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QuickTime Player's merge function increases file size as of MacOS15 - does it re-render? It never used to!

QuickTime Player offers a feature "Add Clip to End". This used to work instantly, without rendering afresh. As of MacOS15 the merged file suddenly takes a long time to save, and its size is about 4-5 times as large as it should be (and used to be).


There's plenty of video editing software around that can merge files in this way - the reason I used QuickTime Player was precisely that I could carry on with a file of managable size. It would be a shame if this feature was dropped!


Or is there a way of doing it the old way still?

MacBook Air 15″, macOS 15.0

Posted on Oct 6, 2024 11:54 AM

Reply
3 replies

Oct 13, 2024 12:07 PM in response to Sandy MacLane

Sandy MacLane wrote:

this problem occurs, reproducibly, on my new MacBook Air M3, but NOT on my old MBAir M2 (2023) on identical mp4 files.

Are you using the exact same movies?


I briefly tested this and could "Add Clip to End" and export it in a blink of an eye in Sequoia QT Player. But ONLY if both movies were the same resolution, codec (AVC, HEVC etc) etc AND if I also exported to the same spec and codec. If not, then a slower re-encoding had to be done. AFAIK different spec and codec movies do not easily mix without re-encoding.

QuickTime Player's merge function increases file size as of MacOS15 - does it re-render? It never used to!

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