| Author |
Message |
Martin Heffels
Guest
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 Posted:
Fri Jun 17, 2005 3:24 am Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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On Thu, 16 Jun 2005 14:34:38 -0700, "PTravel" <ptravel@ruyitang.com>
wrote:
| Quote: | Everything depends on the image, though. For images with a lot of movement,
mpeg2 will drop far more data than DV25.
|
That's what I'm saying all the time already. But at higher datarates,
comparable to DV25, MPEG2 does better than DV25 (providing the source
of origin is standard video, 720x576 if you're in PAL, and you know
the numbers for NTSC).
| Quote: | Well, I'm talking about the camcorder which is the subject of this thread.
It's a video camera for consumers and will not be used to take static shots
of vases. It's intended for the same subject matter as other consumer
camcorders, i.e. moving, chaotic images. It does single-pass, on-the-fly
mpeg encoding. It will not produce video as detailed as a miniDV camcorder.
|
Yes, for that camcorder, with a data-rate of 9MB/s, it's going to
become difficult, I agree.
| Quote: | Video moves and, particularly, with respect to
miniDV, moves a lot. Mpeg2 has higher compression rates and, therefore,
loses more detail (far more detail) than miniDV.
Again, that depends on how you use the codec.
I'm not sure what you mean by how you use the codec. DVD-complaint mpeg
tops out at around 10 mbps. I transcode using tmpgenc and tweak the mpeg,
within DVD spec requirements, quite a bit and get extremely good results.
They are not, however, anywhere near as detailed as the DV25 source.
|
Sorry, I meant to say, coder (or encoder), and not codec. The quality
of the encoder determines the final quality of the picture.
A commercial DVD, encoded with a US$25000+ hardware encoder, will look
better than a Procoder encoded one (one of the better encoders).
And like you said, good quality requires tweaking (datarate,
keyframes, GOP's etc) to get the best result.
cheers
-martin-
--
"Now I want you to say it thrice daily and don't dress a bun"
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Specs
Guest
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| Posted:
Fri Jun 17, 2005 3:43 am Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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"PTravel" <ptravel@ruyitang.com> wrote in message
news:3he9pkFgocoiU1@individual.net...
| Quote: |
"Specs" <No.Spam@Thanks.com> wrote in message
news:42b1e8f4$0$2422$ed2619ec@ptn-nntp-reader02.plus.net...
"PTravel" <ptravel@ruyitang.com> wrote in message
news:3he43nFgo1muU1@individual.net...
"Martin Heffels" <manager@usg-managers.com> wrote in message
news:21j3b1pmvuca8t3pd00uepq6i22h2ne3i5@4ax.com...
On Thu, 16 Jun 2005 11:42:52 -0700, "PTravel" <ptravel@ruyitang.com
wrote:
DVD mpeg compresses at least 3 times as much as DV-25, resulting in
3x
as
much
loss of detail.
Not necessarily. MPEG2 is a different form of compression, because
it
uses _one_ master-frame, and then a saves a bunch of data showing
only
the difference between those frames. With DV25 you save whole frames
all the time, meaning that in the end you have much more data left.
MPEG2 is a better codec then DV25, when it comes to similar
data-rates
from similar sources (SD) [as my buddy Specs also mentioned].
I don't know what you're referencing by SD. Do you mean standard
definition
video? If so, mpeg2 is most decidely NOT a better codec, at least not
for
moving images.
And to
get this good quality, you need a good encoder, and know how to
tweak
the parameters, to get the best results. Let's say, a static shot of
a vase would look good already on 2.5 Mbps, while for a moving shot
you need to go higher to, say 8 Mbps.
You don't honestly think this discussion is about static shots of
vases,
do
you? That's like saying both formats are equal if you are showing a
picture
of detail-less blue wall. Video moves and, particularly, with respect
to
miniDV, moves a lot. Mpeg2 has higher compression rates and,
therefore,
loses more detail (far more detail) than miniDV.
My very good friend Martin was trying to give you a very simple example
to
aid your understanding of the merits of MPEG2 compression. Clearly you
misunderstood.
On the contrary, I understand perfectly. You and your "very good friend"
have trouble staying on topic. Read the thread header. This is not a
discussion about the theoretical limits of mpeg, but about (1) a consumer
mpeg-based camcorder, and (2) DVD-compliant mpeg, both of which are being
used in the real world of moving images, not test still life.
