HiDef Underwater video...

[Bardo]

I'm sure I'm not the only one who has an eye on the future of underwater video. Whilst browsing
Wetpixel.com, I found a link to a site that specialises in underwater video clips filmed using Sony domestic high definition cameras. Whilst they're not quite up to the stunning, retina-blasting quality I've seen from some HD demos, they're certainly worth checking out...

HDV Underwater

[Bantam]

Originally Posted by Bardo

I'm sure I'm not the only one who has an eye on the future of underwater video. Whilst browsing
Wetpixel.com, I found a link to a site that specialises in underwater video clips filmed using Sony domestic high definition cameras. Whilst they're not quite up to the stunning, retina-blasting quality I've seen from some HD demos, they're certainly worth checking out...

HDV Underwater

What's surprising is the cost of the units.

The cameras use standard DV Tapes (the data rate of uncompressed 570i video (i.e. regular TV) is about the same as 1080i when H264 compressed) which is why it works so you can get the tapes anywhere.

The cameras themselves are tiny - there's three at the moment (All Sony) and they range from £800 to about £2000.

THe housings range from £800 to about £1500 too, but to say for £1600 you can get true HD underwater? Bloody bargain IMHO.

Mark.

[Lee B]

Originally Posted by Bantam

What's surprising is the cost of the units.

The cameras use standard DV Tapes (the data rate of uncompressed 570i video (i.e. regular TV) is about the same as 1080i when H264 compressed) which is why it works so you can get the tapes anywhere.

The cameras themselves are tiny - there's three at the moment (All Sony) and they range from £800 to about £2000.

THe housings range from £800 to about £1500 too, but to say for £1600 you can get true HD underwater? Bloody bargain IMHO.

Mark.

Hi Mark, Sorry but there is no such thing as 570i video. There is however 525i (US) and 625i (Europe) these are what are refered to as Standard Definition digital. Uncompressed the data rate is 270MB. The DV Format uses compression to reduce this to 25MB. HD uncompressed has lots of different formats the main 2 that are used over in europe at the moment are 1080i and 720p. Uncompressed the rates are 1.485 Gigs. HDV uses compression (MPEG2 based not H.264) to get this rate down to 25MB. It also uses MPEG1 audio rather than uncompressed PCM like DV to help to achive this.

H.264 or AVC or MPEG4 part 10 is the compression standard that many Broadcasters are usuing to take HD to the home (Sky, Fox, ect)

sorry just trying to stop confussion.

[Bantam]

Originally Posted by Lee B

Hi Mark, Sorry but there is no such thing as 570i video. There is however 525i (US) and 625i (Europe) these are what are refered to as Standard Definition digital. Uncompressed the data rate is 270MB. The DV Format uses compression to reduce this to 25MB. HD uncompressed has lots of different formats the main 2 that are used over in europe at the moment are 1080i and 720p. Uncompressed the rates are 1.485 Gigs. HDV uses compression (MPEG2 based not H.264) to get this rate down to 25MB. It also uses MPEG1 audio rather than uncompressed PCM like DV to help to achive this.

H.264 or AVC or MPEG4 part 10 is the compression standard that many Broadcasters are usuing to take HD to the home (Sky, Fox, ect)

sorry just trying to stop confussion.

A quick scan of the manual (and putting HDV into Wikipedia which gave me almost the same text you've posted above) tells me you're right about the Sony camera - I was led to believe it was AVC but I was obviously wrong.

However, I was correct about the resolutions.

UK SD PAL is classed as 576i not 625i, to be correct. It's 625 scan lines, but the resolution for square pixels is 576i.

Most current HD TV's will generally display 570i for some reason (as does my 42" Plasma - I will post a screenshot of the TV's information display which clearly shows the resolution if you require). When I play a UK DVD my progressive scan player turns that into 570p.

US (SD NTSC) is classed as 480i. When I play a US DVD my progressive scan player outputs 480p.

I also have a HD source (Sony HDR-HC1E) which records at 1080i and outputs the same via Component. However, it is true my TV is changing the resolution as it's actual max resolution of the panel is 720. It is also true that there is virtually no noticeable difference between 720p and 1080i.


So, take a look here at the resolution table at the bottom.

[Lee B]

Originally Posted by Bantam

A quick scan of the manual (and putting HDV into Wikipedia which gave me almost the same text you've posted above) tells me you're right about the Sony camera - I was led to believe it was AVC but I was obviously wrong.

