Re: new-B: xternal card for AD conversion?
- From: "Richard Crowley" <rcrowley@xxxxxxxxx>
- Date: Sun, 5 Mar 2006 12:28:22 -0800
"spud" wrote ...
"Richard Crowley" wrote:"arrya deefmon" wrote ...I guess I should have been more specific. What I meant to say was aThank you, I have now read some reviews of the Canopus
ADVC on your recommendation and I still don't understand
what file extension I end up with after the proprietary
Canopus chip has transferred the video/sound.
The Canopus products (and many others from other vendors)
convert analog video (composite or Y/C) into DV (Digital
Video) via Firewire/1394.
Note that there are other ways of digitizing video/audio.
Particularly the method that digitizes/compresses analog
video & audio directly into MPEG, etc.
One user said the only problem is 1 hour = approximately
13GB,
13.7GB/hour is the standard for DV-encoded video.
which seems wrong to me. A DVD movie is about
2.2G per hour
MPEG is variable-rate and 2.2GB/hour is likely toward
the high end. It could be compressed even more than
that.
commercial DVD movie release being roughly 2 hours at about 4.7G is
somewhere around 2.2G per hour, way different than transferred
firewire digital at 13G, which will obviously have to be dealt with to
get back to a manageable size again. I see you clarified this for me
below.
Note that DV and MPEG are two different ways of
compressing digital video. DV is compressed ~5:1
in the camcorder, while MPEG is compressed up to
10x more than that. Video frames are compressed
separately and independently in DV
MPEG does not contain all the frames. It contains only
full frames every 5~10 frames, and "difference information"
about what changes inbetween frames. This is called
"temporal compression" It makes the files smaller
so they can fit many hours on a 4.7GB (single-layer)
DVD disc.
This is good. But the flipside of that coin is that the
video quality suffers due to irretrievably discarding
the majority of the video information. Commercial
DVDs are hand-encoded where skilled humans
decide, scene-by-scene, how much to compress the
video to stay within the "budget" of the overall disc
size vs. how much they want to cram in there.
that explains the size difference.
The kind of MPEG encoders most of us use at home
are not this good and produce results which may look
as good as commercial DVDs, but also has the potential
to look significantly worse, depending on the content
of the video and the static compression ratio setting
you selected (or the software selected for you).
This ratio is non adjustable in the ADVC 100, correct?
The ADVC products encode DV. DV has a fixed spatial
compression of 5:1 and no temporal compression. This
yields a file size of 13.7GB/hour. None of these parameters
are adjustable.
MPEG compression can vary over a wide range and also
uses temporal compression (which itself is also vairable).
The ADVC products do not encode MPEG.
The magic on-board chip picks the best rate? Or are you
saying I can control the firewire device from software?
DV and MPEG are two different ways of encoding and
storing digitized video. The Canopus products encode
(and decode) only DV, not MPEG.
no, I will eventually want to import video from a hand
held consumer digital cam and compose my own music
as well as import dialog on a pc.
The video from your consumer camera will be either DV
(if it is something like a mini-DV tape camcorder) or
MPEG (if it is a mini-DVD disc camcorder). Note that
if you want to edit the video, you will be much more
satisfied with the result from mini-DV than mini-DVD
because of the MPEG temporal compression.
I've had a sound studio for many years and a devastating
degree of natural ability for virtually any undertaking so
were well on our way here.
Your self-confidence is remarkable.
I'm sort of getting it. I buy the Canopus ADVC 100 (110?)
for $239 and play an hour vcr tape into my pc. An hour
later I have a 13g file in some as yet undetermined software.
There are many different software applications which will
take DV-encoded video via a firewire connection and put
the data in to a DV-AVI file. They range from DV-IO (which
is free) on up to hundreds or thousands of $$$. Most video
editing applications include DV capture as a built-in function.
Then I edit out the commercials/credits and crunch the file
down to MPEG2 via what I hope is the least grungy
compression ratio the software offers. This is where codecs
rear their ugly head? Use of the Canopus requires no
codec for the initial transfer, does the software require it for the
transcoding?
The heads of various codecs are neither "ugly" nor "beautiful".
Any kind of digital conversion/storage of an analog signal
audio, video, or even data) requires knowledge of the encoding
and decoding details. These details are contained in the "codec"
(a contraction of "code" and "decode")
The Canopus (and all other DV) products use the DV codec
which is a standard across all computers and video equipment
brands. Recording the DV that comes from your camcorder or
external box (like the Canopus) doesn't even really involve
using a codec because the digital information is already
encoed in the camcorder (or Canopus box). The data stream
is merely recorded into a comptuer file. When an application
plays back that file (or edits it, or transcodes it, etc.) it uses
the DV codec to understand how to read the file and how to
write it back if you are editing it.
