The whole point of torture porn is to aggravate its opponents. Most will join the chorus of disapproval without actually bothering to watch what they're protesting against. Even fewer will recognise that their revulsion matters more to the director than the knowing gasps of the appreciative genre audience. Lars von Trier knew this when he produced Antichrist (2009) and Dutch provocateur Tom Six plays the same game, perhaps with even greater acuity, in The Human Centipede (First Sequence), right down to ensuring that everyone is aware that he had the idea for the film while joking with friends that the best way to punish a child molester was to stitch their mouth to the anus of an obese trucker.

Unsurprisingly, this calculating shocker has divided the critics, with some tutting in dismay, others applauding the Frankensteinian audacity of the conceit and others still expressing detached disdain while appreciating Six's ability to whip up the precise response he set out to achieve. Few, however, have suggested that The Human Centipede is actually rather tame. The BBFC passed it uncut, as much of the truly hideous action occurs off screen, and veterans of the Hostel and Saw franchises could well find themselves stifling yawns between emitting the occasional chuckle at the gleefully bleak gallows humour and deliberately outré performances.

American twentysomethings Ashley C. Williams and Ashlynn Yennie are travelling in Europe and have been invited to a party in the back of beyond by a German waiter. Naturally, they get lost, puncture a tyre and resort to bickering as they teeter through the woods on high heels looking for help. Just as it starts to rain, however, they see a light in a remote house and ask the sinisterly taciturn occupant if he will call their rental car company. As we have already seen Dieter Laser stalking truck driver Rene de Wit with a rifle, it's pretty safe to assume that he has no intention of phoning anybody and two glasses of rohypnolled water seal the women's fate.

By the time they come to, Williams and Yennie are tethered to beds in Laser's underground laboratory and they watch in horror as he murders De Wit for being surgically incompatible with them. The next time the pair wake, they have been joined by Japanese tourist Akihiro Katsuro and are treated to an overhead projector presentation, in which Laser explains that while he made his name by separating conjoined twins, his real obsession lies in creating single life forms from multiple components. His previous experiment with three rottweilers ended unhappily, but he is nevertheless ready to attempt a human procedure involving oral-anal linkage.

As Laser anaesthetises her companions, Williams manages to free herself and hide in a bedroom. However, Laser smashes the window and sends Williams fleeing into his pool room, where he stands over her, rifle in hand, as she bobs helplessly in the water. A power cut affords another chance to escape, but Williams is sufficiently loyal to Yennie to go back and rescue her and she pays the price by being felled with a tranquilliser dart as she tries to haul her friend's comatose body across the lawn.

A short surgical montage ensues and Laser is soon rousing his creature from its slumbers, with Williams having been placed in the middle as punishment for her intransigence. There's no denying the grotesqueness of the aberration that Laser has fashioned, but strategically placed bandages mask the full extent of the degradingly barbaric connections. Consequently, only some livid cheek scars and the perpetual whimpering of the terrified women convey any sense of the pain and humiliation experienced by the unholy trinity as Laser first attempts to teach his new pet to fetch his paper and then watches in sadistic delight as Williams takes disgusting sustenance after Katsuro has eaten.

But Laser's triumph is short-lived, as he has been careless in covering his tracks and he makes an even bigger mistake in antagonising cops Andreas Leupold and Peter Blankenstein, who vow to return with a search warrant for his cellar. Moreover, Katsuro - who has been foiled in his efforts to alert the detectives to his presence - manages to get hold of a scalpel and he instigates a pitiless round of blood-letting that culminates in a gruesome twist on the Final Girl scenario.

Six has stressed the significance of the characters hailing from nations involved in the Second World War and the importance of the language barrier between Laser and Katsuro that prevents any meaninful interaction between the monstrosity and its creator. But while Laser consciously evokes a Nazi maniac capable of Mengele-like atrocities, the wartime allusion seems to be mere window-dressing to disguise the cynical attempt to hook the cult markets in America and Japan.

The influence of J-horror is certainly strong and Six is clearly indebted to the body horror of David Cronenburg. But the emphasis is much more firmly on suffering than suspense, with the result that this is a disappointingly mundane movie that rather lurches between key moments with an awkwardness to match that of the human hybrid. Laser makes a splendidly maleovlent villain, but his panicked reaction to Leupold and Blankenstein's snooping is clumsily unconvincing and the action rather collapses in on itself after Katsuro's poignant speech about deserving a better fate, in spite of his many, but minor flaws.

More time might profitably have been devoted to the trio coming to terms with its new state or Laser's efforts to bend it to his will. But Six seems disinterested in psychological chills and this prevents the film from having anything more than a mild gross-out effect, when it might have moved away from the genre's trademark focus on humanity's dread of death to the much less explored fear of excruciation and physical mutilation.

An obsession of a much more wholesome sort informs Lilian Franck and Robert Cibis's Pianomania, as it follows Steinway tuner Stefan Knüpfer as he goes about his duties at the Vienna Konzerthaus. A genial perfectionist who revels in his work, Knüpfer makes for an unlikely hero. But such is his innate understanding of both the instruments in his care and the classical repertoire that he reclaims the concept of expertise from the arrogant and often self-promoting nobodies who currently dominate talking-head documentaries and TV shows.

Vaguely resembling the Milky Bar Kid, Knüpfer takes great pride in maintaining the Konzerthaus's pianos and is distraught when one of his favourites is packed up for dispatch to Melbourne. His disappointment is shared by Pierre-Laurent Aimard, who was hoping to use it to record Bach's `The Art of the Fugue' in a few months time. However, Knüpfer promises to have a replacement fine-tuned to Aimard's exacting requirements, even if it means having to survive an eleventh-hour crisis caused by the hammers designed to refine the instrument's tone and colour being 0.7mm too narrow.

Indeed, Knüpfer's ingenuity is regularly tested throughout the picture, whether he has to find a suitably heavy stool for the energetic Lang Lang or modify the higher notes to suit Alfred Brendel. He even concocts comic business for the knockabout team of Aleksey Igudesman and Richard Hyung-Ki Joo, who are quick to extol both his sense of humour and his under-appreciated musicianship. But it's Aimard who makes the greatest demands, particularly in the run up to a concert in Graz, for which Knüpfer has invented a series of sound reflectors to fit inside the Steinway to compensate for the auditorium's hostile acoustics. He is also at the maestro's beck and call throughout the Bach sessions, hurtling down the stairs from the makeshift studio to make the minutest changes to the weight of a hammer or the tension of a wire.

When not shuttling around the Austrian capital in his little white van, Knüpfer is making a pilgrimage to the Steinway & Sons headquarters in Hamburg in order to advise on the timbre of the Konzerthaus's next purchase. He bears the responsibility lightly and his modesty is complemented throughout by the pleasure he takes in the craftsmanship and artistry of others. But he is much more than a mere technician himself, as his fingers caress the keys with the same finesse he uses to coax out a piano's personality with his wrench. Dedicated, enthusiastic and amusing, Stefan Knüpfer is as acute as his senses and it's a privilege to spend time in his company.