Video Object Detection: findface-video-manager and findface-video-worker

Note

The findface-video-worker is delivered in a CPU-accelerated (findface-video-worker-cpu) and a GPU-accelerated (findface-video-worker-gpu) package.

In this section:

Functions of findface-video-manager

The findface-video-manager service is the part of the video object detection module that is used for managing the video object detection functionality.

The findface-video-manager service interfaces with findface-video-worker as follows:

  • It supplies findface-video-worker with settings and the list of to-be-processed video streams. To do so, it issues a so-called job, a video processing task that contains configuration settings and stream data.

  • In a distributed system, it distributes video streams (jobs) across vacant findface-video-worker instances.

Note

The configuration settings passed via jobs have priority over the findface-video-manager.yaml configuration file.

The findface-video-manager service functioning requires etcd, a third-party software that implements a distributed key-value store for findface-video-manager. In the FindFace core, etcd is used as a coordination service, providing the video object detector with fault tolerance.

findface-video-manager functionality:

  • allows for configuring video object detection parameters

  • allows for managing the list of to-be-processed video streams

Functions of findface-video-worker

The findface-video-worker service (on CPU/GPU) is the part of the video object detection module, that recognizes objects in the video. It can work with both live streams and files, and supports most video formats and codecs that can be decoded by FFmpeg.

The findface-video-worker service interfaces with the findface-video-manager and findface-facerouter services as follows:

  • By request, findface-video-worker gets a job with settings and the list of to-be-processed video streams from findface-video-manager.

  • The findface-video-worker posts extracted normalized object images, along with the full frames and metadata (such as bbox, camera ID and detection time) to the findface-facerouter service for further processing.

Note

In FindFace Multi, the findface-facerouter functions are performed by findface-multi-legacy.

findface-video-worker functionality:

  • detects objects in the video,

  • normalizes images of objects,

  • tracking objects in real time and posting the best object snapshot.

When processing a video, findface-video-worker consequently uses the following algorithms:

  • Motion detection. Used to reduce resource consumption. Only when the motion detector recognizes the motion of certain intensity that the object tracker can be triggered.

  • Object tracking. The object tracker traces, detects, and captures objects in the video. It can simultaneously be working with several objects. It also searches for the best object snapshot using the embedded neural network. After the best object snapshot is found, it is posted to findface-facerouter.

The best object snapshot can be found in one of the following modes:

  • Real-time

  • Offline

Real-Time Mode

In the real-time mode, findface-video-worker posts an object on-the-fly after it appears in the camera field. The following posting options are available:

  • If realtime_post_every_interval: true, the object tracker searches for the best object snapshot within each time period equal to realtime_post_interval and posts it to findface-facerouter.

  • If realtime_post_every_interval: false, the object tracker searches for the best face snapshot dynamically:

    1. First, the object tracker estimates whether the quality of an object snapshot exceeds a pre-defined internal threshold. If so, the snapshot is posted to findface-facerouter.

    2. The threshold value increases after each post. Each time the object tracker gets a higher quality snapshot of the same object, it is posted.

    3. When the object disappears from the camera field, the threshold value resets to default.

  • If realtime_post_first_immediately: true, the object tracker doesn’t wait for the first realtime_post_interval to complete and posts the first object from a track immediately after it passes through the quality, size, and ROI filters. The way the subsequent postings are sent depends on the realtime_post_every_interval value. If realtime_post_first_immediately: false, the object tracker posts the first object after the first realtime_post_interval completes.

Offline Mode

The offline mode is less storage intensive than the real-time one as in this mode findface-video-worker posts only one snapshot per track but of the highest quality. In this mode, the object tracker buffers a video stream with an object until the object disappears from the camera field. Then the object tracker picks up the best object snapshot from the buffered video and posts it to findface-facerouter.

