DominO123 Posted October 24, 2003 Report Share Posted October 24, 2003 Theoritically, it is supposed to be 500-520 ligne resolution, and being digital, and yet, after trying one, I realised some anomalies similair to the ones found when compressing digital movies. THe question is, is it directlly compressed on the tape, and the DV/firewire port? THis is how it sound from the look, yes! Sure the quality of the films looks a lot better then s-vhs and other analogue films, but there is still this anomaly I believe detecting, has anyone seen them? Is it all in my haid? If not, is there a way to bypass the film compression? Quote Link to comment Share on other sites More sharing options...
vava Posted October 24, 2003 Report Share Posted October 24, 2003 I'm not too sure about this - maybe you should check with Thoth (i think he does video) but I believe that the Firewire device does the compression when uploading to your machine, and if I'm not mistaken, on more advance miniDV cameras, you can control the compression rates etc... Quote Link to comment Share on other sites More sharing options...
bellthecat Posted October 24, 2003 Report Share Posted October 24, 2003 The data is compresed realtime by the hardware in the camera. If the data was not compressed (into a sequence of jpgs) then the camera would be able to just fit a few minutes worth of material onto a tape, and the tape would probably have to move too quickly for it to be physically possible to record anything. Just sending the data through a firewire port to a computer does not change the compression rate at all. Nor, theoretically anyway, does editing that is restricted to simple cuts. But as soon as you begin to change the raw data (such as using dissolves) then the data is recompressed and the picture quality starts to degrade. I'm not aware of any consumer video camera that can change the compression rate beyond a standard setting such as "long play". The compression rate is fixed and is part of the DV standard. Steve Quote Link to comment Share on other sites More sharing options...
vava Posted October 24, 2003 Report Share Posted October 24, 2003 Yeah, I' don't have too much expertise in digital video - some of my colleagues are quite experienced... what Steve say sounds about right" Although I'm pretty sure data rates can be modified in professional grade cameras (although I may be confusing this with something else.. ) Quote Link to comment Share on other sites More sharing options...
THOTH Posted October 24, 2003 Report Share Posted October 24, 2003 Yeah, I' don't have too much expertise in digital video - some of my colleagues are quite experienced... what Steve say sounds about right" Although I'm pretty sure data rates can be modified in professional grade cameras (although I may be confusing this with something else.. ) Yes - the info is correct. What you may be refering to is frame rate. Soe epro cameras can adjust to film frame rates (I forgot if its 24 or 30 ips...verses video rates...I think film is 24 and video 30) - I don't deal with film or have to worry about this - so I can't tell you for sure. Pro DV also has a setting for a higher capture rate (tape speed) - though its debatable if the quality gain is really descernable - perhaps with frequent edits. But as Steve has said - the camcorder does JPEG compression and no further cmpresion is done upon tranfer to a hard drive etc - which is why DV video needs many gigabits...I think its about 1 gig per minute of vid....or worse... Quote Link to comment Share on other sites More sharing options...
bellthecat Posted October 24, 2003 Report Share Posted October 24, 2003 Yes - the info is correct. What you may be refering to is frame rate. Soe epro cameras can adjust to film frame rates (I forgot if its 24 or 30 ips...verses video rates...I think film is 24 and video 30) - I don't deal with film or have to worry about this - so I can't tell you for sure. Pro DV also has a setting for a higher capture rate (tape speed) - though its debatable if the quality gain is really descernable - perhaps with frequent edits. But as Steve has said - the camcorder does JPEG compression and no further cmpresion is done upon tranfer to a hard drive etc - which is why DV video needs many gigabits...I think its about 1 gig per minute of vid....or worse... But during editing of course you can compress it much more if you want - and it would need to if it was to end up being viewed on cd-rom, or over the internet. What you can't ever do is get back to the original quality once more compression has been added, so always keep an original. I think the main difference between pro and consumer DV (apart from longer tapes) is that the pro format has better sound quality - consumer DV has poor sound recording quality, with very poor built in error correction. Film is 24, Pal is 25, NTSC is 30 frames per second. Pal is better for picture quality since it has a bigger frame size (720x576, NTSC has only 720x480). Quote Link to comment Share on other sites More sharing options...
