PeerStreamer

 * THP ADPCM decoder by Marco Gerards (mgerards@xs4all.nl)

    case CODEC_ID_ADPCM_THP:

      {

        GetBitContext gb;

        int table[16][2];

        unsigned int samplecnt;

        int prev1[2], prev2[2];

        int ch;

        if (buf_size < 80) {

            av_log(avctx, AV_LOG_ERROR, "frame too small\n");

            return -1;

        }

        init_get_bits(&gb, src, buf_size * 8);

        src += buf_size;

                    get_bits_long(&gb, 32); /* Channel size */

        samplecnt = get_bits_long(&gb, 32);

        for (ch = 0; ch < 2; ch++)

            for (i = 0; i < 16; i++)

                table[i][ch] = get_sbits(&gb, 16);

        /* Initialize the previous sample.  */

        for (ch = 0; ch < 2; ch++) {

            prev1[ch] = get_sbits(&gb, 16);

            prev2[ch] = get_sbits(&gb, 16);

        }

        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++) {

                uint8_t index = get_bits (&gb, 4) & 7;

                unsigned int exp = get_bits (&gb, 4);

                int factor1 = table[index * 2][ch];

                int factor2 = table[index * 2 + 1][ch];

                /* Decode 14 samples.  */

                for (n = 0; n < 14; n++) {

                    int sampledat = get_sbits (&gb, 4);

                    *samples = ((prev1[ch]*factor1

                                + prev2[ch]*factor2) >> 11) + (sampledat << exp);

                    prev2[ch] = prev1[ch];

                    prev1[ch] = *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;

      }

ADPCM_CODEC(CODEC_ID_ADPCM_THP, adpcm_thp);