Here are some facts regarding KSL's news production equipment:
The news studio has three Philips LDK-10 cameras with CCD imagers.
The cameras output a standard NTSC signal in a digital transport called SDI (Standard Definition Interface). The physical link standard for this transport is SMPTE 259M on a single 75 ohm coax.
The Philips cameras CCD imagers are capable of and have been switched to generate a 16 x 9 aspect ratio. All video sources in the news room like the graphics systems, weather equipment and field cameras were also set up for a 16 by 9 output. If you were to view the video output of the news room on a standard 4 x 3 monitor, everyone looks tall and skinny.
The output of the news production switcher is sent to two format converters, one for HD and one for standard definition.
The HD format converter 'understands' that the input image is already 16 x 9 in aspect with a pixel resolution of 720 by 480 and up converts via horizontal and vertical re-sampling to 1920 by 1080i. Re-sampling involves a low pass filter so the converted image can't exceed the frequency response of the input. Up converted images are not as detailed even though the pixel count is higher.
The standard definition format converter takes the 16 x 9 input, crops it to 14 by 9 and then letter boxes it in a 4 x 3 standard NTSC frame. The over the air image for analog NTSC is bandwidth limited to 480 x 480 resolution, which is why the HD signal (sampled at 720 x 480) looks marginally better than the analog signal.
KSL is now purchasing new cameras and other news production equipment with hopes of being full HD in July.
Phil Windley
· 1 year ago
Awesome! That's just the kind of info I was wondering about. Thanks!
I've noticed that some channels stay in the same HD mode no matter what they're showing, so anything that wasn't originally shot in that format gets upconverted. I imagine that's what is happening here.
Phil Windley
· 1 year ago
That's kind of what I'm suspecting. Although the broadcast does have a 16:9 aspect ratio.
Does KSL have a camera and infrastructure to generate 1080i video, or have they just oversampled their existing non-1080i video and broadcast it 1080i?
Not that I blame KSL for not having the cameras and plumbing - the bandwidth requirements are significant and I doubt they have so much cash lying around that upgrading is an expense they can easily absorb.
Phil Windley
· 1 year ago
Yeah, that's just what I'm wondering.
This stuff will take time. One thing's for sure--people buying HD TVs is going to put tremendous pressure on stations and other program providers to upgrade the quality of their shows.
A lot of times, TV is shot at 720P and not 1080i. That would explain the "jaggies". The jaggies are from the signal drawing the lines everyother frame, borrowling lines from the previous and next frames. When you are shooting 1080P, or 720P, each frame is drawn individually. So no "jaggies".
My guess is that you are just seeing two different formats, progressive and interlaced.
It is very unlikely that they are upconverting a NTSC signal - the picture would be considerably worse than having a few jaggies were that the case. Rather, they are probably still using SD studio camera equipment (something like DigiBeta or IMX) which outputs SD video at MPEG2 50i (50Mbps iFrame only). This is still a very high quality signal which when up-converted to 1080i will still produce a great picture - albeit as you can see, with some jaggies.
If what you were seeing was converted from NTSC (an analogue recording and transmission format in contrast to the digital, 50Mbps MPEG2 output by studio grade cameras) the picture would be absolutely awful and would include all the colour problems introduced by NTSC.
It is hardly fraudulent of the channel to claim they are broadcasting at 1080i as they clearly are. The fact is that the vast majority of their viewers watch TV in SD on NTSC televisions. For the mintority with HD TVs, an upconverted DigiBeta or IMX SD feed is still a massive improvement over the fidelity enjoyed (suffered) by their SD bretheren.
Phil Windley
· 1 year ago
Agree completely. The signal I have now is much better than the analog signal used to be. I'm not complaining, but I am curious.
I'm not a broadcaster, but I would guess your local station hasn't upgraded all their in-house studio equipment. They are "up-sampling" the standard resolution to a high resolution carrier. The national broadcast is actually high resolution and is just being piped through.
Why? Because KSL is lying to you and every member of their audience when they claim to be an "HD" station. Their studio production equipment (cameras, switchers, etc) has NOT been upgraded to HD. Their studio cameras support a modified 16x9 format, but it is still NTSC video, NOT 1080i. They "upconvert" their studio NTSC signals into the ATSC data stream, but the source material is not 1080 anything. It's as simple as that.
Studios don't output NTSC. In the vast majority of TV studios around the world, the cameras will use a digital format such as DigiBeta or IMX which records and outputs video at 50Mbps MPEG2 iFrame (also called 50i). This is an extremely high quality capture which the station engineers will route to output processors for conversion to NTSC (which is subsequently converted again to MPEG for distribution on some cable and satellite service providers) and digital HD (1080i in this case).
