Observations on quality

[jayn_j]

I did some playing during the superbowl in that I compared OTA vs TWC vs FoxNow feed.

I used the built in tuner on my 4k Samsung 65" 9000 for OTA
The TIVO Roamio for the TWC/Spectrum feed off the primary Fox channel
The built in app for the fox now feed.

Unfortunately, Fox did not support a 4k feed, although they used 4k cameras.
The OTA and streaming were close with the edge going to OTA. My Fox affiliate only runs 1 subchannel (antenna TV). The streaming was close, but had occasional dropouts and periods where quality dropped for a few seconds.

The cable feed however was awful. It was very soft, nearly 480p quality. Colors were muted and overall it just looked dull.

I am now in the process of dropping the cable again. I want the higher speed modem Spectrum is now offering, but I am watching less conventional TV and it is mostly broadcast. Pretty sure I can live without cable again, especially since Spectrum killed my discount rate.

I encourage folks to do some periodic comparisons. MY cable feed was significantly better a year ago.

 

[harshness]

Unfortunately, Fox did not support a 4k feed, although they used 4k cameras.

According to a Forbes magazine article, Fox employed 70 cameras but only six of them were 4K (4 regular cameras and two 4X replays). Then again, we don't really have any way of telling whether or not they used the 4K equipment at all.

 

[jayn_j]

According to a Forbes magazine article, Fox employed 70 cameras but only six of them were 4K (4 regular cameras and two 4X replays). Then again, we don't really have any way of telling whether or not they used the 4K equipment at all.

Not quite. The Forbes article describes the following:

70 total FOX Sports cameras for the #SuperBowl , including:

• 2 ea. high-speed (4X) 4K high-resolution cameras
• 4 ea. normal-speed 4K cameras
• 4 ea. 3X (180FPS) Super Motion cameras
• 2 ea. 6X (360 FPS) Super Motion cameras
• 3ea. 8X (480 FPS) cameras
• 24 ea. pylon cameras (8 pylons x 3 cameras)
• 1 ea. 8K camera

That says that a total of 7 cameras were at least 4k )including the 8k one). The pylon cameras don't really count as they are not being used for primary motion, only for crowd ambience capture. The 9 high speed cameras don't have to be 4k because they are being used for instant replay to see that the ball crossed the line, etc. And that described a total of 40 cameras. What's with the other 30 unreported ones?

But then again, what difference does it make? How does this affect my experiences I was reporting on soft 1080 images via the cable feed?

 

[harshness]

That says that a total of 7 cameras were at least 4k )including the 8k one).

You'll note that I was careful to say 4K and not UHD (that includes 8K). Either way, we don't know if they used any of these cameras for the broadcast feed.

How does this affect my experiences I was reporting on soft 1080 images via the cable feed?

Unless your situation is relatively unique, your images of the Big Game were in 720p. If it was in 1080i, that's a whole other can of worms.

There are many reasons that the cable feed might appear less than stellar and the biggest is probably Fox's well-earned reputation for delivering NFL video that is typically of lesser quality. When you start with diminished video and execute real-time re-compression on it (as part of the QAM multiplexing process), the end product is almost certainly worse for the wear.

You would have to ask someone in engineering at your local Fox affiliate whether the cable feed comes from a direct feed or an OTA feed. Obviously, an OTA feed will have suffered more than a little at the hands of ATSC multiplexing making the subsequent QAM process that much more impactful.

I watched a Comcast feed and it was not great either.

 

[NoReDist]

I did a study of OTA vs a local cable provider on Fox stations for the game. Was interesting to see that some had higher bitrate OTA (squashed by cableco) vs higher bit off cable (presumed beefier fiber feed than afforded to OTA transmitter)

 

[harshness]

Was interesting to see that some had higher bitrate OTA (squashed by cableco) vs higher bit off cable (presumed beefier fiber feed than afforded to OTA transmitter)

Widening the data pipe between the station and the antenna won't make the OTA picture any better. The limiting factor is the <6MHz multiplex that the Fox channel and all of its fellow subchannels has to fit into.

A fiber feed probably doesn't get multiplexed or if it does (executed by some cableco-provided multiplexer), it isn't shoehorned into <6MHz (18.3Mbs?).

 

[comfortably_numb]

Is there any reason why Fox is STILL only 720 and not 1080i? All the other nets are 1080 now.

 

[SpaethCo]

Is there any reason why Fox is STILL only 720 and not 1080i? All the other nets are 1080 now.

It's 720 progressive instead of 1080 interlaced.

For 720p, the screen is updated at a rate of 60 frames per second. For 1080i, it's 60 fields per second, but you need 2 fields to render a full frame. Picture your TV as rows of pixels, 1 field will have odd lines, the next field will have even lines.

1280 x 720 = 921,600 pixels to update every 1/60th of a second
1920 x 1080 / 2 = 1,036,800 pixels to update every 1/60th of a second. (/2 because of interlacing)

So for about the same bandwidth budget, you can deliver smooth full-frame update motion for things like sports without ending up with interlacing artifacts like this:

 

[Trip]

Is there any reason why Fox is STILL only 720 and not 1080i? All the other nets are 1080 now.

ABC is in 720p, as is ION.

- Trip

 

[comfortably_numb]

ABC is in 720p, as is ION.

