[Guide] How to Enable Miracast for Pixel

• Pixel running Android 9.0.0 build number PQ1A.181205.002.A1 or PQ1A.190105.004.
• Bootloader unlocked.
• adb and fastboot tools and drivers are working for your device.

• These steps will change files in your system, your Pixel should run the exact same version of system. Pushing files to different versions of system may cause unknown problems.
• Please check carefully before running each command, a mistaken operation may result in unable to boot up, or destroy your data, or even damage your phone.
• If you are not sure about what these steps are doing, but still want to go ahead, please backup your phone firstly, you may not be able to recover your phone to its original state.
• I have only tested on Pixel 1 with build number PQ1A.181205.002.A1 and PQ1A.190105.004, for other phones or versions, you should build and test on your own.

1. Flash the same version of factory image for your phone.
2. Download the prebuilt files from https://github.com/sbjbs/android-wfd-patch
3. Add this line into "build.prop", without it, we will not be able to enable WiFi-Display:
   
   Code:

   persist.debug.wfd.enable=1

4. Replace some files in system:
   
   Code:

   system/lib/libaudioflinger.so
   system/lib64/libaudioflinger.so
   system/lib/libserviceutility.so
   system/lib64/libserviceutility.so
   system/lib/libmedia.so
   system/lib64/libmedia.so
   system/lib/libwilhelm.so
   system/lib64/libwilhelm.so
   system/lib/libandroid_runtime.so
   system/lib64/libandroid_runtime.so
   system/lib/libstagefright.so
   system/lib64/libstagefright.so
   system/lib/libstagefright_wfd.so
   system/lib64/libstagefright_wfd.so
   system/lib/libmediaplayerservice.so

5. If you have magisk installed, you can refer to Phoenix Wright's post:
   

   Phoenix Wright said:

   using "setprop" to set that property once is enough, no need to touch build.prop; given it's a "persist" property it'll be permanent.
   using magisk to overlay them on /system

   Click to expand...

   Click to collapse

• Remove dm-verity metadata of system.img
  The dm-verity can prevent us from changing the system, and what's more it has a forward-error-correction(FEC) feature, which can detect and correct some corrupted data.
  I spend a lot of time on attempting to change the build.prop but fail again and again, it just always correct the file, and I can't enable wifi-display.
  I don't know how to disable it. Since the error-correcting info should be stored in the dm-verity metadata, I just removed the dm-verity metadata from the stock system.img, and flash the system.img.
  I will list the steps to remove dm-verity metadata, but if you can disable dm-verity entirely, that should work too.
  For phones that have a vbmeta partition (like Pixel 2), seems you can flash an special vbmeta.img to disable AVB. You can build the empty vbmeta image by this command, but I don't have a device to test if it works:
  
  Code:

  avbtool make_vbmeta_image --flag 2 --padding_size 4096 --output vbmeta.img

  
  For Pixel 1, we need to remove dm-verity metadata that attached to system.img, first convert the sparse system.img to an ext4 image:
  
  Code:

  simg2img system.img system.ext4.img

  read the block count to calculate the system size:
  
  Code:

  od -j 1028 -An -N4 -tu system.ext4.img

  for Pixel 1, it should be 516099. You also can read it by a Hex Editor, e.g., WinHEX in Windows, read 4 bytes starting from 1028 bytes, as a little-endian hex value.
  so the real system partition size is 516099 * 4096 = 2113941504 bytes.
  we need to set the data to zero after that position. It's important to do this, since we need to overwrite the metadata in that area, rather than just truncate the size of system.img.
  
  next get the ext4 image size, for Pixel PQ1A.181205.002.A1, it should be 2147483648.
  so we need to write 2147483648 - 2113941504 = 33542144 bytes：
  
  Code:

  dd if=/dev/zero of=system.ext4.img seek=2113941504 count=33542144 oflag=seek_bytes iflag=count_bytes

  we also can use some other tools to do this, e.g., WinHEX in Windows. Open the file in in-place mode, and jump to 2113941504, and select it as the begin, and jump to the end, and select as the end, and fill the selection with all zero.
  
  after that, flash the changed system.ext4.img to Pixel:
  
  Code:

  fastboot flash system system.ext4.img

  Test that you can boot up normally. If not, check what's wrong and fix it.
  
• Temporary boot up by TWRP image
  We don't have to install TWRP, but just use it to temporary boot up, so that we can mount the system partition for writing. If you have TWRP installed, you can just boot to TWRP.
  Download TWRP image for pixel, just need the twrp.img, we won't install the zip file.
  boot your device to bootloader:
  
  Code:

  adb reboot bootloader

  and boot by the twrp.img
  
  Code:

  fastboot boot twrp.img

  after TWRP booted up, just leave it there, no need to unlock or input password, we will change the system by adb.
• Mount system partition for writing.
  In the current version of TWRP for Pixel (twrp-3.2.3-1-sailfish.img), its fstab has an entry for system partition, we can directly mount it.
  
  Code:

  adb shell mount /system

  run mount to check if successfully mounted:
  
  Code:

  adb shell mount

  you should see an entry like this:
  
  Code:

  /dev/block/sda34 on /system type ext4 (rw,seclabel,relatime)

  If not, you should stop now, and check the above steps.
  
  after mount, we can use adb to push files into system.

jean_michmich said:

Hey guy,

You helped me a lot to understand why it was not working with Pie. I tried several custom ROMs + the official Pie and it was not working.
There is Wireless display option in quick settings but it' doesn't find my Microsoft Wireless Display Adaptor also.

I so downgrade to Oreo. With Oreo it works without any issue. (there is an option "allow Wireless display" to tick and then your miracast dongle will appear).

You did a great job to make it working on Pie. Congratulations. I will anyway stay on Oreo. I think google will change that (many people already complained i guess).

Jean Michel

Click to expand...

Click to collapse

jean_michmich said:

OK it's getting more clear. You are right. Wikipedia says : "but support was dropped with Android 6.0 Marshmallow in 2015 in favor of Google's own proprietary Google Cast protocol.[15] Some manufacturers of Android devices step in and support Miracast through their software"

I'm not an "official android ROM" user.

I always use Pixel Dust custom ROM. For this custom ROM, Miracast was supported for Oreo but not for Pie (not yet).

Click to expand...

Click to collapse

Phoenix Wright said:

Tested on Pixel 2 XL and working (for what it's worth, using "setprop" to set that property once is enough, no need to touch build.prop; given it's a "persist" property it'll be permanent). I built the .so files on my local aosp tree and I'm using magisk to overlay them on /system.

Click to expand...

Click to collapse

nitin.chobhe said:

Can you elaborate how you did use "magisk to overlay them on /system"?

I pushed them using adb as mentioned on github but it is stuck at Google splash screen. I've taimen BTW and am on Pixeldust ROM. It booted while writing this post but the screen was not responding to touch.

Nitin

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Click to collapse