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 MemoryWriter weirdness ... bug or mistake?
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| Author | Topic: MemoryWriter weirdness ... bug or mistake? | |
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tuscland Member |
posted 19 April 2006 14:43
 
Here a sound on which I am currently working. There is a kind of leftover of another recording at the beginning (the sine period). Why do I have this? I tried to schelude the Writer on the same processor as the reader, but nothing works. More weird: if I make the "Repeat" MemoryWriter silent, I still get this small sine, as it was coming from elsewhere, but WHERE? Please SSC, could you have a look at this and give me some pointers of where I may be wrong?
[This message has been edited by tuscland (edited 19 April 2006).] IP: Logged | |
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SSC Administrator |
posted 19 April 2006 16:38
If you are muting the MemoryWriter, that would point to the WaveShaper as the source of the audio. That would suggest that the index into the WaveShaper might be incorrect. Can you test the output of Pete's 'Index Ramp' module to see whether its output is correct (maybe its output is 0 or -1 at the beginning? Or maybe it is always counting?) IP: Logged | |
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tuscland Member |
posted 19 April 2006 16:47
I fear it is not that. I had the problem in a totally different setup, and it seems that the problem comes from the Oscilloscope prototype when a Up/Down Counter feeds it. Weird!? I am sorry, I don't have more clues. IP: Logged | |
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SSC Administrator |
posted 19 April 2006 20:27
So when you delete the Oscilloscope that sound goes away? IP: Logged | |
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tuscland Member |
posted 20 April 2006 04:23
Yes, actually the sound seems to be never heard, it is just display thing. IP: Logged | |
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tuscland Member |
posted 20 April 2006 04:59
If you look at the output of RecTriggers, there is this glitch at the beginning of the OscilloscopeDisplay. By the way, in the VCS it should be named RecTriggers, not PlayTriggers, I have not set the names of the widgets manually, so there's some sort of confusion here. If you remove the OscilloscopeDisplay prototype PlayTriggers, the output of RecTroggers, is not the same. Cancel the previous action and now, and delete the RecTriggers module. You can see that small sine period? How could a sine could come out of a GateToTrigger? Weird! Camille [This message has been edited by tuscland (edited 20 April 2006).] IP: Logged | |
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tuscland Member |
posted 20 April 2006 06:17
I think the problem comes from the 1 sample MemoryWriter because I now have a problem in another sound. It seems that there are bad memory interactions between Up/Down Counter, Oscilloscope and MemoryWriter. In this other sound, the is a 1 sample MemoryWriter, if I check Global, I don't have any output, if I don't check Global, I have a scrambled output. This is another manifestation of a strange memory mapping. I absolutely need a one sample feedback loop, is it possible to do it? Best from, IP: Logged | |
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SSC Administrator |
posted 20 April 2006 11:30
The problem you are seeing is due to the StepWriter and the Oscilloscope sharing the same memory. The Sound compiler allows wavetable memory to be reused when the last Sound reading the memory has ended. In this case, the StepWriter's memory has no readers, so the compiler allows the memory to be reused immediately. (This is not really right, since the compiler ought to prevent the memory from being reused until the writer has ended.) You can tell when this is happening by looking in the Memory Status window (in the lower left corner of the display): "Warning: The wavetable named #wtable is never read after it is written for the last time at 0.0 seconds on processor 3". You can get around this behavior by adding something that READS "wtable" (for example, you could add a Sample to your signal flow graph that reads "wtable". If you don't want to hear it you can set its output amplitude to zero). IP: Logged | |
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tuscland Member |
posted 20 April 2006 11:52
Very interesting! However there is something that reads wtable! Is is the waveshaper module. IP: Logged | |
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SSC Administrator |
posted 20 April 2006 13:11
We looked at the reduced version that did not have this waveshaper. Adding a Sample that read from wtable got rid of the little sine wave burst that was seen in the oscilloscope display. IP: Logged | |
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tuscland Member |
posted 20 April 2006 13:17
Right, I have to try this. The problem was that the little sine was also there in the expanded version of the sound. I should check what's written in the Status window. IP: Logged | |
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SSC Administrator |
posted 20 April 2006 14:37
The Sound compiler has been changed for the next release: it will reserve the wavetable memory for the duration of the entire Sound being played whenever the wavetable memory is only written and never read. (This should fix the problem you were seeing when playing only part of the Sound structure.) IP: Logged | |
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tuscland Member |
posted 20 April 2006 16:46
Yes, now I understand. That's because I was playing only a part of the sound structure. Okay! IP: Logged |
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