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Advanced Video Functions Explained

Some of our X Series cameras give a tremendous amount of control over how video is recorded and stored, and understanding these concepts is key to getting your filmmaking projects looking their best.

One of the most complicated aspects of videography for any photographer to get their head around is selecting from the myriad ways in which footage can be recorded to a camera’s internal memory card. Where stills photographers have a small choice of JPEG qualities and file-size settings – plus the option to photograph in RAW, of course – videographers have many more options. For example:

• Not just how much compression is applied to the captured footage, but also the type of compression that’s used.
• How much data is recorded in each frame.
• The number of colours recorded in each frame.

These settings are part of a delicate balance between image quality and practicality. We don’t always need the best performance a camera can offer, especially if this hampers us in terms of how much footage we can store on a card, or the speed with which we can edit footage on a computer.

Comparing Codecs

The term ‘codec’ comes from two words: ‘coder’ and ‘decoder’, and this gives you an idea of what these computer algorithms actually do. Video footage takes up a lot of storage space, so a codec is used to first ‘code’ the recorded data, thereby making it smaller, and then to ‘decode’ it again, so it can be played back. This is done on the fly, either at the point of recording, or the point of playback, by computer code inside the hardware you’re using.

There are thousands of codecs out there, but unless you work as a TV broadcast engineer, you only really need to know about one or two. The H.264 codec is very widely known across the consumer electronics industry and is used for Blu-ray discs and movie downloads, as well as in digital cameras (in fact, it’s the standard setting on your X Series camera). H.264 can be played back and edited on a huge range of computers and software, so it’s great for maximum compatibility.

Also available on some X Series camera is H.265, which, as the name suggests, is the successor to H.264. It boasts better image quality and a smaller file size but, being a new format, it’s not compatible with as many editing workflows.

On some X Series cameras, you can choose between H.264 and H.265 from the Movie Settings menu. The latter enables you to record higher-quality 10-bit colour depth, but can restrict compatibility with older editing systems.

Colour Bit Depth

For a long time, video has been recorded in 8-bit colour. This means each of the red, green, and blue colour channels can detect 28 colours, ie 2x2x2x2x2x2x2x2 = 256. When we multiply these three colour channels together we get 256x256x256 = 16.8 million colours.

That sounds like a lot, but in some circumstances, such as when filming subtly gradating colours, it’s not enough. For this reason, some X Series cameras offer 10-bit colour, where 210 colours are detected in each channel, for a total of a billion colours.

If your camera supports 10-bit colour, then you’ll need to change to the H.265 codec to access it.

• Press MENU OK and navigate to the MOVIE SETTING tab.
• From the H.265(HEVC)/H.264 menu, select H.265(HEVC).

The downside of using 10-bit colour is the extra storage space that this extra information takes up on your memory card and hard disks.

Bit Rate

In your camera’s MOVIE MODE menu, you may also find options for controlling the bit rate at which data is recorded, measured in Mbps. This is all about a trade-off between quality and file size: the more information (megabits) recorded (per second) the higher the image quality is. But it will also take up much more space on your card and hard drive.

When we used to make video in HD resolution and at 30fps, a bit rate of 50Mbps was absolutely fine, but as we’ve increased the resolution and frame rate of our videos, we need the ability to record and process more information per second. This is why going to 200Mbps and even 400Mbps is useful when creating 4K video at 60fps.

Movie Compression

Some X Series cameras give you a choice between two types of video compression, each with its own advantages. These are selectable in MOVIE SETTING > MOVIE COMPRESSION.

ALL-Intra

This is the simpler of the two compression algorithms: every frame is encoded and compressed slightly, and is completely independent of the frames that come before it or after it, just like a series of JPEG still images would be.

Long GOP

This compression technique is slightly more involved: only certain frames, spaced at regular intervals, are encoded as if they were still photos. These are known as ‘I frames.’ The frames between the I frames are created by describing only what has changed since the last frame, which doesn’t require as much data as describing every frame individually.

Long GOP can give much better quality at lower bit rates, and takes up less storage space, but it also needs much more processing power to playback and edit. It can also be prone to artefacts if an edit is made between I frames. For this reason, ALL-Intra is sometimes preferred if there is going to be a lot of editing or post-production work.

Your Next Steps

• CHALLENGE What are your preferred video recording settings and why? Experiment with codec, bit depth, bit rate, and compression and post a clip filmed with your favourite settings to social media, with the hashtag #learnwithfujifilm and #video. You can also submit your work here for a chance to be featured on our social media channels.