However, I was correct about the resolutions.

UK SD PAL is classed as 576i not 625i, to be correct. It's 625 scan lines, but the resolution for square pixels is 576i.

Most current HD TV's will generally display 570i for some reason (as does my 42" Plasma - I will post a screenshot of the TV's information display which clearly shows the resolution if you require). When I play a UK DVD my progressive scan player turns that into 570p.

US (SD NTSC) is classed as 480i. When I play a US DVD my progressive scan player outputs 480p.

I also have a HD source (Sony HDR-HC1E) which records at 1080i and outputs the same via Component. However, it is true my TV is changing the resolution as it's actual max resolution of the panel is 720. It is also true that there is virtually no noticeable difference between 720p and 1080i.


So, take a look here at the resolution table at the bottom.

Sorry mark no such thing as 570i or 480i this is only the number of lines that contain active picture. I do have if you would like a copy for your own use and understanding a few presentations I put together for a training course at sky and BT if you would like a copy. It covers the transition from SD to HD and contains all the formats availible comercially today, and explanations of how the signals are put together. You are welcome to have a copy.

[Bantam]

Originally Posted by Lee B

Sorry mark no such thing as 570i or 480i this is only the number of lines that contain active picture. I do have if you would like a copy for your own use and understanding a few presentations I put together for a training course at sky and BT if you would like a copy. It covers the transition from SD to HD and contains all the formats availible comercially today, and explanations of how the signals are put together. You are welcome to have a copy.

So you're saying that both the Wikipedia entry, my TV (can show you screenshots), and my friend who is the Cameraman for Location, Location, Location, and various things for the Discovery Channel is wrong?

The problem is that all the hardware shows these resolutions including the cameras and the handbooks - so someone somewhere at a high level is making huge mistakes if you are correct?

[Lee B]

Originally Posted by Bantam

So you're saying that both the Wikipedia entry, my TV (can show you screenshots), and my friend who is the Cameraman for Location, Location, Location, and various things for the Discovery Channel is wrong?

The problem is that all the hardware shows these resolutions including the cameras and the handbooks - so someone somewhere at a high level is making huge mistakes if you are correct?

Mark, when a TV show 570 and 480 it is telling you what the screen resolution is and when a camera shows this it is showing what the scanning resolution is. Yes there are many diferent resolutions these included as shown in you table on wikipedia. But these alone will not allow you to have moving pictures and also move them around fro your camera to the TV. There is no such Video Standard of 570i or 480 i. Both these resolutions are i.e as shown on your TV, are PAL or NTSC TV signals, comming from your DVD player, settop box, video recorder camera is a PAL TV Signal or if HD one of the varients of HDMI carrying either Ypbpr or RGB HD analougue or digtal. Your camera and every camera in the world needs to be able to carry other things other than picture in the signal. There is an area you do not see on the left of your TV picture and one above . These are called Vertical and Horizontal blanking. Vertical blanking contains things such as the Sync pulse which is needed in Pal and NTSC systems to start each new line(all 625 or 525 of them) It also contains data in the H blanking things such as teletext can be carried here.

In digital form these are digitised in the camera or plenty of different capture cards and broadcast equipment, so rather than have a sync pulse it has a hex value of 3FF which indicates to the system SAV and EAV, ( start of active video and end of active video.)
when the end of active video is seen by the system it knows it is starting a new line. (an every 625 and 525 of the lines)

The numbers change when we get to HD 1080i and 720p. Again you will sees these on you TV as resolution there is in fact more lines accosiated with these both in HB and VB it is just that the standads are named this as well.

So the Standards are

Pal 625 lines interlaces ( analogue)
NTSC 525 lines interlaced (analougue)
There are component standards but I will not go into these

525 and 625 digital interlaced (EBU rec 601 and SMPTE 125M )

720p HD prgressive ( SMPTE 296M)
1080i HD interlaced (SMPTE 274M)

there are others used in professional broadcasting and also in propriotory systems so again will not touch these. These are standards for video signals

There are however display resolutions where i think you maybee getting these mixed up these are

480p 480i, 525p, 525i, 540p, 625p, 625i, 720p,1035i, 1080i

these resolutions are for display manufactures and for scanning purposes and not for outputting to TVs for that you need one of the formats I have mentioned

[Bantam]

I see where my confusion lay

I stand corrected.