Hey Brian, On Tue, 2011-03-15 at 09:22 -0700, Brian Gix wrote: [...] > No this is the incorrect approach. Thanks (to you and Johan) for the detailed explanation! :) > Both SRC and SNK devices have a variety of endpoints that have > capabilities describing what that endpoint is capable of, the most > important of which is the Codec Capability. Each endpoint is allowed a > single capability of a particular type, which means that an endpoint > that supports SBC should not attempt to use a different codec (for MPEG > in this case). Any device that attempts to wedge both codecs into a > single endpoint would most definitely be non-compliant. > > The SUSPEND/RECONFIGURE/START procedure will not work to switch between > SBC and MPEG for this reason. The purpose for that procedure is to > allow quick changes within the bounds of the current (remote and local) > endpoint capabilities. To quickly switch between a 44.1KHz and 48KHz > sampling for instance. > > The correct procedure to switch between SBC and MPEG would be to close > the existing media channel (but NOT the AVDTP signaling channel) and > reset up a new endpoint. If you know you will be doing this, you can > save time by caching all of the remote devices endpoints the first time > you do an AVDTP_DISCOVER, so that you have all the remote endpoint info > you need to make the switch (and even know if the switch will work). You > also should have all supported local endpoints separated into their own > endpoints of course. > > The to switch, you will need to: > > <halt streaming> > > AVDTP_CLOSE (on AVDTP signaling channel) > > L2CAP_CLOSE (close the media L2CAP channel for SBC) > > <<<< You should Rx AVDTP_CLOSE_CFM > > AVDTP_SET_CONFIG (on AVDTP signaling channel, > specify a local and remote endpoint that are compatible) > > <<<<< You should Rx SET_CONFIG_CFM > > AVDTP_OPEN (on AVDTP signaling channel) > > L2CAP_OPEN (open new media L2CAP channel for MPEG) > > <<<<< You should Rx AVDTP_OPEN_CFM > > AVDTP_START (on AVDTP signaling channel) > > <<<<< You should Rx AVDTP_START_CFM > > <start streaming> I'm quite unfamiliar with how this works, so please excuse any wild inaccuracies in terminology. I believe that I am doing it this way already (mostly discovered by trial and error). When I want to reconfigure, I do the following: - Send a BT_STOP_STREAM request, get the expected response - Send a BT_CLOSE request, get the expected response - Send a BT_OPEN request with the new seid, get the expected response - Send a BT_SET_CONFIGURATION request with the new caps, get the expected response - Send a BT_START_STREAM, wait for the response - Start streaming This actually does work here after I apply my patch, although switching sample rates doesn't seem to actually happen (probably just something broken in my code). So if I understand this correctly, it should be sufficient to modify my patch so we only search for a new remote endpoint if the local endpoint changed (or a more specific change limited to if the codec type changed)? Cheers, Arun -- To unsubscribe from this list: send the line "unsubscribe linux-bluetooth" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
