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

Question

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

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Answer 1

Oct 13, 2024 11:40 AM in response to Sandy MacLane

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

Both are running the latest MacOS (15.0.1) and QuickTime Player 10.5 (1204.42).

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Answer 2

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.

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Answer 3

Oct 13, 2024 1:07 PM in response to Matti Haveri

yes yes - the puzzling thing is that I get different results on the two machines with the same identical files

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