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Record in 4K with Sony Alpha A6400 & Elgato Cam Link 4K

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Record in 4K with Sony Alpha A6400 & Elgato Cam Link 4K
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Most of my programming tutorials, like 5 tips to write better TypeScript code, have an intro in 4K resolution. I record my intros using a Sony Alpha 6400 mirrorless camera. I get the video signal from my Sony A6400 through my PC, but it wasn't that easy to capture it in 4K with 30 frames per second (2160p30). In this post, I will show you how I managed to do it.

Sony Imaging Edge

First I tried using Sony's Imaging Edge Webcam software as I was hoping I could simply use a USB cable and get the video signal. It actually worked but the maximum resolution was limited to 1024×576 pixels. Higher resolutions are not available using the the USB output of the Sony Alpha 6400. Sony's documentation confirms this limitation and also mentions that the Imaging Edge Webcam software does not handle audio from the camera's built-in microphone or a connected microphone.

Elgato Cam Link 4K

Since 4K recording via Micro USB isn't possible with the A6400, I switched to recording via Micro HDMI in combination with a so called video capture card. I bought the Elgato Cam Link 4K as it promises out of the box recording with up to 4K resolution at 30 frames per second.

USB Cable

To connect my camera with the Cam Link 4K, I bought a Micro HDMI to HDMI cable of 3m length that has been certified for 4K at 60Hz. The length of the cable plays an important role. Long HDMI cables can cause a video signal degradation. Best is to check with the HDMI cable manufacturer for more details.

USB Port

I had to make sure that the Capture Card is connected to its own USB port on my mainboard, so that it doesn't share the USB controller with any other device. I connected it to a USB 3.1 port but the documentation says that a USB 3.0 port is sufficient. When I had the Capture Card connected to a USB Hub, then it didn't work as it shared the bandwidth with other devices (such as my webcam) and as a result didn't get enough bandwidth to transfer the video signal without interruptions. I had to balance the load on my USB controllers.

USB Controller

Here is how you can verify if your Cam Link 4K is connected to its own USB controller on Windows:

  1. Open Windows' Device Manager
  2. Select "View" and "Devices by type"
  3. Select "Cameras" and "Cam Link 4K"
  4. Change "View" to "Devices by connection"

It should show you now the USB controller to which your Cam Link 4K is attached. Make sure your capture card doesn't share the USB controller with another device:

Windows Device Manager

For macOS you can find out here how many USB Root Hubs are available on your machine and what is connected to them.

Software

Elgato advertises Plug'n'Play installation which means that you can simply connect the Cam Link 4K USB stick to your computer and use it directly in applications without installing any additional software. While that is true, I recommend you to install the Elgato 4K Capture Utility 1.7.6 for troubleshooting. There is also the Elgato Camera Hub but it won't give you as much recording information as the Capture Utility.

The first thing I noticed in the 4K Capture Utility was that my camera was only sending 25 (not 30!) frames per second. That was mainly because it was set to PAL instead of NTSC.

In the screenshot you can see that there is a problem with the recording setting:

Output problem

Video Settings

Here is how I fixed my recording settings to make the Sony A6400 (ILCE-6400) capturing 4K video with 30fps.

At first you have to turn the mode dial to the "Movie" icon. Afterwards you have to go through the following settings using the "MENU" button:

  1. Setup → Setup2 → NTSC/PAL Selector → Change to NTSC and reboot your camera
  2. Setup → Setup4 → HDMI Settings → HDMI Resolution → Select 2160p/1080p to stream 4K video via HDMI
  3. Setup → Setup4 → HDMI Settings → HDMI Info. Display → Select Off to disable menu icons in your video stream (Clean HDMI Output)
  4. Camera Settings2 → Movie1 → File Format → Select XAVC S 4K to record movies in 4K resolution (3840×2160)
  5. Camera Settings2 → Movie1 → Record Setting → 30p 60M to record with 30 frames per second and a bitrate of approx. 60 Mbps. You can also use 30p 100M if your computer handles the data well during post-processing and you have enough disk storage for 100 Mbps. However, the 4K Capture Utility only supports 70 Mbps and the difference between 60 Mbps & 100 Mbps is marginal.
  6. Connect HDMI cable to your camera to see the 4K Output Select option
  7. Setup → Setup4 → 4K Output Select → HDMI Only (30p) to stream 30 frames per second via HDMI

Here is how it should look in the "4K Capture Utility" when all settings are correct:

2160p30 at 60 Mbps

Note: You don't have to insert a SD card or press the record button on your Sony camera as the video signal will be streamed through the High Definition Multimedia Interface (HDMI). Recording happens on your computer. If you want to record over a longer period of time without draining your battery, then I recommend to buy the Sony NP-FW 50 power adapter.

Exposure Settings

Further settings that I use when recoding my intros:

  1. Camera Settings1 → AF1 → Focus Mode → Continuous AF to make sure that the focus gets automatically adjusted when I move in front of my camera
  2. Camera Settings1 → AF1 → Focus Area → Wide to focus my whole scene / room
  3. Camera Settings1 → Colors → White Balance → Auto so that I can record at different times with different lighting conditions without manually adjusting my white balance setting (WBS)
  4. Camera Settings1 → Exposure1 → ISO Setting → ISO → ISO 100 or in general the lowest value possible that doesn't make my scene look too dark
  5. Camera Settings1 → Exposure1 → Metering Mode → Multi to determine the proper exposure for your entire scene
  6. Camera Settings1 → Exposure1 → Face Priority in Multi Metering → On to make sure that your face always gets exposed in your scene
  7. Camera Settings2 → Movie1 → Exposure Mode → Manual Exposure to control your aperture and shutter-speed manually
  8. Make sure your shutter speed is set to 1/60 to adhere to the "180 Degree Rule of Shutter Speed" (shutter speed should be set to 1/frame rate x 2) when recording with 30fps
  9. Movie → Movie2 → AF Tracking Sens. → Responsive because I am filming just myself and not a crowd so the auto focus should act as soon as it recognizes a (my) movement
  10. Movie → Movie2 → AF drive speed → Normal if you don't move much (don't do sports) in front of your camera to keep the automatic focus adjusment to a minimum
  11. Setup → Setup2 → Auto Power OFF Temp. → High to allow your camera to get hotter during recording without shutting down

I use the control dial to set my aperture to the lowest value possible (in my case F1.4 or ƒ/1.4) to get a bright picture with a nice Bokeh effect. I can recommend you the DOF Simulator to test different focal lengths and settings without a real camera:

DOF Simulator

Recording

If everything is set correctly, you can use your favorite recording software and capture your "Cam Link 4K" device. I am recording my video stream with Camtasia 2021. My audio is being recorded with my Shure SM7B but that's another story.

Camtasia 2021

Razer Ripsaw X

I want to report that I have also tried a Razer Ripsaw X which doesn't come with any software but relies on automatic resolution detection. It failed to record 4K video for me and only allowed me to capture Full HD (1920x1080) resolution.

Resources

Videos that helped me with my settings:

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