DominO123 Posted October 24, 2003 Author Report Share Posted October 24, 2003 Thanks everyone. I am actually sad that it is not possible to bypass the compression, I knew it was impossible to bypass it for the tape, but I was expecting it could with the firewire.(But did realised not very likely after converting the maximal bandwith , so even if it was possible, the firewire would probably not take it). I am surprised that DVs, that are said to be so exeptional, do have this anomaly, it become very frustrating once you see what the problem is. And beside that, why is this thing so unsensible in the dark? I mean, digital cameras(picture) don't seem to have such a problem. Quote Link to comment Share on other sites More sharing options...
vava Posted October 24, 2003 Report Share Posted October 24, 2003 Film is 24, Pal is 25, NTSC is 30 frames per second. Pal is better for picture quality since it has a bigger frame size (720x576, NTSC has only 720x480). And SECAM? (while we're at it....) Quote Link to comment Share on other sites More sharing options...
vava Posted October 24, 2003 Report Share Posted October 24, 2003 And beside that, why is this thing so unsensible in the dark? I mean, digital cameras(picture) don't seem to have such a problem.Domino, camera's designed for Mr & Mrs Everyone are often lacking in features and performance - you might get a better result renting a high-end professional model. That being said - you'll always need some light. You're not meant to film in the dark. I'm surprised that ALL DV has some some of compression (from the camera). Is this also true with DVcam (as opposed to miniDV - is there a difference?) I've seen some very impressive stuff produced using DVcam and an AVID editing suite. Of course they used plenty of video editing effects (with Maya I believe, and some AE) but i can't be too sure... Quote Link to comment Share on other sites More sharing options...
THOTH Posted October 24, 2003 Report Share Posted October 24, 2003 Yes vava - it all is compressed - but you really wouldn't know it - quality is ussually superb. Sometimes there are digital artifacts - but really that is rare. There is really no need for a proffesional camcorder for most applications. Check out the high end Sony, panasonic or Canon pro-sumer camcorders to get 95% of pro capability at a fraction of the price. Pro version only ussualy differ by use of BNC connectors for mics - allowing high end stuff and ability to record ad DCCAM (which is faster)...only real diff that I know...(for most)...and some of the canons (pricy) have interchangable lenses and such - and are pretty awesome...I prefer Sony - tend to do just about everything well - and lots of connection oprttions & such ussually...though I think Panasonic may have slightly better video quality. Quote Link to comment Share on other sites More sharing options...
Sip Posted October 24, 2003 Report Share Posted October 24, 2003 Raw NTSC, if transmitted digitally (I assume 24bit 720x480 at 30fps), would require roughly about 238 Mbps. With enough buffering, that should be ok for a 400 Mbps Firewire link. But then you are talking about 30MB/second of video so you are looking at 18 Gigs for a 10 minute clip of raw NTSC. Quote Link to comment Share on other sites More sharing options...
DominO123 Posted October 25, 2003 Author Report Share Posted October 25, 2003 Raw NTSC, if transmitted digitally (I assume 24bit 720x480 at 30fps), would require roughly about 238 Mbps. With enough buffering, that should be ok for a 400 Mbps Firewire link. But then you are talking about 30MB/second of video so you are looking at 18 Gigs for a 10 minute clip of raw NTSC. Sip, are you telling me that each picture would only take 1 mb when they are not compressed? Does that not sound a little too low? Quote Link to comment Share on other sites More sharing options...
DominO123 Posted October 25, 2003 Author Report Share Posted October 25, 2003 Apparently there is really something wrong with the miniDV, I just recorded movies using the firewire... the films sound awful. Quote Link to comment Share on other sites More sharing options...
