OK, so we all know what Google’s Chromecast is, yes? Someone at the back — why are they always at the back? — seems unsure. In a sentence, then, Chromecast is a small WiFi-connected slug that you slip into a spare HDMI port on your TV, and which plays video and audio under the direction of a remote control app.

Google introduced Chromecast a couple of years ago, but it took a further nine months to get here. There’s no such latency with the latest version: unveiled in September, it was on sale in the UK within a week. The update centres on improved WiFi and a new physical design, but that’s about it. Changes have been made to the software, but they’re being rolled out to first-generation Chromecasts too.

Rather than simply smooth out the original Chromecast’s angular curves, which were formed from a series of straight lines so that Chromecast looked like it had been styled in a Quake level-design package, Google has completely changed it. No longer a stick, Chromecast is now a puck on a string, the cord being an integrated HDMI cable. The upshot is that it dangles off the back of your telly, which the old one only did if you needed to make use of the bundled HDMI extension cable. No extension cable here, so if Chromecast still doesn’t fit, tough luck.

As before, the new Chromecast needs an external power source, either a bundled 5V/1A wall wart or a correct-spec USB port on the TV itself. The latter is handy if, like me, you’ve run out of power sockets. I’ve heard it said that the original ran into trouble playing 1080p video if it wasn’t plugged in to an AC adaptor, but I had no bother. I suspect that’s a case of earlier commentators owning tellies with sub-spec USB port, but it’s possible Google has improved the Chromecast’s innards too.

How well a TV’s USB port will work will also depend on whether the TV keeps it powered while in standby. Mine does, so thanks to Chromecast’s support for HDMI-CEC, I can just fire up BBC iPlayer, tap the Chromecast icon and my TV will turn on and switch input automatically. If everything is turned off physically, Chromecast takes about 20 seconds to boot up before an app can detect it.

Many apps now support Chromecast, among them Netflix, Now TV, Sport, Google Play (natch), YouTube (ditto) and a host more from no-name developers — on the iOS side, many of them from the kinds of Chinese coders caught by last month’s Xcode hack, so some pre-download caution is due.

Google makes its iOS and Android Chromecast SDK readily, available so there’s really no excuse for a content provider not allowing their app to ‘cast’. Apple and Amazon naturally irritate by insisting you play with their toys and no one else’s, but that’s DRM and customer-loathing business practices for you. Prime Minister Corbyn will sort them out…

While mobile apps source material for Chromecast, and control playback, they don’t actually play the material. In fact, all a mobile app does is tell Chromecast where the content is being served from and what app of its own should be run to display that content. Chromecast has a default ‘receiver’ app, but content providers and app developers can build their own if they want to display their own branding and/or UI. Receivers are lightweight apps hosted by Google and built out of HTML 5 and JavaScript.

When the ‘sender’ app — the one running on the phone or tablet — connects to a Chromecast to play a file, it sends the file’s location and the ID of the receiver app that needs to be run first. The rest is just HTTP streaming from source to Chromecast.

The upshot is that unless you’re using an app which allows you to play a video format not natively supported by Chromecast, your mobile device shouldn’t be taxed by Chromecast usage. Which is good news if your phone has poor battery life. Playing unsupported formats requires on-the-fly video conversion, and your mobile will have to do that. Chromecast supports many popular containers and codecs, including MP4, AAC, MP3, WAV, FLAC and Vorbis, but MKV and AVI files are out, I’m afraid. You can read the full list here.

Apps like BBC iPlayer send Chromecast off to their own sites for content, but a number of third-party apps will do local streaming, either from the mobile itself (bear in mind the proviso above) or a shared drive on the network. All my stuff is in MP4 format anyway, so I had no trouble streaming locally, whether playing standard-definition or high-definition footage, either 720p or 1080p HD. The material looked good and certainly on a par with my Slice media player.

In addition to mobile apps, you can stream from a computer provided you run Google’s Chrome browser, for which there’s a casting plug-in. This makes for a decent means to mirror, say, a Google Docs presentation from your laptop screen to a big TV or projector, but you’re limited to browser-viewed content. If you’re not a supporter of Occupy Flash and you still have Adobe Flash on your system, you can use Chrome to display catch-up content from services that don’t offer a mobile app, or insist that you sign up to use one.

The Chrome specificity annoys me. If Google is happy to make casting a feature of iOS, why can’t it support Firefox, Safari et al on desktops?

The new Chromecast features 802.11ac WiFi, but I’m still on 802.11n at home and that worked well enough. The Chromecast’s WiFi upgrade gives it access to the 5GHz band, which is handy if you’re surrounded by 2.4GHz WLANs and your neighbours enjoy microwave cookery. The boosted WiFi gives the Chrome plug-in more bandwidth for its ‘Extreme (720p high bitrate)’ mode, which is handy for streaming browser-accessed media, but doesn’t improve the lag you experience with web pages. There’s still about a second’s delay between scrolling on your laptop and the TV picture being updated.

Verdict

My 2011 Sony TV works a treat, but its version of BBC iPlayer is no longer up to snuff and fares very poorly in comparison with the mobile app versions: it doesn’t display new content as quickly, buffers far more often than the apps do, and the picture quality isn’t as good. Thanks to the Chromecast, I don’t give a proverbial whether the TV iPlayer ever gets fixed. In fact, using HDMI-CEC, I can begin playing a programme much more quickly using Chromecast than I can using the Sony remote and the on-board iPlayer. Win.

Your mileage may very, however. If you have a first-gen Chromecast, there is no point replacing it unless you think the upgraded WiFi will help, and that depends on the relative positions of your WiFi router and your telly. If you have a set-top box for NAS-sourced or on-board hard drive content, that‘s a better option for playing such material because it won’t rely on an ad-filled third-party app for remote control. Chromecast naturally favours Android users — the set-up app has content finding functionality absent from the iOS versions — but the device is easy to set up whichever mobile platform you favour.

The real point is that, at £30, Chromecast is a true impulse purchase, so why not avail yourself of one? Seek out discounts on the old one and get it cheaper if you can. Even if, like me, you only ever use it for one role, like iPlayer, it won’t be money wasted.

Price £30
More Info Google Play

An edited version of this review first appeared on The Register