ios-minicap

iOS Minicap provides a socket interface for streaming realtime screen capture data out of iOS devices. It is built with AVFoundation and iOS Screen mirroring feature.

Requirements

• brew install libjpeg-turbo (>=1.5 is required)
• Xcode (for the Frameworks)
• cmake
• OS X Yosemite (10.9) or higher
• iOS 8 or higher
• Lightning cable. See the list of devices.

Building

./build.sh

You should now have the binaries available in ./build.

Usage

The minicap protocol is a simple push-based binary protocol. When you first connect to the socket, you get a global header followed by the first frame. The global header will not appear again. More frames keep getting sent until you stop minicap.

Before run, please, check that:

• Node.js 6+ is used (required to run example app.js)
• the computer is trusted by the phone
• the phone screen is not turned off

You can try it using:

./run.sh

And in another window:

cd example
npm install
node app.js

Then open http://localhost:9002 in browser

When device have big FPS, minicap is sending frames to example app trough the localhost connection too quickly, so it could not draw it quick enough. That could cause frames to delay.

Global header binary format

Appears once.

Bytes	Length	Type	Explanation
0	1	unsigned char	Version (currently 1)
1	1	unsigned char	Size of the header (from byte 0)
2-5	4	uint32 (low endian)	Pid of the process
6-9	4	uint32 (low endian)	Real display width in pixels
10-13	4	uint32 (low endian)	Real display height in pixels
14-17	4	uint32 (low endian)	Virtual display width in pixels
18-21	4	uint32 (low endian)	Virtual display height in pixels
22	1	unsigned char	Display orientation
23	1	unsigned char	Quirk bitflags (see below)

Quirk bitflags

Currently, the following quirks may be reported:

Value	Name	Explanation
1	QUIRK_DUMB	Frames will get sent even if there are no changes from the previous frame. Informative, doesn't require any actions on your part. You can limit the capture rate by reading frame data slower in your own code if you wish.
2	QUIRK_ALWAYS_UPRIGHT	The frame will always be in upright orientation regardless of the device orientation. This needs to be taken into account when rendering the image.
4	QUIRK_TEAR	Frame tear might be visible. Informative, no action required. Neither of our current two methods exhibit this behavior.

Frame binary format

Appears a potentially unlimited number of times.

Bytes	Length	Type	Explanation
0-3	4	uint32 (low endian)	Frame size in bytes (=n)
4-(n+4)	n	unsigned char[]	Frame in JPG format

Generation for Xcode

Optionally you may want to use Xcode for developing or building. But still, you should use cmake as a build system.

./open_xcode.sh