adpcm.c

mediastreamer2是开源的网络传输媒体流的库

    case CODEC_ID_ADPCM_EA_R1:
    case CODEC_ID_ADPCM_EA_R2:
    case CODEC_ID_ADPCM_EA_R3: {
        /* channel numbering
           2chan: 0=fl, 1=fr
           4chan: 0=fl, 1=rl, 2=fr, 3=rr
           6chan: 0=fl, 1=c,  2=fr, 3=rl,  4=rr, 5=sub */
        const int big_endian = avctx->codec->id == CODEC_ID_ADPCM_EA_R3;
        int32_t previous_sample, current_sample, next_sample;
        int32_t coeff1, coeff2;
        uint8_t shift;
        unsigned int channel;
        uint16_t *samplesC;
        const uint8_t *srcC;

        samples_in_chunk = (big_endian ? bytestream_get_be32(&src)
                                       : bytestream_get_le32(&src)) / 28;
        if (samples_in_chunk > UINT32_MAX/(28*avctx->channels) ||
            28*samples_in_chunk*avctx->channels > samples_end-samples) {
            src += buf_size - 4;
            break;
        }

        for (channel=0; channel<avctx->channels; channel++) {
            srcC = src + (big_endian ? bytestream_get_be32(&src)
                                     : bytestream_get_le32(&src))
                       + (avctx->channels-channel-1) * 4;
            samplesC = samples + channel;

            if (avctx->codec->id == CODEC_ID_ADPCM_EA_R1) {
                current_sample  = (int16_t)bytestream_get_le16(&srcC);
                previous_sample = (int16_t)bytestream_get_le16(&srcC);
            } else {
                current_sample  = c->status[channel].predictor;
                previous_sample = c->status[channel].prev_sample;
            }

            for (count1=0; count1<samples_in_chunk; count1++) {
                if (*srcC == 0xEE) {  /* only seen in R2 and R3 */
                    srcC++;
                    current_sample  = (int16_t)bytestream_get_be16(&srcC);
                    previous_sample = (int16_t)bytestream_get_be16(&srcC);

                    for (count2=0; count2<28; count2++) {
                        *samplesC = (int16_t)bytestream_get_be16(&srcC);
                        samplesC += avctx->channels;
                    }
                } else {
                    coeff1 = ea_adpcm_table[ (*srcC>>4) & 0x0F     ];
                    coeff2 = ea_adpcm_table[((*srcC>>4) & 0x0F) + 4];
                    shift = (*srcC++ & 0x0F) + 8;

                    for (count2=0; count2<28; count2++) {
                        if (count2 & 1)
                            next_sample = ((*srcC++ & 0x0F) << 28) >> shift;
                        else
                            next_sample = ((*srcC   & 0xF0) << 24) >> shift;

                        next_sample += (current_sample  * coeff1) +
                                       (previous_sample * coeff2);
                        next_sample = av_clip_int16(next_sample >> 8);

                        previous_sample = current_sample;
                        current_sample  = next_sample;
                        *samplesC = current_sample;
                        samplesC += avctx->channels;
                    }
                }
            }

            if (avctx->codec->id != CODEC_ID_ADPCM_EA_R1) {
                c->status[channel].predictor   = current_sample;
                c->status[channel].prev_sample = previous_sample;
            }
        }

        src = src + buf_size - (4 + 4*avctx->channels);
        samples += 28 * samples_in_chunk * avctx->channels;
        break;
    }
    case CODEC_ID_ADPCM_EA_XAS:
        if (samples_end-samples < 32*4*avctx->channels
            || buf_size < (4+15)*4*avctx->channels) {
            src += buf_size;
            break;
        }
        for (channel=0; channel<avctx->channels; channel++) {
            int coeff[2][4], shift[4];
            short *s2, *s = &samples[channel];
            for (n=0; n<4; n++, s+=32*avctx->channels) {
                for (i=0; i<2; i++)
                    coeff[i][n] = ea_adpcm_table[(src[0]&0x0F)+4*i];
                shift[n] = (src[2]&0x0F) + 8;
                for (s2=s, i=0; i<2; i++, src+=2, s2+=avctx->channels)
                    s2[0] = (src[0]&0xF0) + (src[1]<<8);
            }

