dBpoweramp Codec Central: m4a, mp4, m4b & aac
 

 m4a. mp4, m4b (decoder) & aac (decoder)  


Requirements

 Windows 98 or newer, dBpoweramp R12 or newer required.

              
    

Download

 m4a Release 7   1047 KB

Information: see below for AAC, or m4b encoder

  
 		  

Description

Successor to mp3, m4a (and mp4) made popular by iTunes and iPods. mp4 is a container that can store many sub-formats:

  • Advanced Audio Compression (AAC), of which are different types: LC (low complexity), HE (high efficiency) to name a few. To encode your audio to be compatible with most audio players, use the LC compression type (used as default by this encoder). High Efficiency (HE AAC) uses SBR technology (not too different as mp3PRO) if the player knows about HE the extra frequency information can be decoded, otherwise half the audio quality will be missing on playback. A newer standard again for ultra low bitrates is AAC+ or AAC HE v2, this uses parametric stereo for even lower bitrates, dBpoweramp is able to decode every AAC type (excluding iTunes m4p protected). 
  • Apples Lossless (ALAC or ALE) this format is like Zip for audio, no audio quality is lost (audio tracks purchased from Apples iMS store are lossy aac).

File Extensions:

  • .m4a are audio content only,
  • .mp4 can contain both audio and video,
  • .m4b these are identical to .m4a except the iPod knows to use them as audio books and allow book marking,
  • .m4v are video files.
  • .m4p protected audio format (tracks purchased from iTunes Music Store are protected), whilst dBpoweramp cannot decode these see Forum for details on fair use.

Adding ID tags to mp4 has standardized on the Apple iTunes format, although a competing Nero tagging format has emerged.

Decodes   .m4a, .mp4, .m4p, .aac      Encodes   .m4a (Apple Lossless, AAC: LC, HE & HE v2)

Notes on Apple Lossless Encoding: certain lossless tracks encoded will not play on iPods, but work fine with iTunes / Airport / Sonos. We are investigating this issue.

 m4b Audio Book Encoder  

Requirements

 Requires above m4a codec to read / write ID Tags from .m4b files as well as to decode .m4b files. Windows 98 or newer, dBpoweramp R12 or newer required.

Download

m4b Release 1  339 KB

Description

Encodes m4b Audio book files, ideal for spoken word on iPods.

Decodes   (none install m4a codec)      Encodes   .m4b
 

 AAC Encoder  

Requirements

 Requires above m4a codec to read / write ID Tags from .aac files as well as to decode .aac files. Windows 98 or newer, dBpoweramp R12 or newer required.

Download

 aac Release 1  474 KB

Description

Encodes 'raw' aac files, normally the m4a codec (above) should be used in preference, depending on player.

Decodes   (none install m4a codec)      Encodes   .aac
 

 m4a Utilities  

Requirements

 Requires above m4a codec to read / write ID Tags. Windows 98 or newer, dBpoweramp R12 or newer required.

Download

m4a Utilities Release 1 515 KB

Description

3 Utility codecs, 2 of which move AAC in and out of the m4a container, and one which can optimize m4a files moving the meta data to the beginning, whilst optionally creating a hint track (used for streaming m4a over Apple Airtunes).