CODEWITHSUNDEEP
ffmpegmp4m4a
Scott
Scott

Reputation: 59

Why does ffmpeg m4a → mp4 reduce file size by 60% if they are the same?

If m4a is the same as mp4 (minus the video), then how is it that doing

ffmpeg -i old.m4a new.mp4

Reduces file size so much? I am using the default settings.

Upvotes: 2

Views: 677

Answers (1)

Gyan
Gyan

Reputation: 93379

That command will re-encode all streams, in which case, the result can be smaller or larger than the source, since the default encoding parameters may be smaller or larger than the source parameters.

To simply transfer source streams to destination, you have to enable streamcopying. To do that, add -c copy (-c is short for -codec)

ffmpeg -i old.m4a -c copy new.mp4

Upvotes: 2

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