adpcm.c

video linux conference

    p_channel->i_sample1 = i_predictor;

    p_channel->i_idelta = ( i_adaptation_table[i_nibble] *
                            p_channel->i_idelta ) / 256;
    if( p_channel->i_idelta < 16 )
    {
        p_channel->i_idelta = 16;
    }
    return( i_predictor );
}

static void DecodeAdpcmMs( decoder_t *p_dec, int16_t *p_sample,
                           uint8_t *p_buffer )
{
    decoder_sys_t *p_sys  = p_dec->p_sys;
    adpcm_ms_channel_t channel[2];
    int i_nibbles;
    int b_stereo;
    int i_block_predictor;

    b_stereo = p_dec->fmt_in.audio.i_channels == 2 ? 1 : 0;

    GetByte( i_block_predictor );
    CLAMP( i_block_predictor, 0, 6 );
    channel[0].i_coeff1 = i_adaptation_coeff1[i_block_predictor];
    channel[0].i_coeff2 = i_adaptation_coeff2[i_block_predictor];

    if( b_stereo )
    {
        GetByte( i_block_predictor );
        CLAMP( i_block_predictor, 0, 6 );
        channel[1].i_coeff1 = i_adaptation_coeff1[i_block_predictor];
        channel[1].i_coeff2 = i_adaptation_coeff2[i_block_predictor];
    }
    GetWord( channel[0].i_idelta );
    if( b_stereo )
    {
        GetWord( channel[1].i_idelta );
    }

    GetWord( channel[0].i_sample1 );
    if( b_stereo )
    {
        GetWord( channel[1].i_sample1 );
    }

    GetWord( channel[0].i_sample2 );
    if( b_stereo )
    {
        GetWord( channel[1].i_sample2 );
    }

    if( b_stereo )
    {
        *p_sample++ = channel[0].i_sample2;
        *p_sample++ = channel[1].i_sample2;
        *p_sample++ = channel[0].i_sample1;
        *p_sample++ = channel[1].i_sample1;
    }
    else
    {
        *p_sample++ = channel[0].i_sample2;
        *p_sample++ = channel[0].i_sample1;
    }

    for( i_nibbles = 2 * (p_sys->i_block - 7 * p_dec->fmt_in.audio.i_channels);
         i_nibbles > 0; i_nibbles -= 2, p_buffer++ )
    {
        *p_sample++ = AdpcmMsExpandNibble( &channel[0], (*p_buffer) >> 4);
        *p_sample++ = AdpcmMsExpandNibble( &channel[b_stereo ? 1 : 0],
                                           (*p_buffer)&0x0f);
    }
}

/*
 * IMA-WAV
 */
typedef struct adpcm_ima_wav_channel_s
{
    int i_predictor;
    int i_step_index;

} adpcm_ima_wav_channel_t;

static int AdpcmImaWavExpandNibble(adpcm_ima_wav_channel_t *p_channel,
                                   int i_nibble )
{
    int i_diff;

    i_diff = i_step_table[p_channel->i_step_index] >> 3;
    if( i_nibble&0x04 ) i_diff += i_step_table[p_channel->i_step_index];
    if( i_nibble&0x02 ) i_diff += i_step_table[p_channel->i_step_index]>>1;
    if( i_nibble&0x01 ) i_diff += i_step_table[p_channel->i_step_index]>>2;
    if( i_nibble&0x08 )
        p_channel->i_predictor -= i_diff;
    else
        p_channel->i_predictor += i_diff;

    CLAMP( p_channel->i_predictor, -32768, 32767 );

    p_channel->i_step_index += i_index_table[i_nibble];

    CLAMP( p_channel->i_step_index, 0, 88 );

    return( p_channel->i_predictor );
}

static void DecodeAdpcmImaWav( decoder_t *p_dec, int16_t *p_sample,
                               uint8_t *p_buffer )
{
    decoder_sys_t *p_sys  = p_dec->p_sys;
    adpcm_ima_wav_channel_t channel[2];
    int                     i_nibbles;
    int                     b_stereo;

    b_stereo = p_dec->fmt_in.audio.i_channels == 2 ? 1 : 0;

