The result is differrent compare to FFmpeg swr_convert

[cocotyty]

For example,if the input sample rate is 16000 and the output sample rate is 48000, the output data size should be 3X input data size.

But the result seems like much less than the expectation.

[cocotyty]

I'm trying to make gomplerate works with the https://github.com/hajimehoshi/oto and https://github.com/hajimehoshi/go-mp3.

I wrote two helper functions below to convert data between float64 slice and byte slice.

func fromFloat64(data []float64) (buf []byte) {
	n := len(data) * 2
	buf = make([]byte, n)
	for i := 0; i < len(data); i++ {
		v16 := int16(data[i] * (1 << 15))
		v1 := uint8(v16)
		v2 := uint8(v16 >> 8)
		buf[i*2] = v1
		buf[i*2+1] = v2
	}
	return buf
}

func getFloat64(data []byte) []float64 {
	n := len(data) / 2
	buf := make([]float64, n)
	for i := 0; i < n; i++ {
		var v float64
		v16 := int16(data[2*i]) | (int16(data[2*i+1]) << 8)
		v = float64(v16) / (1 << 15)
		buf[i] = v
	}
	return buf
}

[zeozeozeo]

Resampling does not affect speed whatsoever. You should be changing the playback rate of it.
For example, if you want to slow down an audio file by 2 times (but keep the playback sample rate), you should resample it to double the sample rate and then play it back at the original sample rate.