New shooters and editors can often get hung up on which codec and data rate they should use, and indeed, choosing the wrong setting can ruin your day. If you just turn up all the settings to their maximum, an SD card can suddenly stop recording, or a more capable recording medium can fill up quicker than expected.
But no matter what the codec, resolution or frame rate in use, it’s the data rate that defines how much storage space a clip takes up. Let’s take a deep dive.
Megabits or MegaBytes?
When you see a number quoted, like “100Mbps”, it’s easy to think that means “100 MegaBytes per second” — but it doesn’t. The lowercase “b” means “bits” while an uppercase “B” would mean “Bytes”, and they’re different by a factor of 8. (To avoid confusion, QuickTime Player uses “Mbit/s” but you’ll see Mbps in the menus of most cameras).
However it’s written, that 100Mbps is actually ~12.5 MegaBytes per second. I prefer to write Mbps or MB/s to make a more obvious distinction between bits and Bytes.
Codecs matter
Many codecs and containers are used by today’s cameras, and in general, you can only optimize for two of these three characteristics: ease of playback, image quality, and small file sizes.
- If you choose ProRes 422 or HQ, you’ll get larger file sizes that are easy to work with and look great.
- If you choose H.264 Long-GOP you’ll get smaller file sizes that are easy to work with on most computers and look pretty good.
- If you choose HEVC, it can be harder to work with on computers without hardware acceleration, but this codec makes smaller files than H.264 at the same file size.
Since all modern Macs have ProRes, HEVC and H.264 acceleration built in, most standard video files play back smoothly. This is not the case for all these codecs on a Windows PC, because hardware encoding varies depending on whether it’s coming from the CPU or GPU, on the drivers, and if your software can take advantage of it.
Data rates are sometimes determined by the codec, and sometimes not. ProRes uses a fixed data rate for each flavor (Proxy, LT, 422, HQ, 4444, etc.) so you know more or less how big a file will be if you know the resolution, frame rate, and codec.
H.264 and HEVC are more flexible. A data rate that’s too low will often produce blocky, artifact-ridden images, but clever encoding techniques can get a lot out of a little. On an iPhone, all those numbers are pretty low. In Final Cut Camera or the Camera app, the HEVC data rate is around 25Mbps in UHD, though if you use the Blackmagic Camera app, you can dial in one of four data rates from 17Mbps to 54Mbps. It’s hard to spot a quality difference between the top three data rates, but the lowest does start to lose a little detail. In general, the more detail in a shot, and the more it changes, the more data it needs. Sending the background out of focus should leave more data for the in-focus areas to look good.
RAW files (in many different formats) tend to have very high data rates and are usually harder to work with, but the quality and flexibility of these formats is worth the sacrifice for many professionals. If you want the flexibility to push an image in the grade, you can’t beat RAW.
Camera manufacturers decide the codecs and data rate combinations that their cameras will offer, and camera operators decide which ones best suit their needs. Expect a camera to make larger files than a phone, though.
Finally, if you shoot on a modern Blackmagic camera then you’ll encounter BRAW, in a variety of compression strengths — run your own tests if you can.
Other specs matter too
In addition to the codec, other factors can determine the final data rate. Shooting in 10-bit rather than 8-bit will require more space, as will shooting in 4:2:2 rather than 4:2:0, or All-I instead of Long-GOP. To explain those factors:
- 8-bit records each channel in the image with one of 256 different values, while 10-bit uses 1024. While 10-bit gives smoother gradients, especially when recording in Log, it’s not well supported in H.264, and on some cameras, you may have to use HEVC. You can also record with more fidelity if you wish — ProRes RAW can use 16-bit.
- 4:2:0 records one color pixel for every 4 luminance pixels, while 4:2:2 records one color pixel for every 2 luminance pixels. If you plan to color grade, 4:2:2 has twice as much color resolution as 4:2:0, but RAW does even better. Shooting at a higher resolution than you plan to deliver makes this factor less important.
- All-Intra (or All-I) records a series of complete still frames, while Long-GOP describes frames in terms of how different a frame is from a nearby frame in the past or future. Some shooters prefer to shoot All-I, but I’ve found it completely unnecessary. Your mileage may vary, but for me, the data rate is much higher, the image quality is not, and the files are much harder to work with.
