mixing

name

mixing

description

Use the `mixing` Python package for video and audio editing tasks: slicing audio/video, fades, cropping, looping, changing speed, replacing or mixing a video's audio, normalizing levels, Ken Burns pan/zoom, concatenating clips, thumbnails, burning in subtitles, speech-to-text + filler removal, chapter detection, and TTS dubbing/translation. Trigger whenever someone wants to edit, transform, transcribe, dub, or assemble audio/video files with Python — e.g. "trim this clip", "add music to a video", "remove the ums", "make a thumbnail", "turn this audio into a podcast", "dub this in French". Start here to pick the right tool and the right sub-skill (mixing-audio / mixing-video / mixing-transcript / mixing-dubbing).

mixing — router & core conventions

mixing edits audio/video from Python. This skill orients you; then jump to the focused sub-skill for the medium you're working in.

Pick a sub-skill

You want to…	Sub-skill
Edit audio (slice, fade, crop, concat, overlay, normalize, align, segment)	mixing-audio
Edit video (slice, crop, loop, speed, replace/normalize audio, Ken Burns, concat, thumbnail, subtitles)	mixing-video
Transcribe speech, remove fillers, make SRT/prose, detect chapters	mixing-transcript
Re-voice / translate via text-to-speech	mixing-dubbing

First moves (every task)

1. Check ffmpeg — most operations need it:

   import mixing
   assert mixing.has_ffmpeg(), "install ffmpeg (brew install ffmpeg / apt install ffmpeg)"
   

2. Import lazily / specifically. import mixing is cheap (no moviepy/opencv loaded until you touch a heavy name). Either use the facade (mixing.Audio, mixing.Video, mixing.replace_audio, …) or import the subpackage (from mixing.audio import Audio).
3. Know the output convention (below) before calling anything that writes.

The output protocol (read this once, applies everywhere)

Every function that produces a result takes one output argument:

crop_video("in.mp4", 5, 15, output="out.mp4")   # write a file → returns Path
crop_video("in.mp4", 5, 15, output="clips/")     # directory → auto-named file
crop_video("in.mp4", 5, 15)                       # None → saves beside input, returns Path
seg = mixing.Audio("song.mp3")[10:30]             # object producers: build first…
seg.fade_in(2).save(output="clip.mp3")            # …then save (or output=None returns Audio)
fade_in("in.mp3", output=lambda a: a.duration)    # a callable sink receives the result

• None → object producers return the in-memory object; file producers save beside the input and return the Path.
• a file path → write there, return Path.
• a directory → write an auto-named file inside, return Path.
• a callable → output(result) is returned (general escape hatch).

Functions that emit several artifacts qualify the destinations instead (remove_fillers(media, output_dir=..., output_media=...)).

Sliceable media

Audio and Video are lazy, sliceable views:

from mixing.audio import Audio
from mixing.video import Video

Audio("song.mp3")[10:30].fade_out(3).save(output="end.mp3")   # seconds by default
Audio("song.mp3", time_unit="samples")[0:44100]               # 1s at 44.1kHz
Video("clip.mp4")[5:15].save(output="cut.mp4")
Video("clip.mp4")[100]                                         # a single frame (np BGR)
with Video("clip.mp4") as v: dur = v.duration                 # context-managed

Optional extras & keys

• pip install mixing[audio] (pydub/soundfile), [gen] (Veo), [llm] (aix for chapter titles + SRT translation), [widget], [clipboard].
• ElevenLabs features (mixing.transcript, mixing.dubbing) need ELEVENLABS_API_KEY (or pass api_key=). Responses are cached on disk, so a re-run of the same input is free and offline.
• Veo (mixing.video.genai) needs Google Cloud auth (GOOGLE_CLOUD_PROJECT + application-default or service-account credentials).

Gotchas

• output=None for file producers writes next to the input — pass an explicit output to control location.
• ElevenLabs/Veo calls cost money; rely on the disk cache and pass cache=True (default for these) / refresh=True to force a re-call.
• mixing.video.replace_audio(..., mix_ratio=): 1.0 = only the new audio, 0.0 = keep original, 0.5 = equal blend.