User:Stevethefiddle/Sample Data Export

Sample Data Export reads the values of successive samples from the selected audio and prints to a file. Additional information may be added as a 'header' at the top of the page.

Accessed by: Analyze > Sample Data Export...

Controls

Show Help File:

• No: Does not show the help screens. To run Sample Data Export this option must be selected.
• Overview: Displays a help screen including a brief overview and descriptions of the first 3 controls.
• File Format: Displays a help screen including a brief description of the file output options.
• Header Text: Displays a help screen including a brief description of the file header options.
• Output Files: Displays a help screen about setting the file output location.
• Save Help File: Saves all four help screens in a single text file.

Limit output to first:....samples

• The number of samples processed will be the number of samples in the selection, up to a maximum of the number entered here.
  • Sample Data Export is limited internally to an absolute maximum of 1 million samples.
  • Processing a large number of samples can create extremely large output files that may be difficult to open. For HTML output it is advisable to limit the number of samples to a maximum of a few hundred to avoid creating an excessively large html file.
  • The track sample rate indicates the number of samples per second and the number of samples in a selection may be viewed in the Selection Toolbar.

Measurement scale:

Sample values may be displayed on a linear scale +/- 1 (as in the Audacity audio track Waveform view) or on a dB scale relative to full scale (as in the Waveform (dB) view).

File data format:

Following any header information:

• Sample List (txt): produces a plain text file with a list of sample values.
• Indexed List (txt): produces a plain text file with an indexed list of sample values: sample number followed by sample value.
• Time Indexed (txt): produces a plain text file with the time (relative to the start of the selection) followed by sample value
• Data (csv): produces a CSV file that contains the sample values separated by commas. This may be suitable for importing into spreadsheet applications for further analysis.
• Web Page (html): produces an HTML 5 document that contains all of the header information and a table of sample data with sample number, time, linear and dB values. Browsers that are not HTML 5 compliant may not display the page correctly.

Include header information:

• None: Prints only the optional header text (leave blank for none) followed by the sample data.
• Minimal: Prints a minimal header that contains:
  • The sample rate.
  • Units (linear or dB).
  • Optional header text (leave blank for none).
• Standard: In addition to the minimal header information, the following is also included:
  • File name.
  • Number of samples.
  • Duration (seconds).
  • Mono/Stereo.
• All: In addition to the standard header information, the following is also included:
  • peak amplitude linear and dB.
  • Unweighted rms level (dB).
  • DC offset.

Optional header text:

This is provided for adding notes to the output file. In text files, use ~~% to start a new line, in HTML files use <br>.

Channel layout for stereo:

The plain text and csv formatted files may be set to print stereo tracks as either alternate left channel sample / right channel sample:

 1	0.59528
 1	0.59528
 2	0.56063
 2	0.56063
 3	0.52377
 3	0.52377
 ...

or all of the left channel followed by all of the right channel:

 Left Channel.

 1	0.59528
 2	0.56063
 3	0.52377
 ...


 Right Channel.

 1	0.59528
 2	0.56063
 3	0.52377
 ...

Show messages:

• Yes: (default) Error, warning and confirmation messages will be shown after processing.
• Errors Only: Only error messages will be shown on completion.
• None: No messages will be shown on completion.

Normally the default setting should be used.

It may be useful to disable confirmation messages if Sample Data Export is to be used in a Chain for batch processing (see below).

File name:

The desired name of the output file. A file extension is not required as it will be added automatically.

Output folder:

OUTPUT FILES.

The default output folder is the "home folder": /home/steve To select a different output folder, enter the full path name. The output folder must exist.

By default, files will not be overwritten. If you select multiple tracks, they will be saved to separate files with a number appended to the name. If you set "Allow files to be overwritten" to "Yes", only the last file for multiple tracks will be retained.

A notification message is displayed on completion indicating the name and location of the file.

If the plug-in is used in a Chain (Audacity 2.0.1 or later) it may be useful to disable messages.

For text/csv output the file header is shown in the debug window.

Batch processing with Sample Data Export

As of Audacity version 2.0.1, Nyquist effect plug-ins are supported in Chains, but Analyze plug-ins are not supported. To use Sample Data Export in a Chain it is necessary to convert it into an Effect plug-in. To do this, the file sample-data-export.ny must be edited in a plain text editor (such as NotePad on Windows).

The file sample-data-export.ny can be found in the plug-Ins folder inside the Audacity installation folder. On Windows computers, this is usually under "Program Files". On Mac OS X, it is usually under "Applications". On Linux, you can use various plug-in locations. To convert Sample Data Export into an Effect type plug-in, open the file in a plain text editor and change the third line:

 ;type analyze

to:

 ;type process

Save the file in the same location and restart Audacity. Sample Data Export... will now appear underneath the divider in the "Effect" menu rather than the "Analyze" menu, and will be available for use in a Chain.