I accidentally set the camera to record the video in CRM (Canon RAW Movie).

For everyday use, MP4 would have been sufficient, but by the time I realized it, I had already shot in 8K RAW.

Since there was no other option, I ultimately processed it using the following steps:

CRM
↓
Convert to MOV using Canon software
↓
Convert to 4K MP4 with ffmpeg

I’m likely to repeat this, so I’m writing it down as a note.

Initially tried to convert CRM directly with ffmpeg

The first thing I thought to try was, of course, converting it directly with ffmpeg.

If I could just do something like

ffmpeg -i input.crm output.mp4

that would have been the easiest.

However, it seemed difficult to handle CRM as a regular video file directly.

At least in my current setup, I couldn’t get as far as converting CRM to a nice MP4 in one step.

So I opted to use Canon’s official software.

Developing CRM with Canon’s software

I load the CRM file using Canon’s Cinema RAW Development.

From there I can export to MOV.

For now

CRM → MOV

I was able to get it that far.

However, when I processed it casually, the colors looked odd.

Since it’s RAW, that’s understandable, but the footage as seen on the camera during shooting differed quite a bit from the MOV I exported.

In this case I’m not aiming for precise color grading as a finished work;

I just want the video that was mistakenly recorded in RAW to be viewable as a normal video.

So, when exporting from CRM to MOV, I chose BT.709.

What tripped me up a bit was where the color settings are located.

At first I tried to align the look by changing the preview settings, but those settings don’t affect the output file.

To set the color of the exported MOV, you need to configure it in Cinema RAW Development’s

Export settings
  ↓
Material file output format
  ↓
Color space / gamma settings

From here, you need to set the parameters.

This time, I chose BT.709 for the color space/gamma settings and exported the MOV.

Since the MOV is ready, convert it to MP4 with ffmpeg

At this point, it’s just a normal video conversion.

Pass the MOV produced by Cinema RAW Development to ffmpeg.

In this case, the source video was 8K.

Ideally I could have kept it at 8K, and I wasn’t actively trying to downscale to 4K.

However, there were playback‑environment issues.

From what I’ve tested locally:

  • On the iPhone 15 series, 8K video playback is choppy.
  • On the iPhone 16 Pro Max, 8K plays back smoothly without any problem.

Since 8K couldn’t be played properly on older iPhones, I reluctantly decided to downscale to 4K this time.

Downscaling from 8K to 4K

Basically, you just need to specify scale.

For 16:9 8K footage,

-vf scale=3840:2160

you can downscale to 4K.

For example, like this:

ffmpeg \
  -i input.mov \
  -vf "scale=3840:2160" \
  -c:v h264_videotoolbox \
  -c:a aac \
  output.mp4

Since I’m on a Mac, I initially tried to convert to H.264 using VideoToolbox.

Something went terribly wrong

However, when I ran it,

Cannot create compression session: -12903
Try -allow_sw 1. The hardware encoder may be busy, or not supported.
Error while opening encoder

an error like that appeared and the conversion failed.

This was the part that gave me the most trouble.

When I tried to downscale the 8K footage to 4K while encoding with VideoToolbox, the creation of the compression session failed.

As the error message indicates,

Try -allow_sw 1

so I allowed a fallback to software encoding.

ffmpeg \
  -i input.mov \
  -vf "scale=3840:2160" \
  -c:v h264_videotoolbox \
  -allow_sw 1 \
  -c:a aac \
  output.mp4

With that, the processing finally worked.

If you don’t need to stick to hardware encoding, you can use libx264 from the start.

ffmpeg \
  -i input.mov \
  -vf "scale=3840:2160" \
  -c:v libx264 \
  -crf 18 \
  -c:a aac \
  output.mp4

It takes longer, but this approach suffers fewer environment‑dependent issues.

Final workflow

Summarizing what I did this time:

Accidentally recorded with 8K CRM
        ↓
Attempt direct conversion with ffmpeg
        ↓
Doesn't work
        ↓
Develop with Cinema RAW Development
        ↓
The color looks off somehow
        ↓
Change the preview settings
        ↓
It does not take effect in the exported MOV
        ↓
Choose BT.709 in the export settings' color space/gamma configuration
        ↓
Export the MOV
        ↓
Feed the MOV to ffmpeg
        ↓
Downscale from 8K to 4K
        ↓
h264_videotoolbox crashes with error code -12903
        ↓
-Add allow_sw 1
        ↓
MP4 completed

That’s basically how it went.

Conclusion

In the end,

Convert the CRM to MOV once using Canon’s official software, then use ffmpeg to turn that MOV into a 4K MP4

was the simplest approach this time.

It’s faster than trying to handle the CRM directly and spending time on it.

Well, as the saying goes, “haste makes waste.”