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Which ProRes Codec to Use? – FK TECH

By June 10, 2019 November 13th, 2019 No Comments

ProRes is one of the most popular video codecs in professional post-production. It enables fast editing of high quality footage while preserving high image quality. But which ProRes codec is right for you?

ProRes was first developed as a codec to be used in Final Cut Pro X. In recent years Apple started licensing it to selected companies for use in their applications. Now ProRes is supported in most of the popular editing applications such as Premiere Pro, Davinci Resolve and Final Cut Pro X. High-end cameras like RED and Arri support recording in ProRes internally as well. Alternatively you can also use an external recorder like the Atomos Shogun to record the incoming signal to a ProRes format.

Apple offers 6 different versions of its ProRes codec with all kinds of fancy names. What do they actually mean and which one is right for you?

The main difference between the versions are the data rate, bitrate and chroma subsampling. To understand the different versions better it is important to have a general understanding of these terms.

Chroma Subsampling

In the ProRes versions you find cryptic numbers such as 4:2:2 and 4:4:4. These numbers tell how Chroma Subsampling is used. Chroma Subsampling is a form of compression used to reduce the amount of data needed to store the signal.

Our eyes are less sensitive to variations in color than variation in luminance. Therefore frames are not stored in RGB, in which each letter stands for the intensity of red, green or blue. Frames are stored in YCbCr. Y stands for the luminance and Cb and Cr for the color.

It uses the full range of luminance information but compresses the color values. It throws away color information which our eyes hardly notice and retains the luminance information which our eyes are more sensitive too. However the loss of color information is a trade off between size and quality. This is especially noticeable in color grading. As a 4:4:4 signal has more color information to work with than a 4:2:0.

Color Depth

The ProRes 4:4:4 and 4:2:2 versions have another key difference. The maximum amount of bits available to be used. The bit depth is the range of the colors the video is able to use to assign a color per pixel. An 8-bit camera can assign a value up to 256 to Red, Green and Blue. Until recently 8-bit was the standard for consumer grade cameras, but recent cameras like the GH5 support 10-bit. Going from 8-bit with 16,777,216 possible colors to 10-bit with 1,073,741,824 possible colors gives more headroom in post-production and a better dynamic range.

ProRes Family

So the ProRes Family is divided into 2 sub groups. 4:2:2 Chroma subsampling supporting 10 bit and 4:4:4 Chroma subsampling supporting 12-bit (16bit with the Alpha Channel).

The HQ in the versions stands for a higher PSNR value leading to greater quality headroom. This increased headroom means that a frame sequence can be decoded and re-encoded over multiple generations and still look visually identical to the original (it won’t look better). So if you have to color grade or do VFX work on your shots while re-exporting the footage. Choosing a HQ version of ProRes will retain the quality better over multiple generations.

Your choice for the right ProRes version for you will depend on two things. The balance between the quality you need and the amount of storage.

ProRes 4444(XQ)

Master and intermediate coloring files. If you want to retain as much information as possible and are planning to do heavy color and effects work on the footage. Better file size than uncompressed but expect humongous files. Due to the 12 bit and no Chroma subsampling the best choice for quality. It supports alpha channels and preserves even the little details in HDR content generated with high quality cameras. The codec supports up to 16bits per image channel (without alpha 12bits per channel).

Use when: Post production with high end color grading and you don’t want to lose any detail and be able to re-render it multiple times without detail loss. Significant file size.

This is the codec we mostly use for high quality master files. It preserves 16bits per RGBA channel.

The codec features mastering quality in 4:4:4:4 RGBA color with an extremely high quality. It is preserving the image quality from nearly every footage we ever worked with. In Contrast to 4444 XQ the target data rate 1180Mb/s with our 4K 25fps footage.

Apple ProRes 422 HQ

This is the third highest data rate version of ProRes. It preserves the visual quality as close as ProRes 4444 but for 4:2:2 image sources. This offers visually lossless preservation of the highest quality footage. This codec is widespread around the camera and video production industry. The codec is a 10-bit pixel depth codec. It retains visually lossless through many decodes and re-encodes.

Use for: Client delivery and final exports for archival

In total this keeps the quality of the footage compared to the file size in a healthy relationship so that we are still able to send the final exports over the internet to our clients. Use when source footage is 422 and you want to use it as a master file.

Apple ProRes 422

This is like 422 HQ but with 66% of the target data rate and file size. The compression can become problematic on certain files. Use when: Good for exports with a reasonable file size. Looks good, but not the best if you have to re-render it and color grade it a bunch of times.

Apple ProRes 422 LT

This is our go-to codec when it comes to Proxies (later more). It provides all the 422 HQ features but is only at a target data rate of 365Mb/s in our 4k 25fps footage. We use this for our on the road workflows that require a small storage capacity at a high quality retain. It is a great codec to edit with. Also it looks good enough to export without significant quality loss for a client review.

Apple ProRes 422 Proxy

The data rate of 422 Proxy is low which means the files are relatively small. Although the quality is also noticeably worse. Would not suggest it for editing. If you want a codec with good playback in editing application while being small this can do the job for you.

Use when: you are limited with storage for editing or have to send it over the internet. Use it when you need performance, like multicam editing . Otherwise go for the LT version.

Become a Pro in ProRes

Now you know the differences of ProRes and the basics of chroma subsampling and bit-depth. You know what to use on your project and when! If you want a more in-depth explanation have a look at the whitepaper from Apple about ProRes.