[audio] Update bitrate calc

[GiviMAD]

I think bitrate was miscalculated after #4116

nBitsPerSecond = nSamplesPerChannelPerSecond * nBitsPerSample * nChannels;

PR seems to make no difference but seems a little clear to me. Feel free to close it if irrelevant.

[GiviMAD]

Hello @lolodomo could you test if these solves #4140?

[lolodomo]

I will try and let you know, thank you for quick investigation.

[lolodomo]

I just tested but unfortunately it does not solve the issue.

[GiviMAD]

It seems like methods getSampleRate and getFrameRate return same value for formats without compression so the PR makes no effect.

[J-N-K]

@GiviMAD Are you working on an improvement?

[GiviMAD]

Nop, I just saw it while reviewing a recent PR and thought at the beginning that it could be wrong, but seems to be right for the case.
I think the API is intended to either do format.getFrameRate() * format.getFrameSize() to get the compressed byte rate or format.getSampleRate() * format.getSampleSizeInBits() to get the uncompressed one. But because of the wav format support not compression format.getFrameRate() and format.getSampleRate() will return same value.