mp3DirectCut is a free audio editor for Windows that cuts, crops, splits and joins MP3 files without decoding and re-encoding them. It also handles AAC and MP2 audio, records to MP3 and runs on Linux through Wine. A separate, lighter mp3DirectCut app exists for Android.
Editing without re-encoding
Most audio editors decode a compressed file to raw PCM, apply the change and compress it again. This takes time and adds a second round of quality loss. mp3DirectCut instead copies the existing compressed data directly into the new file. Removing an intro, trimming silence or taking a section out of a recording leaves the remaining audio exactly as it was encoded. Saving is fast even for long files.
Cut, copy and paste are non-destructive while you work. The edits apply to the playback preview, you can undo them, and mp3DirectCut writes the result only when you save the complete audio.
Selecting and trimming a range
The main view is an MPEG graph built from the compressed data rather than a decoded waveform, so even large files appear quickly. Because of this it tends to reflect the higher frequencies, while a level meter shows the real playback level. A map bar and scrollbar move through the track, and a bitrate display shows how the data rate changes.
You draw a selection with the left mouse button. You adjust its edges with the right button or with Set begin and Set end at the current play position. Keyboard keys nudge the start and end for fine adjustment, and a prelisten mode plays the passage around the cut as it will sound. Trim, crop, fast play and loop play help check the boundaries before pressing Cut.
Fades, gain and normalizing
mp3DirectCut can change levels on MP3 files without re-encoding. You place a simple or two-stage fade at a chosen point. Grey handles on the graph set the gain, shown in dB. Extra zero-length cue points add steps for more complex volume curves. Fades move in 1.5 dB steps, so they are coarser than in a PCM editor. Normalizing and gain changes also apply to MP3 only; AAC and MP2 files can be cut but not faded.
Splitting tracks with cues
You can divide a long recording, such as a digitized album or a radio session, at cue points. The editor sets cues automatically through pause detection or at fixed time intervals, and it reads and writes cue sheets. When the file is split, mp3DirectCut creates the file names and tags for each part. The built-in tag editor writes ID3v1.1 tags and keeps existing ID3v2 tags.
Joining files and batch processing
You can open several files from the dialog, drop them onto the window or load them from an M3U playlist. mp3DirectCut appends dropped files to the open audio and saves them as one file, provided they share the same format, sample rate, stereo mode and CRC setting. A batch dialog processes lists of files, and mp3DirectCut also accepts command-line use for scripted jobs.
Recording to MP3
The recorder encodes directly to MP3 while it captures, using a Windows ACM codec or a LAME encoder library. Level-activated recording starts capturing only when the input passes a set level, which saves trimming silence afterwards.
AAC, MP2 and MP4 audio
MP3 is the native format. AAC playback and cutting need the libfaad2 library placed in the program folder, and an optional mpglib library covers MP2. You can open MP4 and M4A files when you link ffmpeg.exe in the decoder settings. mp3DirectCut extracts their AAC stream, but saves the result as AAC rather than packing it back into MP4.
Android edition
mp3DirectCut for Android is a free, ad-free counterpart with the basic tools: cut, crop, extract, append, copy and paste on MP3 and AAC files. Fading and normalizing are limited to MP3. You can preview selections as cut or as a loop, and save the work as a whole file, a selection or a project file. It also records from the microphone straight to MP3.