If it is transcoding the file, it uses one codec to read the file
and a different one to write the transcoded result.
Note that it is FAR EASIER to eliminate the 60Hz hum
before you digitize the audio than having to do it in
"post-production".
that occurred to me after I posted, although the pc stacked pole
filters and dedicated noise reduction plug-ins are much better suited
than the outboard parametric eqs I have here.
If you "had a sound studio for many years and a devastating
degree of natural ability" you should be able to prevent the
hum rather than trying to eliminate it after the fact. This
is the same advice you would receive over in the audio
newsgroups: news:rec.audio.pro or news:rec.audio.tech
I'd also like to remove the commercials and credits to
save space. Can you recommend software for this?
Many people seem to like applications like Video-Re-Do
to do simple editing (like removing commercials) from
MPEG-encoded files.
thanks, I will look into that.
This is where the rebuilding of the file takes so much time?
This is the tradeoff. You can avoid the transcoding (what
you are calling "rebuilding') between DV and MPEG if you
encode/record directly in MPEG. But you have to live with
the limitations. If you are just removing commercials, this
may be the best solution for you.
I'm not sure the Canopus does that. It's not clear in the advertizing.
It just says it does a splendid job etc.
It quite clearly states...
"Proven DV Codec Technology
At the heart of ADVC110 is the innovative Canopus DV codec
chip, providing the industry's best picture quality preservation
during analog-to-DV and DV-to-analog conversion. "
http://www.canopus.com/products/ADVC110/index.php
MPEG is not even mentioned except the links to their
MPEG hardware encoders...
http://www.canopus.com/products/mpegencoding.php
These appear to use names like "EMR" and "MVR"
where "ADVC" are DV devices.
How would you find out which software would let you do this?
Ask someone who owns the product and is doing (or has
attempted unsucessfully to do) what you are asking for.
All products seem to be represented by the same ad copy
at every site. No vender seems to know anything specific
about a product having never used it.
Duh. Go directly to the source (for example the Canopus
URL I cited above.) If that doesn't answer your question,
other options include: Google, posting questions here, and
product-specific forums.
Many products (both commercial and freeware) have their
own user forums (usually web-based, not Usenet news-
groups like this one). Many forums are hosted by the vendors
themselves, and lots of them are independent of the vendor.
If your video source is a VCR (like VHS, etc.) then your
video may already be low enough quality that using DV
is overkill, and MPEG may be a better compromise.
Some of it's pretty bad, especially the sound. It's in BW if that's
any consideration.
You might want to consider something like the ADVC-300.
While it is more expensive, it includes a rather good TBC
(time-base correction) function which cleans up much of the
artifacts from old analog tapes.
Maybe smaller size?
DV is *always* 13.7 GB per hour. Doesn't matter how good
or bad the video is. Doesn't matter whether it is color or
monochrome. Doesn't matter whether the sound is stereo,
mono, or grungy.
I'm trying to save time when transcoding the edited file.
I thought it might be faster to play back the edited one hour
show in real time as opposed to letting it crunch the numbers
over an hours long period. (I have no experience so I just
assumed it would take many hours even on a capable system).
I was wondering if playing back in one software instance
out through the Canopus and recording back in with a dummy
loop of cable in another software instance would cut down on the
transcoding time.
No. If anything this would increase the time. The DV external
boxes (like the Canopus ADVC and others) only encode and
decode video. Even if you could "loopback" Firewire dtata
(which you really can't) you would only end up with nearly
the same DV data coming back as you sent out.
Note that there ARE MPEG hardware encoders which make
the DV to MPEG conversion faster. See the Canopus MVR
devices in the URL cited above.
Some digital devices won't let you do this, but require a
device inserted in the loop who's controls can be put in
some kind of standby mode, at least this is how it works
in audioland.
But as in audioland, going digital, back out to analog, and
back to digital is a destructive and usually avoidable step.
The Canopus ADVC 100 seems ok at $239 if it actuallyAnd I guess my budget it about $250usd.
works. The Video Guys. I didn't look closely, I just picked
a few sites off the google list for a general idea. The more
expensive ADVC boxes just add more editing and filters
on the way in it looks like. Thanks again.
Yes, the ADVC-110 (the 100 is no longer made) is barely
within your price range. Note, however, that if you have
really "grungy" video tapes you want to digitize, the ADVC-
300 would be a much better choice because of the TBC
functionality.
.
- References:
- Re: new-B: xternal card for AD conversion?
- From: Richard Crowley
- Re: new-B: xternal card for AD conversion?
- Prev by Date: Re: new-B: xternal card for AD conversion?
- Next by Date: Re: new-B: xternal card for AD conversion?
- Previous by thread: Re: new-B: xternal card for AD conversion?
- Next by thread: Re: new-B: xternal card for AD conversion?
- Index(es):
Relevant Pages
|
Loading
