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audio: lossy/lossless/conversions

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@ -9,7 +9,7 @@ Music and Audiobooks can be obtained by buying the digital files or by
Podcasts need a so called Podcatcher. Podcasts need a so called Podcatcher.
A Podcatcher is used to subscribe to podcasts and download them automatically. A Podcatcher is used to subscribe to podcasts and download them automatically.
## Media software ## Media Software
If you want to keep your system clean of much data, you can use this kind of If you want to keep your system clean of much data, you can use this kind of
setup. setup.
@ -33,16 +33,58 @@ There are differences depending on your preffered software interface.
It is self-hostable and can be dockerized. It is self-hostable and can be dockerized.
It has a web-interface and does not feature client software. It has a web-interface and does not feature client software.
## Audio codecs ## Audio Formats
An audio codec is an encoding of an audio file. An audio format is an encoding of an audio file.
There are lossy and lossless codecs, the latter not compromising quality for There are lossy and lossless formats, the latter not compromising quality for
smaller file sizes. smaller file sizes.
Following is a list of codecs written about in this wiki: Following is a list of specific and often used formats:
- [flac](./flac_(codec).md) is a lossless codec - wav is an uncompressed lossless format
- aiff is an uncompressed lossless format
- [flac](./flac_(codec).md) 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
## Extract audio files from CDs ### 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](#lossy-and-lossless-formats-and-their-conversion) can not
be detected by this.
A spectral analysis can detect bad conversions.
For this a audio analyzer like
[Sonic Visualizer](https://www.sonicvisualiser.org/) 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 at
least up to 22kHz.
If the frequency extends up to these 22kHz the file is lossless for sure.
If the frequency is cut before and the file is encoded in a lossless file it is
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. You can convert your CDs to files on your computer.
This way you don't have to search for your CDs all the time. This way you don't have to search for your CDs all the time.
@ -55,20 +97,20 @@ This way you don't have to search for your CDs all the time.
- [MusicBrainz Picard](./picard.md) for linux is a - [MusicBrainz Picard](./picard.md) for linux is a
graphical user interface for tagging files of many different formats. graphical user interface for tagging files of many different formats.
## Quality analysis of different versions of an album ## Analysis of Different Versions of an Album
While deciding on what version of an album is the best visit While deciding on what version of an album is the best visit
[Dynamic Range DB](https://dr.loudness-war.info). [Dynamic Range DB](https://dr.loudness-war.info).
It shows dynamic range scorings of each version. It shows dynamic range scorings of each version.
## Get additional data to an album/single ## Get Additional Data to an Album/Single
If additional information for an album is needed, visit If additional information for an album is needed, visit
[Discogs](https://www.discogs.com). [Discogs](https://www.discogs.com).
Discogs has tracklists, dates and more information to nearly all versions of Discogs has tracklists, dates and more information to nearly all versions of
albums and singles. albums and singles.
## Naming convention ## Naming Convention
It is suggested to place the audio files in a directory named after the album they It is suggested to place the audio files in a directory named after the album they
belong to. belong to.