**TL;DR:** The M4 MacBook Air forces dark/bad HDR on Netflix. After digging into system plists, EDID overrides, and terminal commands, I found that Apple hard-coded the only fix (HDR-to-SDR conversion) to the physical battery state. There is no software workaround.
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Hi everyone,
I wanted to share a deep technical dive regarding HDR playback on the new M4 MacBook Air.
If you watch Netflix via Safari, the system forces a Dolby Vision stream. Since non-XDR screens lack local dimming, Apple's tone mapping crushes mid-tones. The result is a dark, washed-out image compared to SDR.
I spent the last 24h attempting to bypass this to force 4K SDR while on AC power. My goal was to trigger the internal "Optimize video streaming" flag without unplugging the cable.
Here is why every software solution fails on M4:
**1. The "Easy" Fixes (Failed)**
* **Chrome/Firefox:** They force SDR (great colors) but are capped at 1080p due to Widevine L3 limitations on macOS.
* **Color Profiles:** Forcing sRGB/Rec.709 is ignored by the AVFoundation video pipeline, which queries the display hardware directly.
**2. The "Power User" Fixes (Failed)**
* **BetterDisplay / EDID Overrides:** On Apple Silicon M4, the internal display's EDID seems hardware-locked against software overrides. We cannot simply uncheck "Allow HDR".
* **User Agent Spoofing:** Forcing a Windows UA breaks the DRM handshake (Netflix expects Widevine, gets FairPlay).
**3. The "Deep System" Attempts (Failed)**
* **Terminal Manipulation:** I tried `sudo pmset -c lowpowermode 1` hoping to trigger the video optimization boolean. It throttles the CPU but does **NOT** toggle the `kOptimizeVideoStreaming` flag, which appears hard-coded to the physical `ACPower` state in `IOKit`.
* **The "Nuclear" Option:** Editing `/Library/Preferences/SystemConfiguration/com.apple.PowerManagement.plist` or injecting code into `CoreDisplay` would require disabling SIP (System Integrity Protection), which is too risky for a streaming fix.
**The Conclusion:**
Apple has tightly coupled the HDR-to-SDR conversion logic to the physical power source.
**The ONLY way to get proper 4K SDR colors is to literally UNPLUG the MagSafe charger.**
This immediately flips the "Optimize video streaming" state, and the image becomes perfect. Plug it back in, and the "dark" HDR returns.
Has anyone managed to spoof the `ACPower` state specifically for the `powerd` daemon without disabling SIP? We desperately need a "Prefer SDR" toggle.
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UPDATE (Dec 1):
For anyone wanting to reproduce this, here is the quick test workflow:
1. Open Netflix in Safari (it triggers HDR automatically).
2. Look for a dark scene (it will look washed out/dim).
3. Physically UNPLUG the MagSafe charger.
4. Watch the screen brighten up and colors pop instantly (as the "Optimize video streaming" flag kicks in).
5. Plug it back in -> image gets dark again.
If you have an M4 Air, please test this and let me know if you see the same behavior!
---
Hi everyone,
I wanted to share a deep technical dive regarding HDR playback on the new M4 MacBook Air.
If you watch Netflix via Safari, the system forces a Dolby Vision stream. Since non-XDR screens lack local dimming, Apple's tone mapping crushes mid-tones. The result is a dark, washed-out image compared to SDR.
I spent the last 24h attempting to bypass this to force 4K SDR while on AC power. My goal was to trigger the internal "Optimize video streaming" flag without unplugging the cable.
Here is why every software solution fails on M4:
**1. The "Easy" Fixes (Failed)**
* **Chrome/Firefox:** They force SDR (great colors) but are capped at 1080p due to Widevine L3 limitations on macOS.
* **Color Profiles:** Forcing sRGB/Rec.709 is ignored by the AVFoundation video pipeline, which queries the display hardware directly.
**2. The "Power User" Fixes (Failed)**
* **BetterDisplay / EDID Overrides:** On Apple Silicon M4, the internal display's EDID seems hardware-locked against software overrides. We cannot simply uncheck "Allow HDR".
* **User Agent Spoofing:** Forcing a Windows UA breaks the DRM handshake (Netflix expects Widevine, gets FairPlay).
**3. The "Deep System" Attempts (Failed)**
* **Terminal Manipulation:** I tried `sudo pmset -c lowpowermode 1` hoping to trigger the video optimization boolean. It throttles the CPU but does **NOT** toggle the `kOptimizeVideoStreaming` flag, which appears hard-coded to the physical `ACPower` state in `IOKit`.
* **The "Nuclear" Option:** Editing `/Library/Preferences/SystemConfiguration/com.apple.PowerManagement.plist` or injecting code into `CoreDisplay` would require disabling SIP (System Integrity Protection), which is too risky for a streaming fix.
**The Conclusion:**
Apple has tightly coupled the HDR-to-SDR conversion logic to the physical power source.
**The ONLY way to get proper 4K SDR colors is to literally UNPLUG the MagSafe charger.**
This immediately flips the "Optimize video streaming" state, and the image becomes perfect. Plug it back in, and the "dark" HDR returns.
Has anyone managed to spoof the `ACPower` state specifically for the `powerd` daemon without disabling SIP? We desperately need a "Prefer SDR" toggle.
---
UPDATE (Dec 1):
For anyone wanting to reproduce this, here is the quick test workflow:
1. Open Netflix in Safari (it triggers HDR automatically).
2. Look for a dark scene (it will look washed out/dim).
3. Physically UNPLUG the MagSafe charger.
4. Watch the screen brighten up and colors pop instantly (as the "Optimize video streaming" flag kicks in).
5. Plug it back in -> image gets dark again.
If you have an M4 Air, please test this and let me know if you see the same behavior!
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