Convert MP4 to ALAC — Free Online Tool
Convert MP4 video files to ALAC (Apple Lossless Audio Codec) M4A audio, extracting and losslessly compressing the audio stream for perfect fidelity playback on Apple devices and iTunes. ALAC preserves every bit of the original audio data while reducing file size compared to uncompressed formats like WAV or AIFF.
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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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Settings
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
During this conversion, the video stream from the MP4 file is discarded entirely — only the audio stream is extracted and re-encoded. Because MP4 typically carries AAC, MP3, or Opus audio (all lossy formats), the audio must be decoded from its lossy compression and then re-encoded using the ALAC lossless codec. This means the output is losslessly compressed, but it cannot recover detail that was already lost during the original lossy encoding — the ALAC file will be a perfect, bit-for-bit preserved snapshot of whatever audio quality existed in the MP4. The output is stored in an MPEG-4 container with an .m4a extension, which is the standard container for ALAC and is natively recognized by Apple Music, iTunes, and iOS.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg multimedia processing tool, which handles all decoding, stream selection, re-encoding, and container muxing for this MP4-to-ALAC conversion. |
-i input.mp4
|
Specifies the source MP4 file as input. FFmpeg will read the file, identify all streams (video, audio, subtitles), and make them available for the conversion pipeline — in this case, only the audio stream will be used. |
-c:a alac
|
Sets the audio codec to ALAC (Apple Lossless Audio Codec), instructing FFmpeg to decode the MP4's audio stream (typically AAC) and re-encode it as lossless ALAC. This is the core of the conversion and ensures the output is perfectly preserved with no further quality loss. |
output.m4a
|
Defines the output file with the .m4a extension, which is the standard container for ALAC audio. FFmpeg infers from this extension that the output container is MPEG-4 Audio, which is required for ALAC and ensures compatibility with Apple Music, iTunes, and iOS devices. |
Common Use Cases
- Archiving the audio from a purchased or ripped MP4 movie or TV episode into a lossless format for long-term storage in your music library
- Extracting a high-quality music performance or concert video's audio track to add to an iTunes or Apple Music library as an ALAC file
- Preserving the audio from a professionally recorded MP4 video (such as a studio session or podcast recording) without any additional generational quality loss
- Preparing audio for playback on Apple devices like iPhone, iPad, or iPod when you want lossless quality and seamless iTunes/Apple Music integration
- Converting MP4 lecture or audiobook recordings into ALAC M4A files for organized, metadata-tagged storage compatible with Apple's ecosystem
- Stripping video from MP4 files to reduce storage footprint while retaining the full audio fidelity of the source for use in audio production workflows
Frequently Asked Questions
No — ALAC is lossless, meaning it perfectly preserves whatever audio is in the MP4, but it cannot restore quality that was already discarded by the MP4's lossy audio codec (typically AAC or MP3). Think of it like saving a JPEG image as a PNG: the PNG is lossless, but the compression artifacts from the original JPEG remain. Your ALAC file will be an exact, degradation-free copy of the audio as it existed in the MP4, with no further quality loss from this conversion.
ALAC compresses audio losslessly, which generally achieves around 40–60% of the size of uncompressed audio (WAV/AIFF), but it will be larger than lossy formats like AAC or MP3. Since the audio in your MP4 was likely AAC encoded at 128k–256k, decoding it and re-encoding as ALAC inflates the file because ALAC must store the full decoded waveform in its compressed-but-lossless form. This is expected behavior — the trade-off is perfect fidelity reproduction on every playback.
Yes — ALAC is a first-party Apple format and is natively supported across the entire Apple ecosystem including iTunes, Apple Music, iPhone, iPad, iPod, Apple TV, and macOS. The .m4a container produced by this conversion will import directly into your iTunes or Apple Music library without any additional software or plugins. Apple has also published the ALAC codec as open source, so it is increasingly supported on non-Apple platforms as well.
Chapter markers embedded in the MP4 are supported in the ALAC output container, as both MP4 and M4A share the MPEG-4 container structure. However, standard audio metadata tags (ID3-style title, artist, album, artwork) may or may not carry over depending on how they were stored in the source MP4, and subtitle tracks are not supported in ALAC M4A output. If metadata preservation is critical, you may want to verify and re-tag the output file using a tool like MusicBrainz Picard or iTunes itself.
ALAC does not expose quality or bitrate parameters — lossless compression means the output always represents the exact audio waveform, so there is no quality dial to turn. FFmpeg's ALAC encoder does support a compression level flag (-compression_level 0 through 8) that trades encoding speed for smaller file sizes without affecting audio fidelity, but this is not exposed by this tool since the file size difference is modest. If you need to adjust this, copy the displayed FFmpeg command and add -compression_level 5 (default) or a lower value for faster encoding.
Yes — the FFmpeg command displayed can be adapted for batch processing on your desktop. On Linux or macOS, you can run: for f in *.mp4; do ffmpeg -i "$f" -c:a alac "${f%.mp4}.m4a"; done in your terminal to process all MP4 files in a folder. On Windows PowerShell, a similar loop can be constructed using Get-ChildItem. This is especially useful for large collections or files over 1GB, which exceed the browser tool's file size limit.
Technical Notes
ALAC (Apple Lossless Audio Codec) stores audio in an MPEG-4 container, which is why the output extension is .m4a rather than a format-specific extension. The codec uses a linear prediction algorithm similar in concept to FLAC, typically achieving lossless compression ratios of 40–60% compared to raw PCM. Because the source MP4 almost certainly contains lossy audio (AAC being the default and most common codec in MP4 files), the decoded audio fed into the ALAC encoder will contain the quantization artifacts inherent to that lossy encoding — ALAC faithfully preserves these as-is. The output will not contain a video stream, making it unsuitable as a video replacement but ideal as a pure audio archive. Subtitle tracks from the MP4 source are incompatible with the ALAC M4A container and will be dropped. Multiple audio tracks in the source MP4 are also not supported in ALAC output — only the default/primary audio stream will be encoded. The .m4a output file is fully compatible with gapless playback in Apple Music and supports ReplayGain-equivalent Sound Check metadata when tagged via iTunes.