Basler Vision Connector Messaging: Image Format#

To standardize image transfer between camera streaming applications and image-driven applications, use the following format for transferring images. The ZMQ message consists of a multipart message with each frame/part described below.

This message format is prepared to support the streaming of multiple cameras.

Message Envelope for ZMQ Messages on the Pub/Sub Channel#

Frame	Field	説明	タイプ
1	topic	Device identification	Binary string (UTF-8) to identify the device in the following syntax: {DeviceID}/stream
2	metadata	Metadata	Binary metadata JSON (UTF-8)
3	image	Image 1	2進法
4 … n	image	Image n - For multi-stream camera	2進法

Metadata JSON#

Field	Optional	タイプ	Default	説明
version	いいえ	String	1	Metadata format version
count	いいえ	Integer (32-bit unsigned)	1	Number of images on message
timestamp	いいえ	String	-	Date and time string UTF-8 ISO8601. Application host datetime
detail	いいえ	Image Detail Object Array	-	Images details

Image Detail Object#

Field	Optional	タイプ	Default	説明
id	いいえ	String	-	Unique image identifier. Suggested mnemonic format: {camid}_{camstream}_{datetime}
seq	いいえ	Integer (64-bit unsigned)	-	Sequential number for the camera image. Starting at 1, incremented by 1 on each frame grabbed
height	No / Yes (encoded formats)	Integer (32-bit unsigned)	-	Image height
width	No / Yes (encoded formats)	Integer (32-bit unsigned)	-	Image width
formatns	はい	String	Genicam	Image format namespace. For GenICam pixel format use `Genicam` and `Compressed` for compressed formats.^a
format	いいえ	String	-	Image format ^a^b
linepadding	はい	Integer (32-bit unsigned)	0	Number of bytes added to the end of a byte stream to reach a multiple of 4 bytes. E.g. an image with 61 pixels, Mono 8 format, will have a line padding of 3, filling the stream to reach 64 bytes.
timestamp	はい	String^c	-	Timestamp sent by the camera^d

The Basler Vision Connector only supports GenICam, no compressed formats.
For cameras using a standardized GenICam pixel format, it's recommended to use the GenICam naming convention as described in section 4.35 of GenICam_PFNC_2_4.pdf.
A string is used since, in the PTP standard, the tick count is expected to be an 80-bit number. However, the current GenICam protocol returns a 64-bit integer.
Timestamps provided by the cameras are tick counts. Ticks are defined by the camera and therefore vary from camera to camera. This can be either referencing the Unix epoch, or the number of ticks since the camera is on, or count of ticks informed/in sync with the PTP server.

Metadata Example#

{
  "version": "1",
  "count": 1,
  "timestamp": "2014-01-09T13:35:34.000000000+0100",
  "detail":[
    {
      "id":"mycamera_1_2014-01-09T13:35:34.000000000+0100",
      "seq": 3,
      "height": 852,
      "width": 1280,
      "formatns": "Genicam",
      "format": "BGR8",
      "linepadding": 0,
      "timestamp": "123456"
    }
  ]
}