Configure Video Object Detection

The video object detector configuration is done through the following configuration files:

  1. The findface-video-manager configuration file findface-video-manager.yaml. You can find its default content here.

    When configuring findface-video-manager, refer to the following parameters:

    Option

    Description

    etcd → endpoints

    IP address and port of the etcd service. Default value: 127.0.0.1:2379.

    ntls → enabled

    If true, findface-video-manager will send a job to findface-video-worker only if the total number of processed cameras does not exceed the allowed number of cameras from the license. Default value: false.

    ntls → url

    IP address and port of the findface-ntls host. Default value: http://127.0.0.1:3185/.

    router_url

    IP address and port of the findface-facerouter host to receive detected faces from findface-video-worker. In FindFace Multi, findface-facerouter functions are performed by findface-multi-legacy. Default value: http://127.0.0.1:18820/v0/frame.

    The following parameters are available for stream_settings configuration:

    Option

    Description

    play_speed

    If less than zero, the speed is not limited. In other cases, the stream is read with the given play_speed. Not applicable for live streams.

    disable_drops

    Enables posting all appropriate objects without drops. By default, if findface-video-worker does not have enough resources to process all frames with objects, it drops some of them. If this option is active, findface-video-worker puts odd frames on the waiting list to process them later. Default value: false.

    imotion_threshold

    Minimum motion intensity to be detected by the motion detector. The threshold value is to be fitted empirically. Empirical units: zero and positive rational numbers. Milestones: 0 = detector disabled, 0.002 = default value, 0.05 = minimum intensity is too high to detect motion.

    router_timeout_ms

    Timeout for a findface-facerouter (or findface-multi-legacy in the standard FindFace Multi configuration) response to a findface-video-worker API request, in milliseconds. If the timeout has expired, the system will log an error. Default value: 15000.

    router_verify_ssl

    Enables a https certificate verification when findface-video-worker and findface-facerouter (or findface-multi-legacy in the standard FindFace Multi configuration) interact over https. Default value: true. If false, a self-signed certificate can be accepted.

    router_headers

    Additional header fields in a request when posting an object: [“key = value”]. Default value: headers not specified.

    router_body

    Additional body fields in a request body when posting an object: [“key = value”]. Default value: body fields not specified.

    ffmpeg_params

    List of a video stream ffmpeg options with their values as a key=value array: [“rtsp_transpotr=tcp”, .., “ss=00:20:00”]. Check out the FFmpeg web site for the full list of options. Default value: options not specified.

    ffmpeg_format

    Pass FFMPEG format (mxg, flv, etc.) if it cannot be detected automatically.

    use_stream_timestamp

    If true, retrieve and post timestamps from a video stream. If false, post the actual date and time.

    start_stream_timestamp

    Add the specified number of seconds to timestamps from a stream.

    rot

    Enables detecting and tracking objects only inside a clipping rectangle WxH+X+Y. You can use this option to reduce findface-video-worker load. Default value: rectangle not specified.

    stream_data_filter

    POSIX extended regex, if a content of the data stream is matched a filter, it will be sent it to router_url. Default value: not specified.

    video_transform

    Change a video frame orientation right after decoding. Values (case insensitive, JPEG Exif Orientation Tag in brackets): None (1), FlipHorizontal (2), Rotate180 (3), FlipVertical (4), Transpose (5), Rotate90 (6), Transverse (7), Rotate270 (8). Default value: not specified.

    enable_recorder

    Enables video recording for Video Recorder (must be installed).

    enable_liveness

    Enables liveness (must be installed). Default value: false.

    record_audio

    Enables audio recording. Default value: false.

    use_rtsp_time

    If use_stream_timestamp: true, add start stream timestamp of the RTSP source. Default value: true.

