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= Lecture =
Textbook chapter: 4 (though it's rather week weak on this subject).
Sound is a wave in the air. As any wave it has an amplitude and a frequency. The amplitude controls the loudness and the frequency controls the pitch.
== Metadata ==
Most image audio formats (but not WAV and AIFF) can have metadata associated with them. This usually includes the artist, album, and track name, the year, and genre.
Most playback software can be used to edit the metadata. Format conversion software usually also copies the metadata into the appropriate fields.
For MP3 files ID3v1 is the old way of storing metadata inside MP3 files, but it doesn't support unicode so around the world it's not very popular. For example it will not work well even for latin-based languages such as german (they have some non-english characters). ID3v2 is completely different from ID3v1 and pretty much every player these days (software or hardware) supports this.
== Degree Students Audio on the web ==
== Everyone ==
* http://en.wikipedia.org/wiki/Advanced_Audio_Coding
* http://en.wikipedia.org/wiki/Variable_bitrate
* http://www.techterms.com/definition/sampling
= Lab =
This is a marked lab. Please submit it using Moodle (Lab4).
We're going to use this song to play with, because there are no copying rules associated with it: http://www.openbsd.org/lyrics.html#36
=== Part 1 ===
* Go to http://audacity.sourceforge.net/ and download and install the newest windows version, and install it.
* Download the pond-erosa puff ogg file.
* Open that file in audacity. On windows the menu option is "open", on newer versions in linux it's "import".
* Try to export it as mp3. You may get an error saying that lame is not found. Go back to the audacity page and download and install lame for audacity for windows.
* Export as mp3 as well.
* The windows version can't export Export as Flac so I will give you a copy on a usb stick of the Flac versionflac as well.
* Make a screenshot with the folder with all 4 files and audacity with the original open.
* Submit that screenshot
Note that you would normally start with an uncompressed file (wav or flac) and use that to creat the compressed files, but we don't have the uncompressed version of this file so we're just going to pretend.
We're going to blip out some words we don't like in the song.
* Pick a word you don't like (for example "free") that's mentioned at least 3 times in the song and find where it appears in audacity, make a note of the times in a text file. The lyrics are on the website, should make that a little easier.
* Note: you can select a region of the song and play only that.
* Add a new track (mono should do)
* Submit your text file and the screenshot.
== Compression & browser support ==
On linux you can compress things with tar cvzf sourcefile dest.tar.gz sourcefile On windows you'll have to download and install winrar (or another app if you prefer).
* Use the tool to compress every one of your files separately.
* Make an html page with a table with the sizes of the originals and the compressed versions and two more columns.
* In the third column use the HTML5 %<audio> tag to allow the user to play that version of the audio file.
* In the fourth column make a note of which browsers that worked in. In the lab you can test with Firefox, IE9, Chrome,and Safari.
* If no audio files work in IE - try to upload your HTML and audio files to matrix and view the page there.
* Submit the HTML page (without the big files).
