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Thread: What is the hold up? (BT)

  1. #1
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    What is the hold up? (BT)

    I've been waiting for SD to release with BT for quite some time. I remember waiting for BT last year and still nothing in site as for a release date.

    I get that there are issues with software, but is it going to be another year or should I just stop waiting and just buy another program.

    Thanks for your input.

  2. #2
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    I was in the same boat and figured it was coming soon since the dongle went on pre order a very long time ago. I purchased SD and am still waiting

  3. #3
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    Still ironing out some bugs in the software.
    Jan Bennett
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  4. #4
    Raw Wave god_of_cpu's Avatar
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    We are mostly still looking for a viable solution for echo cancellation which has become a hardware project above and beyond what we have already done.
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  5. #5
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    Echo cancellation

    Something that is not really common knowledge...

    Many cellphones have echo cancellation capabilities over bluetooth. In general, these solutions are MUCH better than most other solutions out there (think dozens of Signal Processing researchers working at Qualcomm/Nokia/Motorolla with many many years of experience). Now this does not really help you, but what I wanted to make sure to mention is that if the phone supports this functionality (and you can query this by an AT command that escapes me right now) you should disable your echo cancellation solution as they will interfere with each other and will sound terrible.

    Hopefully this will save you some debugging time,

    Mark


    p.s. Can't wait for SD BT integration - next year our wonderfull Washington legislature comes into effect making cellphone conversations in cars illegal without car kits!

  6. #6
    Raw Wave god_of_cpu's Avatar
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    I don't see how this is possible. I don't doubt that cell phones have built in echo cancellation and you may be able to turn it on and off over bluetooth (the only thing in the GSM AT specification about this though is turning on and off echoing of commands, not echo cancellation of audio), but I don't think it works for audio over bluetooth and I have never seen it work and don't think its theoretically possible with the current state of the art of echo cancellation that I have been exposed to.

    To do echo cancellation, the algorithm has to match up the incoming microphone audio with the what was previously played over the speakers. When you are talking about audio over bluetooth, when cellphone audio is heard over your speakers, it first has to go from the from the cellphone over bluetooth, into the PC, through the PC processing, then out the speakers, there is a good deal of latency in this, usually around a second and it is more often then not a variable amount of latency that varies by a few ms which is enough to pretty much destroy every echo canceling algorithm I have ever seen since it can no longer consistently match up the incoming microphone audio with the exact time it was played over the speakers.

    I have never even seen an echo canceller that can work between different sound cards. i.e. one device is recording while another sound card is playing. The only time I have ever seen echo cancellation work is when both incoming and outgoing audio is played thorugh the same device, there is minimal delay from when the speaker audio is played and when the microphone records it (< 10 ms)
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  7. #7
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    forgive me a head of time for being clueless on the subject but is echo cancellation needed to have bt work out of the gates? I am only asking because I will be happy with a semi decent working BT setup with my SD rather then waiting 2 years for a perfected solution.

    I would even like if you could have a phone book and integrated BT where I atleast know when my phone is ringing in my car to pick it up. I don't even need hands free for now.

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    Human voices typically have a limited range in pitch. Cancelling high and low pitches that we humans cannot recereate, would be a starting point!

    Mobile phones do have echo cancellation but I do not believe it works over bluetooth.

    The mobile phone can be thought of simply as a modem. It receives and sends signals.

    A mobile phone will receive a signal, transform that into a bluetooth signal, the bluetooth signal will convert the bluetooth signal into something a computer can read, the software will interpret that signal and convey it to the end user and vice versa.

    Most soundcard software already feature a echo cancellation already built in and there are directional microphones available that is supposed to cut down on background and echo noise. I got one free with my asus crosshair motherboard.

    Remember when using bluetooth for phone calls, you are not using the phone's microphone, but a standalone mic that you plug into the same soundcard as the speakers??. I.e "Bluetooth Headset" Why would you have two soundcards anyway??

    I don't see why latency issues will be over 1 second anyhow. Once second might not be alot of time, if say your driving 300 miles, but 1 second in electronics is an eternity.

    AQlso if latency is such an issue, look up ASIO drivers for creative products. That pretty much bypasses the CPU and offloads it straight to the soundcard, so there is less latency??

  9. #9
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    Quote Originally Posted by BiG K View Post
    Most soundcard software already feature a echo cancellation already built in and there are directional microphones available that is supposed to cut down on background and echo noise. I got one free with my asus crosshair motherboard.
    This is already noted in the current implementation. The mics that are avaliable on the store have been found to be the best solutions currently but they are not the end-all-be-all solutions.

    AQlso if latency is such an issue, look up ASIO drivers for creative products. That pretty much bypasses the CPU and offloads it straight to the soundcard, so there is less latency??
    That's assuming that every customer is going to be using a Creative sound card, which is just not something we as a company can assume and something that the developers of SD can assume.
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  10. #10
    Raw Wave god_of_cpu's Avatar
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    Quote Originally Posted by BiG K View Post
    Human voices typically have a limited range in pitch. Cancelling high and low pitches that we humans cannot recereate, would be a starting point!
    The echo we are trying to cancel is the human voice of the person you are talking to. Noise cancellation is not the problem at hand.

    Quote Originally Posted by BiG K View Post
    Most soundcard software already feature a echo cancellation already built in and there are directional microphones available that is supposed to cut down on background and echo noise. I got one free with my asus crosshair motherboard.
    No, most sound card software do not have this feature. There are some that do, however, every one that we have evaluated thus far did terribly at echo cancellation and hasn't lived up to the claims. This includes the Andrea microphones that come with systems like the ASUS crosshair. Don't get me wrong, the Andrea mics are fantastic at noise cancellation, but they do echo cancellation nearly as well. Its significantly harder to do echo cancellation in an array microphone.

    Quote Originally Posted by BiG K View Post
    Remember when using bluetooth for phone calls, you are not using the phone's microphone, but a standalone mic that you plug into the same soundcard as the speakers??. I.e "Bluetooth Headset" Why would you have two soundcards anyway??
    The only way it will work is if you plug the microphone into the same sound card, the problem is USB microphones won't work and most USB speaker phones have low quality sound cards in them that are great for voice but not so good for music.

    Quote Originally Posted by BiG K View Post
    I don't see why latency issues will be over 1 second anyhow. Once second might not be alot of time, if say your driving 300 miles, but 1 second in electronics is an eternity.
    You are assuming a perfect connection. The problem is packet loss so some packets are sent out of order and others are simply dropped and have to be resent. If the audio is not buffered, you will get blips and generally distorted audio. The audio also has to pass through a computer which is not a real time hardware system and is running many other tasks.

    Quote Originally Posted by BiG K View Post
    AQlso if latency is such an issue, look up ASIO drivers for creative products. That pretty much bypasses the CPU and offloads it straight to the soundcard, so there is less latency??
    Been there, done that. In any case, its possible to do echo cancellation on a number of PCI cards we tried even without ASIO drivers. Problem is most people can not install a PCI sound card. Also, the problem is not really latency its more that there is a variable amount of latency between the speaker output of a sound card and the microphone input. i.e. the sound card will output 8000 samples in a second, but it will only capture 7089 samples in a second. To perform echo cancellation, you have to capture the same exact number of samples that were output. None of the USB based creative cards I tested were able to do this.


    I've evaluated several different products, every audio product on the MP3Car store and more. I know you can do echo cancellation on the computer. I know there are products that claim to do it, but are impractical to get working or just don't function as designed. The problem that needs to be solved is how do it for the types of systems people install in their cars. What I am interested in hearing is any experience in which you have used an external USB sound card to do echo cancellation and seen for yourself that it actually works.
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