    GetWord( channel[0].i_predictor );
    GetByte( channel[0].i_step_index );
    CLAMP( channel[0].i_step_index, 0, 88 );
    p_buffer++;

    if( b_stereo )
    {
        GetWord( channel[1].i_predictor );
        GetByte( channel[1].i_step_index );
        CLAMP( channel[1].i_step_index, 0, 88 );
        p_buffer++;
    }

    if( b_stereo )
    {
        for( i_nibbles = 2 * (p_sys->i_block - 8);
             i_nibbles > 0;
             i_nibbles -= 16 )
        {
            int i;

            for( i = 0; i < 4; i++ )
            {
                p_sample[i * 4] =
                    AdpcmImaWavExpandNibble(&channel[0],p_buffer[i]&0x0f);
                p_sample[i * 4 + 2] =
                    AdpcmImaWavExpandNibble(&channel[0],p_buffer[i] >> 4);
            }
            p_buffer += 4;

            for( i = 0; i < 4; i++ )
            {
                p_sample[i * 4 + 1] =
                    AdpcmImaWavExpandNibble(&channel[1],p_buffer[i]&0x0f);
                p_sample[i * 4 + 3] =
                    AdpcmImaWavExpandNibble(&channel[1],p_buffer[i] >> 4);
            }
            p_buffer += 4;
            p_sample += 16;

        }


    }
    else
    {
        for( i_nibbles = 2 * (p_sys->i_block - 4);
             i_nibbles > 0;
             i_nibbles -= 2, p_buffer++ )
        {
            *p_sample++ =AdpcmImaWavExpandNibble( &channel[0], (*p_buffer)&0x0f );
            *p_sample++ =AdpcmImaWavExpandNibble( &channel[0], (*p_buffer) >> 4 );
        }
    }
}

/*
 * Ima4 in QT file
 */
static void DecodeAdpcmImaQT( decoder_t *p_dec, int16_t *p_sample,
                              uint8_t *p_buffer )
{
    adpcm_ima_wav_channel_t channel[2];
    int                     i_nibbles;
    int                     i_ch;
    int                     i_step;

    i_step = p_dec->fmt_in.audio.i_channels;

    for( i_ch = 0; i_ch < p_dec->fmt_in.audio.i_channels; i_ch++ )
    {
        /* load preambule */
        channel[i_ch].i_predictor  = (int16_t)((( ( p_buffer[0] << 1 )|(  p_buffer[1] >> 7 ) ))<<7);
        channel[i_ch].i_step_index = p_buffer[1]&0x7f;

        CLAMP( channel[i_ch].i_step_index, 0, 88 );
        p_buffer += 2;

        for( i_nibbles = 0; i_nibbles < 64; i_nibbles +=2 )
        {
            *p_sample = AdpcmImaWavExpandNibble( &channel[i_ch], (*p_buffer)&0x0f);
            p_sample += i_step;

            *p_sample = AdpcmImaWavExpandNibble( &channel[i_ch], (*p_buffer >> 4)&0x0f);
            p_sample += i_step;

            p_buffer++;
        }

        /* Next channel */
        p_sample += 1 - 64 * i_step;
    }
}

/*
 * Dk4
 */
static void DecodeAdpcmDk4( decoder_t *p_dec, int16_t *p_sample,
                            uint8_t *p_buffer )
{
    decoder_sys_t *p_sys  = p_dec->p_sys;
    adpcm_ima_wav_channel_t channel[2];
    int                     i_nibbles;
    int                     b_stereo;

    b_stereo = p_dec->fmt_in.audio.i_channels == 2 ? 1 : 0;

    GetWord( channel[0].i_predictor );
    GetByte( channel[0].i_step_index );
    CLAMP( channel[0].i_step_index, 0, 88 );
    p_buffer++;

    if( b_stereo )
    {
        GetWord( channel[1].i_predictor );
        GetByte( channel[1].i_step_index );
        CLAMP( channel[1].i_step_index, 0, 88 );
        p_buffer++;
    }

    /* first output predictor */
    *p_sample++ = channel[0].i_predictor;
    if( b_stereo )
    {
        *p_sample++ = channel[1].i_predictor;
    }

    for( i_nibbles = 0;
         i_nibbles < p_sys->i_block - 4 * (b_stereo ? 2:1 );
         i_nibbles++ )
    {
        *p_sample++ = AdpcmImaWavExpandNibble( &channel[0],
                                              (*p_buffer) >> 4);
        *p_sample++ = AdpcmImaWavExpandNibble( &channel[b_stereo ? 1 : 0],
                                               (*p_buffer)&0x0f);

        p_buffer++;
    }
}

/*
 * Dk3
 */
static void DecodeAdpcmDk3( decoder_t *p_dec, int16_t *p_sample,
                            uint8_t *p_buffer )
{
    decoder_sys_t *p_sys  = p_dec->p_sys;
    uint8_t                 *p_end = &p_buffer[p_sys->i_block];
    adpcm_ima_wav_channel_t sum;
    adpcm_ima_wav_channel_t diff;
    int                     i_diff_value;

    p_buffer += 10;