It’s true that Long-GOP files used to cause issues, but remember — if you’re on a modern Mac with a modern NLE, it’s hardware accelerated and Long-GOP shouldn’t be a problem. Test before you triple your data rate by following old advice.
Data rate during capture is important
Don’t just choose the highest data rate possible, because your media may not be able to handle it. The number shown on an SD or other media card is usually a maximum read speed, but while you’re recording, that’s irrelevant. Sometimes you might see a second number, a maximum write speed, but that’s not much use either. To avoid dropping frames, you need to know the minimum write speed, and that’s not usually printed on the card. The UHS Speed Class give some very basic standards, but not much more than that.
In general, it’s only older media standards like SD that might have issues with high data rates. If you can, using a faster media card like CF Express Type B will avoid any capture problems and also save you time during offloading — the read speeds are much, much higher.
When you crank up all the settings, recording in ProRes RAW HQ or some flavor of All-I, you’ll be pushing the data rate up into many hundreds of Mbps or even into Gbps territory. On a CF Express Type B card or direct to an SSD, your main problem is the amount of space it takes up. But on an SD card, it’ll start dropping frames well before it gets full.
Of note, an external SSD is required for ProRes RAW on an iPhone 17 Pro. I suspect it’s likely that the storage in an iPhone may sometimes have a minimum write speed lower than is sometimes required by ProRes RAW HQ. Well, it’s that, or lingering legal restrictions from RED’s patent claims over internal RAW recording.
To avoid dropping frames, it’s important to choose a setting with a data rate that your media can handle for the entire planned length of the shoot, with a buffer for safety. Some devices will get slower over time, as they heat up or get full, so it’s critical to read the specs of any media you plan to record to, and do the math.
Data rate during editing and archiving
Of course, a lower data rate also comes with the benefit of taking less space, but that’s largely a benefit for transferring, storing and archiving that data later. At the highest data rates, you’ll need to use faster media than SD cards, and if you’re recording in a demanding format, make sure your SSD is designed for a high continuous write speed — many are not.
ProRes RAW HQ in open gate (4224×3024) on an iPhone 17 Pro Max can require as much as 1.2Gbps, but it’s a little hard to predict exactly — the data rate is variable. 1.2Gbps is 150MB/s, and it adds up fast — one hour is over 500GB. As soon as you start shooting on multiple cameras or for multiple hours, you need to start considering how much storage is going to cost, and even how long it’s going to take to copy that footage.
Obviously, on the largest jobs this becomes the DIT’s problem. The priority is, and should be, the best image at any cost. On an all-day event with one or two shooters, for an output that’ll only see minor corrections applied? Dial the data rate down and save the space. ProRes is perfect for filmmaking and demanding shoots, but often too much for longer events.
By moving to a more compressed format, you will give up some grading flexibility, but it’s not always a problem. If there’s a professional colorist involved, crank it up. If you’re confident that you can set the white balance and expose correctly on set, a more compressed codec can be just fine.
High data rates were the reason I moved away from the Blackmagic Cinema Camera to a Lumix GH5 many years ago. At the time, I could shoot 1080p in ProRes at around 130Mbps on the BMCC, or UHD in H.264 at 100Mbps on the Lumix GH5. Four times the resolution, smaller file sizes, choice made. On those earlier BM cameras, there were no moderately compressed, compatible codecs, though today more compressed BRAW options are available.
What I shoot today
My Lumix GH7 has many (perhaps too many) options for data rate and resolution, but you can make sense of the mess by saving your favorite settings under “My List”. Instead of cycling through countless options, you just add your favourite combinations to the list. This also makes it easy to jump between combinations only found in specific containers — and there are a few.
My usual choices are:
- Open Gate 5760×4320 4:2:0 10-bit at 200Mbps for interviews and anything else I might want to reframe. Huge resolution, relatively low data rate, great most of the time.
- UHD 4:2:2 10-bit at 150Mbps when I need 4K and I’m going to be handing the footage off to someone who wants to color grade but not reframe.
