In school, as a teacher, most of the work that I did in audio with students had to do with soundtracks for small movies, combining, for example, voice and music for a documentary about a nature reserve (the Sado river, near Lisbon, a beautiful place). They voted for the best voice, after some auditions and recordings, and picked some of the songs for the soundtrack, later combining them into groups by using Windows Movie Maker as a draft. Later on, their work was used in Adobe Premiere and Encore to produce a DVD. These are some examples of what we can do with audio, but there are many others, such as:
- Radios (online or regular) and all sorts of programs
- Interviews
- Critiques or commentaries of CDs, songs, movies, books, or articles
- Music CDs and podcasts
- Audio books
- Video soundtracks
- Discussions in Moodle forums with voice or instruments' recordings
Let's start off with a simple task, that is, finding and managing audio using Grooveshark.
Grooveshark (http://www.grooveshark.com) is a community for music sharing where we can find and upload music, broadcast our own radio, create playlists, and embed them in Moodle (and other websites).
We can now have a look at how to upload audio and create playlists in Grooveshark, something that can be used easily in our course in order to give it some musicality! And this doesn't mean that we can only use this for music-related courses. Every course is a good course to have music on!
Uploading in Grooveshark is easy. Again with the WIRED CD http://creativecommons.org/wired as a source of music files, we just need to follow these steps:
The uploaded files will be listed on our Collection list, reachable through the top menu.
In this collection we can manage our uploaded audio.
Instead of having just one song embedded in our Moodle course, we can have an entire sequence of songs, called a playlist. To create a playlist from our uploads (or from the list of songs made available by other users), in the right frame, we should click on Create Playlist and add a title and description to our new playlist. And then, it's as easy as searching for songs and dragging it from the results to the playlist.
After the playlist has all of the songs that you want, you can click on the Playlist name and organize it (for example, changing the order of the songs with drag-and-drop and deleting songs).
Now to get the embed code to add the playlist to Moodle, we must click on the Share button and then on the Embed tab, copying the code.
In our course, a playlist was added in every module's delivery moment to have students experience different music styles and artists.
A playlist was also added to a side block on the main course page as a kind of "course soundtrack".
To embed a particular song, if we hover the mouse over its name, a kind of hyperlink shows up. If we click on it, we are taken to the song page and there we can get the embed code, just like for the playlists.
While teaching several subjects, particularly related to music and language, audio can be extremely useful, almost mandatory. We can give students the opportunity to listen to interviews, stories, audio books, dialogs, music, or even their own voices. More than that, we can give them the opportunity to create all of these on their own.
One of our course modules will be dedicated to Module 3, Music and media, and one of the main tasks in this module, the Soundtrackers activity will be to create a soundtrack for a movie trailer of Tears of Steel (something we saw in the Chapter 2, Picture This, while cropping and resizing pictures). Students will make this soundtrack from songs and sound effects. Let's first focus on the music, and see how we can extract audio from The WIRED CD (http://creativecommons.org/wired) as an example:
Note that we are using a CD that is not copyright protected for this task. These instructions will still work with most copyright protected CDs (which include most CDs that you buy), but be careful that you are not breaking any laws by doing so. Please have a look at Chapter 8, Common Multimedia Issues in Moodle, for some advice on this.
VLC Media Player (http://www.videolan.org/vlc) is a free, cross-platform media player that can play almost any available media file. This can be very important for video, as there is an incredible variety of video codecs that are available these days (DivX, Xvid, H.264, and so on), encapsulated in many container formats (AVI, MP4, ASF, WMV, MOV, and so on). But before we get to work with video, let's start with something simpler, that is, audio.
