Configuring Capture Card Operation

"Blank" frame (blank-picture)

For the correct switching of the source to the previous one when it is disconnected from the capture card, TrueConf Room recognizes the status signal from the capture card.

If the capture card does not support determining the connection status of devices, TrueConf Room provides the option to configure an empty frame, which is used to detect inactivity in such cases.

Operating principle

1. When launched, the program reads all reference files from a specified folder.

2. Each frame from the capture card is reduced to 128×128 and compared with reference images based on brightness, image "structure," etc.

3. If a frame matches the reference based on at least one criterion, the chart is considered non-transmitting (empty frame).

Configuring a "blank" frame

For TrueConf Room to be able to detect an empty frame, it is necessary to:

1. Connect the capture card without displaying an image (disable the signal source).

2. Connect the keyboard to a PC with installed TrueConf Room

3. Take a screenshot of the image of an empty frame from the capture card. The image file must meet the requirements (this can be done, for example, in the Video settings section).

4. Place the file in the folder ../TrueConf/Room/captureCards.

5. Restart TrueConf Room.

6. Check the log files.

Image Requirements

Common raster formats are supported:

Format	Extensions
PNG	.png
JPEG	.jpg, .jpeg
BMP	.bmp
GIF	.gif
Others	TGA, PSD, PNM, HDR

The file must be a standard image. Do not use text files, Word/Excel files, compressed archives, etc. — these are not recognized as images.

Properties of a suitable image:

Parameter	Requirement
Minimum size	no less than 128×128 on each side
Maximum size	no more than 10000×10000 on each side
Maximum file size	no more than 10 MB
Recommended size	from 128×128 to 1920×1080, preferably in the same resolution as the map frame

Any image is automatically resized to 128×128 for comparison, so the exact resolution is not critical, as long as the minimum and maximum are adhered to.

The image should not be monochrome (filled with a single color). Such files are skipped and not included in the comparison.

Detection threshold

In the filename, you can specify the match threshold using the acc token followed by a number (case insensitive, preceded by _ or -):

File name	Threshold	What does it mean?
stub.png	80 (default)	standard accuracy
stub_ACC90.png	90	The frame should closely match the reference.
stub_acc85.png	85	intermediate option
dexpAnycast_ACC91.bmp	91	example originally located in the application folder

How to choose a threshold:

• Frequent false positives (a regular frame is mistakenly considered "empty") -> increase the value, for example, acc95.
• The function does not trigger (empty frame not recognized) -> reduce the number, for example, acc75.

If the acc token is missing or incorrect, the default threshold of 80 is used. The number must be between 0 and 100.

File path

The captureCards folder is located at:

• Windows: C:\Program Files\TrueConf\Room\captureCards

• Linux: /opt/trueconf/room/captureCards

Posting rules:

Where is the file located	Who it is for
Directly in the folder captureCards/	The common reference is checked for all capture cards.
In the subfolder captureCards/<identifier>/	Reference for a specific card only

Subfolder for specific devices

To avoid conflicts when comparing blank images from different capture cards, you can create a separate folder named after the device identifier in the format vid#pid (case-insensitive) to store individual blank screens for specific devices. Examples of already used names: 07ca#0110, 17ef#7219, 17ef#722f.

How to find your vid#pid:

• Windows:  → . A string like USB\VID_07CA&PID_0110, subfolder name 07ca#0110.

• Linux: the lsusb command shows ID 07ca:0110 → the subfolder name will be 07ca#0110.

If the ID is unknown, use the common reference by placing the file directly in ../captureCards.

Log files for performance verification

After starting the program, a line of the following format should appear in the log:

[BlankPicture] Loaded 3 high-priority and 1 low-priority capture card stubs

Search by substring [BlankPicture]

• high-priority - benchmarks in subfolders (for specific devices);
• low-priority - general references (in the root folder).

If the reference fails to upload, a warning [BlankPicture] will appear in the log with reasons such as unsupported format, image too small, solid color image, etc.

Platform	Path to the TCR logs folder
Windows	%USERPROFILE%\AppData\Local<Const name='company-name'/>\Room\logs\
Linux	~/.config/trueconf/room/logs/

Common Issues

• The log does not contain the Loaded ... stubs entry.

  Ensure that the captureCard folder exists and is not empty.

• In the log unsupported format or corrupted

  Ensure that the blank frame file is in an image format.

• In the log Image dimensions too small

  Ensure that the file is of the appropriate size.

• In the log Skipping uniform stub

  The reference file of the blank frame was read as solid-colored.

• An empty frame is not defined.

  The threshold for detecting the reference image is probably too high.

• A regular frame is defined as "empty"

  Ensure that the detection threshold for the reference image is set high enough.