When trying to figure out how to make movies, there are some things that are more technical than others. This is one of those tech-heavy things. Codecs for your footage can make your footage easy to edit or bog down your computer’s processor.
Codec stands for Compression/Decompression. It’s the process of encoding and decoding data, in this case, audio and video files. So, like packing your clothes into a suitcase, and taking them out again.
When determining which codec to use, it’s best to look at whether it’s lossy or lossless.
Lossy vs. Lossless
Lossless allows all the data from the original footage to be recovered when the files are decompressed. Lossy removes “unnecessary” pieces of information for the file to make the file smaller. So, back to thinking about packing, it’s like removing anything you think you won’t need, like your snowsuit for your holiday in the tropics.
When using lossy compression, as you continue to recompress files over and over, you lose more and more data with each compression. The information the lossy compression removes is permanently lost. One compression may not look any different, but compressing the video that’s already been compressed will make it more obvious. Many popular codecs are lossy.
Lossless compression will not reduce the quality of the original footage when it is compressed.
A good way to think about the difference back to packing a suitcase and you have too much to fit in. Lossless would be using space-saver bags and removing all the excess air. Lossy could be compared to removing clothing that you don’t think you’ll need. You may not notice, but if you choose to remove all the shirts, it would become a bit more obvious.
Lossless files tend to be bigger than Lossy files, because they’re holding on to as much information as possible.
Lossy is best for posting your videos on Facebook, YouTube, or sharing with friends. Lossless should be used for capturing footage, during editing, and for delivery of a film. This allows you to keep all the data for any further changes you may have.
There are also some codecs that are described as visually lossless. This means they’re lossy, but the removal of data is limited enough that you won’t notice any diminishing in the picture despite multiple generations (you can recompress it until the cows come home and still won’t notice a difference, as long as you are a cow farmer not a professional editor/filmmaker and if you are a cow farmer why are you reading this article?).
RAW video keeps all the light data for the camera’s sensor — it’s pure information so it’s lossless video. The higher the camera’s resolution, the larger the image, and the larger the file size. This is good for photographers who edit their own pictures. The RAW files, however, are a series of still frames rather than a video, which makes playback a challenge. Editing RAW video may require specialized software and takes a lot of processing power.
H.264/AVCHD is a codec that’s mostly used as lossy, but there’s a lossless form that’s rarely utilized. It’s used for high definition video, is a standard for Blu-Ray, and found extensively for online videos. Due to the compression style, it can be difficult for a standard computer to playback for editing.
MPEG-2 is a lossy codec used for DVDs and digital television.
ProRes is the Apple family video compression. It’s one of those codecs described as visually lossless. It’s used for HD definition broadcasts and web streaming. It’s a more distribution friendly codec than H.264.
DNxHD is the Avid family of high-definition visually lossless codecs. They’re intended to be a video compression to use while editing as well as a presentation format. DNxHR codec was introduced later for higher resolutions. It’s a lossy ultra-high-definition codec developed for 2K, 4K, and even 8K video files.
H.265/HEVC is a newer codec used in BluRay. Like H.264, it has the capability to be lossless, but mostly you’ll see it used as lossy. It’s 2-4 times as efficient as H.264 and is designed to handle up to 8K footage. However, H.265 requires a lot of computing power to compress and decompress.
Choosing your Codec
When deciding on a codec, it’s important to know what your end goal is. If you’re making a YouTube video, you can choose a lossy format that gives you a smaller file. If you’re goal is to show your film on the big screen, you’ll need to use something with a higher quality output.
Within the codecs, you can run exports in lower qualities as proxies to help with playback during the editing. For more information on why proxies are helpful, check out this article, or learn how to make them here.
This may seem like something you don’t need to worry about, but it will help in the editing process and keep your footage as crisp and breathtaking as when you shot it. So, independent filmmakers and film school students alike, think ahead when beginning your film.