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Questions tagged [m4a]

M4A is a file extension for an audio file encoded with advanced audio coding (AAC) which is a lossy compression. It stands for MPEG 4 Audio. They're most often found in Apple's iTunes Store as the format of song downloads.

Apple Inc. started using the .m4a filename extension for MP4 containers with audio data in the lossy Advanced Audio Coding (AAC) or its own Apple Lossless (ALAC) formats.

AAC or M4A file quality is better and file sizes smaller compared to MP3 files. M4A files sound better than MP3 files when encoded at the same bit rate due to some of the enhancements made to the format such as:

  • Compression based on perception (if it is not within human perception, that sound data may be lost without notable effect to quality).

  • Smaller sample block size of 120 or 128 samples rather than 192 for changing (or transient) signals, allowing for more precise details where they are needed.

  • Larger block sizes in stationary signals, 1024 or 960 vs MP3's 576 sample blocks, allowing for less data to represent a portion of the music that does not have the same complexity.

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How to replace an MP3 or M4A in iTunes with a higher quality file, without having to re-do playlists containing the track?

I have in my iTunes library some songs that, years ago, I ripped from CDs at bit rates of only 128kbps. Storage is cheap now and I'd like to replace those songs with higher-quality versions (e.g. 320kbps for the MP3s.) I do intend to re-rip some of…
Chris W. Rea
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Merge multiple m4a files

Is there an easy way to do this? I have several folders with music files that I want to join. So it would be good if there is a batch solution to this problem.
Philip
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How to identify codec (AAC vs ALAC) used in an m4a file

Given that the m4a format is merely a container, and can contain music encoded with a lossy (AAC) or lossless (ALAC) codec, is there a simple way to determine which codec was used for a given file?
Jim Garrison
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Convert ALAC to aac 128k with all metadata intact

I have about 300 gigs of ALAC files (m4a container) with well groomed metadata, album art, etc. (Original source: CD rips with dbPowerAmp). I want to convert my music library to 128kbps AAC (still m4a) to save on hard drive space on a small…
Nelson
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How to replace mp3 files with m4a versions in itunes?

A few points before I get into my question/issue: I am not looking for a way to convert file formats. The library and all music is located on another Mac on the local network (so it is not indexed by spotlight and no spotlight-based applescript…
JVC
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Convert multiple .mp3 files (or single .m4a) into .m4b with ffmpeg and afconvert on macOS

I'm using macOS and have a set of .mp3 files that represent the chapters of an audiobook. I want to combine them into a single .m4b file. How can I do this from command line without significantly increasing file size?
TabsNotSpaces
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Why I cannot play M4A audio on iTunes, but I can play it on QuickTime?

I have some M4A audio files, that I can't play on iTunes (e.g. double click the file, and then iTunes fired up, the audio added to the library, but the play doesn't start. Tried double clicking on the audio on the library, still doesn't start the…
Chen Li Yong
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Can't import m4a files to Audacity

I have installed the latest version of ffmpeg (3.1.2) through homebrew, and I have gone to Preferences -> Libraries and located the ffmpeg library in Audacity (/usr/local/Cellar/ffmpeg/3.0.2/lib/libavutil.55.17.103.dylib). Nothing happens when I…
DisplayName
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How can I convert an m4a to mov?

I have a m4a audio file that I need to convert to a mov file. How can I do this?
ericg
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How to re-encode iTunes m4a files to mp3

I want to convert some of my iTunes m4a files to mp3 files but because I have multiple iTunes accounts, iTunes wont play these files due to computer authorisation issues therefore I can't use iTunes to encode. Can anyone recommend a free music…
user52539
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QuickTime Player 10 doubles track duration

My copy of QuickTime (10.5) on Mojave (10.14.6) is duplicating the duration of (some) tracks I open with it. It isn't modifying the files themselves; it's just the track window that displays twice the time it should. The entire second half is just…
Rain
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Make iTunes recognize MP3 audiobooks with ID3 tag

Apple iTunes recognizes and categorizes MP4 audio files (preferably with an .m4b extension, not .m4a nor .mp4) correctly as audiobooks if the tag field stik MediaType is set to 2 for Audiobook. I shall assume that its successors, i. e. Music,…
Crissov
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How to set custom m4a format audio file as alarm tone on iPhone

How can a custom audio file (m4a format) be set as my alarm tone on an iPhone? I am using an iPhone 8 running iOS 12.3.
Ciasto piekarz
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Good free audio converter for OS X Lion?

Am trying to find a simple audio converter to convert various m4a, wma, mp3, and flac files to standard mp3 128KB VBR (for an ancient mp3 player with limited storage). I'm probably only going to use this once and this is the one thing it needs to do…
herculeesjr
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How to build a simple app that turns text to m4a files

I'm learning Chinese and want a way to quickly generate and save words and phrases to m4a files. I've managed to do pretty much what I want in terminal, but I can't seem to figure out how to make an app out of it. Here is the code I've used in…
Henrik
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