[Discuss-gnuradio] Randomness Introduced in Gnuradio WAV Source Block?

[Tommy Tracy II]

Dear Gnuradio,

I wrote a program that uses a WAV source block. I found that my program ran as expected on my CENTOS and UBUNTU machines (producing the same output for a given input), but I noticed something unusual on my Gentoo machine. If I run the decoder against the same input WAV file, I get different output every time! My program is an APT decoder, so the resulting output is an image. The images look similar, but they have different intensities. (some are darker, some lighter)

I eventually determined, that the randomness was added somewhere in the WAV Source block. Has anyone seen this?

This little program shows where the problem may be. The input is a WAV file. The float stream is converted to chars, and then dumped to a file. This should be completely reproducible, but it doesn't seem to be in the case of my Gentoo machine.

-----------------

class top_block(gr.top_block):

        def __init__(self):

                gr.top_block.__init__(self, "WAV TEST")

                inputFileName = str(sys.argv[1])

                outputFileName = str(sys.argv[2])

                self.gr_wavfile_source_0 = gr.wavfile_source(inputFileName, False)

                self.gr_float_to_uchar_0 = gr.float_to_uchar()

                self.gr_file_sink_0 = gr.file_sink(gr.sizeof_char*1, outputFileName)

                self.gr_file_sink_0.set_unbuffered(False)

                self.connect((self.gr_wavfile_source_0,0), (self.gr_float_to_uchar_0, 0))

                self.connect((self.gr_float_to_uchar_0, 0), (self.gr_file_sink_0, 0))

if __name__ == '__main__':

        tb = top_block()

        tb.run(True)

-----------------

I used the same WAV file input 4 times, and got 4 different outputs.

This is the same problem-computer that gives me the make test errors, so that may be related.

                   Sincerely,

          Tommy James Tracy II

          PhD Student

High Performance Low Power Lab 

           University of Virginia