VLC can be used to play and extract audio from a CD. Audio CDs have been available since 1982 and are used to store music by using a technique called PCM encoding . However, we will use the MP3 format in our Moodle course for several reasons:
- The files have smaller sizes
- Moodle has a MP3 filter that automatically puts a player in place so that we can listen to the song without downloading it, simply by clicking on the play button
- MP3-format songs are easy to edit and to create podcasts from because MP3 has become the standard for sound and music files
We will first convert some of the tracks of this audio CD to MP3 files on our hard disks. This is what we call ripping. So first, let's put the WIRED CD in the CD player of our computer and choose the tracks for our soundtrack.
VLC has a wizard that is helpful in defining the settings to rip the CD track to an MP3 format.
- Open the VLC media player and go to File | Streaming/Exporting Wizard….
- Select the Transcode/Save to file option.
- Click on the Next button as shown in the following screenshot:
In the next window, we need to select a stream (the source that we are going to rip). So, click on the Choose… button and select the CD audio track.
VLC should then take us back to the input window, with the audio track already selected (under Select a stream; in my case, this is file://localhost/Volumes/Audio%20CD/…). So we just need to click on the Next button.
We now have to select the destination audio codec in the Transcode window, so we should select the Transcode audio checkbox and then select the MP3 codec, with a bitrate of 128 kb/s (the frequency of the PCM original file, 44,100 Hz, will be retained) as we saw in the table of reference values in this chapter.
After clicking on Next, the Encapsulation format window is displayed. Here, we should select RAW.
After clicking on the Next button again, we need to choose where to save the file.
- Click on the Choose button.
- Browse to the destination folder.
- Add a filename and specify the file extension
.mp3. - Click on the Next button.
Finally, we are presented with a summary of all the options we selected with the wizard.
After we click on the Finish button, the transcoding will start and the wizard will disappear. The VLC player will look the same, and although nothing appears to be happening, the transcoding process is working in the background. We can recognize this in two ways—by listening to your CD drive working (if it's working, the transcoding is still going on), or by looking at the progress bar at the bottom of the VLC Media Player window, as shown in the following screenshot:
When the time value reaches 00:00, it's done. Now that we have some audio to work with, it's time to start the editing!
Audacity (http://audacity.sourceforge.net) is a free software utility for audio recording and editing that works on several platforms. It can be used to make high-quality recordings with a microphone (or other sources), easy editing and mixing of different sounds, mixing speech and music just like a real radio station, adding different audio effects, and all of this using a multitrack interface, where each audio file is assigned to a different track, which is a kind of layer that we can edit individually. The majority of the music that we listen to is recorded using this multitrack method, meaning that each instrument is recorded separately and then merged into a single audio file for playback.
We will now see how we can use Audacity for some common procedures in audio creation and editing, such as:
- Slicing a track
- Capturing audio from a microphone
- Remixing audio
The following section lists some of the common activities in Audacity, and should be mostly read as a reference when you need to perform one of the described actions.
Audacity's interface has several toolbars:
- The control toolbar: This has the most important tools for editing the audio tracks and controlling the playback and recording
- The meter toolbar: This indicates the input and output levels, so that we can get a visual indication of the levels, for example, if your microphone is very low, or if the final sound is too high
- The mixer toolbar: This has the control sliders for the output level (a standard volume indicator) and your input level (for example, increasing the volume of the microphone before or during the recording)
- The edit toolbar: This has the tools for cutting, copying, and pasting selections, in addition to trimming, silence generation, undo and redo, and zooming
- The input/output selector: This identifies the devices that work as audio input (microphone for example) and output (speakers, for example)
- The playback speed control: This controls the playback speed from zero to three times faster
- The timeline: This indicates the length of the recording or playback in minutes and seconds
- The tracks: These are the different sounds that are a part of the audio project
Let's start with the basic operation of slicing music tracks.
Continuing our work in creating a soundtrack for the Tears of Steel movie trailer, the next step is to create slices of the music tracks that we extracted from the WIRED CD. As we want to create a limited video excerpt, we couldn't fit the entire music tracks, so we will have to cut out the parts that we don't want. This slicing is also useful in Module 1, Music evolves, where students have to create short audio clips from several music eras and post them as attachments in forum posts.