            for (m=2; m<32; m+=2) {
                s = &samples[m*avctx->channels + channel];
                for (n=0; n<4; n++, src++, s+=32*avctx->channels) {
                    for (s2=s, i=0; i<8; i+=4, s2+=avctx->channels) {
                        int level = ((*src & (0xF0>>i)) << (24+i)) >> shift[n];
                        int pred  = s2[-1*avctx->channels] * coeff[0][n]
                                  + s2[-2*avctx->channels] * coeff[1][n];
                        s2[0] = av_clip_int16((level + pred + 0x80) >> 8);
                    }
                }
            }
        }
        samples += 32*4*avctx->channels;
        break;
    case CODEC_ID_ADPCM_IMA_AMV:
    case CODEC_ID_ADPCM_IMA_SMJPEG:
        c->status[0].predictor = (int16_t)bytestream_get_le16(&src);
        c->status[0].step_index = bytestream_get_le16(&src);

        if (avctx->codec->id == CODEC_ID_ADPCM_IMA_AMV)
            src+=4;

        while (src < buf + buf_size) {
            char hi, lo;
            lo = *src & 0x0F;
            hi = (*src >> 4) & 0x0F;

            if (avctx->codec->id == CODEC_ID_ADPCM_IMA_AMV)
                FFSWAP(char, hi, lo);

            *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                lo, 3);
            *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                hi, 3);
            src++;
        }
        break;
    case CODEC_ID_ADPCM_CT:
        while (src < buf + buf_size) {
            if (st) {
                *samples++ = adpcm_ct_expand_nibble(&c->status[0],
                    (src[0] >> 4) & 0x0F);
                *samples++ = adpcm_ct_expand_nibble(&c->status[1],
                    src[0] & 0x0F);
            } else {
                *samples++ = adpcm_ct_expand_nibble(&c->status[0],
                    (src[0] >> 4) & 0x0F);
                *samples++ = adpcm_ct_expand_nibble(&c->status[0],
                    src[0] & 0x0F);
            }
            src++;
        }
        break;
    case CODEC_ID_ADPCM_SBPRO_4:
    case CODEC_ID_ADPCM_SBPRO_3:
    case CODEC_ID_ADPCM_SBPRO_2:
        if (!c->status[0].step_index) {
            /* the first byte is a raw sample */
            *samples++ = 128 * (*src++ - 0x80);
            if (st)
              *samples++ = 128 * (*src++ - 0x80);
            c->status[0].step_index = 1;
        }
        if (avctx->codec->id == CODEC_ID_ADPCM_SBPRO_4) {
            while (src < buf + buf_size) {
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                    (src[0] >> 4) & 0x0F, 4, 0);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[st],
                    src[0] & 0x0F, 4, 0);
                src++;
            }
        } else if (avctx->codec->id == CODEC_ID_ADPCM_SBPRO_3) {
            while (src < buf + buf_size && samples + 2 < samples_end) {
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                    (src[0] >> 5) & 0x07, 3, 0);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                    (src[0] >> 2) & 0x07, 3, 0);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                    src[0] & 0x03, 2, 0);
                src++;
            }
        } else {
            while (src < buf + buf_size && samples + 3 < samples_end) {
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                    (src[0] >> 6) & 0x03, 2, 2);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[st],
                    (src[0] >> 4) & 0x03, 2, 2);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[0],
                    (src[0] >> 2) & 0x03, 2, 2);
                *samples++ = adpcm_sbpro_expand_nibble(&c->status[st],
                    src[0] & 0x03, 2, 2);
                src++;
            }
        }
        break;
    case CODEC_ID_ADPCM_SWF:
    {
        GetBitContext gb;
        const int *table;
        int k0, signmask, nb_bits, count;
        int size = buf_size*8;

        init_get_bits(&gb, buf, size);

