Compro VideoMata U2800F DVB-T Receiver Tested In Belgium

Others/Miscelleneous by geoffrey @ 2009-05-07

Classic analog antenna broadcastings are soon to disappear all around the world and in most cases being replaced by a digital version, in some occasions you might even run into full high definition video broadcastings. Great news for wireless receivers out there, DVB-T is an excellent way to watch quality video wherever you want, but is it really? We tested a Compro VideoMate Vista U2800F USB DVB-T receiver on Belgian grounds and the outcome is not always what you would have wished for... read on!

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Introduction & DVB explored

Introduction

The digital revolution is on and you're not going to escape it! Those of you who have been watching analog antenna broadcastings the past 20 years or more are soon going to look very disappointed when their screen suddenly pulls gray and noisy. Fact is that some country governments have decided to quit broadcasting analog TV signals whether it's done via cable, antenna or satellite, some countries might already have pulled to plug as we speak. Well, you can't really argue with them as digital (HD) TV signals really are superior to the analog signals we've been using the past decades. Yes, there is certain incompatibility involved but at some point there just won't be enough customers for analog broadcastings in order to keep it financially interesting. And let's face it: are you really going to keep on watching analog when you can have video quality which is more than twice as good?

With that in mind let us first have a look at how broadcastings are being offered.

Digital Video Broadcasting explored

Early in the 90's of the previous century some mayor international companies came together to discuss the future of digital TV in Europe. Followed up by the formation of the DVB (Digital Video Broadcasting) consortium we saw the first open standards for digital television broadcastings being released in 1994: DVB-C and DVB-S were born. Later in early 1997 DVB-T was being added to the list with more standards following over the years. Nowadays DVB is slowly taking over the market which was once covered with pure analog signals, some country's like Belgium have already decided to no longer broadcast analog terrestrial (via antenna) video and by 2012 many more European countries will follow in their paths, the digital revolution is nearly complete!

So what mayor standards are available here in Europe...

  • DVB-T: video broadcasting using a transmitter/receiver antenna
  • DVB-S: video broadcasting using a satellite
  • DVB-C: video broadcasting using the cable
  • DVB-H: much alike DVB-T though specially developed for compact and portable devices like Cell phones and PDA's.

    At this moment DVB2 is already surfacing and promises more options, higher efficiency and many more. Downside is that it requires a hardware upgrade...
    Also make note that some companies use IPTV: television via ADSL for example.

    A closer look at DVB-T

    Terrestrial Digital Video Broadcasting using an antenna is what we're going to focus on for our today's product. DVB-T replaces the older analog antenna broadcastings which many of you might have used in the past, digital video is being brought to a transmitter pole via IP/ATM/... where it is then being send into the ether somewhere in the UHF (Ultra High Frequency) electromagnetic frequency band. People can collect signals and receive DVB-T using an antenna, though now with everything being encoded there is still the need for a Set-Top-Box which converts the digital data to a digital/analog signal which can be used by your television.

    Madshrimps (c)


    The benefits from using digital over analog transmissions is that the image quality is mostly better. With analog broadcasting you'll see grain and noise appearing if the signal isn't that great, with digital broadcasting you either receive or don't receive a signal. The upside of all this is that DVB-T requires less transmitting power, its efficiency is greater than that of analog broadcastings: even if your signal quality wasn't that great with analog broadcasting (noise/reflections) the chance is very big you have clear video quality when using DVB-T. On a side not here, DVB-T signal quality isn’t exactly ying or yang like I told you above, sometimes you might see artifacts like black squares if reception isn't the best.

    Nowadays with the open DVB-T2 standard being finalized you might also stumble upon even greater image quality, DVB-T2 promises 30% more capacity over DVB-T which allows High Definition channels to now go life and transmit using terrestrial broadcasting.

    Talking about video quality, latest DVB-T broadcastings use the MPEG-4 H.264/AVC video codec which is nearly twice as efficient as the MPEG-2 codec, it allows DVB-T to increase from broadcasting at 25 frames per second at 720x576 resolution (PAL) to 25fps at 1280x720 resolution. The release of DVB-T2 would allow more channels to broadcast in HD because current DVB-T bandwidth isn't all that great. Aside of all this there is also something called DAB, Digital Audio Broadcasting, the DVB-T for radio's. Again we're talking about better quality, at 192kBit/s you have near CD quality audio, our Compro VideoMate isn't able to receive DAB but instead receive DVB-T radio.

    We’re going to have a view on what DVB options are available for our local Belgians viewers. Broadcastings are very bound to the place you live so we are not able to answer everyone's request on what their options are, if you're not interested in our local politics I suggest you jump straight to page 3!
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    Comment from geoffrey @ 2010/12/03
    It's been a while since this article is launched and I've been using this thing for a while now. I must say it's pretty handy to have one of these, though the software bugs are still there and are sometimes annoying cause they can ruin your recordings.

    This said, I was looking for Linux support but unfortunately there non such, Compro simply hasn't got any drivers for it. I ended up opening the device to have a look at the internals and it seems Compro is using a Trident TV Master TM6010 video decoder. On linux.org I found the following info:

    Quote:
    There were some efforts on developing a driver for tm5600/tm6000/tm6010 chips.
    Michel Ludwig (michel.ludwig gmail.com) did some development mostly focused at DVB-T of tm6000. Mauro Carvalho Chehab did some development moslty focused at analog support, and extended support for tm6010.
    There are some versions of the driver at http://linuxtv.org/~hg that merged both developments.
    The driver is still at the TODO list, however its development is currently frosen. Mauro intends to return back to it, but this is not on his current top priorities.
    Those chips are very buggy and they behave badly if the driver doesn't do exactly the same thing as the original one (it starts to loose frames). The reason is unknown, but it is suspected that there is a firmware or hardware bug at those chips.
    Maybe the conversion of the driver to the new i2c approach could help to fix this issue, since this will avoid sending probing packets at i2c bus, as it is known that some i2c probe sequences can hang those chips.
    Also, on all tests we've done so far, it can't reliably read data from an i2c device. This prevents that tools like scan work, since you can't be sure if a signal lock happened. Also, driver can't even be sure if xc3028 firmware were successfully loaded on this device.
    It is important to notice that the vendor (Trident) doesn't seem to want helping with open source development. Contacts with the vendor were tried during 2007 and 2008 in order to get their help by opening docs, via Linux Foundation NDA program, without success.
    The vendor also seems to be refusing so far to help the development of a driver for their demod DRX-K line that they acquired from Micronas (as pointed at http://linux.terratec.de/tv_en.html).
    In brief, while we want to fix the driver issues, it is recommend to avoid buying any devices with tm5600/tm6000/tm6010 (and DRX demod) chips.
    source: http://linuxtv.org/wiki/index.php/Tr..._based_Devices

    It seems that these random crashes could be caused by a firmware runtime error, although I can not confirm this and neither did Compro at the time I asked them about it. I'd say better be warned...

     

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