Trim CAF — Free Online Tool
Trim a CAF (Core Audio Format) file to a precise segment by specifying start and end timestamps. Because the audio stream is copied without re-encoding, the cut is instant and lossless — whether your CAF file contains raw PCM, AAC, FLAC, or any other supported codec.
to
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
The tool uses FFmpeg's stream-copy mode (-c copy) to extract a time segment from your CAF file without decoding or re-encoding the audio. FFmpeg seeks to the specified start point (-ss) and reads forward until the end point (-to), copying the compressed or raw audio frames directly into a new CAF container. Because no audio decoding or re-encoding occurs, there is no quality loss and the operation is nearly instantaneous regardless of file size. The output preserves the original codec — whether that is lossless PCM (pcm_s16le, pcm_s24le, pcm_s32le), FLAC, or lossy AAC/Opus/Vorbis — exactly as it was in the source file. Note that with stream copy, the trim boundaries are constrained to the nearest keyframe or sample boundary in the original stream, which for most audio codecs means sample-accurate cuts.
What Each Flag Does
| Flag | What it does |
|---|---|
ffmpeg
|
Invokes the FFmpeg binary. This is the entry point for the entire command and must appear first. |
-i input.caf
|
Specifies the input CAF file. FFmpeg will read the audio stream from this file, which may contain any CAF-supported codec such as pcm_s16le, AAC, FLAC, or Opus. |
-ss 00:00:00
|
Sets the trim start point to the beginning of the file in this default example (hours:minutes:seconds). Change this timestamp to seek to any point in the CAF audio before copying begins. |
-to 00:00:10
|
Sets the trim end point to 10 seconds into the file. FFmpeg will stop copying the CAF audio stream at this absolute timestamp. Replace with -t followed by a duration if you prefer to specify a clip length rather than an end time. |
-c copy
|
Instructs FFmpeg to copy the audio stream directly from the input CAF to the output CAF without any decoding or re-encoding. This preserves the original codec (PCM, AAC, FLAC, etc.), bit depth, sample rate, and audio quality exactly. |
output.caf
|
Specifies the output file name and format. The .caf extension tells FFmpeg to wrap the copied audio stream in a new Core Audio Format container, maintaining full compatibility with macOS, iOS, Logic Pro, and other Apple audio tools. |
Common Use Cases
- Extract a specific musical phrase or take from a large multi-hour CAF recording session in Logic Pro without re-encoding the original high-resolution PCM audio.
- Trim a CAF voiceover recording to remove silence or false starts before importing into Final Cut Pro or GarageBand, preserving the original bit depth and sample rate.
- Cut a short ringtone or notification sound from a longer CAF audio asset in an iOS or macOS app project, where CAF is the native system audio format.
- Isolate a specific segment from a CAF podcast master file for review or approval without converting to a lossy format, keeping the lossless FLAC or PCM stream intact.
- Trim a CAF field recording captured on an Apple device to remove handling noise at the start and end before archiving the high-resolution audio file.
- Extract a cue from a large CAF sound effects library file that exceeds the size limits of AIFF or WAV, leveraging CAF's large file support.
Frequently Asked Questions
No. The -c copy flag means FFmpeg reads and writes the existing audio frames without decoding or re-encoding them. Whether your CAF file contains lossless 32-bit float PCM, 24-bit PCM, FLAC, or lossy AAC, the retained audio is bit-for-bit identical to the original. Quality loss can only occur if re-encoding is involved, which this tool explicitly avoids.
For uncompressed PCM codecs (pcm_s16le, pcm_s24le, pcm_s32le, pcm_f32le), trim accuracy is essentially sample-perfect because PCM audio has no interframe dependencies. For codecs like AAC, FLAC, or Opus that use frame-based encoding, the cut will snap to the nearest audio frame boundary, which is typically within a few milliseconds. If sub-frame accuracy is critical for a lossy codec, re-encoding to a new segment would be required at the cost of a generation loss.
Yes. Because -c copy passes the audio stream through unchanged, all stream properties — sample rate, bit depth, channel layout, and codec parameters — are preserved from the source file. This is particularly important for high-resolution CAF recordings (e.g., 96 kHz / 24-bit) used in professional Apple audio workflows, where maintaining the original PCM format is essential.
Yes. With -c copy, FFmpeg keeps whatever codec is present in the source CAF, including AAC. The trimmed output will be a CAF file containing AAC audio, with no transcoding step. This means there is no additional quality degradation beyond what existed in the original AAC encoding.
Modify the values after -ss (start time) and -to (end time) in the command. Both accept the format HH:MM:SS or HH:MM:SS.mmm for millisecond precision. For example, to trim from 1 minute 30 seconds to 2 minutes 45.5 seconds, use -ss 00:01:30 -to 00:02:45.500. You can also replace -to with -t followed by a duration value if you prefer to specify a length rather than an end timestamp.
Yes. On macOS or Linux, you can wrap the command in a shell loop: for f in *.caf; do ffmpeg -i "$f" -ss 00:00:00 -to 00:00:10 -c copy "trimmed_$f"; done. This applies the same start and end times to every CAF file in the current directory. On Windows, an equivalent for loop works in Command Prompt or PowerShell. This is one reason the page displays the exact FFmpeg command — so you can adapt it for bulk processing of large libraries where the 1 GB browser limit may be a constraint.
Technical Notes
CAF (Core Audio Format) is Apple's professional audio container, designed to support files larger than the 4 GB limit of AIFF and WAV, making it common in long recording sessions and large sound libraries on macOS and iOS. Trimming CAF with -c copy works cleanly because CAF supports all of the codecs FFmpeg associates with it — including raw PCM variants (pcm_s16le, pcm_s24le, pcm_s32le, pcm_f32le), lossless FLAC, and lossy codecs such as AAC, Opus, and Vorbis. One known limitation is that CAF does not support chapters, subtitles, or multiple audio tracks in the way that video containers do, so there is nothing to lose in those dimensions during trimming. Metadata stored in CAF info chunks (such as artist or tempo) may or may not be preserved depending on the FFmpeg version and the specific tags present; if metadata preservation is critical, verify the output with afinfo on macOS or ffprobe. Because CAF is a native Apple format, trimmed files are immediately compatible with Logic Pro, GarageBand, Final Cut Pro, and CoreAudio-based apps on macOS and iOS without any additional conversion step.