Calculate the memory size the acquired data takes
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Here is a simple data acquisition code:
ai=analoginput('winsound');
addchannel(ai,1);
rate=setverify(ai,'SampleRate',8000);
set(ai,'SamplesPerTrigger',8000);
set(ai,'TriggerType','Immediate');
1. daqmem(ai);
start(ai)
2. daqmem(ai)
stop (ai)
delete ai
clear ai
*1. daqmem(ai): I execute daqmem here, I get:
winsound0-AI
UsedBytes = 30.00 KB
MaxBytes = 1024.00 MB
2. daqmem(ai): I get:
winsound0-AI
UsedBytes = 16.00 KB
MaxBytes = 1024.00 MB*
UsedBytes =30.00KB, what used the memory?
UsedBytes = 16.00 KB, I know it is acquired data, but the totoal number is 8000, which is double type, how to correspond 8000 to 16 KB?
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답변 (1개)
Walter Roberson
2014년 4월 12일
As speculation: before you have done the start() the internal buffer would be the default, which might be 30 KB. In some ways it makes sense to delay re-sizing the buffer until the next start(), just in case the buffer gets resized yet again (e.g., more channels added.)
winsound normally works internally at 16 bits (2 bytes) per channel, so 8000 samples corresponds to 16000 bytes.
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