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adtfFileReader

Read stream information from ADTF DAT file

    Description

    An adtfFileReader object reads the stream information associated with the various sensors in an Automotive Data and Time-Triggered Framework (ADTF) DAT file. ADTF is a framework developed by Elektrobit, to develop, visualize, test and validate advanced driver assistance systems (ADAS) and automated driving functions. DAT files contain data from various sensors, such as lidars and cameras as well as other automotive data.

    To select messages of a specific type to read from an adtfFileReader object, use the select object function.

    adtfFileReader supports reading both 2.0 and 3.0 versions of ADTF DAT files. Each stream in the DAT file must contain sorted timestamps. This requirement applies to the data within a stream only, and not across multiple streams.

    Creation

    Description

    example

    adtfReader = adtfFileReader(dataFileName) creates an adtfFileReader object, adtfReader, that reads stream information from the specified ADTF DAT file.

    adtfReader = adtfFileReader(dataFileName,descriptionFileName) specifies a description file, descriptionFileName, that defines the structure of the streams in the ADTF DAT file.

    adtfReader = adtfFileReader(dataFileName,descriptionFileName,pluginDirectoryPath) specifies a directory, pluginDirectoryPath, that contains plugins to use when reading information from the ADTF DAT file. Plugins are operating system specific, compiled object files that help in reading DAT files.

    Input Arguments

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    ADTF DAT file name, specified as a string scalar or character vector.

    Description file name, specified as a string scalar or character vector. Description files have the extension as XML or DESCRIPTION.

    Absolute path to ADTF plugin directory, specified as a string scalar or character vector. The object uses only the plugin files within the specified directory that have the .adtffileplugin extension.

    Properties

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    This property is read-only.

    Absolute path to the ADTF DAT file to read, specified as a string scalar.

    This property is read-only.

    Absolute path to the description file, specified as a string scalar.

    This property is read-only.

    Absolute path to ADTF plugin directory, specified as a string scalar.

    This property is read-only.

    Number of streams in DAT file, specified as a positive integer.

    This property is read-only.

    Summary of all streams in the DAT file, specified as a structure.

    Object Functions

    selectCreate reader for selected subset of ADTF DAT file data

    Examples

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    This example shows how to extract and visualize a video stream, stored in an ADTF DAT file. It also shows how to write the video stream into a video file.

    Download the sample video DAT file.

    downloadURL  = 'https://ssd.mathworks.com/supportfiles/driving/data/sample_can_video_dat.zip';
    dataFolder   = fullfile(tempdir, 'adtf-video', filesep); 
    options      = weboptions('Timeout', Inf);
    zipFileName  = [dataFolder, 'sample_can_video_dat.zip'];
    folderExists = exist(dataFolder, 'dir');
    
    % Create a folder in a temporary directory to save the downloaded file.
    if ~folderExists  
        mkdir(dataFolder); 
        disp('Downloading sample_can_video_dat.zip (9.74 MB)...') 
        websave(zipFileName, downloadURL, options); 
        
        % Extract contents of the downloaded file.
        disp('Extracting sample_can_video_dat.zip...') 
        unzip(zipFileName, dataFolder); 
    end

    Create the ADTF File Reader object.

    datFileName = fullfile(dataFolder,"sample_can_video.dat");
    fileReader  = adtfFileReader(datFileName) 
    fileReader = 
                  DataFileName: "C:\Users\latriwal\AppData\Local\Temp\adtf-video\sample_can_video.dat"
           DescriptionFileName: ""
               PluginDirectory: ""
                   StreamCount: 2
                    StreamInfo: 
    
        StreamIndex    StreamName      StreamType       StartTime     EndTime      ItemCount
        ___________    __________    _______________    _________    __________    _________
    
             1         {'rawcan'}    {'UNSUPPORTED'}      0 sec      14.805 sec       743   
             2         {'video' }    {'adtf/image' }      0 sec      14.799 sec       149   
    
    
    

    From the StreamInfo property, note that the index of the video stream is 2. Use the select function of the adtfFileReader object, to select the video stream for reading. The returned adtfStreamReader object has all the information about the selection.

    streamReader = select(fileReader,2) 
    streamReader = 
      adtfStreamReader with properties:
    
               DataFileName: "C:\Users\latriwal\AppData\Local\Temp\adtf-video\sample_can_video.dat"
        DescriptionFileName: ""
            PluginDirectory: ""
                StreamIndex: 2
                 StartIndex: 1
                   EndIndex: 149
         CurrentIndexOffset: 0
                  StartTime: [0×0 duration]
                    EndTime: [0×0 duration]
                  DataCount: 149
    
    

    Note that the value of CurrentIndexOffset is 0. This signifies that the next readNext call will return the first item.

    Preview the first image frame from the stream.

    firstFrame = readNext(streamReader);
    imshow(firstFrame.Data.Item)

    Before creating a video, use the reset function to start reading from the first frame. This resets the value of CurrentIndexOffset to 0.

    reset(streamReader);
    fprintf("CurrentIndexOffset = %d\n",streamReader.CurrentIndexOffset)
    CurrentIndexOffset = 0
    

    Create a VideoWriter object that you can use to write image frames to a video file. Specify a frame rate of 1 frame per second.

    videoWriterObj = VideoWriter("example_video.avi"); 
    videoWriterObj.FrameRate = 1; 
    open(videoWriterObj); 

    Using the streamReader object, iterate over the data items in the selection one-by-one. The hasNext function determines if there is an item left to read as we are incrementally reading the file. readNext returns the data item which is basically a structure containing the data and the associated timestamp. In every iteration, extract the image frame and write it to the video file.

    while streamReader.hasNext()
        streamData = streamReader.readNext(); 
        imageFrame = streamData.Data.Item; 
        frame      = im2frame(streamData.Data.Item, gray); 
        writeVideo(videoWriterObj, frame); 
    end 

    Alternatively, you can read all the image frames at once, using the read function, and iterate over it later.

    allData = read(streamReader)
    allData = struct with fields:
        StreamIndex: 2
               Data: [149×1 struct]
    
    

    Close the connection with the video file.

    close(videoWriterObj);
    close all

    Visualize the output file example_video.avi using Video Viewer.

    implay("example_video.avi") 

    Limitations

    • Reading DAT files on Mac platforms is not supported.

    • Reading these stream types is not supported:

      • adtf/anonymous

      • adtf/plaintype

      • adtf/audio

      • adtf/substreams

    • For reading adtf/video_compressed stream type, only JPEG compression format is supported.

    Version History

    Introduced in R2022a