Function Decode

libhb/declpcm.c:242–371

}

static hb_buffer_t *Decode( hb_work_object_t *w )
{
    hb_work_private_t *pv = w->private_data;
    hb_buffer_t *out;

    if (pv->nsamples == 0)
        return NULL;

    int size = pv->nsamples * pv->nchannels * sizeof( float );
    if (pv->alloc_size != size)
    {
        pv->data = realloc( pv->data, size );
        pv->alloc_size = size;
    }

    float *odat = (float *)pv->data;
    int count = pv->nchunks / pv->nchannels;

    switch( pv->sample_size )
    {
        case 16: // 2 byte, big endian, signed (the right shift sign extends)
        {
            uint8_t *frm = pv->frame;
            while ( count-- )
            {
                int cc;
                for( cc = 0; cc < pv->nchannels; cc++ )
                {
                    // Shifts below result in sign extension which gives
                    // us proper signed values. The final division adjusts
                    // the range to [-1.0 ... 1.0]
                    *odat++ = (float)( ( (int)( frm[0] << 24 ) >> 16 ) |
                                       frm[1] ) / 32768.0;
                    frm += 2;
                }
            }
        } break;
        case 20:
        {
            // There will always be 2 groups of samples.  A group is
            // a collection of samples that spans all channels.
            // The data for the samples is split.  The first 2 msb
            // bytes for all samples is encoded first, then the remaining
            // lsb bits are encoded.
            uint8_t *frm = pv->frame;
            while ( count-- )
            {
                int gg, cc;
                int shift = 4;
                uint8_t *lsb = frm + 4 * pv->nchannels;
                for( gg = 0; gg < 2; gg++ )
                {
                    for( cc = 0; cc < pv->nchannels; cc++ )
                    {
                        // Shifts below result in sign extension which gives
                        // us proper signed values. The final division adjusts
                        // the range to [-1.0 ... 1.0]
                        *odat = (float)( ( (int)( frm[0] << 24 ) >> 12 ) |