- Trip

My local ABC affiliate, KMBC, broadcasts in 1080i OTA. Just double-checked to make sure

 

[osu1991]

My local ABC affiliate, KMBC, broadcasts in 1080i OTA. Just double-checked to make sure

It's rare, WFAA in Dallas is or was, may still be 1080i, but ABC sends out 720p and in general 98% of the affiliates pass that thru

 

[Trip]

My local ABC affiliate, KMBC, broadcasts in 1080i OTA. Just double-checked to make sure

Then, as osu1991 states, they're cross-converting it locally. ABC provides 720p to its affiliates.

- Trip

 

[comfortably_numb]

Then, as osu1991 states, they're cross-converting it locally. ABC provides 720p to its affiliates.

- Trip

Apparently this is something that some Hearst ABC affiliates do. I always just assumed it was ABC sending down a 1080i feed, because I've always seen it in 1080i here

 

[harshness]

Is there any reason why Fox is STILL only 720 and not 1080i? All the other nets are 1080 now.

Here's a list of HD channels (both OTA and cable) along with their HD configuration:

http://hd-report.com/hd-channels

 

[harshness]

So for about the same bandwidth budget, you can deliver smooth full-frame update motion for things like sports without ending up with interlacing artifacts like this:

Fortunately, we humans were endowed with a brain that blends interlaced screens together so that we can't perceive this phenomenon without the aid of a still frame to show us what was happening.

Since CBS at 1080i is typically rated as better quality than ABC and Fox, the progressive scan argument is pretty much lost. That may change going forward as HD channels in larger TV markets are forced to share a channel and bandwidth becomes a huge issue.

 

[navychop]

You'll note that interlacing has been dropped for UHD/"4K".

Interlacing came into existence because when TV rolled out, the technology of the time could do no better. It was the phosphors on the CRT tube that had persistence and glowed just long enough to maintain an image our eyes would construct a reasonable image.

Resolution and frame rates are just part of the package that determines PQ.

Bandwidth requirements for 720p and 1080i aren't that far apart.

 

[harshness]

You'll note that interlacing has been dropped for UHD/"4K".

This probably has more to do with how computationally expensive it is to synthesize an interlaced screen from progressive digital sources. Modern compression schemes also work a whole lot better with progressive scanning.

It was the phosphors on the CRT tube that had persistence and glowed just long enough to maintain an image our eyes would construct a reasonable image.

Digital deinterlacing carries that burden today.

Bandwidth requirements for 720p and 1080i aren't that far apart.

They're far enough apart that you won't find many 1080i feeds sharing a TV channel. My local PBS station is a seemingly rare exception.

I suspect that much of the hardware development has been aimed at 1080 resolution as it provides an even multiple to higher resolutions as opposed to 720 which works in factors of three. Lastly, I don't expect that anyone is using cameras that are anywhere close to 720 native.

 

[comfortably_numb]

This probably has more to do with how computationally expensive it is to synthesize an interlaced screen from progressive digital sources. Modern compression schemes also work a whole lot better with progressive scanning.Digital deinterlacing carries that burden today.They're far enough apart that you won't find many 1080i feeds sharing a TV channel. My local PBS station is a seemingly rare exception.

I suspect that much of the hardware development has been aimed at 1080 resolution as it provides an even multiple to higher resolutions as opposed to 720 which works in factors of three. Lastly, I don't expect that anyone is using cameras that are anywhere close to 720 native.

Harshness, how much total bandwidth is required for 1080i? I, too, have noticed that OTA stations in 1080i have fewer sub-channels, and I don't have any with two 1080i feeds on one channel. KCPT used to have one 1080i, a 720p, and a 480i, but with the addition of PBS kids, they have dropped the main PBS feed down to 720.

 

[harshness]

Bandwidth is capped in broadcast television such that it is less about what is required and more about something that they carefully pack things into. The modulators that produce the ATSC multiplex use lossy MPEG2 compression on the source video streams such that the result plus the audio streams fit in the <6MHz bandwidth. If they fail, you get artifacts. Confetti drops will probably always result in artifacting.

Raw data-wise, 1080i represents 1,036,800 (1920x540) pixels/second where 720p is 921600 (1280x720) pixels/second (12.5% differential).

According to the Rabbitears database, KOPB has two 1080i feeds (OPB and OPB+) along with PBS Kids at 480i and a 480i slide show with three audio configurations (OPB Radio, OPB Music on SAP1 and KMHD Jazz on SAP2). They've surely got some very able modulators but I have to say that the OPB quality seems diminished since the addition.

 

[comfortably_numb]

Bandwidth is capped in broadcast television such that it is less about what is required and more about something that they carefully pack things into. The modulators that produce the ATSC multiplex use lossy MPEG2 compression on the source video streams such that the result plus the audio streams fit in the <6MHz bandwidth. If they fail, you get artifacts. Confetti drops will probably always result in artifacting.

Raw data-wise, 1080i represents 1,036,800 (1920x540) pixels/second where 720p is 921600 (1280x720) pixels/second (12.5% differential).

According to the Rabbitears database, KOPB has two 1080i feeds (OPB and OPB+) along with PBS Kids at 480i and a 480i slide show with three audio configurations (OPB Radio, OPB Music on SAP1 and KMHD Jazz on SAP2). They've surely got some very able modulators but I have to say that the OPB quality seems diminished since the addition.

Our PBS quality has also diminished since the addition of PBS Kids. I wish they would have reduced KCPT 2 to 480i and kept the 1080i on the main channel. The drop in quality is very noticeable.