whats wrong in the following?

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VINAYAK KARANDIKAR 2019-1-10

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https://ww2.mathworks.cn/matlabcentral/answers/439063-whats-wrong-in-the-following

评论： VINAYAK KARANDIKAR 2019-1-13

[y, Fs] = audioread('Track48.wav');
 
 y1 = y(:,1); y2 = y(:,2);
 
 Y = [y1 y2];
 
 wavwrite(Y ,Fs, 'newfile.wav');
% %audiowrite('newfile.wav', Y ,Fs);

........................................................................................

Error on running:

Error using wavwrite>OpenWaveWrite (line 170)

Unable to open file. Reason: Permission denied

Error in wavwrite (line 96)

fid = OpenWaveWrite(wavefile);

Error in Test2 (line 16)

wavwrite(Y ,Fs, 'newfile.wav');

Thanks a lot

回答（1 个）

madhan ravi 2019-1-10

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https://ww2.mathworks.cn/matlabcentral/answers/439063-whats-wrong-in-the-following#answer_355789

编辑：madhan ravi 2019-1-10

See https://www.mathworks.com/matlabcentral/answers/49367-i-want-to-write-wav-to-a-file-useing-wavwrite-function#answer_60311

Try changing the working directory or run as administrator it is clear from the message that file permission is denied.

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Walter Roberson 2019-1-13

在 MATLAB Online 中打开

The file is samples of radio frequency transmissions. Storing it in a .wav was convenient to the people who created it, but that does not mean that it was audio in the human sense. It is just data recordings.

The data was recorded with the program SDR# (SDRSharp)

See https://www.rtl-sdr.com/about-rtl-sdr/

audioinfo() reports that it is 16 bits per sample, and examining the data I see differences in value at the int16 level as small as 1, but the top bit does not seem to be used. This suggests that it really is 16 bits, rather than 12 bits stuffed into 16. However, if you look at histogram in more detail, it looks likely that the samples are in bins of width 2^8 (256) at the int16 level, as if there were roughly 91 frequency bins that are 256 apart and that for whatever reason, values are distributed around those centers instead of being exactly those centers (perhaps for phase reasons, perhaps for signal edge transition reasons, perhaps for noise reasons.) But if you

[data,fs] = audioread('SDRSharp_20170415_070322Z_97990kHz_IQ.wav', 'native');
N = 8; histogram(floor(data(:)/(2^N)),-2^(14-N):2^(14-N)-1)

then you do get a nice smooth bimodal distribution with the peaks near +/- 3072 (and distinctly non-trivial counts between.) This is not a binary encoding.

You mentioned FM: frequency modulation around centers 256 apart could plausibly account for the bin shapes.

The file name hints at 97.9 MHz, which is plausible for FM Channel 250 https://en.wikipedia.org/wiki/List_of_channel_numbers_assigned_to_FM_frequencies_in_North_America for non-digital FM radio, but the file name also hints at 97.99 MHz which could be "98.0 MHz" which could be from Europe or Africa (in North America, only odd frequencies are used.)

I am getting a bit lost following the technical description of how FM encodes stereo.

Atch, I just realized that in part I have been mentally confusing frequency vs amplitude. The histograms I am referring to above are about amplitude. You need to do a frequency analysis.

Walter Roberson 2019-1-13

https://www.mathworks.com/help/matlab/ref/matlab.graphics.chart.primitive.histogram.html

Introduced in R2014b

You can use hist() instead of histogram() for this purpose.

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