Troubleshooting

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Troubleshooting frequent load problems

A source file is locked.

One of your files is locked by the operating system and cannot be opened. Check to make sure that no other application is currently using the file in the folder.

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About the .instructions file

About
Every bus must include a corresponding instructions file. The instructions file tells MAPPS how it should process a given log file. The file allows you to specify the columns of interest, data types, units, and a friendly name. If you use the Record Manager, an instructions file will be built for you automatically and you do not need to write your own.

Name
The instructions file should have the same base name as the bus of interest. The extension of the file is .instructions. For example, if you have an eye tracking bus stored in 'eye_tracking.log', your instructions file would be called 'eye_tracking.instructions'.

Format
The instructions file is an XML based file.

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There is no .instructions file

One of your buses does not have an associated '.instructions' file. This file is required for all buses and tells the MAPPS how to process a bus. The name of the instructions file should match the bus name. For example, a bus named eye_tracking would have its data stored in a file named eye_tracking.log and its instructions in eye_tracking.instructions. Buses recorded with the Record Manager tool should have instructions automatically generated for them.

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There is no .log file

A bus that you have requested to be loaded in sources.xml does not exist. Each bus is described in its .log file.

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About timestamps

About
In MAPPS, each frame of data must be timestamped. This allows MAPPS to synchronized different buses of data and present them together. MAPPS does not assume that a bus will operate at a fixed frequency. While a manufacturer may claim that a device runs at a specified rate, in practice that rate is usually just an average. Some samples may be faster, others slower. By timestamping each and every frame, we are able to capture the true sample time. It also allows MAPPS to support buses that operate a very different rates.

Format
Timestamps are represented as the number of 100-nanosecond ticks since 1600, in UTC time. For binary representations, each timestamp is stored as an unsigned 64-bit integer representing the number of ticks. In text files, the timestamp is represented as an ASCII integer. For example, the value of '128714912880562858' corresponds to a UTC time of November 18, 2008 at 14:14:48.056 UTC.

Caution: If you work in Excel, ensure that the timestamp field remains an integer number. By default, Excel will attempt to convert it to a floating point number presented in scientific notation. This format will not work.

Modern operating systems provide a mechanism for obtaining and converting timestamps. The documentation for the Windows API for generating timestamps can be found at MSDN.

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Bus has no UserTimeStamp field

Every log file must include a UserTimeStamp field. This field lets us time synchronize different buses and video.

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A UserTimeStamp value appears corrupt.

The text value in the UserTimeStamp field appears corrupt and is not a number. This could be caused by corruption of the log file itself. An approximate line number should be given where the error was encountered. Check your source file.

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A timestamp is out of range.

If MAPPS was unable to load a particular data set, it will mark it with a large red '!'. In the readout area, MAPPS will provide a short description of the problem. Clicking on the project will launch your browser with a more detailed message of the problem that was detected. If you fix the problem, you'll need to restart MAPPS for the message to be updated. You cannot load a data set that has been marked with problems.

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The timestamps move backwards in time.

The timestamps in the log file move backwards. Each line of the log file should be in time sequential order.

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The data is unusually long.

The total length of the project is unusually long. Often, this means that you have two buses with mismatched timestamps (perhaps one bus with timestamps from one day and a second bus with timestamps from a different day). Check your timestamps to ensure they match.

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The number of timestamps don't match.

Video data consists of a video file (usually a .avi or a .mpeg file) plus a timestamps file (.txt). The number of frames of video should match the number of timestamps in the txt file. Your data set has a mismatch.

If the two are mismatched by only a single frame, this may be a harmless artifact from the recording where the final value did not get written to disk before the recording ended. In this case, it is generally safe to simply prune the end of the file by a single frame.

However, if the two are mismatched by more than a frame, something else is wrong with the wrong with the recording. Check your files to ensure they are correct.

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