Introduction to Digital Audio
The specifics of digital audio processing and various audio formats can be intimidating and confusing. You've probably heard about things like encoding, transcoding, bitrate, id3v2 metadata, and file extensions (.wav, .aiff, .mp3, etc). But what does it all mean, and how do these different technical specs impact workflows in and outside of DISCO?
This article seeks to demystify digital audio, with some real-world applications so you can spend less time troubleshooting files and folders and more time getting to the heart of your projects.
We’ll cover:
- Common digital audio characteristics and terminologies
- Prepping different audio formats, and when to use them
- How DISCO streamlines digital audio processing
Terminology
Disclaimer: this is an extremely simplified way of explaining digital audio - googling or going to university should help fill in the gaps.
Encoding
When sound is recorded on a computer, the analogue audio is encoded (converted into digital code) to create an audio file.
Different encoding methods result in different file formats (e.g., .mp3, .wav, .aiff, .flac, .m4a, etc.). Each format has unique characteristics related to audio quality, file size, and metadata.
Transcoding
Transcoding is the process of converting a file from one format to another, such as generating an AIFF or MP3 from a WAV file.
Bitrate
Bitrate describes the amount of data being transferred into audio. A higher bitrate means that more information is getting captured, and generally correlates to higher audio quality. This also means larger file sizes.
Sample Rate and Bit Depth
Sample rate is the number of times a snapshot of audio is taken per second. Most digital audio has a sampling rate of 44.1kHz (44,100 samples per second).
Bit depth is the number of bits of information being captured in each sample.
Adobe provides this great article on audio bitrates if you'd like to learn some of the finer details. In the meantime, I've extracted this simple explanation of “uncompressed,” “compressed lossless,” and “compressed lossy” files from it:
- Uncompressed files: These audio files are very large, and include all of the possible information that audio equipment can detect. Uncompressed file formats include WAV, AIFF, and PCM.
- Compressed lossless files: These file types are compressed, but in a way that no information gets lost. They include FLAC, WMA, and ALAC. These files are larger than compressed files, and smaller than uncompressed files.
- Compressed or lossy files: Generally the smallest types of file formats, compressed files remove some information that is not entirely essential. Popular lossy audio file formats include MP3s and AACs. These are the formats typically streamed on Apple Music and Spotify.
Characteristics of Common Audio Formats
Below we've outlined several popular audio formats and how their characteristics impact our day-to-day work.
We are primarily interested in each type’s audio quality, file size (which affects delivery/streaming speed), and metadata-carrying qualities.
WAV
- An audio file format associated with Microsoft Windows that can save music files at different bit rates.
- High quality, but large file size.
- Does not carry id3 metadata in and out of DISCO (or other common platforms like iTunes).
- Commonly used to deliver master recordings for writing to CDs or distribution to DSPs like Spotify.
AIFF
- A container format for audio files developed by Apple.
- High quality, but large file size.
- Does carry id3 metadata.
- Commonly used by trailer houses and sync to take advantage of high quality audio and traveling metadata.
MP3
- A compressed lossy audio format.
- Low quality (but bitrate can vary), small file size.
- Does carry id3 metadata.
- Commonly used for quickly sharing across the Internet and streaming.
FLAC
- A lossless audio file format that can compress file size without changing audio quality.
- High quality, with a relatively small file size.
- Does carry id3 metadata.
- Commonly used by streaming platforms like Tidal and Qobuz to deliver high-resolution audio.
When to Use Each Format
Our goal is to make a living from music. We achieve this by pitching music for media, sync opportunities, broadcast, physical release and distribution, etc.
With that in mind, we can see that audio files support two distinct jobs - high speed pitching and high quality playback. Each job requires different characteristics from our audio files:
Pitching
Heaps of people pitch heaps of files for opportunities, but only a small percentage of tracks "win" and end up getting placement. Therefore, the goal when we pitch is to make it as easy as possible for decision makers to access and listen to files. They also need to be able to access metadata, which provides helpful information about the material (ownership, contact info, lyrics, year of release, etc.).