For slicing, we should start by creating a new audio project.
To create audio clips from larger music files, the first thing to do is to create a new audio project. This means that we will have a folder where we can keep all of our files. So after opening Audacity, go to the File menu, click on Save project as..., and select a destination folder. A project file with the .aup extension will be created (in my case, I called it soundtrack) and a subfolder (soundtrack_data) will automatically be created by Audacity to contain all of the changes that we make to the original files. It's a good idea to create a folder in the destination folder, for the original music files that we will be using in the soundtrack project (I have called it music) and another one just for sound effects (I've called it fx).
Hence, the folder structure will look similar to the following screenshot:
The first part of the slicing process consists of importing a music file into the workspace as a track. We call this importing audio, and we need to go to the File menu, go to Import | Audio…, select the original music file (in MP3 format by now in our music folder), and then click on OK.
We have two options for deleting the parts of the music file that we are not interested in. The first is to use the Selection tool in the control toolbar, and then drag the mouse over the selection of the waveform that we wish to delete, finally pressing on the Delete key to delete it.
The second method is ideal for selecting an excerpt from the middle of the music file. In this method we use the Trim tool in the Edit toolbar. This will remove the audio regions before and after the excerpt that we select.
If we remove parts of the track at the beginning and/or end of the music file, it can happen that if we play it now (using the control bar play button or by pressing Space bar), it starts and ends abruptly. Audacity has an option to make these smoother—the fade in and out effects.
To use these effects, we will first have to select a portion of the beginning of the excerpt, usually around three seconds. We can see this duration in the timeline and set it to more or less by using the Zoom tool. Then, after selecting around three seconds of music, go to Effect | Fade In, and it's done for this part.
We should apply the same principles to the end of the excerpt, in this case, using the Fade Out effect.
Due to copyright issues, Audacity cannot export audio files to the MP3 format out of the box, so we will need to install an MP3 encoder called LAME, which is available free of cost.
- Go to the LAME MP3 Encoder download page at http://lame1.buanzo.com.ar/#lamewindl.
- Save the EXE or DMG file for our OS to our computer and install it. It should contain the encoder file. We should keep this file in a folder that we will not accidentally delete.
- Open up Audacity. Go to the Edit | Preferences... and in the Quality tab, set the default rate to 44,100 Hz (CD quality). Also, in the Libraries tab, locate the encoder file file to allow Audacity to export files in the MP3 format (you will only need to do this once). After doing this, click on the OK button to go back to the project.
Finally, we should export our music selection to an MP3 file by going to File | Export and selecting the MP3 format, specifying some of the metadata. Our files will then be ready to Moodle! Note two things about this:
- We can use this procedure to convert another audio format to MP3, first opening it in Audacity and then exporting to MP3
- To save MP3 audio files with other rates and bitrates (for example, voice recordings), we should first click on the Options button in the Export dialog box and then export the result
Capturing audio from a microphone (or any other input device) can be useful for many activities, such as:
- Adding audio comments to Moodle forums
- Recording an instrument
- Recording the audio that is playing through your speakers
- Converting old K7 recordings to digital audio
Combining music excerpts with voice comments can be interesting in our music course. In Module 10, What's good music?, students will act as music critics and create a collaborative database of CD reviews. These reviews will consist of a short text accompanied by their own voice comments, interleaved with excerpts from the CD that they've chosen to review.
So let's have a look at how we can first capture our own voice, and later, remix it with music excerpts.
In the Input device drop-down menu on Audacity's Input/Output selector, the first thing to choose is the microphone as the input source. When we click on the Record button, Audacity will capture whatever sound is coming from our microphone.
For a better voice recording, most soundcards have an option to amplify the microphone signal. This option differs depending upon the operating system that we are using (Windows Vista, Windows XP, or Linux), so the best thing to do is to perform a web search with the keywords mic + boost + operating system. We will be able to find guidance for your operating system very easily. For Mac, the amplification of the built-in microphone should be enough.
