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Do You need an External Video Recorder?

External video recorders are becoming a standard need in creative pipelines. With output resolutions scaling ever-upward, the advantages of offloading processor work simply makes more and more sense, especially where high frame rates and pixel-perfect resolution are involved. But how can we balance needs with cost? Let’s take a look at some of the use cases, and a few options to address the varying levels of need.

Potential Uses

Let’s say you’re using a ton of resources on your main system generating content and you want to render out for client review, archiving or documentation.

It can be an entire hassle to do that recording on the main machine. Especially with audio reactive content, where there are a lot of hoops to make it work with offline recording. And while it’s also possible to set up a second recording rig that can take an HDMI feed, that can also become bulky.

Another common example is in broadcast settings, at conferences or similar. You might need to take another person’s powerpoint or other content source as a feed into your system. Or you might have cameras at a concert that you want to feed into your system so you can add effects on them for concert visuals. A basic HDMI capture card ought to be fine just to pull in a signal but things get more complex if you want to record.

USB Capture Devices

Of course, there are many basic dongle sized capture cards, and kits like the Elgato suite of tools for basic streaming.

an image of the Elgato HD60x video capture card

Similarly you could use a capture card like the Avermedia or Magewell to get that signal into TouchDesigner for processing and working with.

These workflows are great, but they can still take up system resources such as your write speeds on storage or more CPU cycles. Some of these units have dedicated encoding chips on them to help with the CPU drain, but every little bit adds up. There’s also times where you may want higher quality recording capabilities than what a lot of these USB devices offer. That’s where fully dedicated external recorders can come into play.

Another important concern here is quality, and retaining it. The biggest factors to be considered are compression and frame interpolation. What are they and how do they affect our recordings?

an AI generated image to illustrate the various levels of video compression and encoding

4:2:0 Subsampling & Frame Interpolation

4:2:0 is a chroma subsampling method used in video compression. The numbers represent the ratio of luminance (Y) to chrominance (U and V) samples. So, for every 4 luma (Y) samples, there are 2 chroma (U and V) samples horizontally but importantly, no chroma samples vertically, effectively reducing the chroma resolution by half in both directions compared to luma. The colour depth here is 8-Bit.

4:2:0 compression is widely used in video recording and distribution, including formats/codecs like MPEG-2, H.264/AVC, and HEVC. It provides a good balance between video quality and compression efficiency, as the human visual system is more sensitive to changes in brightness (luma) than to changes in color (chroma). Therefore, reducing the chroma resolution can significantly reduce file size or bitrate without a significant loss in perceived image quality.

Frame interpolation, also known as motion interpolation or motion-compensated frame interpolation, is a technique used in video processing to create new frames between existing frames. This technique is often employed in video compression and recording to increase the frame rate of a video, improve its smoothness, or convert it to a different frame rate.

Even at low frame rates, recording with compression can introduce frame interpolation. Literally recording less frames and smudging pixels between them because at regular playback speed it generally isn’t noticeable. This can be perfectly acceptable for streaming or web viewing, and if that is the end goal there are numerous options available.

However, these efficiencies come at a cost and that cost is pixel accuracy, which is crucial if you’re wanting to mix and mingle that footage in other projects.

In this case, we are looking for RAW source capture, which will give us the most flexibility afterwards in our post-processing.

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an AI generated image to illustrate the various levels of video compression and encoding

4:2:2 10-bit Recording

Using the same logic as before, 4:2:2 subsampling is where for every 4 luma (Y) samples, there are 2 chroma (U and V) samples horizontally AND 2 chroma samples vertically. While this still isn’t 4:4:4 absolute lossless quality, it’s considered adequate for ‘broadcast quality’ video recording.

The “10-bit” part refers to the bit depth of the samples. In this case, each color channel (Y, U, V) is represented using 10 bits, allowing for more color information compared to 8-bit recordings.

Where 8-bit color provides 16.7 million colors (256 shades each of R, G, and B), 10-bit color provides 1.07 billion colors (1024 shades each), allowing for more accurate and detailed color representation. 10 Bit quality also significantly increases the gamma range, or color depth.

The increased color and depth quality will make a massive difference for any post-processing you’d like, including reusing footage from one project as source material for another.

4:2:2 10-bit recording is used in professional video production where preserving high-quality color information is crucial. This format offers higher color fidelity and better chroma resolution than 4:2:0, making it suitable for applications where color accuracy is important, such as in film production or high-end video editing.

Recorder Recommendations

Two of the most popular options currently are the Atmos Ninja and the Blackmagic Video Assist.

Comparison here feels a bit like apples/oranges, yin/yang, vhs/beta. They’re both sweet and powerful and get the job done well. Each of them has appealing advantages.

The Atmos Ninja is stylish, independent, and self-contained. To me it feels more of a ‘pro-sumer’ model, which means there’s a nice balance of strong functionality coupled with stylish design and ease of use. There are some really appealing upgrades available like SSD and network streaming, so you can increase capacity over time rather than diving all-in at once. One gold star feature is ProRes RAW 12-bit recording with lossless 4:4:4 subsampling.

Blackmagic Video Assist also includes easy connections for SSD recording, and 4:2:2 ProRes quality. Because it’s part of the larger Blackmagic ecosystem it has the advantage fitting easily into professional production setups, and has SDI video in/out as well as HDMI 2.0, dual analog audio inputs, dual SD card slots, dual hot-swappable batteries. It’s a robust construct designed to be part of larger setups, which leaves a lot of doors open for future expansion.

Honourable Mention

an image of the GoStream Deck

Another option that’s worth a bookmark could be the GoStream Deck Kit. It’s already a great choice for multi-cam livestreaming, and definitely an interesting kit. If their NextGen upgrades include RAW capture this could be a heavy hitter.

Weighing in at <5kg, bundled in a sturdy Croc-like touring case, it runs on AC & DC, and can supply 5V power as well. Worth watching!

Wrap up

There are many paths to the ideal solution, which itself may be changing from gig to gig. External HDMI recorders bring professional quality recording to your production setup, high resolution uncompressed recording, with no additional equipment required, while retaining the ability to do streaming pass through to lower end tech.

Finding the perfect piece of equipment can be elusive, but understanding of the limitations and advantages in each possibility help simplify finding the Venn-centric solution that will address the greatest range of needs with fewest headaches at the most agreeable price and the most longevity for your toolkit.