Hello all,

I've found a simple tutorial here
http://www.linuxjournal.com/article/6735?page=0,0 and have a bit of a
problem with listing #3.

First off , when I executed the program it had a long delay executing the
"snd_pcm_hw_params_set_rate_near()" function, which turned out to be related
to the "dir" argument not being initialised (with Zero).

#1: I'm using gcc on a Raspberry Pi in geany.  Is there some sort of setting
I should add to have gcc include code to automatically clear declared
variables ?

Or should I assume that the code simply isn't complete (would explain a few
things).

#2: The length out the outputted sample doesn't seem to be five seconds,
even when the code promises it to be.

1) I checked that by clearing the buffer and only execute "rc = read(0,
buffer, size);" when the "loops" counter was zero.   No sound was to be
heard.

2) when I added an "usleep()" of a second before the "snd_pcm_drain()" call
I did hear something (read: the data was there, just not outputted)

3) I've measure the time starting just befor the loop to just after the
"snd_pcm_drain()" call using "gettimeofday()" like described here
https://www.techiedelight.com/find-execution-time-c-program/ , and the
measured time is indeed less than the promised five seconds.


#3: The problem gets even more pronounced when I changed the sampling rate
from 44100 to 8000.  After that change the sound is outputted for less than
a single second (time measured using the above method). :-(

Using the same 1) and 2) checks I found that the full five seconds of sound
data was again there, but those four seconds worth of it just doesn't get
outputted.


Can anyone confirm this behaviour  (read: its just some incomplete example
code) ?
And most important: What is missing from that code that causes the sound
output the be cut-off like that ?

I've been searching my ass off for quite some time now, but have not been
able to find anything that could shed some light on it. :-(

Regards,
Rudy Wieser

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