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Is DV still better than Flash Memory in 2009?
ergophobe

WebmasterWorld Administrator ergophobe us a WebmasterWorld Top Contributor of All Time 10+ Year Member



 
Msg#: 4064775 posted 4:46 am on Jan 21, 2010 (gmt 0)

Reading through, everyone says that DV is better because with a massive 14GB of storage on a tape, the format is less compressed.

But I'm thinking that 16GB-32GB SDHC is pretty common these days. Are flash memory cameras still recording lower quality video than DV cameras (thinking standard def here). Obviously you can get HD cams that record to SDHC, but I'm thinking just as it pertains to a cheap Std Def cam.

 

thecoalman

WebmasterWorld Senior Member 10+ Year Member



 
Msg#: 4064775 posted 9:06 pm on Jan 21, 2010 (gmt 0)

As far as I know SD camcorders that record to flash all use MPEG2 because it is the standard format for DVD, it's quite convenient if you want to get it to DVD. The larger data storage doesn't mean higher quality because they are still using the same format to record in. Having said that MPEG2 will never be the equal of DV.

DV is lightly compressed, each frame of video is stored individually. MPEG does not store each frame, it uses content from other frames when it doesn't change. That's why you can have low bitrate video without any movement and it will look great until you get movement and the macroblocks flare up.

Comparing DV converted to MPEG2 to a MPEG2 directly from a flash cam assuming everything else is equal will show negligible differences however here is a simple experiment you can try. Find a high quality DV sample with a lot of action.

1. Convert the DV to a 720*480 3000kbps MPEG2.

2. Convert the DV to 720*480 6000kbps MPEG2(which is typical for flash cam) then convert that to 720*480 3000kbps MPEG2.

Note that 3000kbps is entirely too low for that size resolution when using MPEG2. These are both going to look bad but what you're going to find is #2 is significantly worse than #1.

While a SD camcorder using flash may be convenient for the consumer for anything professional especially where you will be converting to a highly compressed web format you're going to want to start with highest quality format you can as a source.

ergophobe

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Msg#: 4064775 posted 5:07 am on Jan 22, 2010 (gmt 0)

where you will be converting to a highly compressed web format you're going to want to start with highest quality format you can as a source.

That's precisely where I would think it would not matter. I don't have the equipment to do the experiment you suggest (as you might have guessed from my question), but I believe you.

Other threads had more or less convinced me that for my purposes, I did not HD and would have some downsides from that. I just don't see needing the HD... but it is tempting at current prices.

I think I'll look around for an SD cam that's not SD (i.e. Std Def that's not flash)!

thecoalman

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Msg#: 4064775 posted 11:49 am on Jan 22, 2010 (gmt 0)

Garbage in, garbage out. You always want to source from the highest quality material possible. For example if you needed a file at different bitrates you would not do this:

DV >> WMV@ 2000kbps >> WMV@ 1000kbps >> WMV@ 500kbps....etc

Instead:

DV >> WMV@ 2000kbps

DV >> WMV@ 1000kbps

DV >> WMV@ 500kbps

When you feed an encoder nice clean material the better off the results will be even at lower bitrates. For example a typical Hollywood DVD is 6000kbps and if done right can produce great results at that bitrate. If you're encoding home footage from VHS which is typically very noisy and hand held you need to apply much more bitrate to compensate for all the noise and movement.

Same thing applies with MPEG2 when comparing it to DV since the MPEG2 contains so much less information. Macroblocking in MPEG2 is not really noticeable at the higher bitrates but it is there on a very small scale.

FYI you don't necessarily need any equipment for that experiment except to produce the original DV file, you should be able to find samples on the web. It would all be done with software.

ergophobe

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Msg#: 4064775 posted 3:20 am on Jan 23, 2010 (gmt 0)

So, I looked around... turns out DV cams at the consumer level are becoming pretty rare. B&H only had 1 under $1000.

It looks like DV is becoming a pro and prosumer format only. I think if I were going to drop a couple thousand dollars... well, I'm not, so I guess that's irrelevant.

phranque

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Msg#: 4064775 posted 8:46 am on Jan 23, 2010 (gmt 0)

last i looked the best bang for the buck in the prosumer DV range was the panasonic PV-GS250 & PV-GS400.
you can check out the reviews to see the advantages of each.
i don't think either has been made for a while but you might still be able to find a gently used one for a good price.

thecoalman

WebmasterWorld Senior Member 10+ Year Member



 
Msg#: 4064775 posted 12:34 pm on Jan 23, 2010 (gmt 0)

My brother picked up a Canon HV20 last Christmas for a steal from B&H. Think he got it for like $500. I'd probably use that over my CanonGL2 in outside situations where light is not a big factor or didn't need the options the GL2 affords. I think they are up to the HV40 now... somewhere around $700.

It does DV and HDV. It has progressive mode too.

ergophobe

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Msg#: 4064775 posted 8:43 pm on Jan 23, 2010 (gmt 0)

Thanks guys. Those suggestions give me some good directions to look in.

I was looking at the HF20/HF40 and didn't see that there's also an HV20/HV40.

The GS250 is dirt cheap used on Amazon and has 3 CCDs. No HD (500 lines resolution). GS400 is $1000 used, which means there are a lot of options.

One thing is that I also want a small camera. I'd be taking this doing things like backcountry skiing and such, so size and weight are fairly significant considerations.

Robert Charlton

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Msg#: 4064775 posted 12:08 am on Feb 22, 2010 (gmt 0)

Some rushed comments (with the caveats that these are hurried and I'm not a video-compression expert)....

