tacman1123
7th August 2008, 02:33
First, the story.
About 2 years ago, my girlfriend's father was nearing the end of his battle with cancer. I went out and bought a video camera and lav mic, and we jumped on a plane so I could get a chance to meet him and record some memories for his family.
When I downloaded the miniDV tapes to my computer, I discovered to my horror that the audio was missing quite often. As I was very new to the camera, I thought maybe I had let the mic on and the battery had run out, or the microphone had gotten tucked under a sheet, or something. I literally couldn't sleep the night I discovered this, as he died 2 days after we arrived there, obviously no chance for a second take.
I switch cameras, switched software, but still this problem has plagued me, though never with the level of gravity of that situation. Finally this weekend I discovered what the problem was, which I'll post here in the event that someone else is going crazy looking for it.
The problem was that the lavaliere microphone is a mono-aural jack, and the Canon camera has a stereo microphone input. I discovered this by looking at some recently-recorded video and only seeing the VU meter on the left channel, not both. Some research and discussion with Mark, the technical editor of VideoMaker Magazine, pointed to the jack problem. A $3 Radio Shack adapter fixed the problem for future takes.
I'm re-importing the 6+ hours of tape I took of him, and now have a few audio issues I'd like to discuss with the experts here. On most of the clips, the audio is just on the left channel, the right channel is a faint reproduction of the voice on the left channel. I'm assuming that's some sort of noise or interference that's hardware related, the stereo input reading from the mono plug got some sort of echo.
What is the best way to extract just the left channel and add it back to the clip? IF, and I'm not certain this is the case yet, it also comes in on the right channel, should I sum the audio together and add it back? Test for something and pick one side?
In some cases, much more than I would have expected, ONLY the hum and slight voice is on the tracks. This is the most frustrating part -- no idea why at least one channel didn't come in. In some cases, it just starts happening in the middle of the tape, and I now no longer believe it was a problem with the battery or the microphone being hidden but rather some sort of audio/electrical issue that the stereo input wasn't reading the mono input. So the next question: Is there any way to de-noise the signal and see if I can extract any audio? I'm looking at SoundSoap, but was wondering if there's an Avisynth way of doing something similar.
Finally, in all cases there's a hiss or hum on the audio track. I see in the changelog that there is a function called LowPassAudio, but there seems to be no documentation on it. Could someone point me to instructions on how to use it, if it's applicable here?
Thanks in advance, this community really is a great resource for us video enthusiasts.
Tac
About 2 years ago, my girlfriend's father was nearing the end of his battle with cancer. I went out and bought a video camera and lav mic, and we jumped on a plane so I could get a chance to meet him and record some memories for his family.
When I downloaded the miniDV tapes to my computer, I discovered to my horror that the audio was missing quite often. As I was very new to the camera, I thought maybe I had let the mic on and the battery had run out, or the microphone had gotten tucked under a sheet, or something. I literally couldn't sleep the night I discovered this, as he died 2 days after we arrived there, obviously no chance for a second take.
I switch cameras, switched software, but still this problem has plagued me, though never with the level of gravity of that situation. Finally this weekend I discovered what the problem was, which I'll post here in the event that someone else is going crazy looking for it.
The problem was that the lavaliere microphone is a mono-aural jack, and the Canon camera has a stereo microphone input. I discovered this by looking at some recently-recorded video and only seeing the VU meter on the left channel, not both. Some research and discussion with Mark, the technical editor of VideoMaker Magazine, pointed to the jack problem. A $3 Radio Shack adapter fixed the problem for future takes.
I'm re-importing the 6+ hours of tape I took of him, and now have a few audio issues I'd like to discuss with the experts here. On most of the clips, the audio is just on the left channel, the right channel is a faint reproduction of the voice on the left channel. I'm assuming that's some sort of noise or interference that's hardware related, the stereo input reading from the mono plug got some sort of echo.
What is the best way to extract just the left channel and add it back to the clip? IF, and I'm not certain this is the case yet, it also comes in on the right channel, should I sum the audio together and add it back? Test for something and pick one side?
In some cases, much more than I would have expected, ONLY the hum and slight voice is on the tracks. This is the most frustrating part -- no idea why at least one channel didn't come in. In some cases, it just starts happening in the middle of the tape, and I now no longer believe it was a problem with the battery or the microphone being hidden but rather some sort of audio/electrical issue that the stereo input wasn't reading the mono input. So the next question: Is there any way to de-noise the signal and see if I can extract any audio? I'm looking at SoundSoap, but was wondering if there's an Avisynth way of doing something similar.
Finally, in all cases there's a hiss or hum on the audio track. I see in the changelog that there is a function called LowPassAudio, but there seems to be no documentation on it. Could someone point me to instructions on how to use it, if it's applicable here?
Thanks in advance, this community really is a great resource for us video enthusiasts.
Tac