Keep originals and working copies distinct
A proxy is a smaller working representation. Optimized media is another derived representation for editing. Both retain a relationship to an original source; neither makes the original disposable. Do not substitute an unrelated smaller file simply because playback is faster.
Mac: open File → Project Media → Manage Media… or Playback → Proxy & Optimized Media…. iPhone/iPad: use Project Options → Media Management or Activity → Proxy & Optimized Media.
Generate or attach a representation
Select the intended source, choose the available Proxy codec and Frame size, and use Generate Proxy. Optimize creates the optimized representation. The media-job list reports progress and failures. Attach Verified Package… attaches a compatible package; identity checks can refuse a mismatch.
Derived format support depends on the platform. A listed choice is not proof that a physical iPhone supports every ProRes combination. Try an available alternative or create the representation on a verified Mac if a device refuses the codec.
Choose playback and output independently
The media-management Playback setting chooses working representations; the Mac Playback menu also exposes media selection. Delivery Source quality or source policy is independent.
For original-quality delivery, keep originals available even if you edited entirely with proxies. Meridian verifies original sources for that policy. An offline original can block export or collection while proxy preview still plays normally.
Review before committing a long job
Compare a representative original-quality export with the working preview. Check framing, source timing, color, and sound alignment, especially for retimed or variable-rate footage. A proxy is a performance tool, not a separate color or timing authority.
Resolve a failed media job's stated issue before retrying. Keep attached derived files under the app's management rather than manually rewriting their paths. When moving a project, collect the media needed by the destination and inspect both original and representation availability there.