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Posted by Neil Smith [MVP Digital Media] on 02/01/06 11:56
On Tue, 31 Jan 2006 19:00:14 +0000, Margolotta
<naggingdoubt@thebackofyourmind.invalid> wrote:
>Apologies if I'm in the wrong group, but my server doesn't appear to carry a
>Mac-specific video group, nor can I find one for Final Cut Pro, which a
>friend has lent me because iMovie just wasn't cutting it.
>
>I know next to nothing about shooting video (I'm more of a stills girl) and
>have just shot 20 minutes of DV and was shocked to discover that ti's taking
>up 4.5GB!
I'd expect it to be about that rate, yes : See WikiPedia for gory
details http://en.wikipedia.org/wiki/MiniDV#Video_compression
> I need to edit it (I reckon at least half is surplus to
>requirements, if not more),
OK so you're down to 10 minutes, about 2.2GB or so as long as you
avoid any heavy duty transitions between scenes.
Later on, when you compress it, transitions such as fades can cause
the encoder to work much harder, inecreasing the bit rate needed to
get a good picture. If you're trying to get near 10MB I'd stick to
scene jumps or wipes (mentioned by sbdy earlier in the week in this
group) rather than anything fancy. Make it very basic edits.
> enhance the lighting (it's quite dark
All video editing packages I can think of can increase the overall
level to a degree. But there's a small chance your camcorder will have
introduced some noise onto the picture by increasing it's gain to get
a better picture.
Noise is another thing that makes good compression hard to achieve, as
the encoder assumes it's "signal" and tries to reproduce it.
> and out of focus as my camcorder - Canon MV400i - seems to have a problem with
That's going to be more of a problem, and there are only limited
things you can do to mitigate that. Since you're *definitely* going to
be reducing the image size to reach 10MB, it might not be as
noticeable in the finished product, depends how bad it is.
There are very few ways to recover badly focused content, other than
re-taking the video if it's possible to do that it could be your best
shot.
>autofocus, but I cannot afford to replace it) and compress it so that it's
>under 10MB as I need to email (and I have been instructed to email) it to a
>friend who has a single-line ISDN connection.
>
>Just thought, the audio could do with enhancing as well as the built-in mic
>seems to pick up more background noise than what it's actually supposed to be
>recording and, although I thought I was speaking clearly, apparently I
>wasn't, and all you can hear are the cars going past the window (I live on a
>main road).
OMG and the audio is knackered too ? Sheesh ! Although it's possible
to mask some noise, for example constant rumble - or reduce it using a
"graphic equaliser" and isolate just the spoken word, it's not that
easy to get good results, and is really a trial and error job.
I had to do this before, and I ended up splitting the audio track out
from the video. I then loaded the audio into SoundForge (but Audacity
would work just as well)
Audacity is free from http://audacity.sourceforge.net/
I then tried to cut down the high end 'hiss' noise as well as low-end
'rumble' using the graphic EQ. You can also try to enhance the voice
range a bit, usually boost the middle of the range will help. There's
a general discussion of this on the sound-on-sound website :
http://www.soundonsound.com/sos/Aug01/articles/usingeq.asp
At the end, you'll have to re-introduce the audio track to the video.
Probably you want to do your edits first, then export the combined
audio clips as a single file.
That way it's easy to slide it back into position on the timeline
rather than having to try to line up multiple audio clips so they stay
in lip-sync with the actor.
>Is this possible? FCP has me completely overwhelmed. I'd like to lose as
>little quality as possible (though, obviously, I'm going to lose a helluva
>lot, compressing it that much!)
You also have to consider what format can be played by the recipient.
If they're on a PC you might consider windows media format, but to
create that on your Mac you'll need to buy the Flip4Mac component for
Quicktime (Flip4Mac WMV Studio ), about £30 GBP / $49
http://www.flip4mac.com/wmv_upgrades.htm
You could dump it out as H264 video, that would get very good
compression in theory - but the recipient would probably need
Quicktime 7 installed for playback. And the encode time is very long
even with good hardware, so you'll have some time to spend getting the
settings right.
I'd probably start by taking the video down to 1/4 size (half width
and height) to reduce the bitrate. I don't know about the content but
it sound like it's a talking-head indoor sort of clip.
You might well be able to compromise and reduce the video rate to 15
frames per second there, and save a little encoded bitrate. 1Meg per
minute is still not-very-much even with good codecs though.
It works out to about 133kbps (kilobits / second) and you have to use
Audio on top of that, so probably at least 20-48kbps shaved off it.
That gives you about 95kbps for your video part of the content, which
is very little, really. It's going to mean a hige compromise in the
content quality - so get the best you can out of the video initially
and you'll still have to work hard to get that down to 130kbps average
video rate.
You can use "VBR" variable bitrate in some cases, which can reduce the
overall bitrate use of sections of video with almost no movement, and
give it back to those sections with significant movement between
frames.
>I shall be shooting again on Friday (have just had to order another batch of
>tapes) and I don't want to run into the same problems, so I need a little
>education before then if at all possible.
You haven't got much time - better start burning the midnight oil !
HTH
Cheers - Neil
MVP Digital Media [2004-2006]
http://mvp.support.microsoft.com
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