Hi,

Here is a break down of what's happening with your 10-bit 4K videos in CapCut on your MacBook.

CapCut (especially the free desktop version) is known to internally process and export video primarily in an 8-bit color space, even if you import 10-bit footage.

Here's why this causes the problems you're seeing and why CapCut likely works this way:

1. What is 10-bit vs 8-bit?

   • Bit depth refers to the amount of color information stored per color channel (Red, Green, Blue).
   • 8-bit video: Can display 28=256 shades per color channel. This results in about 16.7 million possible colors ($256\times 256\times 256$).
   • 10-bit video: Can display 210=1024 shades per color channel. This results in over 1 billion possible colors ($1024\times 1024\times 1024$).
   • The Difference: 10-bit video contains significantly more color information, allowing for much smoother gradients (like skies, walls, subtle skin tone variations) and more flexibility in color correction and grading without falling apart.

2. Why Conversion Causes Banding and Noise:

   • When CapCut converts your 10-bit footage (with its 1024 shades per channel) down to 8-bit (only 256 shades), it has to discard a lot of that subtle color information.
   • Smooth gradients in your original footage no longer have enough distinct color values to be represented smoothly in 8-bit. The software approximates, creating noticeable steps or bands between colors where there used to be a seamless transition. This is called banding or posterization.
   • Aggressive color grading or adjustments (like trying to recover highlights/shadows or shifting colors) applied after the conversion to 8-bit further stresses the limited color data, making the banding more obvious and potentially amplifying underlying noise.
   • Denoise tools often struggle because the primary issue isn't traditional sensor noise but the artifacting (banding) caused by the loss of color depth.

3. Why Can't You Edit in 10-bit in CapCut?

   • Target Audience & Simplicity: CapCut is primarily designed for ease of use, speed, and social media creators. Full 10-bit workflows are computationally more demanding and complex. Sticking to an 8-bit pipeline simplifies the software architecture and ensures it runs smoothly on a wider range of hardware, including less powerful computers and mobile devices (CapCut's origin).
   • Processing Power: Decoding, processing effects, rendering, and encoding 10-bit video (especially 4K H.265 10-bit) requires significantly more CPU, GPU, and RAM resources than 8-bit. Supporting it robustly increases development complexity and system requirements.
   • Development Priorities: CapCut's focus is more on effects, templates, and features popular for social media rather than professional-grade color workflows.
   • Codec and Color Management: Properly handling various 10-bit codecs and associated color spaces (like Rec.709, Rec.2020, HLG, PQ) requires sophisticated color management, which adds complexity often found in more professional editing software.
   • CapCut’s denoise tool is quite basic and it doesn’t leverage temporal or advanced AI-based noise reduction. In 10-bit footage with fine grain, the downconversion exaggerates the noise and the denoiser can't clean it effectively.
   • Full 10-bit export is often still a limitation even in CapCut Pro

What Can You Do?

Unfortunately, CapCut fundamentally processes video in 8-bit internally, you cannot force it to maintain a 10-bit workflow. Your options are:

1. Use Different Software: This is the most effective solution for preserving 10-bit quality. Consider these alternatives available on macOS:

   • DaVinci Resolve: Free and incredibly powerful, industry standard for color grading. Fully supports 10-bit (and higher) workflows. It has a steeper learning curve than CapCut but offers professional results. Runs well on modern Macs, especially Apple Silicon.
   • Final Cut Pro: Paid (one-time purchase), Apple's professional NLE. Highly optimized for Macs, excellent performance, full 10-bit support, and relatively user-friendly interface compared to Resolve or Premiere.
   • Adobe Premiere Pro: Paid (subscription), industry-standard NLE. Full 10-bit support, integrates with other Adobe apps. Can be resource-intensive.

2. Minimize Grading in CapCut: If you absolutely must use CapCut, try to do minimal color adjustments. The less you push the colors, the less pronounced the banding might be. This largely defeats the purpose of shooting in 10-bit.

3. Preprocess Before CapCut:
   • Convert 10-bit to high-quality 8-bit manually using a tool like FFmpeg or Shutter Encoder with dithering enabled. This gives you more control over how color is compressed.
   • Add noise-reduction or LUTs in pre-processing to reduce stress on CapCut’s limited pipeline.
4. Test Lower Resolution or Bitrate:
   • Try editing proxies (e.g., 1080p 8-bit) in CapCut and color grade the final render elsewhere. This can help manage performance and color control separately.

CapCut is converting your 10-bit footage to 8-bit due to its design focus on simplicity and broader compatibility, sacrificing color depth. To maintain the quality and flexibility of your 10-bit recordings throughout the editing process, you will need to use more advanced editing software like DaVinci Resolve, Final Cut Pro, or Adobe Premiere Pro.