Re: [LAD] Calculate R M S

Hallo! You might look into the replay gain standard: http://replaygain.hydrogenaudio.org/ There is also a libreplaygain somewhere around - look also at http://en.wikipedia.org/wiki/Replay_Gain for implementations. (I have also seen once a small commandline program for replay gain normalization, can't find it ATM ...) That's not as easy as one might think ... Calculating the RMS level is a good start, but there are other things to consider: - from the replay gain side: "The human ear does not perceive sounds of all frequencies as having equal loudness. For example, a full scale sine wave at 1kHz sounds much louder than a full scale sine wave at 10kHz, even though the two have identical energy. To account for this, the signal is filtered by an inverted approximation to the equal loudness curves (sometimes referred to as Fletcher-Munson curves)." - Try e.g. to calculate the loudness of speech: the RMS value will be much lower as perceived, because during speech there are periods of silence which are included in the RMS calculation, but we perceive the loudness only from the parts where the voice is active. Replay gain tries to consider this problem by doing some statistical post-processing (see http://replaygain.hydrogenaudio.org/statistical_process.html). However, there are different approaches for that: e.g. only calculate the RMS value from regions where the voice is active (requires some voice activity detection). LG Georg -- http://grh.mur.at