Apple lists a target bitrate of 884Mbps for 3840 by 2160 ProRes 422 HQ video at 30 fps. At that rate, a full terabyte holds about 151 minutes of video before audio, file overhead, and formatting are accounted for.
Switch to 60 fps, and the estimate drops to roughly 75 minutes. At 120 fps, it falls to about 38 minutes. Same capacity, much less shooting time.
Those calculations help you judge the Lexar Muse's recording capacity without mistaking a storage specification for a promise about an entire shoot. They assume ProRes 422 HQ, not every format carrying the ProRes name.
Blackmagic also separates color space from codec in its settings, so an Apple Log label does not identify the compression format. Keep both settings in your notes when comparing clips; otherwise, two tests described as “4K Log” can have different storage demands.
For the HQ example, divide 884 by eight to convert megabits into megabytes, then multiply by 60. You get 6,630 megabytes, or 6.63GB, per minute. Dividing 1,000GB by 6.63 gives approximately 151 minutes.
A nominal 512GB SSD works out to about 77 minutes under the same assumptions. These are video-only calculations using decimal gigabytes, with 1TB counted as 1,000GB. Your remaining free space, rather than the capacity on the box, belongs in the calculation once the drive contains files.
At the same resolution and 30 fps, ProRes 422's 589Mbps target works out to roughly 226 minutes per nominal terabyte. No capacity upgrade involved. You changed the compression setting, so don't treat the two estimates as conflicting measurements of the same format.
On a nominal 512GB drive, those rates allow roughly 39 minutes at 60 fps or 19 minutes at 120 fps. Even a 1TB drive cannot hold an uninterrupted hour of that 120 fps HQ footage at the calculated target rate.
Apple specifies a drive capable of writing at least 440MB/s for iPhone 4K120 ProRes capture. It's a minimum storage-performance requirement, not a fixed promise that every recording consumes 440MB each second. Dividing capacity by that requirement alone gives the wrong basis for predicting file size.
ProRes also uses a variable bitrate, with Apple describing a per-frame maximum about 10 percent above its target. Allow for that rate, and the nominal 1TB budget becomes roughly 137 minutes at 30 fps. It falls to 69 minutes at 60 fps and 34 minutes at 120 fps.
The ten percent allowance applies to the video bitrate, not the SSD's advertised capacity. You still need to subtract existing files and allow for audio and overhead, rather than treating those rounded times as permission to fill every available byte.
Suppose you plan 40 minutes of interview footage at 30 fps and eight minutes of 120 fps cutaways, all in HQ. The target-rate calculation needs about 265GB for the interview and 212GB for the cutaways. Together, the video takes roughly 477GB.
Eight minutes of high-frame-rate footage nearly matches the storage used by 40 minutes of your interview. Add the 10 percent bitrate allowance and the combined video budget reaches about 525GB. A nominal 512GB SSD no longer covers the plan, even before audio and other overhead.
For a recording budget based on actual free space, measure a short clip using your intended app, codec, resolution, and frame rate. Divide its file size by its duration in minutes, then divide available drive space by the resulting gigabytes per minute.
Use several representative samples rather than letting one unusually small file set your schedule. A clip-size check estimates storage consumption; a sustained recording test checks whether the phone, cable, and drive keep working for the intended take.
Keep the lens uncovered and include the kind of detail you expect to film. ProRes can allocate fewer bits to simple images. A nearly black test clip can therefore exaggerate how much time your drive will provide.
Switch to 60 fps, and the estimate drops to roughly 75 minutes. At 120 fps, it falls to about 38 minutes. Same capacity, much less shooting time.
Those calculations help you judge the Lexar Muse's recording capacity without mistaking a storage specification for a promise about an entire shoot. They assume ProRes 422 HQ, not every format carrying the ProRes name.
The codec setting changes your recording time
Blackmagic Camera offers both ProRes 422 HQ and ProRes 422 on supported iPhones. Check which one is selected before applying a recording-time estimate. “4K ProRes” alone leaves out a setting that changes how long you can record.Blackmagic also separates color space from codec in its settings, so an Apple Log label does not identify the compression format. Keep both settings in your notes when comparing clips; otherwise, two tests described as “4K Log” can have different storage demands.
For the HQ example, divide 884 by eight to convert megabits into megabytes, then multiply by 60. You get 6,630 megabytes, or 6.63GB, per minute. Dividing 1,000GB by 6.63 gives approximately 151 minutes.
A nominal 512GB SSD works out to about 77 minutes under the same assumptions. These are video-only calculations using decimal gigabytes, with 1TB counted as 1,000GB. Your remaining free space, rather than the capacity on the box, belongs in the calculation once the drive contains files.
At the same resolution and 30 fps, ProRes 422's 589Mbps target works out to roughly 226 minutes per nominal terabyte. No capacity upgrade involved. You changed the compression setting, so don't treat the two estimates as conflicting measurements of the same format.
High frame rates leave less room for a long take
Apple's 60 fps target for the HQ format is 1,768Mbps, twice the listed 30 fps rate. Scaling that rate to 120 fps gives 3,536Mbps, or 26.52GB per minute. The 120 fps figure is a calculated estimate, not a measurement from a particular iPhone or SSD.On a nominal 512GB drive, those rates allow roughly 39 minutes at 60 fps or 19 minutes at 120 fps. Even a 1TB drive cannot hold an uninterrupted hour of that 120 fps HQ footage at the calculated target rate.
Apple specifies a drive capable of writing at least 440MB/s for iPhone 4K120 ProRes capture. It's a minimum storage-performance requirement, not a fixed promise that every recording consumes 440MB each second. Dividing capacity by that requirement alone gives the wrong basis for predicting file size.
ProRes also uses a variable bitrate, with Apple describing a per-frame maximum about 10 percent above its target. Allow for that rate, and the nominal 1TB budget becomes roughly 137 minutes at 30 fps. It falls to 69 minutes at 60 fps and 34 minutes at 120 fps.
The ten percent allowance applies to the video bitrate, not the SSD's advertised capacity. You still need to subtract existing files and allow for audio and overhead, rather than treating those rounded times as permission to fill every available byte.
A mixed shoot needs a mixed recording budget
Budget the time you expect the camera to record, including retakes and pauses you leave in. A ten-minute finished interview may come from much more footage, and trimming it later won't reduce the space needed during capture.Suppose you plan 40 minutes of interview footage at 30 fps and eight minutes of 120 fps cutaways, all in HQ. The target-rate calculation needs about 265GB for the interview and 212GB for the cutaways. Together, the video takes roughly 477GB.
Eight minutes of high-frame-rate footage nearly matches the storage used by 40 minutes of your interview. Add the 10 percent bitrate allowance and the combined video budget reaches about 525GB. A nominal 512GB SSD no longer covers the plan, even before audio and other overhead.
For a recording budget based on actual free space, measure a short clip using your intended app, codec, resolution, and frame rate. Divide its file size by its duration in minutes, then divide available drive space by the resulting gigabytes per minute.
Use several representative samples rather than letting one unusually small file set your schedule. A clip-size check estimates storage consumption; a sustained recording test checks whether the phone, cable, and drive keep working for the intended take.
Keep the lens uncovered and include the kind of detail you expect to film. ProRes can allocate fewer bits to simple images. A nearly black test clip can therefore exaggerate how much time your drive will provide.