MPEG2 is a more efficient codec than DV25. As we know DV25 is, er, a
25Mbps
SD stream. If one were to shoot a 25 Mbps MPEG2 SD stream it would give
a
superior image to the DV25 image.
Perhaps so. DVD-compliant mpeg tops out around 10 mbps, so your point is
completely irrelevant.
MPEG2 gets a bad rap because most people
only ever see low bit rate versions on DVD, Sat or Cable.
We are talking about mpeg2 in the context of DVD, only. If you want to
have
a discussion about theoretical efficiencies at non-standard bit rates,
start
another thread.
MPEG2 is going to be around for a while with HDV, XDCAM and XDCAM HD
coming
early next year. The two Sony XDCAM HD are expected to support 4:2:0
VBR
long GOP at 36 Mbps and the more expensive version 4:2:2 VBR long GOP at
72
Mbps. Both will record 1440x1080i. I don't know about 24p yet.
It should also be pointed MPEG2 has various Profiles and Levels which
can
drastically change the quality of the image.
See above. Not relevant in the least tot his discussion.
You should't write crap like this, |
"MiniDV is a video format, i.e. not used for static shots, and that was the
basis for the original comparison. Yes, mpeg and DV-25 use different
compression formats. And for virtually all video uses, e.g. excluding
static slide shows and the like, DV-25 is going to display more detail than
mpeg."
And this,
"I don't know what you're referencing by SD. Do you mean standard
definition
video? If so, mpeg2 is most decidely NOT a better codec, at least not for
moving images."
And this,
"Hunh? Of course it does. Both DV-25 and mpeg are lossy compression
formats. However, DV-25 results in about 5-to-1 compression, whereas mpeg
is another order of magnitude greater."
And not expect to be re-educated...
Goodnight. |
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Dave Martindale
Guest
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| Posted:
Fri Jun 17, 2005 8:05 pm Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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"PTravel" <ptravel@ruyitang.com> writes:
| Quote: | One more time: the OP was asking about a specific camcorder, not the
theoretical limits of audio and video compression.
|
Even thought that's how the thread started, threads drift. You
shouldn't make statements that may be true in the restricted context of
the original question, but aren't generally true, without qualifying the
context.
| Quote: | No, we're talking about whether mpeg video is inherently worse than
dv25 video.
Nope. We're talking about whether the particular implementation of the mpeg
codec in a specific camcorder is inherently worse than DV25 video.
|
The two of you are clearly talking about different things. But there's
no referee to say which of you is right and which is wrong. If you make
statements that apply only to a specific camcorder, say that. Don't say
"MPEG is worse than DV", because that statement is wrong on its own.
You also said that MPEG at 1/3 the bit rate "throws away 3 times the
detail". That's just plain wrong, even in the context of specific
consumer camcorders. There's no direct connection between bit rate and
perceived detail, particularly when you're comparing MPEG to DV.
| Quote: | If a particular implementation happens to do a worse job,
that proves nothing about the general case.
And we're not talking about the general case.
|
He is, you aren't. That's life on Usenet.
Dave |
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PTravel
Guest
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| Posted:
Fri Jun 17, 2005 8:32 pm Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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"Paul Rubin" <http://phr.cx@NOSPAM.invalid> wrote in message
news:7xmzppx3um.fsf@ruckus.brouhaha.com...
| Quote: | "PTravel" <ptravel@ruyitang.com> writes:
"There's nothing special about the DV format. Just because it uses a
lower compression ratio than mpeg-2 doesn't mean the quality is
better."
We're not talking about Micro-MV, which is another toy format.
MicroMV uses mpeg-2.
|
So what? Read the the subject line.
| Quote: |
PCM is not lossy, versus MP3, which is. That's apples and oranges.
We're
comparing mpeg and DV-25, both of which are lossy compression formats.
Irrelevant. For example, 128 kbit MP4 (AAC) sounds better than 160 kbit
MP3. Both are lossy.
|
Okay, try to focus: we were talking about an mpeg2-using hard-drive
camcorder versus miniDV. You want to talk about audio? Go to a different
newsgroup, or at least start a new thread.
| Quote: |
DVD mpeg compresses at least 3 times as much as DV-25, resulting in
3x as much loss of detail.
That's plain bogus.
