Convert M4A to AIFC — Free Online Tool
Convert M4A audio files (typically AAC-encoded) to AIFC format using PCM encoding directly in your browser. This conversion decodes your compressed AAC audio and re-encodes it as uncompressed 16-bit big-endian PCM — the format used in Apple's professional AIFF/AIFC ecosystem for high-fidelity audio work.
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FFmpeg Command
Copy this command to run the same conversion locally with FFmpeg on your desktop. Download FFmpeg
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Note: Browser-based encoding uses approximate quality targets. For precise CRF compression, copy the FFmpeg command above and run it on your desktop.
Estimated output:
Conversion Complete!
DownloadHow It Works
M4A files store audio using the AAC (Advanced Audio Coding) codec, a lossy compression format. During this conversion, FFmpeg fully decodes the AAC-compressed audio stream to raw PCM samples, then re-encodes those samples as pcm_s16be — signed 16-bit big-endian PCM — wrapped in an AIFC container. Because AAC is lossy, the original audio data cannot be perfectly recovered; the AIFC output will be a lossless PCM representation of the decoded AAC signal, not the original pre-compression audio. The resulting file will be significantly larger than the source M4A since PCM stores every sample uncompressed. Any iTunes metadata or chapter markers present in the M4A will not carry over, as AIFC does not support these features.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg program, the open-source multimedia processing engine that handles decoding the AAC audio from the M4A container and encoding it to PCM inside an AIFC file. |
-i input.m4a
|
Specifies the input file — an M4A file containing an AAC-encoded audio stream inside an MPEG-4 container. FFmpeg reads and decodes this AAC stream to raw PCM samples in memory before re-encoding. |
-c:a pcm_s16be
|
Sets the audio codec for the output to pcm_s16be — signed 16-bit big-endian PCM — which is the standard uncompressed audio encoding for the AIFC container format and matches the byte order required by the AIFF/AIFC specification. |
-b:a 128k
|
Specifies a target audio bitrate of 128 kbps. For uncompressed PCM codecs like pcm_s16be, the actual bitrate is determined by sample rate and bit depth rather than this parameter, so its effect is minimal here; the true output bitrate will typically be 1411 kbps for 44.1 kHz stereo 16-bit PCM. |
output.aifc
|
Defines the output filename with the .aifc extension, which signals FFmpeg to wrap the encoded pcm_s16be audio stream in an AIFC container rather than standard AIFF or any other format. |
Common Use Cases
- Importing purchased iTunes or Apple Music tracks (saved as M4A) into professional audio workstations like Pro Tools or Logic Pro that prefer uncompressed AIFC files for editing timelines
- Preparing podcast episode masters stored as M4A for delivery to a mastering engineer who requires uncompressed AIFC or AIFF source files
- Converting M4A audiobook files into AIFC so audio restoration software can process the PCM samples directly without dealing with AAC decoding artifacts mid-workflow
- Archiving AAC-encoded field recordings from an iPhone (which saves as M4A) into uncompressed AIFC for long-term storage in a professional audio archive alongside other AIFF/AIFC assets
- Feeding M4A voice-over recordings into legacy Apple professional audio applications or hardware samplers that accept AIFC but not MPEG-4 container formats
Frequently Asked Questions
No. M4A files use AAC, which is a lossy codec — some audio information is permanently discarded during the original AAC encoding. Converting to AIFC with PCM audio produces an uncompressed file, but it is an uncompressed copy of the already-decoded AAC signal. The AIFC output will not recover detail lost by AAC compression. What you gain is a format that introduces no additional generational quality loss if you re-export from a DAW.
AAC compression in M4A files achieves ratios of roughly 10:1 or more compared to uncompressed audio. AIFC with pcm_s16be stores every audio sample in full 16-bit resolution with no compression, so a 5 MB M4A file can expand to 50 MB or more as AIFC. This is expected and is a fundamental property of converting from a compressed format to uncompressed PCM.
No. AIFC does not support chapter markers or iTunes-style metadata tags, both of which are features specific to the MPEG-4 container used by M4A. During this conversion, those chapters and metadata fields will be lost. If preserving metadata is important, you should export it separately before converting.
pcm_s16be stands for signed 16-bit big-endian PCM — the native uncompressed audio format for Apple's AIFF/AIFC container. It uses 16-bit depth, which matches CD-quality audio, and big-endian byte ordering as required by the AIFC specification. If your source M4A was encoded at a high bitrate and you need higher bit depth for professional audio work, you could modify the command to use pcm_s24be (24-bit) instead, though no real new information is gained from the lossy AAC source.
To change the PCM bit depth, replace pcm_s16be in the command with another supported codec such as pcm_s24be for 24-bit or pcm_s32be for 32-bit audio: ffmpeg -i input.m4a -c:a pcm_s24be output.aifc. The -b:a flag has limited effect on uncompressed PCM codecs since bitrate is determined by sample rate and bit depth, so the most meaningful change you can make is adjusting the codec and optionally adding -ar to resample, e.g. -ar 48000 to set 48 kHz output.
Yes. On macOS or Linux you can use a shell loop: for f in *.m4a; do ffmpeg -i "$f" -c:a pcm_s16be "${f%.m4a}.aifc"; done. On Windows Command Prompt, use: for %f in (*.m4a) do ffmpeg -i "%f" -c:a pcm_s16be "%~nf.aifc". This is particularly useful for large batches or files over 1 GB that exceed the browser tool's limit.
Technical Notes
AIFC (AIFF-C) is an extension of Apple's AIFF format defined to support compressed audio in addition to raw PCM, though in professional practice it is most commonly used with PCM codecs — particularly pcm_s16be and pcm_s24be — making it functionally similar to standard AIFF but with a different container identifier. The big-endian byte ordering of pcm_s16be is intrinsic to the AIFC/AIFF specification, originating from Motorola's 68000 processor architecture used in classic Macs. FFmpeg correctly handles this endianness when writing AIFC output. One important limitation: the AIFC container does not support metadata beyond basic AIFF chunks, so iTunes tags (artist, album, artwork, etc.) embedded in the M4A source will be silently dropped. Additionally, M4A's gapless playback information, which is stored as iTunSMPB metadata, has no equivalent in AIFC. If the M4A source was encoded with a non-standard sample rate, FFmpeg will preserve that rate in the AIFC output, which may cause compatibility issues with some hardware or software expecting 44.1 kHz or 48 kHz. Verify sample rate compatibility with your target application before batch converting large libraries.