USB Audio Input??? - page 5 - Feature Requests - CHDK Forum
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USB Audio Input???

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Offline cybercom

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Re: USB Audio Input???
« Reply #40 on: 08 / May / 2008, 10:46:13 »
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Yes, that could give us some insight into how to use the USB data stream info from a USB Mixer.

The above method should help us find the relevant buffers to use for throughput.
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Offline BB

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Re: USB Audio Input???
« Reply #41 on: 08 / May / 2008, 11:46:33 »
If the state of CHKD is still what I think it is--finding the communications and control hooks for the USB controller in the camera is still the first stopping point...

At the risk of making another off-thread suggestion (assuming that USB comm is not happening soon)...  :'(

The only other high speed method, that I am aware of, which can access camera data while the camera is operating are the Wifi type SD Cards...

I don't have any experience with them, but for a $100, it might be worth experimenting with a Eye-Fi &raquo; Home 2GB card...

Plug the USB mixer into a WiFi enabled laptop and a process monitor would allow you to download the USB sound and the Camera video (once the recording has been stopped) to the laptop for immediate "joining" (software work required to automate).

You would still need to sync the start of the video with the start of the USB audio recording... You could use the computer to control the USB remote to start/stop the camera (or use the auto-focus LED under uBasic control fed back to the laptop)--you would get withing ~10mseconds--or possibly down to the 10usec. syncing of data (look at the stereo camera threads--I think with their software/process they go to <10usec sync between the two cameras).

Another "exact" sync possibility would be to place a small transducer at both the camera and USB mic's and emit a click a few 10's of mseconds into the recording and look for that when aligning.

Another method would be to simply log the video start time (from file and/or sync pulse from camera to USB recording computer) with the USB audio file (tag or log file)--again using the Eye-Fi card to access the camera data in near real time.

-Bill  :-X
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Offline cybercom

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Re: USB Audio Input???
« Reply #42 on: 08 / May / 2008, 12:16:48 »
Quote from: cybercom on 24 / April / 2008, 08:08:47
please, let's stay on the topic of the feature request, "USB Audio."

We do not want to start chasing other ideas and recommendations about ways to do audio recording in the field. Just how to get USB audio directly into a CANON camera's USB port.

I'm not being dismissive of input, but do try to understand that I am coming at this concept with an immense body of experience behind me. If there was some other, better way to accomplish what I'm trying to do, I would not have submitted this feature request in the first place.

Second guessing the concept from a position of "...what I think..." and "...don't have any experience with..." brings nothing of solid value to the discussion and simply diverts attention and energy away from the main points by making people read through inapplicable and inappropriate off-topic ideas, especially repetitious ideas that have already been addressed earlier.

Perhaps you could help out by doing udumper dumps and comparisons as mentioned in my previous post? This would be really useful in finding the available buffers used by the camera, thus adding to the Forum's body of USB knowledge.

TIA,
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Offline cybercom

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Re: USB Audio Input???
« Reply #43 on: 08 / May / 2008, 12:38:36 »
@PhyrePhoX,

While I was a little disappointed to find that gphoto is Unix only, these libraries may have code that can be used to open the USB Port to the outside world by addressing the Host hardware on board the camera.

Could you please look at the code sometime and see?

TIA,
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Offline BB

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Re: USB Audio Input???
« Reply #44 on: 08 / May / 2008, 12:59:53 »
Quote from: cybercom on 08 / May / 2008, 12:16:48
Perhaps you could help out by doing udumper dumps and comparisons as mentioned in my previous post? This would be really useful in finding the available buffers used by the camera, thus adding to the Forum's body of USB knowledge.

TIA,

As far as I know--finding the buffers by themselves will achieve nothing... You have currently have no method of communicating high speed digital real time data into the camera if you do not address CHDK lack of USB communications hooks (let alone the question of processor overhead and bandwidth available to run video+USB+memory data streams.

Since you seem to be ignoring the lack of USB support--I was suggesting the only other high speed data access method that I have seen that may work via Eye-Fi.

If, on the other hand you  have already solve the USB comm support issue (real time bi-directional communications between a USB device/host and CHDK while the camera is otherwise operational--taking videos in this case)--I am sure that everyone here would be very excited to port it to CHDK.

-Bill
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Offline PhyrePhoX

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Re: USB Audio Input???
« Reply #45 on: 08 / May / 2008, 15:25:46 »
Quote from: cybercom on 08 / May / 2008, 12:38:36
@PhyrePhoX,

While I was a little disappointed to find that gphoto is Unix only, these libraries may have code that can be used to open the USB Port to the outside world by addressing the Host hardware on board the camera.

Could you please look at the code sometime and see?

TIA,
i think we will have more success if we examine the official canon sdks. so far i couldnt find one for my s3is (or a620 that is).
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Offline cybercom

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Re: USB Audio Input???
« Reply #46 on: 22 / May / 2008, 15:29:31 »
I'm once again on the road with limited access to the forum, but I will begin some of the R&D mentioned in the above thread when I return.

I'm glad to see the link to this thread. Please vote for #38...!!!

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