    The following parameters are available for configuration for each detector type (face, body, car):

    Option

    Description

    filter_min_quality

    Minimum threshold value for an object image quality. Default value: subject to the object type. Do not change the default value without consulting with our technical experts (support@ntechlab.com).

    filter_min_size

    Minimum size of an object in pixels. Calculated as the square root of the relevant bbox area. Undersized objects are not posted. Default value: 1.

    filter_max_size

    Maximum size of an object in pixels. Calculated as the square root of the relevant bbox area. Oversized objects are not posted. Default value: 8192.

    roi

    Enable posting objects detected only inside a region of interest WxH+X+Y. Default value: region not specified.

    fullframe_crop_rot

    Crop posted full frames by ROT. Default value: false.

    fullframe_use_png

    Send full frames in PNG and not in JPEG as set by default. Do not enable this parameter without supervision from our team as it can affect the entire system functioning. Default value: false (send in JPEG).

    jpeg_quality

    Quality of an original frame JPEG compression, in percents. Default value: 95%.

    overall_only

    Enables the offline mode for the best object search. Default value: true (CPU), false (GPU).

    realtime_post_first_immediately

    Enable posting an object image right after it appears in a camera field of view (real-time mode). Default value: false.

    realtime_post_interval

    Only for the real-time mode. Defines the time period in seconds within which the object tracker picks up the best snapshot and posts it to findface-facerouter. Default value: 1.

    realtime_post_every_interval

    Only for the real-time mode. Post best snapshots obtained within each realtime_post_interval time period. If false, search for the best snapshot dynamically and send snapshots in order of increasing quality. Default value: false.

    track_interpolate_bboxes

    Interpolate missed bboxes of objects in track. For example, if frames #1 and #4 have bboxes and #2 and #3 do not, the system will reconstruct the absent bboxes #2 and #3 based on the #1 and #4 data. Enabling this option allows you to increase the detection quality on account of performance. Default value: true.

    track_miss_interval

    The system closes a track if there has been no new object in the track within the specified time (seconds). Default value: 1.

    track_overlap_threshold

    Tracker IoU overlap threshold. Default value: 0.25.

    track_max_duration_frames

    The maximum approximate number of frames in a track after which the track is forcefully completed. Enable it to forcefully complete “eternal tracks,” for example, tracks with objects from advertisement media. The default value: 0 (option disabled).

    track_send_history

    Send track history. Default value: false.

    post_best_track_frame

    Send full frames of detected objects. Default value: true.

    post_best_track_normalize

    Send normalized images for detected objects. Default value: true.

    post_first_track_frame

    Post the first frame of a track. Default value: false.

    post_last_track_frame

    Post the last frame of a track. Default value: false.

    tracker_type

    Tracker type (simple_iou or deep_sort). Default value: simple_iou.

    track_deep_sort_matching_threshold

    Track features matching threshold (confidence) for deep_sort tracker. Default value: 0.65.

    track_deep_sort_filter_unconfirmed_tracks

    Filter unconfirmed (too short) tracks in deep sort tracker. Default value: true.

    track_object_is_principal

    Track by this object in N-in-1 detector/tracker. Default value: false.

    track_history_active_track_miss_interval

    Don’t count track as active if N seconds have passed, only if track_send_history=true. Default value: 0.

    filter_track_min_duration_frames

    Post only if object track length at least N frames. Default value: 1.

    extractors_track_triggers

    Tracker events that trigger the extractor.

  2. The findface-video-worker configuration file findface-video-worker-cpu.yaml or findface-video-worker-gpu.yaml, subject to the acceleration type in use.

    When configuring findface-video-worker (on CPU/GPU), refer to the following parameters:

    CPU

    GPU

    Description

    batch_size

    Post faces in batches of the given size.

    capacity

    Maximum number of video streams to be processed by findface-video-worker.

    N/a
    video_decoder

    → cpu

    If necessary, decode video on CPU.

