Raw Data File Playback

The raw data file hardware sub system has the ability to playback previously recorded raw data files.  In order to playback a raw data file, the data file name must be set inside the hardware sub system.  In order to do this, a filename can be set as the last argument for the -CreateHardwareSubSystem command.  If this argument is not set, when processing this command, a file selection dialog box will appear allowing the user to select a file name.  If a file is not selected the hardware sub system creation will fail.  Once a file has been set, starting acquisition will read data from the raw data file and push it through the __prod_name system.  The data playback rate is not set to a specific value.  It is based upon the processing speed of the PC.  When the end of the file is reached, data will stop being sent through the system.  There is an option to continuously play data back from the data file.  By using the -SetContinuousRawDataFilePlayback command, whenever the end of file is reached, acquisition will stop and then restart itself.  Continuous Playback Mode is disabled by default but may be modified at any time.  If this property is modified, a message will be output to the logfile describing the change.  Acquisition and recording will be stopped when playback reaches the end of the data contained in the file.  If acquisition is stopped and restarted, playback will resume from the last stopping point instead of reverting back to the start of the file.  The raw data file must contain the same session ID that exists in the Session Index and Subject file or it will not be allowed to be played back.  Timestamps being processed from the file will not be modified in any way when being used as the source of the Real Time Clock.  

NOTE: Pegasus requires that the selected Subject and Session during startup match the Subject and Session used when the selected Raw Data File (NRD) was originally recorded.
The hardware system properties are shown via the View menu in __prod_name.



Raw Data File Playback Hardware System Properties Dialog


1.  System Name This is the unique name that is used to identify this system in __prod_name.  It is the name you chose when you created the hardware system.
2.  Sample Frequency The sample frequency for this system is read from the raw data file.  This value is based on the hardware that was being used when recording the raw data file and cannot be changed.  However, the sampling rate of individual acquisition entities can be changed.  See the help section for the type of acquisition entity whose sampling rate you wish to change for more information.
3.   Channel Count
This number represents the total potential channel count available in the system when the raw data file was generated.  When setting up acquisition entities, they cannot have an AD channel number greater than channel count - 1 (i.e.If Channel Count is 64, as shown above, the last AD channel is channel 63).
4.  File Name This section will show the raw data file that is currently being played back.  For more information on setting up raw data file playback, see  Raw Data File Commands.
5.  Continuous File Playback
Continuous playback can be in either of the following states:
  1. Checked: Sets __prod_name to continually loop the current raw data file.  Once __prod_name is done processing the file, it will immediately restart the same file from the beginning.  This setting is mainly used for presentation or testing purposes.  It is not intended for data collection use.  
  2. Unchecked:  __prod_name will process all the data from the current raw data file once, and then turn off  acquisition and recording.  The file can be restarted by starting acquisition again. 
Acquisition and recording will be stopped when playback reaches the end of the data contained in the file. The data file will act as the main data source for the application, allowing all processing functions and properties to be performed on the data.  Starting and stopping acquisition will control when data is read from the file and processed by the application.  If acquisition is stopped and restarted, playback will resume from the last stopping point instead of reverting back to the start of the file.  Data processing will not represent real time playback.  The sample frequency used for the data source will be retrieved from the raw data files header.   The raw data file must contain the same session ID that exists in the Session Index and Subject file or it will not be allowed to be played back.  Timestamps being processed from the file will not be modified in any way when being used as the source of the Real Time Clock.  A valid timestamp can be specified as the starting point of the raw data file playback.

Playback will start with the first data record in the file unless otherwise specified.  The user may specify a timestamp at which to start acquisition with in order to bypass a portion of the file.  A file must be opened and acquisition must be turned off in order for a timestamp to be specified.  Data will begin being played back starting with data timestamped at the request value or as close to it as possible without preceding it.  If file playback comes to an end and the user restarts playback or has continuous mode enabled, playback will restart from the beginning of the file.  This value is not stored to the settings file.
6. Timestamp Range This displays the timestamp range found in the playback file. Shown as "first_timestamp : last_timestamp" This value cannot be changed.
7. Start Timestamp This input shows the starting timestamp for file playback.
8. Playback Position This slider control can be used to jump to a timestamp within the file.
9. Current Offset This displays the timestamp of the current playback position within the file.
10.    Min Input Range This is the smallest input range that the system used to record this data file was capable of recording.  This value cannot be changed.
11.  Max Input Range This is the largest input range that the system  was capable of recording.  This value cannot be changed.
12. Playback Speed This input can be changed to adjust the rate at which the raw data is played back in the application.
13. File Duration This is the total duration of the playback file.  This value cannot be changed.