adpcm.c

linux下的MPEG1

    case CODEC_ID_ADPCM_IMA_DK3:
        if (avctx->block_align != 0 && buf_size > avctx->block_align)
            buf_size = avctx->block_align;

        c->status[0].predictor = (int16_t)(src[10] | (src[11] << 8));
        c->status[1].predictor = (int16_t)(src[12] | (src[13] << 8));
        c->status[0].step_index = src[14];
        c->status[1].step_index = src[15];
        /* sign extend the predictors */
        src += 16;
        diff_channel = c->status[1].predictor;

        /* the DK3_GET_NEXT_NIBBLE macro issues the break statement when
         * the buffer is consumed */
        while (1) {

            /* for this algorithm, c->status[0] is the sum channel and
             * c->status[1] is the diff channel */

            /* process the first predictor of the sum channel */
            DK3_GET_NEXT_NIBBLE();
            adpcm_ima_expand_nibble(&c->status[0], nibble, 3);

            /* process the diff channel predictor */
            DK3_GET_NEXT_NIBBLE();
            adpcm_ima_expand_nibble(&c->status[1], nibble, 3);

            /* process the first pair of stereo PCM samples */
            diff_channel = (diff_channel + c->status[1].predictor) / 2;
            *samples++ = c->status[0].predictor + c->status[1].predictor;
            *samples++ = c->status[0].predictor - c->status[1].predictor;

            /* process the second predictor of the sum channel */
            DK3_GET_NEXT_NIBBLE();
            adpcm_ima_expand_nibble(&c->status[0], nibble, 3);

            /* process the second pair of stereo PCM samples */
            diff_channel = (diff_channel + c->status[1].predictor) / 2;
            *samples++ = c->status[0].predictor + c->status[1].predictor;
            *samples++ = c->status[0].predictor - c->status[1].predictor;
        }
        break;
    case CODEC_ID_ADPCM_IMA_WS:
        /* no per-block initialization; just start decoding the data */
        while (src < buf + buf_size) {

            if (st) {
                *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                    (src[0] >> 4) & 0x0F, 3);
                *samples++ = adpcm_ima_expand_nibble(&c->status[1],
                    src[0] & 0x0F, 3);
            } else {
                *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                    (src[0] >> 4) & 0x0F, 3);
                *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                    src[0] & 0x0F, 3);
            }

            src++;
        }
        break;
    case CODEC_ID_ADPCM_XA:
        c->status[0].sample1 = c->status[0].sample2 =
        c->status[1].sample1 = c->status[1].sample2 = 0;
        while (buf_size >= 128) {
            xa_decode(samples, src, &c->status[0], &c->status[1],
                avctx->channels);
            src += 128;
            samples += 28 * 8;
            buf_size -= 128;
        }
        break;
    case CODEC_ID_ADPCM_EA:
        samples_in_chunk = AV_RL32(src);
        if (samples_in_chunk >= ((buf_size - 12) * 2)) {
            src += buf_size;
            break;
        }
        src += 4;
        current_left_sample = (int16_t)AV_RL16(src);
        src += 2;
        previous_left_sample = (int16_t)AV_RL16(src);
        src += 2;
        current_right_sample = (int16_t)AV_RL16(src);
        src += 2;
        previous_right_sample = (int16_t)AV_RL16(src);
        src += 2;

        for (count1 = 0; count1 < samples_in_chunk/28;count1++) {
            coeff1l = ea_adpcm_table[(*src >> 4) & 0x0F];
            coeff2l = ea_adpcm_table[((*src >> 4) & 0x0F) + 4];
            coeff1r = ea_adpcm_table[*src & 0x0F];
            coeff2r = ea_adpcm_table[(*src & 0x0F) + 4];
            src++;

            shift_left = ((*src >> 4) & 0x0F) + 8;
            shift_right = (*src & 0x0F) + 8;
            src++;

            for (count2 = 0; count2 < 28; count2++) {
                next_left_sample = (((*src & 0xF0) << 24) >> shift_left);
                next_right_sample = (((*src & 0x0F) << 28) >> shift_right);
                src++;

