AVAssetWriterInput preferredVolume not working

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Created Jan ’21

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I am recording a video using AVAssetWriter. Now I want to control the volume level for the output file using the "preferredVolume"(0.0-1.0 values) parameter of audio AVAssetWriterInput.
But final out video does not change the volume level. Any Help/Suggestions?

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Answer 1

Media Engineer OP

Apple

Jan ’21

The AVAssetWriter property does not change the volume of the audio samples written to file. Instead, it writes an annotation to the file that the value specify is the preferred volume. It is then up to the software the plays the file to respect the preference. If you want to modify the volume of the actual audio in the file, you need to do that yourself before you append the samples to the asset writer.

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