> Message: 2 > Date: Sat, 14 Apr 2012 09:35:54 +0700 > From: Benny Prijono<bennylp@xxxxxxxxx> > To: pjsip list<pjsip at lists.pjsip.org> > Subject: Re: overcome the sound device > Message-ID: > <CAN6v_a_FikUMh7mUnba1-NGRNMgUWA53nK6pwJxzT+fWFjGArg at mail.gmail.com> > Content-Type: text/plain; charset="iso-8859-1" > > 2012/4/12 Mario Raffin<raffin at ermes-cctv.com> > > Dear All, > I trying to use pjsip with an ARM9 architecture with sound device and > co-processor for echo cancellation and a-law and u-law. > > In order to use the co-processor features (echo, a-law, u-law) I see > different choices: > > 1) use audio driver and modify the Sound Device Port to use my echo lib > and pjmedia for the codecs; > > 2) work at the Audio device API abstraction level as for the APS and VAS; > > 3) work at the Sound Device port level implementing my own port with > get_frame and put_frame functions which provide echo cancelled PCM audio > frames to the conference bridge obtained through the co-processor lib I > have. Eventually I can the modify pjmedia perform u-law and a-law with the > coprocessor library; > > This last solution appears the simplest but I am not sure about the > timings. Since the timings are defined by the audio device, how can I make > sure that the Conference bridge receives frames with a correct cadence? Is > it sufficent to make a blocking function "get_frame" which for instance > provides 160 samples each 20ms (at 8Khz)? > > > Yes that should be sufficient. But the problem with solution 1 and 3 is > they all require modification to pjmedia, with more modifications in > solution 3 than solution 1. This is not good in the long run and I always > discourage this. Solution 2 is then the cleanest, you can bunde the > audio_dev code with your app and register the devices to the audio_dev > manager at run-time. > > -Benny Thank you for your detailed answer, Benny. The idea was to use the strategy 3 with no modifications to pjmedia but it seems not possible since pjmedia try to open the audio driver I have already opened and it returns an error (Unable to find default audio device). So I would opt for the cleanest solution. While the way to register a new device is well documented, it is still not clear how manage the audio_dev code. Have I to build a new audio driver? It is not clear to me, for instance, how can be used the null_dev.c device in pjmedia-audiodev. I also wonder if in order to create my new device I have to follow the procedure descibed here: https://trac.pjsip.org/repos/wiki/External_Sound_Device Thank you, mario -------------- next part -------------- A non-text attachment was scrubbed... Name: raffin.vcf Type: text/x-vcard Size: 266 bytes Desc: not available URL: <http://lists.pjsip.org/pipermail/pjsip_lists.pjsip.org/attachments/20120419/63676fd6/attachment.vcf>