We're not talking about audio formats, but video. As I said in another
post, if you can't see the difference between mpeg compression and
DV-25,
then you need a better television, or should get your eyes checked.
Except for some special pathological cases (someone mentioned fast pans),
almost everyone agrees that HDV (mpeg) looks better than mini-DV at the
same bit rate.
|
One more time: we're not talking about mpeg-encoded HDV, but about the
comparision between the 30 GB hard drive camcorder in the subject line and
miniDV.
| Quote: | If you want to compare 4 megabit mpeg2 to dv25, that's
one thing. But Mpeg is a variable bit rate compressor.
|
Doesn't matter. Read the subject line.
| Quote: |
"[B]ecause [DV-25] uses a lower compression ratio than mpeg-2 doesn't
mean
the quality is better."
The statement is incorrect.
False, see the HDV vs Mini-DV example. Now imagine HDV at 24.5 mbits
vs Mini-DV at 25 mbits. Do you think HDV will fall apart because of
using 2% more compression? |
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PTravel
Guest
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| Posted:
Fri Jun 17, 2005 8:33 pm Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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"Gene E. Bloch" <hamburger@NOT_SPAM.invalid> wrote in message
news:Xns9677B6FAAEBCAstrolabe@216.196.97.136...
| Quote: | "PTravel" <ptravel@ruyitang.com> wrote in news:3hdks7Fgj31pU1
@individual.net:
SNIP
Hunh? Of course it does. Both DV-25 and mpeg are lossy compression
formats. However, DV-25 results in about 5-to-1 compression, whereas
mpeg is another order of magnitude greater.
SNIP
You need to check your math. An order of magnitude is a factor of ten,
and 9 Mbps is 1/2.77 of 25 Mbps, not 1/10 of 25 Mbps.
As a physicist, mathematician, and programmer, I have always used the
definition of order of magnitude as a factor of ten. However, to be
safe, I also took the precaution of looking in my American Heritage
Dictionary, in case the 'civilian' definition differed. It did not.
|
You're right, I over-stated the case.
| Quote: |
HTH,
Gino
--
Gene E. Bloch (Gino)
letters617blochg3251
replace the numbers by "at" and "dotcom" |
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Rick Merrill
Guest
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| Posted:
Fri Jun 17, 2005 10:51 pm Post subject:
Re: 30GB Hard Drive Camcorder: File Implications? |
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George S wrote:
you connect it to a Windows XP system, what are the file extensions that
will be seen in the mounted camcorder?
DV25? MMX? |
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Paul Rubin
Guest
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| Posted:
Fri Jun 17, 2005 10:53 pm Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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"PTravel" <ptravel@ruyitang.com> writes:
| Quote: | We're not talking about Micro-MV, which is another toy format.
MicroMV uses mpeg-2. [at 12 mbits]
So what? Read the the subject line.
|
The subject line is about a 30gb hard drive camcorder. Nothing stops
it from using mpeg-2 at the same bit rate as mpeg-3. What are you getting
at?
| Quote: | PCM is not lossy, versus MP3, which is. That's apples and
oranges. We're comparing mpeg and DV-25, both of which are
lossy compression formats.
Irrelevant. For example, 128 kbit MP4 (AAC) sounds better than 160 kbit
MP3. Both are lossy.
Okay, try to focus: we were talking about an mpeg2-using hard-drive
camcorder versus miniDV. You want to talk about audio? Go to a different
newsgroup, or at least start a new thread.
|
There's nothing special about video. Lossy compressor X can give higher
quality than lossy compressor Y even if X uses a lower bit rate, just
like with audio compressors. It just depends on the characteristics
of the specific compressor.
| Quote: | One more time: we're not talking about mpeg-encoded HDV, but about the
comparision between the 30 GB hard drive camcorder in the subject line and
miniDV.
|
No, we're talking about whether mpeg video is inherently worse than
dv25 video. If a particular implementation happens to do a worse job,
that proves nothing about the general case.
| Quote: | If you want to compare 4 megabit mpeg2 to dv25, that's
one thing. But Mpeg is a variable bit rate compressor.
