How can I calculate the audio time by byte position (bytes to secounds)?

Question

I have the audio file and byte range. I want get time for each byte position. I'm use php.

I tried to calculate that using this formula: $time = $byte/($bitRate * $sampleRate * $cannels) But it doesn't work.

So how can I calculate this? I used ffmpeg (php-ffmpeg), and if you know how to find this data with ffmpeg, that would be fine;