Home > Blackmagic Design, Codecs, FFmbc, Video > Blackmagic Decklink SDI and Linux

Blackmagic Decklink SDI and Linux

Almost a year ago, I invested in a central London based post-production company. At the time, I had dreams of pushing open source software solutions into the professional post-production arena. Things haven’t quite worked out as planned, and I’ve made very limited headway on this project. Business imperatives took over and changing a whole ecosystem is a big job. I’ve continued to use Linux on my laptop and happily connect to printers and network drives, but that’s about all.

Recently I had an opportunity to change all that. We needed a tape digitisation solution, separate from our Avid editing suites, for a new project. I’ve know for a while that Blackmagic’s Decklink range of cards work with Linux and were pretty good for capturing from SDI. We purchased the basic Decklink SDI card, re-cycled an old machine onto which I installed Linux Mint Debian and away we went….

Things weren’t entirely smooth from the start. I upgraded the Mint Debian ISO, including the kernel to 2.6.39. This was my first mistake. The card was not recognised with this kernel. Booting into the original 2.6.32 kernel overcame this problem and the card was recognised. I had to download the relevant Linux software from the Blackmagic website, as the accompanying DVD only included Windows software. The available Linux software from Blackmagic included the relevant drivers, firmware and Media Express software. Unfortunately, other advertised items such as the drive speed test and alpha keying utilities are not available for Linux.

Once everything was up and running, it was time to capture. The Media Express 2.3.1 software was pretty straight forward to use. Setting in and out points allowed the software to control the J30 Digibeta deck and content was captured in Uncompressed 10-bit YUV formate. The other limited codec options included Uncompressed 8-bit YUV, RGB and MotionJPEG. This uncompressed file was then transcoded to IMX50 using FFMbc. The whole process seemed to work reasonably well, and I’m just now waiting to send the IMX50 sample off for technical inspection.

Unfortunately, the Media Express software as supplied did not provide options to change the SD captured frame size from 720×576 to anything else. Ideally I was looking for 720×608 so that VITC was also captured. A phone call to Blackmagic revealed that this was possible with the Windows and Mac version of their software, but not on Linux. Their Linux SDK did expose the necessary calls, but the software had not been written to include them. Essentially, if I wanted VITC, I’d need to write a capture utility myself. Somewhat disappointing.

Overall, I’m pleased that we now have an SDI capture solution running on Linux. However, the Blackmagic Decklink card still feels a little half baked and Linux was perhaps only an afterthought for them.

About these ads
  1. June 24, 2011 at 23:54 | #1

    MLT and Kdenlive (as used by MLT) supports DeckLink. You can do keyer output from melt, MLT’s command line utility (as well as viewing, capture, live encoding, etc.). At the moment, you can not capture 720×608, and I am not sure at the moment how to do that.

  2. June 25, 2011 at 05:19 | #2

    Thanks for the response Dan.

    Blackmagic have told me on the phone that their SDK supports capture at 720×608 for retention of VITC.

    http://www.blackmagic-design.com/support/detail/?sid=3945&pid=4013&os=linux&leg=0

    There’s a Linux SDK manual alongside this too.

    I am not clever enough to implement something like this, but perhaps you can.

  3. brao
    June 27, 2011 at 13:54 | #3

    Hello; there is a commercial gstreamer plugin for Blackmagic Design products, you should check it out ! I tried it with Intensity Pro with success, don’t know for the product you are using.

    http://mediamagictechnologies.com/products.html

  4. June 29, 2011 at 20:14 | #4

    The Blackmagic cards won’t let you capture the Vertical Blanking lines directly as a 720×608 image, you have to use the special SDK functions to extract each line one-by-one for that. We’re using these cards to capture AFD and captions which are then encapsulated and passed into the MPEG-4 encoder.

    The lower end cards which are PCI 1x only allow access to lines after the switching point. They don’t mention that anywhere, which caused a bit of a headache until I contacted support.

    Hopefully the new set of drivers coming out will support 2.6.39.

    “I had dreams of pushing open source software solutions into the professional post-production arena”

    I can’t really speak for post-production but there’s a growing list of well known names using encoding discs with x264 for Blu-Ray – see http://www.x264bluray.com/x264-encoded-releases

    I’m of the opinion that Open Source has spent too long making “jack of all trades, master of none” tools like ffmpeg and vlc. It’s going to be slightly more specialised tools like ffmbc which will be better for professional use.

  5. September 25, 2011 at 04:03 | #5

    Speaking of ffbmc, your readers might want to actually download a binary for this tool.
    http://forum.doom9.org/showthread.php?goto=newpost&t=162615

  1. July 21, 2011 at 15:44 | #1

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s

Follow

Get every new post delivered to your Inbox.

%d bloggers like this: