This Apple Lossless Encoder (ALAC) use the Apple Open Source Library and encodes to .m4a files, both 16 & 24 bit are supported.

m4a can also contain m4a AAC a lossy compression, this codec is installed separately from Codec Central.

Portions are (c) Apple and are licensed under the Apache License.

Supported by this Codec:

• Encoding: Yes   [.m4a (Apple Lossless)]
• Multi-processor Encoding: Yes  (with dBpoweramp reference)
• Decoding: Yes   [.m4a, .mp4, .m4b]
• ID Tag Reading: Yes   [iTunes Comments]
• ID Tag Writing: Yes   [iTunes Comments]
• Unicode Tagging:Yes
• Supports Album Art: Yes
• Gapless Encoding & Decoding: Yes
• Explorer Audio Popup Information: Yes
• Unicode Filenames: Yes

Compression Options

Apple Lossless does not have many options, it does not need any (being lossless).

Verify Written Audio will read back the compressed file and compare it with source audio ensuring error free compression (both hardware & codec are verified).


Advanced Options

dBpoweramp Configuration offers advanced options for this codec (dBpoweramp Control Center >> Audio Codecs 'List / Options'):

m4a / mp4 Tagging

m4a Layout can be 'Optimized for Streaming' (where the audio details and tags are placed before audio data), or 'Streaming Incompatible' where audio data appears first.

Tag Padding by using padding, minor tag changes save the whole file being shuffled (as tags are generally before the audio)

Compatibility Sony and Nokia players require an id3v1 tag, whilst strictly breaking the m4a standard, this option will write those for compatibility.

m4a / mp4 Decoder

Output (AAC) 16 bit, 24 or 32 bit gives the option to select the output from the decoder, 32 bit is automatically selected when an encoder can use the higher resolution. This option requires dBpoweramp Reference. Note Apple Lossless files always decode exactly as the source bit depth.

Corrupt AAC File gives the option to continue decoding an aac file after a stream error has been detected (ie corrupt audio file), or stop on such an error.

Terminology

Encoding:  compress and write audio track,
Decoding:  uncompress and read the track,
ID Tags:  meta data such as artist & album are embedded inside the audio file,
Lossless:  compression without audio quality loss,
Lossy:  audio quality is sacrificed (how much depends on bitrate and codec used) to achieve smaller files,
Gapless:  allows the decoder to decode audio stream without gaps (silence),
Explorer Audio Popup:  a dBpoweramp function, hold the mouse over a supported audio file and details contained are displayed,
Multi-processor Encoding:  for multi core processors multiple files can be compressed at once fully using all cores.
Command Line:  text interface, where commands are typed (start >> run >> cmd  to get to the command line)

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