Pitching small, streamable files is the priority (MP3, M4A).
Playback
When we land an opportunity, we of course want the highest quality file to be played. The file might need to be imported into an editing system to cut into a TV show, downloaded into a radio playback automation system for broadcast, pressed onto vinyl, etc.
Using large, uncompressed downloadable files is the priority (WAV, AIFF).
Now that we have an idea about why we need multiple formats for each track, let's see what it takes to prepare our files for the potential opportunities.
It is best practice to export audio [from Pro Tools and other major digital audio workstations] at the same sample rate at which it was recorded.
The sample rate doesn’t matter as much when pitching to Music Editors, because whatever sample rate you send them will be adjusted to match their own session when the audio file is imported.
Preparing Each Format
Recordings are stored in different formats depending on various pitch and playback factors, including specific requirements of the job and/or the platform on which the music will eventually be used.
It is most common to start with high-quality WAV files received through the recording and mastering process.
WAVs are generally accepted, or even required, for the playback, or “using” part of a job - whether the use is pressing CDs, distributing to DSPs, radio play, media syncs, etc.
For pitching, we require quick transfer, streaming, and contextual information about the files. WAVs don't fulfill any of these jobs because they are too big and don't carry metadata that is easily accessible!
As mentioned above, metadata carries information about who to contact for licensing audio. It also makes files discoverable by providing contextual information around specific search parameters.
So to be well prepared and start pitching, we need to first transcode our WAVs into MP3s.
In the sync world, AIFFs are preferred for the editing process, because they are high quality and carry metadata. Therefore, we should also transcode the WAVs into AIFFs.
Note that DISCO would never convert an MP3 to a WAV, because low-quality files cannot regain the quality that is lost when they get compressed.
We also need to transcode all the instrumental, background vocal (BGVl, and a capella versions of each track into MP3 and AIFF files.
What about storing and organizing all these files?
Here is a common example of a hard drive folder structure to store different formats:
And let's not forget to add metadata to every MP3 and AIFF file, too.
Sounds like a lot of work yeah? This is where DISCO comes in to save the day.
How DISCO Streamlines the Job
We now understand:
- The basic characteristics of each audio format
- How they are created (encoded) and converted (transcoded) into other formats
- Which format is better suited for specific job requirements
- How to manually prepare files
Let's see how DISCO can simplify all this file wrangling for us.
How Tracks Link Multiple Formats Together
A Track is generated as soon as you upload a file into DISCO.
But in DISCO terms, a “track” doesn’t just refer to audio; it can be any file type (video, audio, document, image, zip, etc.).
Each track can have two formats associated with it: a high-quality "original" file and an “optimized,” streamable file. Both formats are available when we share a track.
This immediately saves space and simplifies our organization, as we no longer require separate folders for WAVs and MP3s since they are now paired together. The structure looks like this on a hard drive:
...and it looks like this in DISCO, the playlist (folder) contains the main and instrumental versions, and each track has both formats connected to it:
Automatic transcoding
When high resolution, lossless files (e.g. AIFFs or WAVs) are uploaded to DISCO, they are automatically transcoded to create an MP3.
As mentioned above, each track in DISCO can have two files (e.g. WAV and MP3) linked to it.
An additional transcoder is available on the Artist and Pro plans (and above) that converts WAV to AIFF or AIFF to WAV.
With this feature, the three most common file formats are available for every track:
Lastly, files can also be replaced or updated at any time from the manage files and formats option in the Track menu:
Tip: Users can customize their track info hover to show available formats and other helpful data.
Wrap-Up
To summarize, success in the music industry requires multiple digital audio formats to cater to various needs. Manually transcoding and managing numerous formats for each track, however, can be a time-consuming and thankless task.
DISCO streamlines this process by automating transcoding and consolidating multiple formats into a single, easily accessible storage solution. With DISCO, you can leave digital formatting complexities and manual transcoding behind. Now, responding to last-minute requests for an instrumental AIFF is just a few clicks away in-app!