Convert Y4M to AIFC — Free Online Tool
Convert Y4M (YUV4MPEG2) video files to AIFC audio format, extracting and encoding the audio stream as big-endian PCM using the pcm_s16be codec. This is useful when you need to pull professional-grade audio from an uncompressed intermediate video file into Apple's AIFC container for use in pro audio workflows.
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FFmpeg Command
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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:
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DownloadHow It Works
Y4M is a raw, uncompressed video format that stores YUV pixel data and is typically used as an intermediate format when piping video between tools like FFmpeg, x264, or VapourSynth. It contains no compressed video codec — just raw frames — and may carry an audio stream alongside the video. This conversion discards the raw video data entirely and extracts the audio stream, encoding it into AIFC using the pcm_s16be codec (16-bit signed big-endian PCM). AIFC is Apple's extended AIFF format capable of holding both uncompressed PCM and compressed audio; here, the output uses lossless PCM, so no audio quality is lost in the conversion. The result is a standalone AIFC audio file suitable for import into professional audio editors like Pro Tools or Logic Pro.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary — the underlying engine that performs all media demuxing, decoding, and encoding. In the browser-based tool, this runs as a WebAssembly (FFmpeg.wasm) instance entirely client-side. |
-i input.y4m
|
Specifies the input file in Y4M (YUV4MPEG2) format. FFmpeg reads the raw uncompressed YUV video frames and any accompanying audio stream from this file. |
-c:a pcm_s16be
|
Sets the audio codec to pcm_s16be — signed 16-bit big-endian PCM — which is the standard lossless audio encoding used in AIFC files. This produces uncompressed audio compatible with Apple professional audio tools. |
-b:a 128k
|
Specifies a target audio bitrate of 128k. For the lossless pcm_s16be codec used here, this parameter does not meaningfully alter the output — PCM bitrate is fixed by sample rate and bit depth — but it is included as a default parameter in the tool. |
output.aifc
|
Defines the output filename and signals FFmpeg to write an AIFC container. The .aifc extension tells FFmpeg to use Apple's extended AIFF muxer, which wraps the pcm_s16be audio stream in a big-endian AIFC file. |
Common Use Cases
- Extracting a reference audio track from a Y4M intermediate file produced during a lossless video encoding pipeline to review sync or audio quality in a DAW
- Archiving the audio portion of an uncompressed Y4M capture from a video digitization workflow into a professional AIFC container for long-term storage
- Delivering isolated audio stems from a Y4M intermediate to an audio post-production team working in Logic Pro or Pro Tools, which natively support AIFC
- Stripping the audio track from a Y4M file generated by VapourSynth or AviSynth to perform separate audio mastering before remuxing with the final video
- Converting Y4M test sequences used in codec development into AIFC audio files for acoustic quality evaluation in Apple-centric audio tools
- Preparing audio from a Y4M broadcast capture for use in a macOS-based audio editing environment where AIFC is the preferred import format
Frequently Asked Questions
No — this conversion uses the pcm_s16be codec, which is lossless 16-bit PCM audio. As long as the source audio in the Y4M file is 16-bit or lower bit-depth, the output AIFC will be a bit-perfect representation. If the source audio was encoded at a higher bit depth (e.g., 24-bit), some precision may be reduced to 16-bit, so you can specify pcm_s24be in the command if you need to preserve higher resolution.
The raw YUV video frames stored in the Y4M file are completely discarded. FFmpeg reads the input file, ignores the video stream, and only processes the audio stream for output. The resulting AIFC file is audio-only — no video data is retained or carried over in any form.
The '-b:a 128k' flag is included as a default parameter, but for PCM codecs like pcm_s16be, the actual bitrate is determined by the sample rate and bit depth rather than a target bitrate setting. PCM audio is uncompressed and lossless by nature, so the bitrate flag has no meaningful effect on quality or file size in this specific conversion — the output bitrate will reflect the true PCM data rate of the audio stream.
Yes. The AIFC format supports several PCM variants: pcm_s24be (24-bit), pcm_s32be (32-bit), pcm_f32be (32-bit float), and pcm_f64be (64-bit float), all in big-endian byte order. Replace '-c:a pcm_s16be' in the command with your preferred codec, for example: ffmpeg -i input.y4m -c:a pcm_s24be output.aifc. Choose the bit depth that matches or exceeds the source audio to avoid any downsampling.
On Linux or macOS, you can loop over all Y4M files in a directory with a shell command: for f in *.y4m; do ffmpeg -i "$f" -c:a pcm_s16be "${f%.y4m}.aifc"; done. On Windows Command Prompt, use: for %f in (*.y4m) do ffmpeg -i "%f" -c:a pcm_s16be "%~nf.aifc". Each Y4M file will produce a corresponding AIFC file with the same base name.
Yes. Both Logic Pro and Pro Tools have native support for AIFC files with PCM audio, as the format originates from Apple's professional audio ecosystem. The pcm_s16be codec produces standard big-endian 16-bit PCM, which is the canonical AIFC format and will import without any compatibility issues into either application.
Technical Notes
Y4M files store raw planar YUV video data with a simple text header and do not use any video compression codec — each frame is stored as uncompressed YUV samples. When audio is present in a Y4M file, it is typically uncompressed or minimally encoded. AIFC uses big-endian byte ordering for its PCM variants (pcm_s16be, pcm_s24be, etc.), which distinguishes it from WAV, which uses little-endian PCM. This big-endian convention is a legacy of the Motorola 68000 architecture used in early Apple hardware. The AIFC container does not support multiple audio tracks, subtitles, chapters, or video — it is strictly a single-stream audio container. Metadata support in AIFC is limited compared to modern formats; standard fields like title and artist can be stored, but complex tagging schemes are not supported. File sizes for the AIFC output will be determined solely by the audio stream duration, sample rate, and bit depth, since PCM is uncompressed — a 60-second stereo 44.1kHz 16-bit AIFC file will be approximately 10MB regardless of how large the source Y4M video file was.