Before we start recording, there's one last thing to keep in mind—the input volume. There is a potential problem that might arise from talking too close to the microphone—the sound can get distorted and the recording will be difficult to hear (we usually call this clipping or distortion). Another potential problem is the input being too low, and the recording will again be difficult to hear. The best way to control this is to monitor the input levels by clicking on the microphone levels in the Meter toolbar and start talking to the microphone. If the levels are low (the red bar is short), we can adjust the input volume in the Mixer toolbar. So, if you have a microphone or other input source attached to your computer, you will be able to control the level of the audio before you start recording.
The input meter shows us many things: the left and right channels input level (the L and R bars), the average audio level (in a lighter red) and the peak audio level (in a darker red), and the blue peak hold lines at the right of the level bars showing the maximum audio level achieved in the last three seconds.
A good reference point while controlling the input volume in the Mixer toolbar is the rightmost edge of the bar for the loudest audio level (and the average below that, of course). So we should try talking (especially in the parts we think will be louder), check the peaks, and control the input volume with the input volume slider in the Meter bar.
Finally, we can click on the Record button. Every time we click on this button (after stopping the previous recording), a new track is created. If we are doing a retake because something went wrong in our first take, we can remove the previous track by clicking on the cross in the upper corner of the track to close it.
If we still have an amplification problem, the solution is to amplify an audio selection. After selecting the section of the recording that you want to amplify, go to Effect | Amplify… and increase the amplification (dB). Make sure that the waveform doesn't reach the top (value 1.0). For example, in the following screenshot, refer to the waveforms to the left of the first red bar and you can see a clipped recording. In the middle is a balanced recording, and on the right of the second red bar is a recording with a low input level.
We can import audio tracks to the project by going to the menu and selecting Project | Import | Audio. This can be useful for importing music tracks and alternating them with voice comments.
To reorder tracks in the timeline, we can use the Time shift tool in the Control toolbar. By left-clicking on an audio track and dragging it to the left or right, we can position it where we want it in the timeline.
After we have all of the voice and music clips sequenced, we can export the result as an MP3 file. In the case of voice-only projects, and if it is not a special voice recording, we can save a lot of disk space as follows. Before we start recording, we should go to the Quality tab in the Preferences tab in Audacity and choose the default sample rate as 11,025 Hz, the default sample format as 16 bits, and in Options in the Export dialog, select a bitrate of 48 kbps. Finally, export the project to MP3.
Remixing audio is everywhere in the digital world. In TV and radio shows, Audio CDs, DVD movies, all of these use some degree of remixed audio from several sources.
We are now going to start mixing our music and sound effects, for the movie trailer soundtrack.
With the Selection tool, we can cut, copy, and paste audio selections in the same way as in a text processor with regular text. But now, instead of paragraphs, the concept to use is a new audio track that is created to insert the copied or cut slices. We can then move these slices around and sequence them as we saw previously with the Time shift tool.
We can create an empty new audio track for our project. For this, we just need to go to Tracks | Add New | Audio Track. Here we can cut and paste or copy and paste the selections in it.
Editing the amplitude envelope lets us change the volume of a track, gradually over time, by adding a number of control points to the track. Each control point sets the amplitude (volume) at that point in time. This can be as low as zero, and as high as 150 percent of the normal maximum volume, and the volume is interpolated smoothly between the points.
The following screenshot shows a track for which an amplitude envelope was created with the help of the Envelope tool.
In the preceding screenshot, there are several control points identified by small squares. Each control point has up to four handles, arranged vertically. The top and bottom handles are positioned at the target volume and the middle handles are positioned a quarter screen below, giving us a way to move the envelope above the 1.0 level.
To create a new control point, just click. To move a point, just drag. To remove a point, we have to click on it and drag it onto an area outside of the track, and then release the mouse button.