Hello Takashi, Thanks for your response. On 10/5/06, Takashi Iwai <tiwai@xxxxxxx> wrote: > At Thu, 5 Oct 2006 10:26:18 -0400, > Eduardo Valentin wrote: > > > > Hello all, > > > > > > I'd like to announce an alsa plugin project to add support for > > ALSA application on nokia 770. I'd like also to ask you comments and > > suggestions about the code. > > > > Although n770 hasn't ALSA kernel driver, it is possible to write a > > user-space driver to communicate with n770's audio system. > > Great, does the plugin work well? yes, it does. I tested it with aplay, arecord, alsamixer, amixer, mplayer and alsaplayer. Of course, there are some issues. There is a list of limitations in the end of REAME file. I'll put it here: - Some application does not recognize the plugin (ekiga, for example). I think that they look for real card. These are related to the n770 audio system: - While the plugin is using a pcm task node, another applications, for example gstreamer, can not use the same task node. This will cause unexpected behaviour. - To prevent more than one application access per task node, I need to do a processes synchronization. I did it using semaphores from libc (sys/sem.h). However, If an application does not close alsa device properly, this plugin will not have chance to release all reserved resouces. One expected behaviour in this case is to have -EBUSY error for following applications whose try to open the same alsa device. This issue was partialy solved (version 0.6) with __attribute__((destructor)) functions. But if the application receives an uncaught signal, resources may be kept unreleased. - If many requests to volume information read / write is done in the same alsa device while it is being used to do playback, this playback could be affected and some little stops can be heard. > > > The n770's audio system is based on DSP gateway project: > > (http://dspgateway.sourceforge.net/pub/index.php) > > > > To add ALSA support, an EXT PCM I/O plugin and EXT CTL plugin were > > written. The code is based on SDK documentation from the alsa-project > > site. > > > > The project is in garage.maemo: > > https://garage.maemo.org/projects/dsp-alsa/ > > > > You can have a look at its REAME file in: > > https://garage.maemo.org/plugins/scmsvn/viewcvs.php/alsa-plugin/debian/README?root=dsp-alsa&view=markup > > > > It is possible also to browse the its source code svn repository in: > > https://garage.maemo.org/plugins/scmsvn/viewcvs.php/alsa-plugin/?root=dsp-alsa > > The code looks good at a short glance. > (But what is the reason to include <linux/soundcard.h>?) Just a mistake. Thanks to advice me. > > Do you think of merging this to upstream (likely in alsa-plugins > repository)? It would be a great. But how would it happen? What is the process/requirements to merge it? > > > thanks, > > Takashi > -- Eduardo Bezerra Valentin ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys -- and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ Alsa-devel mailing list Alsa-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-devel
