How to Create an Audio CD or Digital Music Files from Digital and Analog Sources Using Only Open Source Software

You might have a collection digital audio files -- such as MP3 files -- or a source of analog audio -- like the headphone output from your phone, tablet or computer, or a vinyl record, a cassette tape, VHS tape, or any other old school audio format -- and you want to share it with someone who has a CD player in their boom box or their car's audio system. Or maybe you just like making mix tapes and you want to update your game for the 21st century.

In this post, I'll  cover:

• how to convert your analog audio to a digital audio format, 
• how to convert your digital audio into the specific format you need to make an Audio CD, the type of CD that will pay in a stand-alone CD player or the CD player in a car's sound system. 

To burn an Audio CD, your track files must be in a specific WAV file formats (details below). Note that you could easily use these steps to convert existing digital audio, like AIFF files, to another format, like MP3s, or to covert analog audio to any digital format, like FLAC. But the focus of these steps is to create a high quality CD from any analog source, including the analog output of any digital device, like the 3.5 mm headphone jack.

I'm going to use Ubuntu-compatible software to do this, but I'm going to do most of the work in Audacity, the excellent open-source audio editor, which is also available on the Mac or Windows. In fact, all the software I use to convert audio and to burn CDs is completely free. In Ubuntu, you can download and install all of the software I use in this article from the Ubuntu Software app. You'll have to pay for your computer hardware and of course, blank CDs, but that's it.

Analog Audio

You might have some audio on your smart phone or tablet, or an old cassette or vinyl record you want to convert to an Audio CD. To record this audio, you need the cables to connect the audio source (stereo amplifier, smart phone, or tablet, for instance) to your computer's audio input. Most computers have a stereo mini jack you can use, or you can get a higher quality external A/D (Analog/Digital) converter box, which usually connects via USB. I typically use a stereo 3.5 mm mini plug to connect my phone's headphone jack to the input on my computer. If you need something more esoteric, like RCA to mini, you can find it online.

Following these steps could allow you to record audio files that are covered by copyright restrictions. Please don't do this, especially if it means cheating artists out of their livelihood!

Recording songs or audio from your smartphone, tablet or computer

If you use an device like a notebook, iPhone or Android tablet to play your audio source through an analog output line, you'll need to shut it up. Unlike an analog stereo amplifier, which simply plays whatever audio you feed into it from your cassette or record player, your computer, phone or tablet will chirp and beep at random intervals if you get a new message or email or Snapchat or whatever. You want to shut that noisy notification system off while you're playing your audio source, so the audio you record is clean and free of chimes and other sound effects that weren't in the original recording.

Plug It In

Especially if you are recording lots of audio (a CD can hold 74 minutes of music and up to 99 songs), plug your device in so it doesn't go to sleep or run out of batteries in the middle of your recording session.

Download Files

If you're playing audio from an online source, like Dropbox, download the audio to your device first. This procedure differs from app to app, and some apps won't let you do this at all. If that's the case, try to use a reliable high speed Internet connection. You don't want pauses in your audio while the network times out.

Mute your device

Apple devices have a physical mute switch, which will turn off notifications and rings, but not the audio from any media you're playing. Activate this switch so mute is ON. If you're using a computer or Android device, muting the volume may also turn down your media player. Instead, go to Settings to turn off notifications.

Turn On Do Not Disturb or Turn Off Interruptions

Apple devices offer a Do Not Disturb option which block all notifications except alarms. Slide up the Control Center from the bottom of the screen and tap the "moon" button so it is highlighted.

Android devices let you turn off interruptions. When I use the volume control buttons on my Android tablet, a pop-up window appears that shows me the volume level. In that window, I can select NO INTERRUPTIONS and even specify how long that should be in effect.

Use Airplane Mode

Since most notifications are triggered by incoming calls, emails, tweets -- basically anything that comes in over the radios -- you can block all of this activity by setting your device to Airplane Mode. If you are playing something from an online source, like YouTube, for instance, this won't work.

Turn Off Alarms

Double check to ensure you don't have any alarms set to go off while you're recording. Even activating Do Not Disturb and Mute on the iPhone won't silence any alarms you've set up.

Use Playlists

If you are playing your source audio from an app that supports playlists, you can record CD Audio tracks all at once directly from your playlist. After you create this large audio file in Audacity, you'll mark up the audio track so you can export your individual CD Audio track files with one Export command.

Some playlist settings to review:

• If your app supports playlist cross fade, where a new song starts playing while the last one fades out, turn this feature off! Otherwise, you can't slice your large audio file into individual tracks. If you can't turn it off, you can't use a playlist.
• I like to set up my track order in my music app so I want to turn OFF Shuffle when I play the playlist.

Record your Audio

Now it's time to record. If your audio source (record player and stereo amplifier or smart phone, for example) is ready to go and properly connected to the recording computer, it's time to check levels and recording settings.

Start Audacity and Check Bit Quality

With your audio source connected to your computer, start Audacity. You should see a new document window when Audacity loads.

To configure Audacity for your CD-compatible recording,

1. At the bottom left of the Audacity window, set the Project Rate to 44100 Hz.
2. If your Project does not already contain a stereo track, select Tracks : Add New : Stereo Track. It does not matter that this track is empty, its purpose is just to make Audacity export your recording as a stereo file.