If the station were really converting the NTSC output to 1080i the quality would be drastically worse than what is represented here. The output of a 50Mbps studio camera is very high quality and very suitable for up-conversion to HD. This is a significant cost saving to stations as professional HD cameras and processing equipment are extremely expensive - especially for a comparitively small local station. Additionally, the changes required to lighting, make-up and post-production are not trivial.
Meanwhile an SD up-convert from 50Mbps iFrame MPEG2 actually gives you a great, albeit imperfect picture which is orders of magnitude better than that viewed by your neighbour with an NTSC analogue set.
All Comments
The news studio has three Philips LDK-10 cameras with CCD imagers.
The cameras output a standard NTSC signal in a digital transport called SDI (Standard Definition Interface). The physical link standard for this transport is SMPTE 259M on a single 75 ohm coax.
The Philips cameras CCD imagers are capable of and have been switched to generate a 16 x 9 aspect ratio. All video sources in the news room like the graphics systems, weather equipment and field cameras were also set up for a 16 by 9 output. If you were to view the video output of the news room on a standard 4 x 3 monitor, everyone looks tall and skinny.
The output of the news production switcher is sent to two format converters, one for HD and one for standard definition.
The HD format converter 'understands' that the input image is already 16 x 9 in aspect with a pixel resolution of 720 by 480 and up converts via horizontal and vertical re-sampling to 1920 by 1080i. Re-sampling involves a low pass filter so the converted image can't exceed the frequency response of the input. Up converted images are not as detailed even though the pixel count is higher.
The standard definition format converter takes the 16 x 9 input, crops it to 14 by 9 and then letter boxes it in a 4 x 3 standard NTSC frame. The over the air image for analog NTSC is bandwidth limited to 480 x 480 resolution, which is why the HD signal (sampled at 720 x 480) looks marginally better than the analog signal.
KSL is now purchasing new cameras and other news production equipment with hopes of being full HD in July.
--phil--
Phil Windley
www.windley.com
www.itconversations.com
a 16:9 aspect ratio.
--phil--
Phil Windley
www.windley.com
www.itconversations.com
Not that I blame KSL for not having the cameras and plumbing - the bandwidth requirements are significant and I doubt they have so much cash lying around that upgrading is an expense they can easily absorb.
This stuff will take time. One thing's for sure--people buying HD TVs
is going to put tremendous pressure on stations and other program
providers to upgrade the quality of their shows.
--phil--
Phil Windley
www.windley.com
www.itconversations.com
My guess is that you are just seeing two different formats, progressive and interlaced.
Just a guess though...
--phil--
Phil Windley
www.windley.com
www.itconversations.com
If what you were seeing was converted from NTSC (an analogue recording and transmission format in contrast to the digital, 50Mbps MPEG2 output by studio grade cameras) the picture would be absolutely awful and would include all the colour problems introduced by NTSC.
It is hardly fraudulent of the channel to claim they are broadcasting at 1080i as they clearly are. The fact is that the vast majority of their viewers watch TV in SD on NTSC televisions. For the mintority with HD TVs, an upconverted DigiBeta or IMX SD feed is still a massive improvement over the fidelity enjoyed (suffered) by their SD bretheren.
analog signal used to be. I'm not complaining, but I am curious.
--phil--
Phil Windley
www.windley.com
www.itconversations.com
--phil--
Phil Windley
www.windley.com
www.itconversations.com
--phil--
Phil Windley
www.windley.com
www.itconversations.com
Studios don't output NTSC. In the vast majority of TV studios around the world, the cameras will use a digital format such as DigiBeta or IMX which records and outputs video at 50Mbps MPEG2 iFrame (also called 50i). This is an extremely high quality capture which the station engineers will route to output processors for conversion to NTSC (which is subsequently converted again to MPEG for distribution on some cable and satellite service providers) and digital HD (1080i in this case).
If the station were really converting the NTSC output to 1080i the quality would be drastically worse than what is represented here. The output of a 50Mbps studio camera is very high quality and very suitable for up-conversion to HD. This is a significant cost saving to stations as professional HD cameras and processing equipment are extremely expensive - especially for a comparitively small local station. Additionally, the changes required to lighting, make-up and post-production are not trivial.
Meanwhile an SD up-convert from 50Mbps iFrame MPEG2 actually gives you a great, albeit imperfect picture which is orders of magnitude better than that viewed by your neighbour with an NTSC analogue set.