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Screen Capture engine

Updated

You can capture a whole screen, part of a screen or a window with Medialooks DXGI/DX11 ScreenCapture engine. You can use the engine as a video device in an MLive object in MPlatform SDK or in an MFLive object in MFormats SDK.

Usage with MPlatform SDK

You can use a full name of ScreenCapture engine  to set up it:

myLive.DeviceSet("video", "Medialooks DXGI/DX11 ScreenCapture", "")

Usage with MFormats SDK

Devices in MFormats SDK are based on its index, so to find a correct index of the ScreenCapture engine you should get the amount of all possible video sources and check video sources names:

int deviceCount = 0;
liveObj.DeviceGetCount(eMFDeviceType.eMFDT_Video, out deviceCount);
for (int i = 0; i < deviceCount; i++)
{
    string currentDeviceName = "";
    int currentDeviceBusy = 0;
    liveObj.DeviceGetByIndex(eMFDeviceType.eMFDT_Video, i, out currentDeviceName, out currentDeviceBusy);
    if (currentDeviceName == "Medialooks DXGI/DX11 ScreenCapture")
    {
        liveObj.DeviceSet(eMFDeviceType.eMFDT_Video, i, "");
        break;
    }
}

Properties

You can manage the engine behavior with different properties by using a PropsSet method or by setting them through the system registry:

HKEY_CURRENT_USER\SOFTWARE\Medialooks\MFormats\MFLive\MFDeviceSCR

And once specified in the registry, all the instances of ScreenCapture engine use these values. PropsSet method manages only a single instance of the object.

  Name   Default value   Description
capture.show_mouse show Sets behavior of the mouse pointer capturing.
Possible values:
  • show - display the mouse pointer on captured video.
  • hide - don't display the mouse pointer.
  • hide_inactive(<timeout>) - mouse pointer will be hidden if it is inactive after <timeout> milliseconds elapsed.
capture.show_clicks true Indicates whether mouse clicks are highlighted on video.
Possible values: true, false
capture.focus_change_speed 0.2 Speed of focus changing in fraction per frame units.
Possible values: from 0.1 to 1.0
capture.mode auto Screen capture mode.
Possible values:
  • auto - Capture modes are applied in the following order: DXGI -> DirectX -> GDI. The first applicable mode is used.
  • DXGI - Fastest mode of hardware capturing
  • DirectX - Software screenshot and hardware processing
  • GDI - software-only processing
capture.current_mode Pending Current screen capture mode. Read-only.
capture.dxgi.audio_samples_max_mul
 3 Changes the maximum allowed audio buffer size and thereby avoids audio drops. Audio drops can occur due to local timing of exceeding the specified maximum audio buffer size due to jitter in video and audio frame capture.
The value can be set in the range from 1 to 100 inclusive. The value is equal to the duration of the video frames.
capture.memory_format HDYC Pixel memory format for hardware mode.
Possible values:
  • HDYC - Faster capturing but slightly lower quality
  • ARGB - Slower capturing but slightly better quality
capture.fps_limit 30.0 FPS value (for high values frames can be duplicated on low-performance machines).
Possible values: range between 1 and 60. Otherwise, the default value is used.
capture.frame_size 1920x1080 Size of the captured frame.
Possible values:
  • <width>x<height> - desired size
  • screen - frame size fits the screen size
  • area - frame size fits captured area size
capture.screen_enumeration_mode DXGI

Choose the enumeration mode.
Possible values:

  • DXGI - 0 is the default monitor. No matter what index it has in the system settings;
  • GDI - monitors enumerate depend on the index in the system;
capture.screenshot_timeout 15 Integer value in milliseconds which indicates the amount of time that API waits for changes on the screen to take a screenshot. Affects only DXGI hardware mode.
Possible values: from 5 to 50 ms.
capture.highlight_mouse show Show mouse highlight on screen capture frame.
Possible values:
  • show - highlight the mouse pointer on captured video.
  • hide - don't highlight the mouse pointer.
  • hide_inactive(<timeout>) - mouse pointer highlight will be hidden if it is inactive after <timeout> milliseconds elapsed.
capture.highlight_mouse_color Yellow(136) Color of mouse highlight.
Possible values:
  • <color_name>(<alpha>) - valid for limited number of colors, e.g. "green", "red", "blue"
  • hex-code of a color
capture.show_keypresses false Show key presses.
Possible values: true, false
capture.screen_index 0 Index of the captured screen (apply when many screens are used). Screens are enumerated according to the system order.
capture.keypress_text_size 1.0 Size of keypress info text.
Possible values: range from 0.5 to 2.0
capture.following_mode none Following mode. Indicates behavior of the engine on mouse movement.
Possible values:
  • none - don't change a source
  • active_wnd - follow the active window
  • cursor - follow the cursor
capture.follow_window_by_handle none Capture window by a handle. Once set, "capture.following_mode" is ignored.
Possible values:
  • none - don't follow a window
  • <window_handler> - follow specified window 
capture.area   Capture rectangular area relative to the current screen. Once set, "capture.following_mode" is ignored.
Format: <Left>,<Top>,<Right>,<Bottom>, for example "100, 150, 800, 600"
capture.background_color Black(170) Background color.
Possible values:
  • <color_name>(<alpha>) - valid for limited number of colors, e.g. "green", "red", "blue"
  • hex-code of a color
capture.screen_edges all Capturing screen edges in following mode.
Possible values:
  • all - Show all edges
  • scale - Scale visibly captured areas
  • stick_to_visible - Capture only visible parts of screen without scaling
capture.aspect_ratio keep Aspect ratio mode.
Possible values:
  • stretch - Stretch to a frame
  • keep - Use the screen aspect ratio
  • frame - Use the frame aspect ratio
capture.sampler_type linear Type of a sampler for hardware rendering.
Possible values:
  • point - Point sampler used. Recommended for precise capturing of the full screen when the frame size is equal to the screen resolution.
  • linear - Linear mode for good scaling.
  • anisotropic - anisotropic mode.
capture.wait_frame_msec 0 Frame wait timeout in milliseconds.
capture.software_scaling letter-box Scaling type for software screen capture.
Possible values:
  • default
  • ignore-ar
  • letter-box
  • crop
  • no-scale
  • none
capture.async_resize false Async output frame resize (experimental property).
Possible values: true, false.
capture.audio_device default Audio device for capturing sound.
Possible values:
  • none - don't capture sound
  • PC Sounds (Loopback) - capture system sound
timecode.print false Enable timecode overlay.
Possible values: true, false.
capture.min_delay false Reduces frame delay but increases jitter.
Possible values: true, false.
capture.no_frame_max_count 100 Sets an interval of "No Video" frames after which the engine is reset. Use "0" to disable.
capture.external_process false Once enabled, the ScreenCapture is processed in a separated MServer.exe process.

You can specify any of these properties with a PropsSet method.

MPlatform SDK:

(myLive as IMProps).PropsSet("device::capture.fps_limit", "29.97"); // note the "device::" prefix please

MFormats SDK:

(myLive as IMFProps).PropsSet("capture.fps_limit", "29.97");

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