Problem 1 Array A stores stereo audio samples in floating point form. The left and right channels are interleaved, with left first and right second. The sampling rate is R=23457, and A contains 11924 samples. What is the index into A of the right channel sample nearest to time t = 256 ms from the start of audio sample? Problem 2 The following are mono audio samples in floating point format. We are to scale the data by 2.3 dB. Find the resulting values that would be written to a 8-bit WAVE file. Some values may need to be clipped. 0.781 -0.042 -0.594 Formulas f = 2p/1200 fo dB = 20 log Miscellaneous logarithm formulas. logo2 loga 1 = logo 2 logo XP = plog 2 loga * = log, a logo 2P = p logo2 log, a In particular, if you need to compute the logarithm base 2, you would use log 2 The above formulas will appear as stated on the midterm exam. What follows is more detailed description. Inc log2x = in or log21 = log2 Pitch. A change in pitch of p cents gives a change in frequency by a factor of u= 2P/1200 That is, if the original frequency is fo, then the resulting frequency is f = ufo. There are 1200 cents in one octave, with one semi-tone (half step) being equal to 100 cents. Decibels. The change in voltage from Voto Vi corresponds to the decibel value D= 20 log The ratio g = V is called the linear gain factor, so a linear gain factor of g corresponds to a change of D = 20 log g decibels. Problem 1 Array A stores stereo audio samples in floating point form. The left and right channels are interleaved, with left first and right second. The sampling rate is R=23457, and A contains 11924 samples. What is the index into A of the right channel sample nearest to time t = 256 ms from the start of audio sample? Problem 2 The following are mono audio samples in floating point format. We are to scale the data by 2.3 dB. Find the resulting values that would be written to a 8-bit WAVE file. Some values may need to be clipped. 0.781 -0.042 -0.594 Formulas f = 2p/1200 fo dB = 20 log Miscellaneous logarithm formulas. logo2 loga 1 = logo 2 logo XP = plog 2 loga * = log, a logo 2P = p logo2 log, a In particular, if you need to compute the logarithm base 2, you would use log 2 The above formulas will appear as stated on the midterm exam. What follows is more detailed description. Inc log2x = in or log21 = log2 Pitch. A change in pitch of p cents gives a change in frequency by a factor of u= 2P/1200 That is, if the original frequency is fo, then the resulting frequency is f = ufo. There are 1200 cents in one octave, with one semi-tone (half step) being equal to 100 cents. Decibels. The change in voltage from Voto Vi corresponds to the decibel value D= 20 log The ratio g = V is called the linear gain factor, so a linear gain factor of g corresponds to a change of D = 20 log g decibels