developing audio with ALSA

developing audio with ALSA

[Henry Ho]

Hi

I'm developing audio application using ALSA library. My target platform is ARM 
platform baseboard. I use GNU toolchain cross compiler as you can see from 
the following message:

arm-none-linux-gnueabi-gcc -lasound -g -O2 -I./alsa-lib-1.0.17rc2/include -o pcm pcm.c
/usr/bin/../lib/gcc/arm-none-linux-gnueabi/4.2.0/../../../../arm-none-linux-gnueabi/bin/ld: cannot find -lasound
collect2: ld returned 1 exit status
make: *** [versatile] Error 1

I know that is because the linker cannot find the asound library. Should I cross compiling 
ALSA driver/lib/utils first?

Henry
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Re: developing audio with ALSA

[Colin Guthrie]

Henry Ho wrote:
> Hi
> 
> I'm developing audio application using ALSA library. My target platform is ARM 
> platform baseboard. I use GNU toolchain cross compiler as you can see from 
> the following message:
> 
> arm-none-linux-gnueabi-gcc -lasound -g -O2 -I./alsa-lib-1.0.17rc2/include -o pcm pcm.c
> /usr/bin/../lib/gcc/arm-none-linux-gnueabi/4.2.0/../../../../arm-none-linux-gnueabi/bin/ld: cannot find -lasound
> collect2: ld returned 1 exit status
> make: *** [versatile] Error 1
> 
> I know that is because the linker cannot find the asound library. Should I cross compiling 
> ALSA driver/lib/utils first?

The drivers will possibly already be in your kernel, and the utils will 
help you initialise your sound hardware properly (set volumes, switches 
etc.).

And the library, well, you defo need that  :)

Col

Re: developing audio with ALSA

[Henry Ho]

Hi

After reading the cross-compilation instruction in INSTALL file, 
I already successfully configured the alsa-lib-2.0.17. I also 
successfully made the library. Adding --prefix=xxx during 
configuration can set the output directory to xxx.

I also modify my Makefile for application, including the search 
path of libasound.so.2.***. Now I can successfully make it.

However, when I run my application on the target, I got the following 
error message:

******************************************************************************************
./pcm: error while loading shared libraries: libasound.so.2: cannot open 
shared object file: No such file or directory
******************************************************************************************

I have put libasound.so.2.0.0 in /tmp of the target. I also modified 
/etc/ld.so.conf, adding /tmp in ld.so.conf file. However, I cannot 
find ldconfig on the target. Is anyone can tell me how to solve it?
Should I rebuild a busybox with this command?

Henry


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Re: developing audio with ALSA

[Alan Horstmann]

On Monday 18 August 2008 10:15, Henry Ho wrote:
> Hi
>
> After reading the cross-compilation instruction in INSTALL file,
> I already successfully configured the alsa-lib-2.0.17. I also
> successfully made the library. Adding --prefix=xxx during
> configuration can set the output directory to xxx.
>
> I also modify my Makefile for application, including the search
> path of libasound.so.2.***. Now I can successfully make it.
>
> However, when I run my application on the target, I got the following
> error message:
>
> ***************************************************************************
>*************** ./pcm: error while loading shared libraries: libasound.so.2:
> cannot open shared object file: No such file or directory
> ***************************************************************************
>***************
>
> I have put libasound.so.2.0.0 in /tmp of the target. I also modified
> /etc/ld.so.conf, adding /tmp in ld.so.conf file. However, I cannot
> find ldconfig on the target. Is anyone can tell me how to solve it?
> Should I rebuild a busybox with this command?

(I'm no expert); is there a link on the target from libasound.so.2 > 
libasound.so.2.0.0 ?  That should be needed to find the actual version you 
have.

Alan

Re: developing audio with ALSA

[Colin Guthrie]

Henry Ho wrote:
> Hi
> 
> After reading the cross-compilation instruction in INSTALL file, 
> I already successfully configured the alsa-lib-2.0.17. I also 
> successfully made the library. Adding --prefix=xxx during 
> configuration can set the output directory to xxx.
> 
> I also modify my Makefile for application, including the search 
> path of libasound.so.2.***. Now I can successfully make it.
> 
> However, when I run my application on the target, I got the following 
> error message:
> 
> ******************************************************************************************
> ./pcm: error while loading shared libraries: libasound.so.2: cannot open 
> shared object file: No such file or directory
> ******************************************************************************************
> 
> I have put libasound.so.2.0.0 in /tmp of the target. I also modified 
> /etc/ld.so.conf, adding /tmp in ld.so.conf file. However, I cannot 
> find ldconfig on the target. Is anyone can tell me how to solve it?
> Should I rebuild a busybox with this command?

I'm wondering if you are mixing up --prefix and DESTDIR...

--prefix is the location that should be the *running systems* path on 
normal use. Even if you have a folder on your development machine that 
is different to that. e.g. say you are booting from compact flash: on 
your dev machine this may be mounted as /media/cf, but when you use it 
to boot it is actually the / of that system.

In this case I'd recommend you do:
./configure --prefix=/usr ....
make
sudo make DESTDIR=/media/cf install

That will install things in /media/cf.

You then need to modify other parts of your build to look in /media/cf 
for stuff and to strip out /media/cf from the linking, but that's 
another story.


All that said, I'd imagine you just didn't copy the symlinks that 
accoumpany the file libasound.so.2.0.0 ... it should come sith some 
symlinks that give it the name libasound.so.2 as well. (i.e. 
libasound.so.2 is a symlink to libasound.so.2.0.0)


Col