EBC Exercise 17 Using ALSA for Audio Processing - Revision history

Richarsm: /* Part b - Audio Playback */

2012-09-21T00:34:33Z

‎Part b - Audio Playback

Shinnsm: /* DBG vs ERR */

2012-09-20T02:36:28Z

‎DBG vs ERR

Shinnsm: /* DBG vs ERR */

2012-09-20T02:35:12Z

‎DBG vs ERR

Yoder: /* Part a - Audio Record */

2012-09-12T16:34:00Z

‎Part a - Audio Record

Yoder: moved EBC Exercise 08 Using ALSA for Audio Processing to EBC Exercise 17 Using ALSA for Audio Processing

2012-07-17T19:29:43Z

moved EBC Exercise 08 Using ALSA for Audio Processing to EBC Exercise 17 Using ALSA for Audio Processing

Yoder: /* Build and Test */

2012-05-31T13:57:31Z

‎Build and Test

Yoder: /* File Management */

2012-05-31T13:56:54Z

‎File Management

Yoder: /* DBG vs ERR */

2012-05-31T13:55:45Z

‎DBG vs ERR

Yoder: /* Build and Run the application */ Formatting

2012-05-31T13:54:26Z

‎Build and Run the application: Formatting

Yoder: /* Reference */ Added

2012-05-29T14:24:21Z

‎Reference: Added

@@ Line 164: / Line 164: @@
 The goal of this part is to analyze the function calls necessary to play back audio from a recorded file to the driver.
-* Copy the AudioThru files from [http://www.rose-hulman.edu/~yoder/Beagle/exercises/ here] to your Beagle.
+* Change directories to '''lab06b_audio_playback'''
-* Change directories to AudioThru/lab06'''b'''_audio_playback
+* List the files used to build this application:
 * Use a text editor to examine '''audio_thread.c'''.

@@ Line 151: / Line 151: @@
   beagle$ '''PROFILE=RELEASE make'''  // Make the RELEASE version
   beagle$ '''./app_DEBUG.Beagle'''    // Runs the DEBUG version
-  beagle$ '''./app_RELEASE.Beagle''  // Runs the RELEASE version
+  beagle$ '''./app_RELEASE.Beagle'''  // Runs the RELEASE version
 Does your new statement show up in the terminal when you execute the program app_DEBUG.Beagle? Does it show up when app_RELEASE.Beagle?

@@ Line 151: / Line 151: @@
   beagle$ '''PROFILE=RELEASE make'''  // Make the RELEASE version
   beagle$ '''./app_DEBUG.Beagle'''    // Runs the DEBUG version
-  beagle$ '''./app_RELEASE.BEAGLE'''  // Runs the RELEASE version
+  beagle$ '''./app_RELEASE.Beagle''  // Runs the RELEASE version
 Does your new statement show up in the terminal when you execute the program app_DEBUG.Beagle? Does it show up when app_RELEASE.Beagle?

@@ Line 26: / Line 26: @@
   beagle$ '''ls'''
-(See [[EBC_Exercise_01a_Getting_Exercise_Support_Materials | here]] if this doesn't work.)
+(See [[EBC Exercise 05 Getting Exercise Support Materials]] if this doesn't work.)
 Make sure the ALSA utils are installed

@@ Line 260: / Line 260: @@
 * Build and run the application.
-<pre>
-$ make
+ beagle$ '''make'''
-$ app_DEBUG.Beagle
+ beagle$ '''app_DEBUG.Beagle'''
-</pre>
 You should hear audio playing.

@@ Line 241: / Line 241: @@
 === File Management ===
 * Begin by copying all files from lab06b_audio_playback into lab06c_audio_loopthru with the following:
-<pre>
-$ cd ..
+ beagle$ '''cd ..'''
-$ mkdir –p lab06c_audio_loopthru
+ beagle$ '''mkdir –p lab06c_audio_loopthru'''
-$ cp –R –f lab06b_audio_playback/* lab06c_audio_loopthru
+ beagle$ '''cp –R –f lab06b_audio_playback/* lab06c_audio_loopthru'''
-</pre>
 The mkdir “–p” option prevents an error if the directory already exists.

@@ Line 147: / Line 147: @@
 </pre>
 * Build both debug and release profiles on the Beagle, run then and compare their outputs.
-<pre>
-$ make                  // Defaults to making the DEBUG version
+ beagle$ '''make'''                  // Defaults to making the DEBUG version
-$ PROFILE=RELEASE make  // Make the RELEASE version
+ beagle$ '''PROFILE=RELEASE make'''  // Make the RELEASE version
-$ ./app_DEBUG.Beagle    // Runs the DEBUG version
+ beagle$ '''./app_DEBUG.Beagle'''    // Runs the DEBUG version
-$ ./app_RELEASE.BEAGLE  // Runs the RELEASE version
+ beagle$ '''./app_RELEASE.BEAGLE'''  // Runs the RELEASE version
-</pre>
 Does your new statement show up in the terminal when you execute the program app_DEBUG.Beagle? Does it show up when app_RELEASE.Beagle?

@@ Line 90: / Line 90: @@
 * Test your audio connection:
-  $ arecord –f cd | aplay –f cd
+  beagle$ '''arecord –f cd | aplay –f cd'''
 This command uses the '''arecord''' (“ALSA recorder”) utility to capture audio and, instead of sending to a file, uses a Linux process pipe to send the data to the '''aplay''' (“ALSA player”) application. This will loop audio through the board. If you have a working audio input and the board is connected to a speaker, you should hear the audio play over the speakers. '''arecord''' defaults to using the Beagle's on-board audio.  To use the mikes on the PS EYE use the following to switch input devices.
-  $ arecord -D plughw:1,0 | aplay
+  beagle$ '''arecord -D plughw:1,0 | aplay'''
 Press ctrl-c to quit.
@@ Line 126: / Line 126: @@
 * Press Ctrl-C to exit the application.
 After a suitable amount of time press Ctrl-C in the terminal to exit from the application. You can list the /tmp/audio.raw file with the –lsa options to see the size of the file and verify that it has recorded properly:
-<pre>
-ls –lsa /tmp/audio.raw
+ beagle$ '''ls –lsa /tmp/audio.raw'''
-</pre>
 Recall that a signal handler was placed in main.c to trap the SIGINT (Ctrl-C) signal. When Ctrl-C is placed, this signal handler will execute, signaling the audio thread to exit its main loop, proceed to cleanup, and then exit.
 * Use the Linux '''aplay''' utility to confirm successful recording.
 Because this application saves the audio as a raw stream you may also check that the record has operated properly using the aplay utility.
-<pre>
-$ aplay –f dat /tmp/audio.raw
+ beagle$ '''aplay –f dat /tmp/audio.raw'''
-</pre>
 === DBG vs ERR ===

@@ Line 290: / Line 290: @@
 # Write code to delay one channel by N samples.  Be careful, You'll need to carry some samples over from one buffer to the next.
 # Apply a filter to the audio.
 {{YoderFoot}}