Flash memory vs tape should have little to do with what format is recorded. There are professional DV cameras that record beautifully to flash memory (usually, though, to variants of the original mini-DV format). There is, in fact, a big push in professional camcorders toward more use of flash memory... in large part because of faster workflow.

I think with regard to the original question, the key here is camera price. It is a marketing issue. Flash memory is where manufacturers want to go, and compromises in small, low-end, flash memory cameras for the consumer market are thus driven by chip capacity and price.

It's important to note that MPEG constrains how you compress, but not how much. Typically, consumer cameras hyper-compress, and this leads to problems with certain kinds of material. MPEG compresses static frames and then compresses motion in intervening frames.

DV compresses, among other things, color information, which produces some artifacts that I don't like... but there are ways of making DV look fairly good.

Initially, MPEG's motion compression made it much harder to edit than DV. Generally, I hear, this issue has been more or less resolved. MPEG editors go to an intermediate format... but, depending on all sorts of factors, including the initial degree of compression, there are likely to be losses in this stage.

In thinking about MPEG compression, it's helpful to note that MPEG-compressed video... eg, DVDs for consumer end-use... are held to a lower bitrate, not because of deficiencies in the compression methods, but because of limitations both in disk capacity and in the computing capabilities of the hardware. MPEG for archiving video, eg, is encoded at a much higher bitrate than is MPEG for DVD release. Even on commercially released DVDs where there's scene-to-scene control of the data throughput, I've seen spots that will break up on every DVD player I've tried but which play fine on a computer. This MPEG breakup is typically on material in which there's a lot of motion.

So, in what you're planning to shoot, highly compressed MPEG (as you'll get on a cheap camera) is liable to be less satisfactory in skiing action, snowstorms, fast camera movements, etc. But MPEG might be more attractive than DV on static landscape shots. Hard to say how it would survive decoding and re-encoding.

The use of flash memory, I should mention, also creates some archiving issues, which, IMO, are unresolved.

I think for your subject matter and scale of operation, I'd go for DV. I think at the price range you're talking about, the HD cameras are not likely to be satisfactory.

The GS250 and the GS400, like all consumer cameras, have a lot of tradeoffs, but they've also got a lot to recommend them. From the features and reviews only... and I have no personal experience with either camera... I'd tend towards the GS400. I'm generally impressed by Panasonic.

Both cameras have actual viewfinders. I feel that it's important for a camera that's going to be hand-held to have an actual viewfinder, a feature that's increasingly being eliminated in consumer cameras.

While an LCD screen is a great extra accessory, good for low-angle shots, moving shots while skiing and the like, they're not easy to use outdoors as a primary viewfinder... and the ergonomics of LCD panel viewing only, which require you to extend your arms in front of you to see the screen, are, IMO, ridiculous. This is particularly true on a low-mass video camera.

One more point... to get an idea what kind of image a camera will produce online, do a search for the camera model on various of the video sharing sites. Vimeo in particular has active communities built around various pieces of hardware. You won't know, of course, how the video has been processed, but if you look at the best examples that match the kind of subject matter you'd be shooting, you'll have some basis for comparison.

ergophobe

WebmasterWorld Administrator ergophobe us a WebmasterWorld Top Contributor of All Time 10+ Year Member



 
Msg#: 4064775 posted 2:11 am on Feb 23, 2010 (gmt 0)

>>Typically, consumer cameras hyper-compress,

I can understand this by analogy. I hate shooting JPEG with a still camera because if you need to push the exposure or color balance, you have so little to work with, whereas in RAW, you have those extra 4 bits in each color channel, so you have so much more room to work.

And yes, I mostly imagine myself shooting moving people at a fair distance. I'll stick with still for my flower/macro photography.

The more I think about it, though, the more I realize that size is more important than quality for most of what I want (though decent low-light capability would be nice, and I assume that has a lot to do with lens and sensor size as it would in still photography).

I've even thought about one of those POV helmet cams, but decided against it.

Robert Charlton

WebmasterWorld Administrator robert_charlton us a WebmasterWorld Top Contributor of All Time 10+ Year Member Top Contributors Of The Month



 
Msg#: 4064775 posted 3:39 am on Feb 23, 2010 (gmt 0)

And yes, I mostly imagine myself shooting moving people at a fair distance.


This conflicts with your desire for small size/ light weight. If you're going to pan with your subjects, or hold on them with a long lens, you may need to consider a fluid-head tripod, which typically needs to be heavier than the camera.

You may think you can do this hand held, but even with image stabilization, you won't be able to... and hand held pans generally don't look very good. Also, paradoxically, the smaller and lighter the camera is, the harder it will be to hand hold (less mass => less inertia).

You could, of course, go for a very wild style... but I've seldom seen hand-held long lens shots work for even an extended sequence, unless the subject matter itself is all that counts.

If you're fussy about JPEG vs RAW (and I am too), you may not be happy with either consumer DV or with consumer MPEG.

Note that DV doesn't use motion compression, but its 4:1:1 color compression gives you an unpleasant edging effect between different color areas. You also get edging because of camera sharpening circuits, which are common in consumer cameras.

Flash memory, it should be noted, will generally make for a lighter camera. DV has got a tape transport mechanism, motors, tape heads, etc.

I've seen some superb video shot with DSLRs, but in video mode you need to lock up the mirrors, and the form factor then isn't ideal for video shooting. Also, the big Canons get pretty big. Nikon has a small DSLR that will shoot video. These do record on memory cards.

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