s->gb, buf, size * 8);
            s->data_size = size * 8;
            buf += size;
            got_bs = 1;
            break;
        default:
            buf += size;
        }
        if(id & WP_IDF_ODD) buf++;
    }
    if(!got_terms){
        av_log(avctx, AV_LOG_ERROR, "No block with decorrelation terms\n");
        return -1;
    }
    if(!got_weights){
        av_log(avctx, AV_LOG_ERROR, "No block with decorrelation weights\n");
        return -1;
    }
    if(!got_samples){
        av_log(avctx, AV_LOG_ERROR, "No block with decorrelation samples\n");
        return -1;
    }
    if(!got_entropy){
        av_log(avctx, AV_LOG_ERROR, "No block with entropy info\n");
        return -1;
    }
    if(!got_bs){
        av_log(avctx, AV_LOG_ERROR, "Packed samples not found\n");
        return -1;
    }

    if(s->stereo)
        samplecount = wv_unpack_stereo(s, &s->gb, samples);
    else
        samplecount = wv_unpack_mono(s, &s->gb, samples);
    *data_size = samplecount * 2;

    return buf_size;
}

AVCodec wavpack_decoder = {
    "wavpack",
    CODEC_TYPE_AUDIO,
    CODEC_ID_WAVPACK,
    sizeof(WavpackContext),
    wavpack_decode_init,
    NULL,
    wavpack_decode_close,
    wavpack_decode_frame,
};