A dedicated "♪ Extract audio" button on the transport row grabs an exact
length of audio (set via the adjacent length box, from the playhead) and opens
a Save As dialog. Output format follows the chosen extension — WAV (pcm_s16le),
MP3 (libmp3lame), FLAC, m4a/aac, ogg/opus — re-encoding as needed; unknown
extensions let ffmpeg pick from the container.
- core.ffmpeg.build_audio_clip_command(input, start, duration, out_path):
fast-seek + exact -t duration + -vn, codec by extension. Verified end-to-end
(wav/mp3/flac all land at exactly the requested duration).
- Timeline shows the audio area as a distinct teal dashed band spanning
[cursor, cursor+length], updated live as the playhead or length changes, so
you see exactly what will be extracted.
- Length + last save dir persist in QSettings; button enabled once a file loads.
Tests: 3 core (codec-by-extension, exact length, case-insensitive) + 2 GUI
(controls exist, band tracks cursor/length).
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>