Android fast screen capture - image or compressed image stream output

• Android fast screen capture take a screenshot or compressed stream on any other Android device.
• Not needed root devices.
• ADB required (default run permissions using).
• For best perfomance using OpenMP for Android.
• Include all using system library, fake version (for Android 5.1.1 headers)
• Default build tools: ndk-build, including Code::Blocks project using C::B NDK project template, NDK build auto configuration support.

• Features
• Stream/Image compressed - header format using
• Installing pre-build binary
• Using from command line
• Example using SDL2 output format

Features

• image output format: raw bitmap 24 bpp, include header.
• video stream output format: raw compressed bitmap lz4 stream - 24 bpp, include header + packet header.
• video stream is 5 - 20 fps, depends on the CPU device.
• pack image by ratio: valid values 1-9 (lz4).
• resize image by ratio: valid values 1-5.
• rotate image: 90,180,270
• mirror image.
• SDL2 Texture output compatible mode: Landscape screen.
• save image to location specified (bmp format).
• default save path: /data/local/tmp/AScreenCap.bmp

Run time statistic, milliseconds:

        5 ms. - load and initialization
   40-151 ms. - capture screen - android::ScreenshotClient(), depends on the CPU device   
       40 ms. - image convert, resize and rotate
      196 ms. - maximal total time

Stream/Image compressed - header format using

Packet stream include no pack header, size 160bit uint32[5], after image compressed body:

• octet 0 - unique identifier BMZ1 (0x315a4d42/828001602).
• octet 1 - size to uncompressed image.
• octet 2 - size to compressed image.
• octet 3 - image width.
• octet 4 - image height.

Installing pre-build

Download binary for you device from dist/ directory:

Building details:

Android 5.x - 7.x | armeabi-v7a | arm64-v8a | x86 | x86_64

Application platform: android-21
Android system AOSP library version compatible: 5.1.1 - 7.x.x
NDK build version: r20-beta2

Android 8.x | armeabi-v7a | arm64-v8a | x86 | x86_64

Application platform: android-27
Android system AOSP library version compatible: 8.0.0 - 8.1.x
NDK build version: r20-beta2

Android 9.x | armeabi-v7a | arm64-v8a | x86 | x86_64

Application platform: android-28
Android system AOSP library version compatible: 9.0.0 - 9.1.x
NDK build version: r20-beta2

Using ADB to send binary to device:

  adb push dist/<my platform>/ascreencap /data/local/tmp/
  adb shell chmod 0777 /data/local/tmp/ascreencap

Using

Command line options:

-f  --file      : output save to file, value is name
-s  --stream    : output to loop stream (STDOUT)
    --stdout    : output to STDOUT
-p  --pack      : output pack lz4 algorithm, valid value 1-9
    --sdl       : output SDL2 Texture compatible mode: Landscape screen
    --ratio     : image resize ratio, valid scale 1-5
    --rotate    : image rotate: 90,180,270, value 360 = mirror
-h  --help      : this help screen

Example run:

   adb exec-out /data/local/tmp/ascreencap -f /data/local/tmp/my.bmp
   adb exec-out /data/local/tmp/ascreencap -f /data/local/tmp/my.bmz // << save lz4 compressed image
   adb exec-out /data/local/tmp/ascreencap --rotate 90 --ratio 2
   adb exec-out /data/local/tmp/ascreencap --rotate 360 // << mirror image :)
   adb exec-out /data/local/tmp/ascreencap --stream

Example using SDL2 output format

Run:

adb exec-out /data/local/tmp/ascreencap --stream --sdl --ratio 2 | my-capture-prog.executable

Part of code my-capture-prog.executable

    /// check data header valid
    uint32_t *id = 'data from ascreencap';
    if (*id != 0x315a4d42)
        return;

    /// begin SDL2 Create Texture
    uint32_t *width  = 'data from ascreencap' + (sizeof(uint32_t) * 3);
    uint32_t *height = 'data from ascreencap' + (sizeof(uint32_t) * 4);

    SDL_Texture *texture = SDL_CreateTexture(
                renderer,
                SDL_PIXELFORMAT_RGB24,
                SDL_TEXTUREACCESS_STREAMING,
                *width,
                *height
            );

    /// ...

    /// get uncompressed size from header
    uint32_t *psize = 'data from ascreencap' + sizeof(uint32_t);
    /// offset data = first 160bit uint32[5] data header from ascreencap
    uint32_t offset = sizeof(uint32_t) * 5;
    /// uncompress data from ascreencap, using lz4
    uint8_t *uncompressdata = ...lz4('data from ascreencap' + offset)

    void *pix = nullptr;
    int32_t pitch = 0;

    SDL_LockTexture(texture, nullptr, &pix, &pitch);
    if ((!pix) || (!pitch))
        return;

    ::memcpy(pix, uncompressdata, *psize);

    SDL_UnlockTexture(texture);

See full ADB capture source