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Audio issues IOHD
First, MBP, 10.4.11, IOHD up to date firmware and software.
Last night I took part in a live web broadcast for a radio show. HDSDI 1080 60i and stereo XLR into 1 & 2, Downconvert in control panel to 525i and analog audio was selected. Feed then went to a flash site for live viewing (www.stickam.com) The video feed worked perfectly but the audio was terribly garbled. To fix it, I had to take the XLR’s to mini stereo and input to built in input on the MBP. Then it worked great. The website had a flash encoder built in and it recognized the IOHD video and also audio. I had to switch the audio to built in audio and it worked.
My question is why did the audio not pass through correctly? In the control panel, I noticed the setup tab. Don’t know how to change the settings there and I am not on my MBP now so ican’t read the choices. I do remember something like dbu settings and framerate choices.
Lastly, I could have sent the audio into my camera. I am using a Z-1 with a miranda AD converter that takes precompression HDV and converts it to 1920×1080 HDSDI. There is also an audio cable that can take the camera audio and embed it into the HDSDI cable. I should have done that but I got to the venue late and didn’t have the time to do this. I presume I would have just selected embedded 1-8 right? It almost sounded like a looping delay. I know there were some audio and video delay sliders. These were both set to zero in my original setup.
Jeff
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2 Replies
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you can’t feed an analog +4dBu signal (the XLR output of the AJA) in to http://www.stickam.com which has a stereo mini audio input (which is probably expecting a signal lower than -10dBu). You need to ATTENUATE this signal. The garbaled signal is called distortion.
The cheapest way to do this is with any cheapo audio mixer, like a Behringer, which you can get for less than $100.
You will never ever get away from using an audio mixer in our industry – no matter what product you purchase.
Bob Zelin
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Thanks Bob. I have a couple AJA ADA4’s. They have dip switches to go from +4 to -10. You think putting two of those before the IOHD would’ve worked? So I guess my MBP could take an xlr to mini and attenuate it internally? Cause that’s how we got the webcast done – 1080i60 to 535 down convert for the video and then 2 XLR’s to a mini split stereo into built in input.
One other thing I may have done wrong. I was in low light and I thought I was adjusting the gain but I accidently went from 60 frames to 30 and then to 15. When I noticed it, I went back to 60 and adjusted the gain. It might have been coincidence that is when we switched the audio. Could it have been a frame rate distortion? Also, next time I intend to send the mic feeds to the camera and then send the audio down the sdi. Will that give me the same problems?
Jeff
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