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  1.    #1  
    I've read for a for a while now that while we can hook up a Treo with A2DP to stereo BT headsets with Softick Audio Gateway, there's no way to hook up music (or streaming talk radio or audiobooks) through a mono BT headset. Well, what I don't understand is this: why is it that you can do it with a Windows Mobile phone?

    I have a TMobile SDA (actually using it unlocked through Cingular), and I found a free program on the internet called BTaudio, and it sends all audio in the device through the BT headset. Now I'd rather be using a Treo, but I got two buggy 680's that I returned, and there's a few things that I really appreciate that this phone does that my Treo doesn't do. Somehow I was under the impression that this was too advanced to do. Well, you can do it on another OS. What's taking Palm developers so long?
  2. #2  
    Quote Originally Posted by libmanj View Post
    I've read for a for a while now that while we can hook up a Treo with A2DP to stereo BT headsets with Softick Audio Gateway, there's no way to hook up music (or streaming talk radio or audiobooks) through a mono BT headset. Well, what I don't understand is this: why is it that you can do it with a Windows Mobile phone?

    I have a TMobile SDA (actually using it unlocked through Cingular), and I found a free program on the internet called BTaudio, and it sends all audio in the device through the BT headset. Now I'd rather be using a Treo, but I got two buggy 680's that I returned, and there's a few things that I really appreciate that this phone does that my Treo doesn't do. Somehow I was under the impression that this was too advanced to do. Well, you can do it on another OS. What's taking Palm developers so long?
    The answer is a little complicated, but it has to do partially with the plumbing of the Treo, the difference between mono and stereo Bluetooth audio, and the lack of an audio mixer in the Palm OS.

    Mono audio in Bluetooth is transmitted on special connections called SCO Links. In most Bluetooth radio modules, audio can be sent directly from the audio hardware of a device to a pin on the Bluetooth chip, which then transmits the audio over the SCO Link. This is what Treo does. In order for an application to do what BTaudio does, it would need access to the Bluetooth stack to create SCO Links (no API is provided to do this), as well as the ability to pipe audio from a media player to the Bluetooth chip (no audio mixer exists to mix the system audio into the audio that is transmitted over the SCO Link).

    Stereo Audio is quite different. It is transmitted over connections called ACL Links. ACL Links are used to transmit all kinds of data, and PalmOS has an API for sending and receiving data over these kinds of links. SAG is basically an application that accesses the PalmOS system audio, encodes the audio into the proper format (SBC), and then transmits the data using the provided API.

    I'm not saying that it is impossible to create an app like BtAudio for the Treo, but it will take a significant amount of undocumented knowledge about the Bluetooth on the Treo to do it. That is probably why you don't see an application yet.
    The wise man breaks wind and is gone... - J. Tull
  3.    #3  
    Quote Originally Posted by paesano View Post
    The answer is a little complicated, but it has to do partially with the plumbing of the Treo, the difference between mono and stereo Bluetooth audio, and the lack of an audio mixer in the Palm OS.

    Mono audio in Bluetooth is transmitted on special connections called SCO Links. In most Bluetooth radio modules, audio can be sent directly from the audio hardware of a device to a pin on the Bluetooth chip, which then transmits the audio over the SCO Link. This is what Treo does. In order for an application to do what BTaudio does, it would need access to the Bluetooth stack to create SCO Links (no API is provided to do this), as well as the ability to pipe audio from a media player to the Bluetooth chip (no audio mixer exists to mix the system audio into the audio that is transmitted over the SCO Link).

    Stereo Audio is quite different. It is transmitted over connections called ACL Links. ACL Links are used to transmit all kinds of data, and PalmOS has an API for sending and receiving data over these kinds of links. SAG is basically an application that accesses the PalmOS system audio, encodes the audio into the proper format (SBC), and then transmits the data using the provided API.

    I'm not saying that it is impossible to create an app like BtAudio for the Treo, but it will take a significant amount of undocumented knowledge about the Bluetooth on the Treo to do it. That is probably why you don't see an application yet.
    This is a heck of a specific answer. Thanks.

    So does my Windows Smartphone have an audio mixer? Is that why I can do this successfully with that phone?
  4. #4  
    Quote Originally Posted by paesano View Post
    The answer is a little complicated, but it has to do partially with the plumbing of the Treo, the difference between mono and stereo Bluetooth audio, and the lack of an audio mixer in the Palm OS.

    Mono audio in Bluetooth is transmitted on special connections called SCO Links. In most Bluetooth radio modules, audio can be sent directly from the audio hardware of a device to a pin on the Bluetooth chip, which then transmits the audio over the SCO Link. This is what Treo does. In order for an application to do what BTaudio does, it would need access to the Bluetooth stack to create SCO Links (no API is provided to do this), as well as the ability to pipe audio from a media player to the Bluetooth chip (no audio mixer exists to mix the system audio into the audio that is transmitted over the SCO Link).

    Stereo Audio is quite different. It is transmitted over connections called ACL Links. ACL Links are used to transmit all kinds of data, and PalmOS has an API for sending and receiving data over these kinds of links. SAG is basically an application that accesses the PalmOS system audio, encodes the audio into the proper format (SBC), and then transmits the data using the provided API.

    I'm not saying that it is impossible to create an app like BtAudio for the Treo, but it will take a significant amount of undocumented knowledge about the Bluetooth on the Treo to do it. That is probably why you don't see an application yet.
    Great Post! Way to help a lot of people out, including myself!
  5. #5  
    Quote Originally Posted by libmanj View Post
    This is a heck of a specific answer. Thanks.

    So does my Windows Smartphone have an audio mixer? Is that why I can do this successfully with that phone?
    Possibly. I don't know much about Windows Smartphones, but it may have the ability to mix the system audio and the phone audio. It may also just be able to use an alternate interface to the Bluetooth radio for transmitting audio data. There are other ways to send mono audio over a SCO link (as opposed to using a hard-wired connection to a pin on the chip).
    The wise man breaks wind and is gone... - J. Tull

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