    N/a

    device_number

    GPU device number to use.

    exit_on_first_finished

    (Only if input is specified) Exit on the first finished job.

    input

    Process streams from file, ignoring stream data from findface-video-manager.

    labels

    Labels used to allocate a video object detector instance to a certain group of cameras. See Allocate findface-video-worker to Camera Group.

    mgr → cmd

    (Optional, instead of the mgr → static parameter) A command to obtain the IP address of the findface-video-manager host.

    mgr → static

    IP address of the findface-video-manager host to provide findface-video-worker with settings and the list of to-be-processed streams.

    metrics_port

    HTTP server port to send metrics. If 0, the metrics are not sent.

    min_size

    Minimum object size to be detected.

    ntls_addr

    IP address and port of the findface-ntls host.

    resize_scale

    Rescale video frames with the given coefficient.

    resolutions

    Preinitialize findface-video-worker to work with specified resolutions. Example: “640x480;1920x1080”.

    save_dir

    (For debug) Save detected objects to the given directory.

    streamer → port, url

    IP address and port to access the video wall.

    use_time_from_sei

    (For MPEG-2) Use SEI (supplemental enhancement information) timestamps.

    If necessary, you can also enable neural network models and normalizers to detect bodies, cars, and liveness. You can find the detailed step-by-step instructions in the following sections:

    See also

    Configure Video Recorder

Jobs

The findface-video-manager service provides findface-video-worker with a so-called job, a video processing task that contains configuration settings and stream data.

You can find a job example here.

Each job has the following parameters:

  • id: job id.

  • enabled: active status.

  • stream_url: URL/address of video stream/file to process.

  • labels: key-value labels, that will be used by the router component (findface-multi-legacy in the standard FindFace Multi configuration) to find processing directives for objects detected in this stream.

  • router_url: URL/address of the router component (findface-facerouter, findface-multi-legacy) to receive detected objects from the findface-video-worker component for processing.

  • router_events_url: URL/address of the router component ( findface-facerouter, findface-multi-legacy), that uses events extraction.

  • single_pass: if true, disable restarting video processing upon error (by default, false).

  • stream_settings: video stream settings that duplicate those in the findface-video-manager.yaml configuration file (while having priority over them).

  • stream_settings_gpu: deprecated video stream settings. Not recommended for use. Only for compatibility.

  • status: job status.

  • status_msg: additional job status info.

  • statistic: job progress statistics (progress duration, number of posted and not posted objects, processing fps, the number of processed and dropped frames, job start time, etc.).

  • restream_url: websocket URL where processing stream with detected objects streams live time.

  • restream_direct_url: websocket URL where original stream with input quality streams live time.

  • shots_url: HTTP URL where actual stream screenshot can be downloaded.

  • worker_id: unique id of the findface-video-worker instance with a processing job.

  • version: job version.

Time Settings

When you create a job, it is possible to specify time parameters. These parameters determine how the event timestamps will be generated on posting or upon recording in to the VMS, which is important for calculating the final timestamp of an event. The default time parameter in the video-worker.yaml is use_time_from_sei: false. The default time parameters in the video-manager.yaml are use_stream_timestamp: false, use_rtsp_time: true.

Let’s consider various configurations:

  1. use_stream_timestamp: false, use_time_from_sei: either true or false, use_rtsp_time: either true or false.

    The current server time (wall-clock time) will be used.

  2. use_stream_timestamp: true, use_time_from_sei: true, use_rtsp_time: either true or false.

    SEI timestamps (if any) or stream timestamps (pts) will be used unchanged.

  3. use_stream_timestamp: true, use_time_from_sei: false, use_rtsp_time: true.

    The final timestamp will be calculated by the formula: final_ts = pts - start_pts + start_stream_timestamp + rtsp_start_time, where

    • pts — pts stream timestamps.

    • start_pts — the minimum observed pts of the stream, subtracted to make the first frame time equal to 0.

    • start_stream_timestamp — a job setting within stream_settings.

    • rtsp_start_time — “Start time of the stream in real world time”, specified by certain RTSP servers.

  4. use_stream_timestamp: true, use_time_from_sei: false, use_rtsp_time: false.

    The final timestamp will be calculated by the formula: final_ts = pts - start_pts + start_stream_timestamp.