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wiki/wiki/audio.md

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Audio

Music, audiobooks and podcast are widely enjoyed. There are multiple different approaches on how to get them onto your system depending on your needs. This entry describes how to handle audio data. Music and Audiobooks can be obtained by buying the digital files or by extracting them off of a CD. Podcasts need a so called Podcatcher. A Podcatcher is used to subscribe to podcasts and download them automatically. For Linux specific music software navigate to the corresponding wiki entry.

Media Software

If you want to keep your system clean of much data, you can use this kind of setup. There are differences depending on your preffered software interface.

Software for Music/Podcasts/Audiobooks

The following is a list of server software, that is featured in this wiki. The corresponding client software is handled in the server softwares wiki entry.

  • Subsonic is a media streamer for music, podcasts and audiobooks. Subsonic is self-hostable. Subsonic that can be dockerized and has a web-interface aswell as several clients that can be used. There are also the free and open-source implementations - that feature all the same features and using its API - named Airsonic (no longer maintained) and its inofficial successor Airsonic-advanced.

Software for Podcasts

  • Podgrab is a free and open-source podcatcher that can also be used to listen to them. It is self-hostable and can be dockerized. It has a web-interface and does not feature client software.

Audio Formats

An audio format is an encoding of an audio file. There are lossy and lossless formats, the latter not compromising quality for smaller file sizes. Following is a list of often used formats:

  • wav is an uncompressed lossless format
  • aiff is an uncompressed lossless format
  • flac is a compressed lossless format
  • alac is a compressed lossless format
  • ape is a compressed lossless format
  • mp3 is a compressed lossy codec
  • aac is a compressed lossy codec
  • wma is a compressed lossy codec
  • ac3 is a compressed lossy codec usually found in DVDs
  • dts is a compressed lossy codec usually found in DVDs

Lossy and Lossless Formats and Their Conversion

Music files can either be encoded lossy or lossless. Lossless formats can be converted from and to each other without loosing information. Lossless formats can also be converted to lossy formats to make the files smaller and save space. Files should not be converted to lossy formats more than once. Additionally lossy formats should not be converted to lossless formats as it increases the file size without adding any audio information. These not recommended conversions are called bad conversions.

Detect Bad Conversions

The bitrate, format and the sample rate can be usually checked with simple tools. For Linux a simple software solution for this is the file command. Running it will display these features of a given audio file. This will however only display the format features. Bad convserions as described in the previous section can not be detected by this. A spectral analysis can detect bad conversions. For this a audio analyzer like Sonic Visualizer is needed. Select a audio file and press Add Spectogram under Layer. This will display a spectogram. Music off of a retail CD and lossless songs have frequencies that extend up to 22kHz and can extend even further for hi-res music. If the frequency extends up to at least 22kHz the file is lossless for sure. If the frequency is cut before and the file is encoded in a lossless file it has undergone a bad conversion and is not really lossless.

Extract Audio Files from CDs

You can convert your CDs to files on your computer. This way you don't have to search for your CDs all the time.

  • Exact Audio Copy for windows can rip music and automatically tag it with the help of a list of databases.
  • fre:ac is a free cross-platform audio converter and CD ripper with support for various popular formats.
  • metaflac for linux is a programm to edit the tags of flac files from the command line. It is bundled in the flac package for debian and arch based systems.
  • MusicBrainz Picard for linux is a graphical user interface for tagging files of many different formats.

Analysis of Different Versions of an Album

While deciding on what version of an album is the best visit Dynamic Range DB. It shows dynamic range scorings of each version.

Get Additional Data to an Album/Single

If additional information for an album is needed, visit Discogs. Discogs has tracklists, dates and more information to nearly all versions of albums and singles.

Naming Convention

It is suggested to place the audio files in a directory named after the album they belong to. These album directories are placed in directories named after the album artist. Files can be named in the following scheme:

  • music: [<discnumber>.]<tracknumber>._<artist>_-_<title>
  • audiobooks: [<discnumber>.]<tracknumber>._<artist>_-_<album>_<tracknumber>

Cue Files

.cue files act as a table of contents for a CD rip. These can be created when the audio of a CD is extracted. Usually this appears together with a single file for the whole CD. The audio file can then be split according to the .cue file. For splitting of .flac files on a Linux system check the a flac (package) entry for further informations.