Posts Tagged ‘Decklink’

Blackmagic Media Express Failure

July 21, 2011 4 comments

About one month ago I posted that we are now using a Blackmagic Decklink SDI card to capture via SDI in some workflows at The Station. Unfortunately it became clear quite quickly that the Media Express 2.3.1 software we were using, for capturing and controlling the decks, had some shortcomings.

Apparently the Linux version of this software does not support capture of VITC information where present. This made creating valid IMX50 (D10) files harder than it needed to be. We would capture the SD content from tape into 10-bit uncompressed at 720×576, then when transcoding using FFmbc, we needed to pad the top of the file with 36 lines of blanking, to create a valid IMX50 at 720×608. This process caused a few problems with the resulting files’ aspect ratio information.

After speaking with the support staff ot Blackmagic Design, it became clear the the Windows and Mac versions of Media Express 2.3.1 do support capture of VITC, just not the Linux version. The relevant API calls are exposed in the freely available SDK, but we would need to build our own application to take advantage of this.

My next hope was that the new version of Media Express would include this additional functionality on Linux. On April 11th 2011, Blackmagic published a press release stating that Media Express 3.0 would be available for Windows, Mac and Linux. The software would be available for free download from their website in June.

Today I went searching for the software but could not find it. Looking on the Blackmagic software download page, the latest Desktop Video download for Linux is 8.0.1 from May 13th, 2011. Clearly this would not include the new 3.0 version, as this file is what I downloaded a month ago to obtain version 2.3.1.

I phoned Blackmagic support again to enquire about where to find Media Express 3.0. They informed me that a beta version of this software was available for Mac platforms, but that was all. They were also unable to speculate regarding a formal release date for the software, nor whether the Linux version would be available at the same time as the Windows and Mac version. All in all, not very helpful.

June finished 21 days ago. I want my Media Express 3.0 software for Linux!

Blackmagic Decklink SDI and Linux

June 24, 2011 6 comments

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.


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