                next_left_sample = (next_left_sample +
                    (current_left_sample * coeff1l) +
                    (previous_left_sample * coeff2l) + 0x80) >> 8;
                next_right_sample = (next_right_sample +
                    (current_right_sample * coeff1r) +
                    (previous_right_sample * coeff2r) + 0x80) >> 8;
                CLAMP_TO_SHORT(next_left_sample);
                CLAMP_TO_SHORT(next_right_sample);

                previous_left_sample = current_left_sample;
                current_left_sample = next_left_sample;
                previous_right_sample = current_right_sample;
                current_right_sample = next_right_sample;
                *samples++ = (unsigned short)current_left_sample;
                *samples++ = (unsigned short)current_right_sample;
            }
        }
        break;
    case CODEC_ID_ADPCM_IMA_SMJPEG:
        c->status[0].predictor = *src;
        src += 2;
        c->status[0].step_index = *src++;
        src++;  /* skip another byte before getting to the meat */
        while (src < buf + buf_size) {
            *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                *src & 0x0F, 3);
            *samples++ = adpcm_ima_expand_nibble(&c->status[0],
                (*src >> 4) & 0x0F, 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++ = 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++ = 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;
        int size = buf_size*8;

        init_get_bits(&gb, buf, size);

        // first frame, read bits & inital values
        if (!c->nb_bits)
        {
            c->nb_bits = get_bits(&gb, 2)+2;
//            av_log(NULL,AV_LOG_INFO,"nb_bits: %d\n", c->nb_bits);
        }

        table = swf_index_tables[c->nb_bits-2];
        k0 = 1 << (c->nb_bits-2);
        signmask = 1 << (c->nb_bits-1);

        while (get_bits_count(&gb) <= size)
        {
            int i;

            c->nb_samples++;
            // wrap around at every 4096 samples...
            if ((c->nb_samples & 0xfff) == 1)
            {
                for (i = 0; i <= st; i++)
                {
                    *samples++ = c->status[i].predictor = get_sbits(&gb, 16);
                    c->status[i].step_index = get_bits(&gb, 6);
                }
            }

            // similar to IMA adpcm
            for (i = 0; i <= st; i++)
            {
                int delta = get_bits(&gb, c->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 = clip(c->status[i].step_index, 0, 88);
                c->status[i].predictor = clip(c->status[i].predictor, -32768, 32767);

                *samples++ = c->status[i].predictor;
            }
        }

//        src += get_bits_count(&gb)*8;
        src += 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;
    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_CODEC(CODEC_ID_ADPCM_IMA_QT, adpcm_ima_qt);
ADPCM_CODEC(CODEC_ID_ADPCM_IMA_WAV, adpcm_ima_wav);
ADPCM_CODEC(CODEC_ID_ADPCM_IMA_DK3, adpcm_ima_dk3);
ADPCM_CODEC(CODEC_ID_ADPCM_IMA_DK4, adpcm_ima_dk4);
ADPCM_CODEC(CODEC_ID_ADPCM_IMA_WS, adpcm_ima_ws);
ADPCM_CODEC(CODEC_ID_ADPCM_IMA_SMJPEG, adpcm_ima_smjpeg);
ADPCM_CODEC(CODEC_ID_ADPCM_MS, adpcm_ms);
ADPCM_CODEC(CODEC_ID_ADPCM_4XM, adpcm_4xm);
ADPCM_CODEC(CODEC_ID_ADPCM_XA, adpcm_xa);
ADPCM_CODEC(CODEC_ID_ADPCM_EA, adpcm_ea);
ADPCM_CODEC(CODEC_ID_ADPCM_CT, adpcm_ct);
ADPCM_CODEC(CODEC_ID_ADPCM_SWF, adpcm_swf);
ADPCM_CODEC(CODEC_ID_ADPCM_YAMAHA, adpcm_yamaha);
ADPCM_CODEC(CODEC_ID_ADPCM_SBPRO_4, adpcm_sbpro_4);
ADPCM_CODEC(CODEC_ID_ADPCM_SBPRO_3, adpcm_sbpro_3);
ADPCM_CODEC(CODEC_ID_ADPCM_SBPRO_2, adpcm_sbpro_2);

#undef ADPCM_CODEC