    GetWord( sum.i_predictor );
    GetWord( diff.i_predictor );
    GetByte( sum.i_step_index );
    GetByte( diff.i_step_index );

    i_diff_value = diff.i_predictor;
    /* we process 6 nibbles at once */
    while( p_buffer + 1 <= p_end )
    {
        /* first 3 nibbles */
        AdpcmImaWavExpandNibble( &sum,
                                 (*p_buffer)&0x0f);

        AdpcmImaWavExpandNibble( &diff,
                                 (*p_buffer) >> 4 );

        i_diff_value = ( i_diff_value + diff.i_predictor ) / 2;

        *p_sample++ = sum.i_predictor + i_diff_value;
        *p_sample++ = sum.i_predictor - i_diff_value;

        p_buffer++;

        AdpcmImaWavExpandNibble( &sum,
                                 (*p_buffer)&0x0f);

        *p_sample++ = sum.i_predictor + i_diff_value;
        *p_sample++ = sum.i_predictor - i_diff_value;

        /* now last 3 nibbles */
        AdpcmImaWavExpandNibble( &sum,
                                 (*p_buffer)>>4);
        p_buffer++;
        if( p_buffer < p_end )
        {
            AdpcmImaWavExpandNibble( &diff,
                                     (*p_buffer)&0x0f );

            i_diff_value = ( i_diff_value + diff.i_predictor ) / 2;

            *p_sample++ = sum.i_predictor + i_diff_value;
            *p_sample++ = sum.i_predictor - i_diff_value;

            AdpcmImaWavExpandNibble( &sum,
                                     (*p_buffer)>>4);
            p_buffer++;

            *p_sample++ = sum.i_predictor + i_diff_value;
            *p_sample++ = sum.i_predictor - i_diff_value;
        }
    }
}


/*
 * EA ADPCM
 */
#define MAX_CHAN 5
static void DecodeAdpcmEA( decoder_t *p_dec, int16_t *p_sample,
                           uint8_t *p_buffer )
{
    static const uint32_t EATable[]=
    {
        0x00000000, 0x000000F0, 0x000001CC, 0x00000188,
        0x00000000, 0x00000000, 0xFFFFFF30, 0xFFFFFF24,
        0x00000000, 0x00000001, 0x00000003, 0x00000004,
        0x00000007, 0x00000008, 0x0000000A, 0x0000000B,
        0x00000000, 0xFFFFFFFF, 0xFFFFFFFD, 0xFFFFFFFC
    };
    decoder_sys_t *p_sys  = p_dec->p_sys;
    uint8_t *p_end;
    unsigned i_channels, c;
    int16_t *prev, *cur;
    int32_t c1[MAX_CHAN], c2[MAX_CHAN];
    int8_t d[MAX_CHAN];

    i_channels = p_dec->fmt_in.audio.i_channels;
    p_end = &p_buffer[p_sys->i_block];

    prev = (int16_t *)p_dec->fmt_in.p_extra;
    cur = prev + i_channels;

    for (c = 0; c < i_channels; c++)
    {
        uint8_t input;

        input = p_buffer[c];
        c1[c] = EATable[input >> 4];
        c2[c] = EATable[(input >> 4) + 4];
        d[c] = (input & 0xf) + 8;
    }

    for( p_buffer += i_channels; p_buffer < p_end ; p_buffer += i_channels)
    {
        for (c = 0; c < i_channels; c++)
        {
            int32_t spl;

            spl = (p_buffer[c] >> 4) & 0xf;
            spl = (spl << 0x1c) >> d[c];
            spl = (spl + cur[c] * c1[c] + prev[c] * c2[c] + 0x80) >> 8;
            CLAMP( spl, -32768, 32767 );
            prev[c] = cur[c];
            cur[c] = spl;

            *(p_sample++) = spl;
        }

        for (c = 0; c < i_channels; c++)
        {
            int32_t spl;

            spl = p_buffer[c] & 0xf;
            spl = (spl << 0x1c) >> d[c];
            spl = (spl + cur[c] * c1[c] + prev[c] * c2[c] + 0x80) >> 8;
            CLAMP( spl, -32768, 32767 );
            prev[c] = cur[c];
            cur[c] = spl;

            *(p_sample++) = spl;
        }
    }
}