static inline void put_dct(MpegEncContext *s,
                           int16_t *block, int i, uint8_t *dest, int line_size, int qscale)
{
    s->dct_unquantize_intra(s, block, i, qscale);
    s->idsp.idct_put(dest, line_size, block);
}

The product dereferences a pointer that it expects to be valid but is NULL.