Rich Posted May 11, 2005 Posted May 11, 2005 I'd be interested in your calculations.My generous "back of a fag packet" numbers say: PAL is 576*720 resolution at 25 frames per second. Colour depth can probably be accomodated by 16 bits (2 bytes). My calculator says 576*720*25*2 = 20,736,000 20Mbytes is a lot less than 4.7Gbytes. Incidentally I occasionally capture broadcast signals at broadcast quality on my PC though I don't have full-res ones around at present. Just checked a half-resolution file (actually 288*384) with 16-bit colour which is of course a quarter the data and that was using just over 5Mbytes per second. 52629[/snapback] I mean Broadcast quality video, Up to 60 fps. As used by Pro cameras. Not broadcast TV.
Guest fathead Posted May 11, 2005 Posted May 11, 2005 Hope this helps. A few facts from the published spec. For DV standard only the 720 X 480-pixel area of active video is digitised. This cuts the uncompressed data rate back from 162Mbit/s to 127Mbit/s. Video is then compressed at a ratio of 5:1 inside the camera down to approx 25 Mbit/s. These figures only apply to DV standard there are several different standards for digital video cameras. For digital TV broadcast. Depending on the encoding used, a single standard DTV program can be made to use 5 Mbit/s. Often less. USB 1,1 --- 12 Mbit/s USB 2 --- 480Mbit/s Firewire --- 400Mbit/s Gigabit Ethernet --- 1000Mbit/s
Guest fathead Posted May 11, 2005 Posted May 11, 2005 I mean Broadcast quality video, Up to 60 fps. As used by Pro cameras.Not broadcast TV. 52641[/snapback] If you mean the equipment used in studios for HDTV I believe it has to be capable of 1.5Gbit/sec
secboy Posted May 12, 2005 Posted May 12, 2005 Forget it! The Chineese, Tiawaneese and all the others will be streets ahead of you............... 52622[/snapback] A -ha!!! does this mean that camcorder technology will be the new generation for cctv???? I don't want to be ahead of anyone I'm just discussing from Fatheads lead what might be a technology route for cctv in the future,regards Paul
Guest fathead Posted May 12, 2005 Posted May 12, 2005 A -ha!!! does this mean that camcorder technology will be the new generation for cctv???? I don't want to be ahead of anyone I'm just discussing from Fatheads lead what might be a technology route for cctv in the future,regards Paul 52761[/snapback] The only real difference is camcorders output a digital signal. Most current CCTV cams are analogue
amateurandy Posted May 12, 2005 Posted May 12, 2005 The only real difference is camcorders output a digital signal.Most current CCTV cams are analogue
Guest fathead Posted May 12, 2005 Posted May 12, 2005 All of which implies that there's a lot of A/D and D/A conversion going on.Presumably the light sensors (or the electronics immediately behind them) in cameras produce a digital signal. So could this be modulated (with or without lossy or lossless compression) straight onto a carrier signal onto a standard coax? Then demodulated straight into a DVR or similar. Digital TV manages this over the air, and you can now buy "Freeview-only" DVR's that are cheap because there's no A/D conversion in them. They just record the off-air digital signal onto a digital medium. Whether transmission is over an IP network or whatever is a different issue, but simplifying the end-to-end process would surely be a good aim? Simple, cheap and reliable. 52767[/snapback] All CCDs turn energy from light into electrical energy but it is an analogue signal. Conventional cams may use digital processors to clean up the signal alter balance and lots of other stuff but still output as analogue. Digital cameras take the analogue signal from the CCD and process it into digital signals. Whether transmission is over an IP network ....... Absolutely bang on
secboy Posted May 12, 2005 Posted May 12, 2005 All of which implies that there's a lot of A/D and D/A conversion going on.Presumably the light sensors (or the electronics immediately behind them) in cameras produce a digital signal. So could this be modulated (with or without lossy or lossless compression) straight onto a carrier signal onto a standard coax? Then demodulated straight into a DVR or similar. Digital TV manages this over the air, and you can now buy "Freeview-only" DVR's that are cheap because there's no A/D conversion in them. They just record the off-air digital signal onto a digital medium. Whether transmission is over an IP network or whatever is a different issue, but simplifying the end-to-end process would surely be a good aim? Simple, cheap and reliable. 52767[/snapback] Nice one guys I think we all agree then that things are moving very fast in cctv both in the recording and transmission of signals , on that note has anyone read up on the new 360 camera from vista?? its priced at £1200! will be looking to have a peak at it on tuesday at IFSEC, (will we all be wearing our printed lapel badges )you know the template that dave posted??? it would be interesting to see how many of us were there!! Paul.
Guest fathead Posted May 12, 2005 Posted May 12, 2005 Nice one guys I think we all agree then that things are moving very fast in cctv both in the recording and transmission of signals , on that note has anyone read up on the new 360 camera from vista?? its priced at £1200! will be looking to have a peak at it on tuesday at IFSEC, (will we all be wearing our printed lapel badges )you know the template that dave posted??? it would be interesting to see how many of us were there!! Paul. 52773[/snapback] Also, IBM Cell processor is on the way and may provide an answer Was demonstrated recently decoding 48 streams of mpeg2 video simultaneously! Supposed to be 10 X faster than any current desktop processor. And the cost of this amazing processor? They are planning to put it in a toy for kids (like me )
ian.cant Posted May 12, 2005 Posted May 12, 2005 does this mean that camcorder technology will be the new generation for cctv The Camcorder mkt has always led the way, chips size is related to the camcorder makers as it happens.
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