Mis à jour le 26 February 2019.
Patent licensing for the MP3 format expired a few days ago, which means the Fraunhofer Institute can no longer collect license fees for its leading format. Will this event sound the death knell for the MP3 format and favor the expansion of HD formats such as MQA and DSD?
MP3: a very old format
The MP3 format wasn’t born yesterday. While officially commercialized in 1992, its working principle has been in development since the invention of the telephone. Compressing sound to improve transmission (over long distances) was essential. The MP3 format is the fruit of research in psychoacoustics, a field of study which aims to determine which sounds are the least perceptible to the human ear in order to suppress them. An audio track in MP3 format could thus require 4 to 12 times less storage space than a CD-quality file (uncompressed).
The reduced storage space required for MP3 audio files led to the release of the first portable digital players, which had the particularity of being ultra compact thanks to the use of a memory card (SD, MMC, Compact Flash, etc.). The MP3 also became the format most commonly used by Internet radios, and still is to this day.
Not long ago, the MP3 format regained popularity with the emergence of online streaming services. Deezer decided to use this format to stream millions of albums to its subscribers? smartphones and computers.
Will the MP3 format be replaced by an upgraded, lossless format?
Spotify and Apple Music decided to go with the OGG Vorbis and AAC format, respectively. These two formats offer superior quality for files with a lower bit rate (128 kbps), but their superiority is questionable for files with a medium bit rate (320 kbps). Most people actually cannot tell MP3, OGG, and AAC formats apart.
Can the MP3 format not be replaced’
The absence of a patent doesn’t mean that the MP3 format cannot be used anymore. To think of it, it is very unlikely that Deezer will re-encode tens of millions of albums in a new format. Although it would be greatly beneficial for the streaming service, as it would use up a lot less bandwidth, re-encoding everything and developing a major update for playback apps would be very expensive. Moreover, the MP3 format at medium bit rate (320 Kbits), as used by Deezer Premium and Google Play Music, ensures completely satisfactory results for a small hi-fi system, wireless speaker, or Bluetooth headphones.
FLAC format ready to take over
Deezer and Spotify generate their MP3 files from audio CDs. The original disc is not directly converted to MP3 but is first encoded in the intermediary FLAC format (compressed but lossless). By using this format first, the online service can generate the various versions of the MP3 file (low, medium, high bit rate), and can even test encoding without having to load the audio CD in a player. The existence of a FLAC format version of all albums on Deezer and Spotify even allowed these two services to offer the Deezer Elite and Spotify Hi-Fi subscriptions, which enable the listener to listen to music in FLAC format (CD quality).
Nevertheless, it is rather unlikely that a lossless format such as the FLAC or DSD format completely replaces the MP3 standard (and its equivalents). Changing all the Premium/Elite/Hi-Fi memberships would mean using up the totality of the servers? bandwidth. However, this does not apply to Qobuz and Tidal as these streaming services have a lower number of subscribers and already use the FLAC format, even FLAC HD for Qobuz. In other words, lossless audio formats should still share the spotlight with the MP3 format for a few more years.
The MQA meridian format
Well aware that CD-quality HD files require a lot more bandwidth, Meridian Audio developed the MQA coding algorithm. This compression process is applicable to HD audio sources (> 96kHz) and generates an HD file similar to an audio CD track in size (50MB for about 5 minutes). The audible frequency range (20Hz – 20kHz) undergoes a lossless compression process, while frequencies beyond 20kHz -which are not audible but do impact the harmonics- go through damaging compression (similar to the MP3 format). Meridian Audio uses FLAC containers for its MQA files.
Used exclusively for SACDs at first, the DSD format took on a life of its own and is now offered in the form of DSF files (by a handful of websites). Its particularity is that it uses 1-bit samples, as opposed to 16 for audio CDs. As a result, the sample rate is particularly high, with a minimum of 2.8 million samples per second (DSD64) and up to 22.4 million (DSD512). The DSD format corrects one of the flaws often held against PCM coding (audio CD and derivative formats), which is micro-interruptions during playback. Between each sound sample there is? a gap. According to certain studies, these micro-gaps are the reason why listening to a CD is less enjoyable than listening to a vinyl record (in which there are no micro-gaps). DSD encoding solves this problem.