Technical Test Thread

I recently installed an audio recording program called Audacity (open source freeware), thinking that sometimes all you want is the sound and it would be less heavy on resources... Well, I had a go but it wouldn't record anything so I went on the forum and was told that it won't record from video+audio stream, must be audio-only :-(

HOWEVER, I had a whinge about this 'n that and a kind chap demo'd how Audacity, with a plug-in, can remove "mains hum", which is a great part of what we were suffering from last season at LG (nothing to do with broadband, he said).  Dig this :o

He said:

That’s a far worse example : There’s hum at (least) two different fundamental frequencies on that one, and their harmonics occupy much more of the sound spectrum than the previous owl example.

If most of those mains hum harmonic frequencies are removed there’s very little left of the eagle sound , (and using lots of notch filters introduce their own type of distortion called ringing).

But nevertheless I’ve had a go, you can see (and download) the result from the google link below …

LOOK WHAT HE DID!!!!  docs.google.com/.../edit

If I left more hum behind the eagle noises would be less distorted: it's a trade-off.

BTW1 the electrocution-type noise from 10-16seconds is irreparable.

BTW2 the audio is out of sync with the video, which is correctable with a video editor, but I've left as is.

BTW3 the mains hum noises, (60Hz USA, 50Hz UK), are not caused by broadband:

They would be on the video’s audio before it was transmitted over ‘tinternet.

BTW4 you can get a plugin to de-hum audio in audacity here ... viewtopic.php?p=79907#p79907

I do wish I could get my head around Audacity but just looking at it causes implosion :o

scylla   That is a wonderful piece of work. Mind you it reminds me how pretty Cally is.

I thought it was so kind of him.  The program itself is rather like VLC but audio - but the help on the forum is not like VLC, where the authors reply with 3-4 word answers that might as well be hieroglyphics :-(  If only I could begin to understand it (Audacity, that is) :-/

scylla said:

If only I could begin to understand it (Audacity, that is) :-/

Knowing about it is the first step to understanding it. Clearly ospreys have led to a whole new passion for you.

That is brilliant scylla :)

I have Audacity on my desktop but have yet to investigate it properly.

Agree with ChloeB, Scylla  you are so clever, Thank you, it is so wonderful watching the Ospreys( and others) knowing, you are around capturing all the amazing events, for us all to view at our leisure.

It really is appreciated...

Now come on 'take the plunge and work through the 'Audacity' in stages, instead of trying to understand the whole works at first..You CAN do it...

Thanks again

Kate.

Good stuff scylla, and well done to the helpful forum poster - you see, they do exist ;-)

I was pretty sure myself that the noise was introduced at the site, and the observation of mains hum would agree with what I saw of the jerry-built microphone amplifier in the forward hide (where the audio and video feeds come in before being sent off to the osprey centre, and thence t'Internet). I have no idea how old it is, but it's the sort of thing I would have built in my youth. From my experience of converting old battery-powered radios to mains use, mains hum can be a real problem in audio circuits. Of course in the early days there it would probably have run off a battery, and there would have been no such problems. I think the whole system at Loch Garten needs 'renovating'.

The VLC forum is not for the feint-hearted, or more correctly the non-geeks it would appear. I don't like that kind of attitude myself, but that seems to be the culture over there. I can understand most of it myself, but it's not helpful to non-programmers! If I can find the time (and brain power!) to get to grips with the internals of VLC, I may be of some help in this area.....

Nice one SCYLLA :-) Great work by the helpful forumite de-humming your video....what a difference!

I have used Audacity but not a huge lot and certainly have not tried to de-click or de-hum any audio streams....yet! (must check out the plugin) :-)

How nice to long-time-no-see you, BADGIE :-)

RtB, I'm longing for the day you mastermind a timeline for VLC, but you know that already.  I managed to write something that put the date and time on everything you played but couldn't do what's needed, current at time of recording.

As far as Audacity goes, I just can't seem to concentrate or focus on new things any more - I am the proverbial old dog :o

Scylla that video sure shows Caledonia to be the beauty that she is, with or without noise it was great seeing it again.