Doesn't matter. Read the subject line.
|
The subject line says nothing about the bit rate that the 30gb hard
drive camcorder uses. |
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Martin Heffels
Guest
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| Posted:
Fri Jun 17, 2005 11:07 pm Post subject:
Re: 30GB Hard Drive Camcorder: File Implications? |
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|
On Fri, 17 Jun 2005 13:51:06 -0400, Rick Merrill <jaynehm@comcast.net>
wrote:
How about MPEG2 :)
-martin-
--
"Now I want you to say it thrice daily and don't dress a bun" |
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PTravel
Guest
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| Posted:
Fri Jun 17, 2005 11:39 pm Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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|
"Paul Rubin" <http://phr.cx@NOSPAM.invalid> wrote in message
news:7x7jgseupl.fsf@ruckus.brouhaha.com...
| Quote: | "PTravel" <ptravel@ruyitang.com> writes:
We're not talking about Micro-MV, which is another toy format.
MicroMV uses mpeg-2. [at 12 mbits]
So what? Read the the subject line.
The subject line is about a 30gb hard drive camcorder. Nothing stops
it from using mpeg-2 at the same bit rate as mpeg-3. What are you getting
at?
|
Nothing stops it -- except the manufacturer's firmware.
| Quote: |
PCM is not lossy, versus MP3, which is. That's apples and
oranges. We're comparing mpeg and DV-25, both of which are
lossy compression formats.
Irrelevant. For example, 128 kbit MP4 (AAC) sounds better than 160
kbit
MP3. Both are lossy.
Okay, try to focus: we were talking about an mpeg2-using hard-drive
camcorder versus miniDV. You want to talk about audio? Go to a
different
newsgroup, or at least start a new thread.
There's nothing special about video. Lossy compressor X can give higher
quality than lossy compressor Y even if X uses a lower bit rate, just
like with audio compressors. It just depends on the characteristics
of the specific compressor.
|
One more time: the OP was asking about a specific camcorder, not the
theoretical limits of audio and video compression.
| Quote: |
One more time: we're not talking about mpeg-encoded HDV, but about the
comparision between the 30 GB hard drive camcorder in the subject line
and
miniDV.
No, we're talking about whether mpeg video is inherently worse than
dv25 video.
|
Nope. We're talking about whether the particular implementation of the mpeg
codec in a specific camcorder is inherently worse than DV25 video.
| Quote: | If a particular implementation happens to do a worse job,
that proves nothing about the general case.
|
And we're not talking about the general case.
| Quote: |
If you want to compare 4 megabit mpeg2 to dv25, that's
one thing. But Mpeg is a variable bit rate compressor.
Doesn't matter. Read the subject line.
The subject line says nothing about the bit rate that the 30gb hard
drive camcorder uses.
|
Read the specs on the camera. |
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PTravel
Guest
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| Posted:
Sat Jun 18, 2005 1:41 am Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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|
"Dave Martindale" <davem@cs.ubc.ca> wrote in message
news:d8vael$6cn$1@mughi.cs.ubc.ca...
| Quote: | "PTravel" <ptravel@ruyitang.com> writes:
One more time: the OP was asking about a specific camcorder, not the
theoretical limits of audio and video compression.
Even thought that's how the thread started, threads drift. You
shouldn't make statements that may be true in the restricted context of
the original question, but aren't generally true, without qualifying the
context.
|
I thought the context was sufficiently clear. There is a small cadre of
mpeg boosters in these newsgroups who think mpeg is the answer to
everything -- I suspect that at least some of the drift is attributable to
that. My feeling is, the right tool for the right job. I jumped into this
thread because I feel that gimmicky cheapo camcorders, like the one in the
thread and the raft of DVDcams now out, aren't the right tools for anything.
| Quote: |
No, we're talking about whether mpeg video is inherently worse than
dv25 video.
Nope. We're talking about whether the particular implementation of the
mpeg
codec in a specific camcorder is inherently worse than DV25 video.
The two of you are clearly talking about different things.
|
Exactly.
| Quote: | But there's
no referee to say which of you is right and which is wrong. If you make
statements that apply only to a specific camcorder, say that. Don't say
"MPEG is worse than DV", because that statement is wrong on its own.
|
I think, after the initial clash of swords, I made the context of my remarks
pretty clear.
| Quote: |
You also said that MPEG at 1/3 the bit rate "throws away 3 times the
detail". That's just plain wrong, even in the context of specific
consumer camcorders. There's no direct connection between bit rate and
perceived detail, particularly when you're comparing MPEG to DV.
|
I agree that there isn't an exact relationship between the bitrate of mpeg
vs. DV25 and the amount of detail that is discarded. The point, though, is
that both discard detail, and mpeg2, at DVD-compliant rates, discards more
(for moving video) than DV25.
| Quote: |
If a particular implementation happens to do a worse job,
that proves nothing about the general case.
