By way of an introduction, if you haven't heard of it before the Popcorn Hour range of media streamers aims to offer a way of playing back pretty much any kind of video and audio. When Syabas started making the A100 - the first-generation device - there was almost no hardware that could extract video from MKV files. Now, of course, everything from TVs to mobile phones can play most of these formerly exotic formats.The latest in the line-up is the A-400: it differs from the previous models in some ways, and is identical to them in others. One thing that is new is the case, which now feels like it could make it through a war as some sort of bulletproofing. A large sticker on the top warns that the unit will get hot during use, because it uses passive cooling. There's also the suggestion that you should give it some space to take care of business.The user interface isn't much changed since the C-200. That's a mixed bag, because it has always been quite good, but elsewhere things have moved on. Look at Plex, for example, which runs on phones, computers, tablets and even some TVs. It's a fully featured media management system that produces well-organised media and numerous ways to sort, and thus access, your videos.Of course, the A-400 has a rich media interface available too, which you can opt to use over the plain text system. On older players, this interface was a bit sluggish, but the A-400 has a new dual-core processor, and a dedicated video processor. It's here that the company wants to get you hooked, because its attention to the hardware in the Popcorn Hour devices is one of the things that sets it apart from a laptop or media centre PC.Pretty much every type of video or audio format is supported, as with previous models. For example, you can easily play 1080p video in MKVs, but there's support for most types of MPEG video and data rates can be high, and the A-400 won't get out of its depth. HD audio is also supported, so you can get those glorious 7.2 channel soundtracks reproduced perfectly too.It's not all plain sailing: for example, there's no support for HEVC (high efficiency video coding) yet. As the standard isn't set, that's not a surprise, but it would be nice to see it supported on the Popcorn Hour via an update. HEVC is likely to be a big deal this year, as everyone looks to save a bit of space otherwise swallowed by bulky video.There's an app store too, although we've never found it especially appealing, as there isn't a huge number of useful apps, for a variety of reasons. If you're looking to watch Netflix on this little beauty, get ready for some disappointment.Media can be accessed either from your network - there's gigabit Ethernet - or from USB devices and, if you prefer, an internal hard drive. You'll have to provide this yourself, but it allows you to upload video to the Popcorn Hour and play it without any risk of stuttering playback. We have previously enjoyed this when our home network wasn't capable of delivering high-bitrate 1080p video.A full review is coming in the next few weeks. We'll look in more depth at the picture quality, user interface and how to get the best out the device.