        //read bits & initial values
        nb_bits = get_bits(&gb, 2)+2;
        //av_log(NULL,AV_LOG_INFO,"nb_bits: %d\n", nb_bits);
        table = swf_index_tables[nb_bits-2];
        k0 = 1 << (nb_bits-2);
        signmask = 1 << (nb_bits-1);

        while (get_bits_count(&gb) <= size - 22*avctx->channels) {
            for (i = 0; i < avctx->channels; i++) {
                *samples++ = c->status[i].predictor = get_sbits(&gb, 16);
                c->status[i].step_index = get_bits(&gb, 6);
            }

            for (count = 0; get_bits_count(&gb) <= size - nb_bits*avctx->channels && count < 4095; count++) {
                int i;

                for (i = 0; i < avctx->channels; i++) {
                    // similar to IMA adpcm
                    int delta = get_bits(&gb, nb_bits);
                    int step = step_table[c->status[i].step_index];
                    long vpdiff = 0; // vpdiff = (delta+0.5)*step/4
                    int k = k0;

                    do {
                        if (delta & k)
                            vpdiff += step;
                        step >>= 1;
                        k >>= 1;
                    } while(k);
                    vpdiff += step;

                    if (delta & signmask)
                        c->status[i].predictor -= vpdiff;
                    else
                        c->status[i].predictor += vpdiff;

                    c->status[i].step_index += table[delta & (~signmask)];

                    c->status[i].step_index = av_clip(c->status[i].step_index, 0, 88);
                    c->status[i].predictor = av_clip_int16(c->status[i].predictor);

                    *samples++ = c->status[i].predictor;
                    if (samples >= samples_end) {
                        av_log(avctx, AV_LOG_ERROR, "allocated output buffer is too small\n");
                        return -1;
                    }
                }
            }
        }
        src += buf_size;
        break;
    }
    case CODEC_ID_ADPCM_YAMAHA:
        while (src < buf + buf_size) {
            if (st) {
                *samples++ = adpcm_yamaha_expand_nibble(&c->status[0],
                        src[0] & 0x0F);
                *samples++ = adpcm_yamaha_expand_nibble(&c->status[1],
                        (src[0] >> 4) & 0x0F);
            } else {
                *samples++ = adpcm_yamaha_expand_nibble(&c->status[0],
                        src[0] & 0x0F);
                *samples++ = adpcm_yamaha_expand_nibble(&c->status[0],
                        (src[0] >> 4) & 0x0F);
            }
            src++;
        }
        break;
    case CODEC_ID_ADPCM_THP:
    {
        int table[2][16];
        unsigned int samplecnt;
        int prev[2][2];
        int ch;

        if (buf_size < 80) {
            av_log(avctx, AV_LOG_ERROR, "frame too small\n");
            return -1;
        }

        src+=4;
        samplecnt = bytestream_get_be32(&src);

        for (i = 0; i < 32; i++)
            table[0][i] = (int16_t)bytestream_get_be16(&src);

        /* Initialize the previous sample.  */
        for (i = 0; i < 4; i++)
            prev[0][i] = (int16_t)bytestream_get_be16(&src);

        if (samplecnt >= (samples_end - samples) /  (st + 1)) {
            av_log(avctx, AV_LOG_ERROR, "allocated output buffer is too small\n");
            return -1;
        }

        for (ch = 0; ch <= st; ch++) {
            samples = (unsigned short *) data + ch;

            /* Read in every sample for this channel.  */
            for (i = 0; i < samplecnt / 14; i++) {
                int index = (*src >> 4) & 7;
                unsigned int exp = 28 - (*src++ & 15);
                int factor1 = table[ch][index * 2];
                int factor2 = table[ch][index * 2 + 1];

