Resolve Capture Decklink Studio 4K on Linux

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Doug Marsh

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Resolve Capture Decklink Studio 4K on Linux

PostSun Sep 24, 2017 2:41 am

I got the machine assembled and tested. Did some preliminary things (firmware update, test captures/playbacks in Media Express, even tested OBS capturing -- everything works, there are quirks with keeping audio and video in sync inside OBS, but that's outside THIS support)

Inside Resolve (lite 14) there is a capture option inside the media view, click on project settings,one cap capture in DPX or Quicktime, Under Quicktime there are options for DNxHD and Uncompressed.

The video I have coming in is set to 1080p59.94 and p60 but plan to test out more sources (once I find a cable that walked off all by itself)

I tried several options, permutations etc... and for a second or two the video comes up in the preview monitor (output from Decklink Studio 4K). Resolve comes up with message about "There is no valid input video signal detected. -- Please check the video connections are secured and selected video format is matching the input video. "

Does the capture INSIDE Resolve only capture from SDI ?! IF so then I'll need to get HDMI to SDI conversion and cables..

If NOT, then why does Resolve not detect the input when OBS and Media Express can see the video. (the audio sync is another issue inside OBS).

--Doug (dx9s)
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Peter Chamberlain

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Re: Resolve Capture Decklink Studio 4K on Linux

PostSun Sep 24, 2017 7:39 am

Resolve only captures from SDI and only at a constant frame rate. If your OBS can generate a constant frame rate in hdmi you can use a BMD converter to SDI.
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Doug Marsh

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Re: Resolve Capture Decklink Studio 4K on Linux

PostSun Sep 24, 2017 8:38 pm

Not sure why then I got the Studio 4K as it has HDMI in and out... Should have gotten a different model and purchased HDMI to SDI converter and saved money... Little irritated at that information not being clear. I would like to capture directly into Resolve (eventually Resolve Studio) as DNxHD or uncompressed YUV instead of capturing external and transcoding/importing.

The Express Media only supports MJPEG for compressed (seems like 8-bit limited color range, but not sure) in addition to the 2650Mbps+ (one test I did) uncompressed (over 340MB/sec).. I am gonna have to purchase a few more 6TB spinning drives and setup in RAID 0 to capture some things.

OBS (full name OBS Studio, not to be confused with Decklink Studio 4K, or Resolve Studio) is a different capture program intended for (in part) live streaming but can also be used for capture to disk as well.

I can capture video inside OBS, but when I enable audio (2CH for example) the audio and video drift (get out of since, and if I enable buffering, the buffer gets discarded to bring them into sync on a regular bases, but causes video drops/stutters). OBS has support for Decklink cards but only "auto" input seems to work.

I know the source on one device is 60000/1001 (59.94).. Still trying to find my mini HDMI to full HDMI so I can test capture that into the Decklink from a Hero 5 (as a test).

You answered my question about ONLY being able to capture SDI input, even tho the Decklink Studio 4K can playback fine (audio and video) to external HDMI TV (59.94) for timeline previewing.

ALL-IN-ALL not a bad product, but I found an issue in the DeskdopVideoHelper not shutting down at poweroff/reboot. It (the machine) was "hanging" for 90 seconds (there abouts) on shutdown

(I added the line about ExecStop below)
/usr/lib/systemd/system/DesktopVideoHelper.service:
Code: Select all
#** -LICENSE-START-
#** Copyright (c) 2013 Blackmagic Design
#**
#** Permission is hereby granted, free of charge, to any person or organization
#** obtaining a copy of the software and accompanying documentation covered by
#** this license (the "Software") to use, reproduce, display, distribute,
#** execute, and transmit the Software, and to prepare derivative works of the
#** Software, and to permit third-parties to whom the Software is furnished to
#** do so, all subject to the following:
#**
#** The copyright notices in the Software and this entire statement, including
#** the above license grant, this restriction and the following disclaimer,
#** must be included in all copies of the Software, in whole or in part, and
#** all derivative works of the Software, unless such copies or derivative
#** works are solely in the form of machine-executable object code generated by
#** a source language processor.
#**
#** THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
#** IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
#** FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
#** SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
#** FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
#** ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
#** DEALINGS IN THE SOFTWARE.
#** -LICENSE-END-

[Unit]
Description=DesktopVideo helper daemon
After=syslog.target local-fs.target

[Service]
Type=simple
ExecStart=/usr/sbin/DesktopVideoHelper -n
ExecStop=/usr/bin/killall -9 DesktopVideoHelper

[Install]
WantedBy=multi-user.target


Lastly, I also noticed inside Media Express that sometimes capturing (from HDMI) that the audio gets misalligned (sounds distorted and tinny, meaning the byte alignment gets screwed up).. On a stretch of video around 1 hour long I test recorded to MJPEG AVI, it happened twice so not something that people MIGHT notice if they record short segments at a time. Probably will require research and eventually a firmware update for the Studio 4K.

--Doug (dx9s)

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