DominO123 Posted October 25, 2003 Author Report Share Posted October 25, 2003 (edited) Ah and another thing... it is digital, so why the fk am I having those awful noises on the films. Edited October 25, 2003 by Fadix Quote Link to comment Share on other sites More sharing options...
Sip Posted October 25, 2003 Report Share Posted October 25, 2003 Sip, are you telling me that each picture would only take 1 mb when they are not compressed? Does that not sound a little too low? 24 bit * 720 * 480 = 0.9888 MB If 32 bits, then it will require 1.32 MB (4 bytes per pixel) Quote Link to comment Share on other sites More sharing options...
Sip Posted October 25, 2003 Report Share Posted October 25, 2003 Fad, you are recording digitally but your sensors are capturing an analog signal. If there is something wrong with the sensor or the analog to digital converter assosiated with it, then you can easily get noise. Quote Link to comment Share on other sites More sharing options...
bellthecat Posted October 25, 2003 Report Share Posted October 25, 2003 Fad, you are recording digitally but your sensors are capturing an analog signal. If there is something wrong with the sensor or the analog to digital converter assosiated with it, then you can easily get noise. Don't think that is the problem. Sounds like it is something to do with the connection between the camera and the computer or maybe it is the computer's soundcard. Domino - does the sound sound OK when you hear it played through your camcorder or TV. Digital cameras are better at recording dark scenes because they can take longer to record the scene, allowing more light to reach the chip. A camcorder can take no longer than 1/50th of a second per frame - if it took longer then it would not have time to record the frame before it was time to record the next frame. Quote Link to comment Share on other sites More sharing options...
DominO123 Posted October 29, 2003 Author Report Share Posted October 29, 2003 Don't think that is the problem. Sounds like it is something to do with the connection between the camera and the computer or maybe it is the computer's soundcard. Domino - does the sound sound OK when you hear it played through your camcorder or TV. Digital cameras are better at recording dark scenes because they can take longer to record the scene, allowing more light to reach the chip. A camcorder can take no longer than 1/50th of a second per frame - if it took longer then it would not have time to record the frame before it was time to record the next frame. Sound is recorded OK. I showed my recordings to someone that do have S-VHS cam, we compared, there is less noises on the minidv, but still there is more than I thought there should have been. Do you think that best quality minidvs have less noise ratio? Another thing, when I recorded the film in my computer, I realised the film is interlaced. Are minidvs as a new technology still using interlacing? Quote Link to comment Share on other sites More sharing options...
Sip Posted October 29, 2003 Report Share Posted October 29, 2003 Domino, I think this site should answer a lot of your questions. I especially like the The DV, DVCAM, & DVCPRO Formats • Technical Details with a nice table of the details. About interlacing ... I am guessing it's interlaced since TV is interlaced. But I don't know. Quote Link to comment Share on other sites More sharing options...
THOTH Posted October 29, 2003 Report Share Posted October 29, 2003 Yes - most (DV) cams shoot interlaced. I actually have a camcorder that shoots either interlaced or non - switchable..ome of the only ones I've ever seen with this feature - it is a high end Sony). However any movement in non-interlaced mode becomes a bit Jerky (speaking of such - if you've seen my stills [and know the pics I'm talking about..."no camera" in specific] - they were taken non-interlaced and extracted from the vid - must cripser pic that way - and twice the pixs)...not sure that non-interlaced motion vid would be any better for you - but perhaps better on a (non-interlaced) comp screen then on a TV - don't know - but doubt it... Also you shold realize - not all DV cams are the same. The better ones (most $$$$) have better optics, image stabalizers (optical) and CCDs (mine used 3 - which is recommended for highest quality & color accuracy)...and of course you certanly get what you pay for. And it makes a great diofference. My vids look great - even expanded onto a large projection set - where other DV cams start to look grainy. I can even splice in my DV cam shots with DigiBetacam and Beta SP stuff and you often can;'t tell the difference. Another facto of course is lighhting. You must have excellent lighting to get the best pic - otherwise you are introducing noise up front...and with editing wtc - this only compounds... Quote Link to comment Share on other sites More sharing options...
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