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Convertessa hands your MOV to FFmpeg, which pulls the audio track out of the QuickTime container, discards the video entirely and re-encodes what is left as MP3 through LAME. A two-hour interview becomes a file that plays anywhere: phone, car stereo, transcription service. Drop a folder of recordings and the whole batch runs in one pass on your Mac, with every original MOV left exactly as it was.
MOV is Apple's QuickTime container, and it is a container in the literal sense: a wrapper holding one or more independent tracks that happen to share a timeline. A clip off an iPhone holds HEVC or H.264 video plus a single AAC audio track. A screen recording from QuickTime Player may hold microphone audio, system audio, or none at all. A ProRes master out of Final Cut can hold uncompressed PCM stems, with dialogue on one track, music on another and effects on a third.
MP3 is a single-programme format. FFmpeg takes one audio track from the MOV and encodes that; the remaining audio tracks, the video, any chapter markers and the timecode track are all discarded. If your MOV came out of an editing suite with separate stems, check which one you got before assuming you have the full mix.
MP3 carries mono or stereo only, so a 5.1 soundtrack is downmixed to two channels on the way in and centre-channel dialogue ends up sharing space with the music bed. Sample rate is limited too: MPEG-1 Layer III supports 32, 44.1 and 48 kHz, so a 96 kHz PCM track is resampled to 48 kHz before the encoder sees it.
If the MOV holds PCM or ALAC, the MP3 is a single clean generation of loss and the quality value you set is the only real variable. If it holds AAC — which covers virtually every phone clip and screen recording — you are re-encoding already-lossy audio, and the two codecs throw away different things, so artifacts stack rather than overlap. Pick MP3 when universal playback matters more than fidelity, and give it room: convertessa interview.mov --to mp3 --quality high.
Drag one clip or a folder of screen recordings onto the queue. QuickTime files from iPhone, Final Cut, OBS and Photo Booth are all read, and the video track rides along only to be discarded.
Select MP3 as the output and set quality. The high preset suits speech you intend to publish, while balanced is plenty for lecture captures and voice memos that only need to stay intelligible.
Run the queue, then confirm the MP3 duration matches the MOV. A short file usually means the recording carried more than one audio track and only the selected one reached the encoder.
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The MOV most likely has no audio track. macOS screen recordings capture sound only if you enable microphone or system audio before you start, and a silent capture produces a video-only QuickTime file. Check in QuickTime Player: if the volume slider is greyed out, there is nothing there to extract. Time-lapse clips from an iPhone are also recorded without audio by design, so they behave the same way.
FFmpeg selects one, normally the first or the one it scores highest, and encodes that alone, because MP3 cannot hold parallel tracks. This matters for exports from Final Cut or Premiere carrying separate dialogue, music and effects stems, and for multi-camera clips with one audio track per angle. If the MP3 sounds thin or the music is missing, you have the wrong stem: mix down to a single track in your editor and export the MOV again.
Not at all. Video and audio sit in separate tracks inside the QuickTime container, and the video is discarded untouched, so its codec, frame rate and resolution have no bearing on the result. A 4K ProRes master and a heavily compressed screen capture of the same interview yield identical audio input, provided the audio track itself is the same. It is also why this conversion is so quick: no frames are ever decoded.
Not to MP3. The audio inside a MOV is essentially never already MP3 — it is AAC on phones and screen recordings, PCM on masters out of Final Cut — so an encode is unavoidable. If a second generation of lossy encoding is the concern, target WAV or FLAC instead: both store the decoded audio without discarding anything further, at the cost of far larger files. Choose MP3 when the file has to play on absolutely anything.
It is downmixed to stereo, because MP3 carries mono or stereo only. The centre channel, where dialogue usually lives, is folded into both sides along with music and effects, so speech that sat cleanly separated in the surround mix can sit lower against the bed. For a film or a game capture that is often perfectly acceptable, but for anything you plan to transcribe it is worth listening to a minute of the result before batching the rest.
No. QuickTime keeps that information in its own metadata atoms while MP3 uses ID3 tags, the two do not map across, and Convertessa does not write them. Your MP3 arrives with its filename and little else, which is fine for a voice memo and awkward for a podcast episode. Set the tags afterwards in Music or a dedicated tagger before you publish the file or hand it to anyone.
Drop the folder onto the queue, or work from the terminal:
convertessa ./Recordings/*.mov --to mp3 --quality high -o ~/Podcast
Each MOV is processed in turn and written into the output folder under the same base name with an .mp3 extension. The originals are only ever read. Long batches tend to be disk-bound rather than processor-bound, because only the audio track is decoded.
Because the video was most of the file. In a typical screen recording or phone clip the picture accounts for well over ninety per cent of the bytes and the audio for a few per cent. Dropping the video and then encoding the audio routinely takes an hour-long 1.4 GB capture down to a few tens of megabytes. That is the conversion working, not a truncated file — compare the durations if you want to be certain.