On 17.05.2017 04:28, Steven Wawryk wrote:
Hello,
I've been reading up and experimenting on both the simple and async
APIs. In one experiment, I used a CLI file that sets up a set of
module-sine modules with output remapped by module-remap-sink modules
to a stream fed to a module-null-sink module.
I then wrote 2 programs, one using the simple API and the other the
async API to read date from the module-null-sink monitor source and
write the data to file (both based on examples to provide "parec"
functionality). Then I could unload either all the module-sine
modules or all the module-remap-sink modules to interrupt the data
source to the module-null-sink module.
Both programs gave the same result, which I don't completely understand.
The issues I've found are:
1. After the data source is gone, the program continues to write data
to file. There doesn't seem to be any way to detect a stream of
"zero" data using the APIs.
That is expected behavior. null-sink.monitor is not different from other
sources, which means
if there is no input to the null-sink, it will generate silence. It's
like recording from an unplugged
mic or line-in input.
2. If I run it for 20 seconds, with 10 seconds of sinusoidal data
followed by 10 seconds of null data, the file ends up with anything
from 30 to 40 seconds worth of data in it.
3. The files written from case 2, above, show the initial sinusoidal
data as expected, but then, following data stream interruption, about
5 to 10 seconds of switching back and forth between segments of
sinusoidal data and null data, before finally settling to null data
only till the end of file.
Did you test if the same happens with parec? If yes, are there any log
messages
during the time?
Can anyone explain to me why it behaves like this? Or if there's
something in the async API that I'm missing in detecting null data?
Thanks,
Steve
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