Test Levels

In your new audio project, press the record button. Then play your audio source, preferably from a point where the music or sound is particularly loud. Look at the recording meter, You should see some yellow, but no red. If the signal is too "hot" (meaning, if you see red on the meter) turn down the volume on your audio source.

From the Audacity Tutorial Meter Toolbars:

The bars remain green until the signal reaches -12 dB then merge to yellow as the signal approaches -6 dB (which is a good maximum signal level to aim for). If the signal exceeds -6 dB the bars merge from yellow to red. The red color warns that the signal is becoming too "hot" (approaching 0 dB) and that clipping may occur.

Once you've set your levels, you are ready to record. If you have no levels at all, you need to troubleshoot your connection from your audio source to the recording computer.

Record

In Audacity,

1. Create a new audio project (File : New) . It inherits the settings of the last project.
2. Press the Record button.
3. Press play on your audio source.

That's it. I like to set an alarm on my watch to remind me when it's time to stop recording. If you like, open System Monitor to keep an eye on your CPU and Memory usage. It shouldn't be a problem if all you are doing is recording your audio and maybe some light typing, but this probably isn't the time to watch Netflix on your recording computer. If you are getting close to 100% CPU or Memory usage, quit some other applications.

When you're done recording:

1. Press the Stop button.
2. Save (and name) your new audio project.

I strongly recommend that you listen to the recorded file all the way through. Listen closely for distortion or other audio problems. 

Export your CD Audio Files

Here's how to export the WAV files you need to create an Audio CD. If you don't need to create a CD, but just want to listen to your music on your phone or MP3 player, select the appropriate format, such as MP3 or AIFF, when exporting. 

From the Audacity Tutorial Burning music files to a CD

• An audio CD will play on any standalone or in-car CD player and in your computer and in modern DVD players.

Audio CDs don't have files or a file system like data CDs and other computer storage media, but consist essentially of a stream of bits on the disc in a single spiral "track" with a TOC (Table of Contents) index.

• Audio CDs are generally limited to 74 minutes playing time on a 650 MB disc ("Red Book Standard") or 80 minutes on a 700 MB disc.
• Audio CDs always contain uncompressed PCM stereo audio at 44100 Hz sample rate, 16-bit sample format. So to burn an audio CD, export the file(s) you want to burn as a 44100 Hz 16-bit stereo WAV.

Ideally, I like to burn Red Book Standard (650 MB) discs because they play on all CD players, so I keep it under 74 minutes and 99 tracks. It's hard to find 650 MB CD-R discs these days, so I usually burn a 700 MB disc (80 minutes total audio).

Normalize track volume

If you set your levels correctly when you recorded your analog source (i.e., kept the levels low enough so there was no distortion or clipping, red on the recording meter), the volume of your recording is probably too low for a CD. 

From Splitting a recording for export as separate tracks:

In order for the CD to be burned at maximum volume and thus match other CDs in your collection we need to fix this.

1. Click on Edit : Select : All, or use shortcut CTRL + A
2. Click on Effect : Normalize...

The default choice in this dialog is to amplify to a maximum of -1.0 dB. The maximum setting is 0 dB, but the default setting of -1.0 dB provides a little headroom as some players can have playback problems with audio at 0 dB.

Export a single track

If your Audacity project contains only a single track for your CD, export it as follows:

Select File : Export Audio and choose WAV (Microsoft) signed 16-bit PCM in the "Save as type" box. Give your WAV file a name and click the Export button.

Export Multiple Tracks at Once

If your recording consists of several tracks in a row, which is the case if you recorded the audio from a playlist, a cassette tape or vinyl record, Audacity has all the tools you need to export all of the individual tracks with one single Export command. Follow the steps described in Splitting a recording for export as separate tracks. Summary:

1. Clean up the recording
2. Label each track
3. Maximize the volume
4. Export Multiple ...

Read the superb and detailed instructions in Splitting a recording for export as separate tracks for all the details you need.

Burn Your Audio CD

Use your favorite CD burning software to burn your new CD. Some choices in Ubuntu include:

• Brasero
• K3b
• SimpleBurn
• Xfburn

Using Brasero to Burn an Audio CD

The steps you'll perform in other CD burning software is similar. Here's how to do it in Brasero:

1. Open Brasero.
2. Under Create a new project: click [Audio project / Create a traditional audio CD].
3. Drag the files you want to include on your CD into the main Brasero window.
4. To change the order of tracks, drag and drop each track until the track order is correct. 
5. When you are ready to make your CD, select your CD/DVD drive and click [Burn...] in the lower right corner.
6. Confirm the options and click [OK]

Brasero Tips

• Make an ISO image to create multiple copies of your CD quickly
• Use the slowest burn time to improve disc quality
• Be sure to test your CD in different CD players. I like to test mine in an old boom box.

Enjoy your new CD or digital audio files. If you created MP3 files instead of a CD, you might want to use a MP3 tag editor like Audio Tag Tool, EasyTAG, or Ex Falso to update song titles, artist and album info, and even album art. 

If you have any questions, or suggestions for software you prefer, just post a comment below.