- UHD 4:2:0 10-bit at 72Mbps (MP4 container only) for events where I might want to reframe, but the cameras aren’t moving much, the frames aren’t complex, and color correction won’t be extreme.
- ProRes RAW 5728×3024, full sensor data, 16-bit at up to 2.3Gbps (but maybe only 1.6Gbps) for the most demanding projects.
While I love having the option of ProRes, I don’t often need to shoot in ProRes. If you shoot a lot of longer events like I do, there’s real value in knowing that you definitely won’t run out of media, and probably won’t even need to swap cards. If I shot ProRes I’d be going through terabytes each shoot day, and I wouldn’t be able to record to CF + SD cards simultaneously for safety.
Image quality is not always the only important factor. If your files are going to end up online, at a lower resolution than you’re shooting in, consider all the variables before just cranking everything up.
Capture ≠ delivery
The data rate you capture in isn’t relevant to the data rate you export in. Instead, every compression step just needs to be high enough to avoid introducing artifacts. After you upload to a delivery platform, it will be recompressed again, and viewers will be shown a file with an even lower data rate.
A shooter on a GH7 might record at 150–200Mbps in the HEVC codec, export a UHD HEVC at 40-50Mbps, and that might be seen by many viewers as a smaller 1080p at just 2.5Mbps. (Even if the original footage came from an iPhone capturing UHD at 25Mbps, the main UHD HEVC export should still be at 40-50Mbps.)
On the “High Quality – Adaptive High Bitrate” options in Premiere, or the “Computer” option in Final Cut Pro, you’ll be exporting a file that’s well above what any of your viewers will ever see. YouTube or Vimeo will compress it heavily into a variety of different resolutions and codecs, all far lower quality than the one you sent, and there’s nothing you can do about it. Capturing in a higher quality format helps with color correction, but it all gets mashed into a small pipe eventually.
Because you don’t control the final output, and most platforms set the output data rate as low as their customers will tolerate, you simply have to avoid images that look bad in low-data rate 4:2:0, including:
- Red text on a black background — 4:2:0 will ruin this combination every time
- Confetti cannons — everything changes every frame, and compression falls apart
- Super-detailed shots, like a drone flying through a leafless forest with everything in focus — too much detail means the picture falls apart
If you are delivering online, to YouTube or another similar platform, you really don’t need to worry much about what you upload. You can upload ProRes, you can upload a high quality HEVC file, you can upload H.264 if you like. For SDR output, H.264 8-bit will be fine, though you’ll want to jump to HEVC (and ideally 10-bit) for HDR output.
So who does need to care about output? Anyone following a spec sheet. Sending a TVC to air in Australia? You’re probably sending ProRes with Adstream’s specs, and since ProRes defines its own data rates per resolution and frame rate, it’s all out of your hands. Same with any larger streamers — just follow the specs.
Also, anyone pushing weird boundaries, producing dual 5K @ 50fps stereoscopic videos for the Apple Vision Pro, then… yes, you’ll want to run some experiments with high and very high data rates to find the right balance. Apple’s Compressor and Adobe Media Encoder both offer many controls with a focus on professional encoding needs.
The last group that needs to worry about data rate is anyone producing video files to be shared directly to clients. If you’re creating training videos to be sent to staff and played from an internal server, you probably shouldn’t be creating 20Mbps 1080p videos. If a store has a 100Mbps internet connection, and 50 staff at that store are sent a video to watch, you’ve just saturated their bandwidth many times over.
Instead, get that data rate down to 2Mbps or so, probably with Handbrake, because it produces files that look good at low data rates. Want more control? Shutter Encoder is your friend. But again, you may not need it.
Conclusion
A quick summary, then:
- Shoot the best image your camera offers, but only if you don’t have to compromise too much on file size.
- All-I is not always the best choice.
- Know the limits of your media, and pick the best compromise that won’t drop frames or fill up too many cards or drives too quickly.
- Test your choices before you commit. Things change.
- iPhone default data rates are on the low side, but they still look pretty good.
- Working with a colorist? RAW if you can.
- Follow specs if you have them, or high quality presets if you don’t.
- It’ll look better on your computer than it ever will again.
Disagreement is welcome in the comments.