Hi,
Gerald Grabner wrote:
>Hi everybody,
>
>I'm wondering how to correctly build a shared library using alsa
>pcm. Setting the hardware parameters in a function which is part of a
>shared library produces an error, snd_pcm_hw_params gives "invalid
>argument". The example below with three primitive files (main file,
>header and function code) illustrates the problem. With a static
>library, everything works fine.
>
>My system: gcc 3.4.6 on Gentoo with alsa 1.0.11.
>
>Does anybody have an idea about the cause of this problem or how to
>solve it?
>
>Many thanks,
>Gerald
>
>***
>
>main.c:
> #include "object.h"
> int main()
> {
> object () ;
> return 0;
> }
>
>object.h:
> void object();
>
>object.c:
> #include <alsa/asoundlib.h>
> #include "object.h"
> void object ()
> {
> snd_pcm_t* pcm;
> snd_pcm_hw_params_t* hwparams;
> int rc;
> unsigned int rate = 44100;
> unsigned int channels = 2;
> int dir = 0;
> if ( snd_pcm_open(&pcm, "default", SND_PCM_STREAM_PLAYBACK, 0) < 0 )
> printf("Cannot open pcm.\n");
> snd_pcm_hw_params_alloca(&hwparams);
> snd_pcm_hw_params_any(pcm, hwparams);
> snd_pcm_hw_params_set_access(pcm, hwparams,
>SND_PCM_ACCESS_RW_INTERLEAVED);
> snd_pcm_hw_params_set_format(pcm, hwparams, SND_PCM_FORMAT_S16_LE);
> snd_pcm_hw_params_set_channels (pcm, hwparams, channels);
> snd_pcm_hw_params_set_rate_near(pcm, hwparams, &rate, &dir);
> rc = snd_pcm_hw_params(pcm, hwparams) ;
> if ( rc < 0 )
> printf("Error setting hw params: %s.\n", snd_strerror(rc));
> }
>
>Compilation:
> gcc -c -fPIC object.c
> gcc -shared -fPIC -o libTest.so object.o
> gcc -o main main.c -L. -lTest -lasound
>
>
and what if you try to link your dynamic library with asound (actually,
this is the really needer of the link, not your test program) ? I think
this could help...
gcc -shared -fPIC -o libTest.so object.o -lasound
-- Ben
>Output:
> Error setting hw params: Invalid argument.
>
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>
Using Tomcat but need to do more? Need to support web services, security?
Get stuff done quickly with pre-integrated technology to make your job easier
Download IBM WebSphere Application Server v.1.0.1 based on Apache Geronimo
http://sel.as-us.falkag.net/sel?cmd=lnk&kid=120709&bid=263057&dat=121642
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