                /* Decode 14 samples.  */
                for (n = 0; n < 14; n++) {
                    int32_t sampledat;
                    if(n&1) sampledat=  *src++    <<28;
                    else    sampledat= (*src&0xF0)<<24;

                    sampledat = ((prev[ch][0]*factor1
                                + prev[ch][1]*factor2) >> 11) + (sampledat>>exp);
                    *samples = av_clip_int16(sampledat);
                    prev[ch][1] = prev[ch][0];
                    prev[ch][0] = *samples++;

                    /* In case of stereo, skip one sample, this sample
                       is for the other channel.  */
                    samples += st;
                }
            }
        }

        /* In the previous loop, in case stereo is used, samples is
           increased exactly one time too often.  */
        samples -= st;
        break;
    }

    default:
        return -1;
    }
    *data_size = (uint8_t *)samples - (uint8_t *)data;
    return src - buf;
}



#ifdef CONFIG_ENCODERS
#define ADPCM_ENCODER(id,name)                  \
AVCodec name ## _encoder = {                    \
    #name,                                      \
    CODEC_TYPE_AUDIO,                           \
    id,                                         \
    sizeof(ADPCMContext),                       \
    adpcm_encode_init,                          \
    adpcm_encode_frame,                         \
    adpcm_encode_close,                         \
    NULL,                                       \
};
#else
#define ADPCM_ENCODER(id,name)
#endif

#ifdef CONFIG_DECODERS
#define ADPCM_DECODER(id,name)                  \
AVCodec name ## _decoder = {                    \
    #name,                                      \
    CODEC_TYPE_AUDIO,                           \
    id,                                         \
    sizeof(ADPCMContext),                       \
    adpcm_decode_init,                          \
    NULL,                                       \
    NULL,                                       \
    adpcm_decode_frame,                         \
};
#else
#define ADPCM_DECODER(id,name)
#endif

#define ADPCM_CODEC(id, name)                   \
ADPCM_ENCODER(id,name) ADPCM_DECODER(id,name)

ADPCM_DECODER(CODEC_ID_ADPCM_4XM, adpcm_4xm);
ADPCM_DECODER(CODEC_ID_ADPCM_CT, adpcm_ct);
ADPCM_DECODER(CODEC_ID_ADPCM_EA, adpcm_ea);
ADPCM_DECODER(CODEC_ID_ADPCM_EA_R1, adpcm_ea_r1);
ADPCM_DECODER(CODEC_ID_ADPCM_EA_R2, adpcm_ea_r2);
ADPCM_DECODER(CODEC_ID_ADPCM_EA_R3, adpcm_ea_r3);
ADPCM_DECODER(CODEC_ID_ADPCM_EA_XAS, adpcm_ea_xas);
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_AMV, adpcm_ima_amv);
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_DK3, adpcm_ima_dk3);
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_DK4, adpcm_ima_dk4);
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_EA_EACS, adpcm_ima_ea_eacs);
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_EA_SEAD, adpcm_ima_ea_sead);
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_QT, adpcm_ima_qt);
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_SMJPEG, adpcm_ima_smjpeg);
ADPCM_CODEC  (CODEC_ID_ADPCM_IMA_WAV, adpcm_ima_wav);
ADPCM_DECODER(CODEC_ID_ADPCM_IMA_WS, adpcm_ima_ws);
ADPCM_CODEC  (CODEC_ID_ADPCM_MS, adpcm_ms);
ADPCM_DECODER(CODEC_ID_ADPCM_SBPRO_4, adpcm_sbpro_4);
ADPCM_DECODER(CODEC_ID_ADPCM_SBPRO_3, adpcm_sbpro_3);
ADPCM_DECODER(CODEC_ID_ADPCM_SBPRO_2, adpcm_sbpro_2);
ADPCM_CODEC  (CODEC_ID_ADPCM_SWF, adpcm_swf);
ADPCM_DECODER(CODEC_ID_ADPCM_THP, adpcm_thp);
ADPCM_DECODER(CODEC_ID_ADPCM_XA, adpcm_xa);
ADPCM_CODEC  (CODEC_ID_ADPCM_YAMAHA, adpcm_yamaha);