And we're not talking about the general case.
He is, you aren't. That's life on Usenet.
|
Guess so.
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Paul Rubin
Guest
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| Posted:
Sat Jun 18, 2005 1:43 am Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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"PTravel" <ptravel@ruyitang.com> writes:
| Quote: | I agree that there isn't an exact relationship between the bitrate of mpeg
vs. DV25 and the amount of detail that is discarded. The point, though, is
that both discard detail, and mpeg2, at DVD-compliant rates, discards more
(for moving video) than DV25.
|
There is no reason that a camera with a 30gb hard drive (see the subject
line) needs to record at dvd-compliant rates. |
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Martin Heffels
Guest
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| Posted:
Sat Jun 18, 2005 2:00 am Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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On 17 Jun 2005 13:43:21 -0700, Paul Rubin
<http://phr.cx@NOSPAM.invalid> wrote:
| Quote: | There is no reason that a camera with a 30gb hard drive (see the subject
line) needs to record at dvd-compliant rates.
|
Tough on you, but the camera discussed in this thread does so :)
-martin-
--
"Now I want you to say it thrice daily and don't dress a bun" |
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PTravel
Guest
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| Posted:
Sat Jun 18, 2005 2:19 am Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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"Paul Rubin" <http://phr.cx@NOSPAM.invalid> wrote in message
news:7xslzgd89i.fsf@ruckus.brouhaha.com...
| Quote: | "PTravel" <ptravel@ruyitang.com> writes:
I agree that there isn't an exact relationship between the bitrate of
mpeg
vs. DV25 and the amount of detail that is discarded. The point, though,
is
that both discard detail, and mpeg2, at DVD-compliant rates, discards
more
(for moving video) than DV25.
There is no reason that a camera with a 30gb hard drive (see the subject
line) needs to record at dvd-compliant rates.
|
Except that this one does. Read the specs. |
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George S
Guest
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| Posted:
Sat Jun 18, 2005 2:30 am Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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|
"Dave Martindale" <davem@cs.ubc.ca> wrote in message
news:d8vael$6cn$1@mughi.cs.ubc.ca...
| Quote: | "PTravel" <ptravel@ruyitang.com> writes:
One more time: the OP was asking about a specific camcorder, not the
theoretical limits of audio and video compression.
Even thought that's how the thread started, threads drift. You
shouldn't make statements that may be true in the restricted context of
the original question, but aren't generally true, without qualifying the
context.
|
snip
I agree that threads drift, and one thing leads to another. But I have
learned a lot from the discussion and I am really grateful to you
all for your detailed responses. It all goes to show that although you
might think that the use of DV tape is getting a bit outdated, it is
still a very good choice if you are subsequently doing sophisticated
video editing, which is one of my main interests.
I know this needs a new thread and has been discussed many times,
but I guess solid state memory sticks / secure digital memory cards
would be better for storage in the future than hard drives. I know that
1GB cards are now common with 4GB promised at the consumer
level. But if we were able to choose between a 50GB memory
stick and a 50GB hard drive as storage, I guess we would choose
the 50GB memory stick? I wonder what the maximum commercial
solid state / memory card capacity is at the present? In other words,
are hard drives for camcorders likely to survive long into the future?
Thanks for your help
George |
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Paul Rubin
Guest
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| Posted:
Sat Jun 18, 2005 2:51 am Post subject:
Re: 30GB Hard Drive Camcorder: Editing Implications? |
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"George S" <George S@enquiry.org> writes:
| Quote: | level. But if we were able to choose between a 50GB memory
stick and a 50GB hard drive as storage, I guess we would choose
the 50GB memory stick? I wonder what the maximum commercial
solid state / memory card capacity is at the present? In other words,
are hard drives for camcorders likely to survive long into the future?
|
You can buy 50GB solid state memory modules but they cost a bloody bundle.
Hard drives will stay cheaper than solid state for the foreseeable future.
Right now, in fact, hard drives are even cheaper than tape. |
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