Tools: Test: Audio: Update the README file

This patch converts the README to Markdown .md format and
updates the descriptions for key scripts for audio tests.

Signed-off-by: Seppo Ingalsuo <seppo.ingalsuo@linux.intel.com>

tools/test/audio/README.md

@@ -0,0 +1,107 @@
+# SOF Audio Processing Components Tests
+
+### Test for processing components
+
+The script process_test.m provides tests to help to check that audio
+performance requirements are met with run of SOF testbench with test
+topologies. The tests are currently for measured audio objective
+quality parameters. The used criteria for performance is only an
+initial assumption and need to be adjusted for various applications
+needs.
+
+The scripts support currently support the next list of objective
+quality parameters. The test scripts need Matlab(R) [2] or GNU Octave
+scientific programming language [3].
+
+	- Gain
+	- Frequency Response
+	- THD+N vs. Frequency
+	- Dynamic Range
+	- Attenuation of Alias Products
+	- Attenuation of Image Products
+	- Level Dependent Logarithmic Gain
+
+Note: The metric is an effort to follow AES17 [1] recommendation for
+parameters and test procedures. This was created to help developers to
+quickly check their work but has not been verified to be
+compliant. Professional equipment and formal calibration process is
+recommended for professional applications where both accurate absolute
+and relative metric is needed.
+
+The process_test.m script is started from Octave or Matlab command shell.
+
+```
+octave --gui &
+```
+
+Examples of usage for it is shown with command help
+
+```
+help process_test
+```
+
+Tests for IIR equalizer with S32_LE input and output format with 48
+kHz rate, full test, plots shown, can be run with following command
+
+```
+process_test('eqiir', 32, 32, 48000, 1, 1);
+
+```
+
+The components those can be tested with process_test are shown in the
+next table. For sof-testbench4 use the 2nd column names,for
+sof-testbench3 use the 3rd column names.
+
+| Component                       | IPC4 ID       | IPC3 ID       |
+|---------------------------------|---------------|---------------|
+| ARIA                            | aria          |               |
+| ASRC                            | asrc          | asrc          |
+| DC blocker                      | dcblock       | dcblock       |
+| Dynamic range control           | drc           | drc           |
+| FIR equalizer                   | eqfir         | eq-fir        |
+| Gain                            | gain          | volume        |
+| IIR equalizer                   | eqiir         | eq-iir        |
+| Multiband dynamic range control | drc_multiband | multiband-drc |
+| SRC                             | src           | src           |
+| Time domain fixed beamformer    | tdfb          | tdfb          |
+
+
+See README.md in tools/testbench provdes more information about using
+the testbench.
+
+### Tests for component SRC and ASRC
+
+The Octave or Matlab script to test sample rate conversion is
+src_test.m. See the help for src_test to see the usage.
+
+The top level shell script to launch tests is src_test.sh. See script
+src_run.sh for assumed install location of SOF host test bench
+executable and component libraries. Exit code 0 indicates success and
+exit code 1 indicates failed test cases.
+
+The default in/out rates matrix to test is defined in the beginning of
+script src_test.m. The matrix can be also passed from calling function
+src_test_top.m if need.
+
+The key objective quality parameters requiremements are in the
+beginning of script src_test.m as well under comment Generic test
+pass/fail criteria.
+
+Test run creates plots into directory "plots". Brief text format
+reports are placed to directory "reports".
+
+### Tests for component TDFB
+
+Scripts for testing special features of the multi-microphone beamformer
+are in tdfb_test.m and tdfb_direction_test.m. See the help texts for usage.
+Running the test needs special input files those have been created in blobs
+export. See directory src/audio/tdfb/tune how to rebuild the blobs are
+create simulation data files.
+
+References
+----------
+
+[1]	AES17-2020 standard, http://www.aes.org/publications/standards/search.cfm?docID=21
+[2]	Matlab(R), https://www.mathworks.com/products/matlab.html
+[3]	GNU Octave, https://www.gnu.org/software/octave/
+[4]	SoX - Sound eXchange, http://sox.sourceforge.net/