Mentor
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15 Messages
what's up with 1080i setting but no 1080p?
So I ordered HD upgrade. On the DVR settings I figured I'd see what settings there are, so I go the screen settings and the highest one is 1080i...
What's up with that? Am I really getting interlaced frames? Can this DVR not output 1080p?
What am I missing here?
I have to believe you guys are getting 1080p...
What's up with that? Am I really getting interlaced frames? Can this DVR not output 1080p?
What am I missing here?
I have to believe you guys are getting 1080p...
oz_1
Master
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85 Messages
13 years ago
You are right in the affect you are not going to get Blue Ray quality but its do to more varibles than just interlaced vs progressive but your flat panel will show native resolution.
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longhornsk57
Mentor
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15 Messages
13 years ago
Yeah I hear that, and I optimized my TV yesterday with the visual EQ settings (LCD - 1080p) and was watching some of the HD stuff and it looked really amazing, so yeah I definitely like the quality.
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oufanindallas
ACE - Master
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480 Messages
13 years ago
Has nothing to do with bandwidth. Even OTA broadcasts are 1080i. It's a network issue not a provider issue. Their is a reason on one provider (DirectTV) has any 1080p content and those are strictly on demand movies.
*I am not a DIRECTV employee, and the views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
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SomeJoe7777
Expert
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346 Messages
13 years ago
All modern TVs have a video processing chip inside them usually called the scaler/deinterlacer. This chip is responsible for changing any incoming signal format into what the display can actually display natively.
The scaler/deinterlacer is the chip that is responsible for changing the 1080i/60 signal from the broadcaster into a progressive signal that the (LCD Panel, Plasma Panel, etc.) can display.
It converts interlaced video into progressive video by using motion-adaptive interpolation.
A 1080i signal does not have frames. It is a sequence of fields that alternate between the top field (scan lines 1, 3, 5, etc.) and the bottom field (scan lines 2, 4, 6, etc.). There are 60 fields per second in a 1080i signal. Each field is independent in BOTH space and time. That means that the pixels in each field come from a different part of the image captured by the camera (spatially independent) AND each field was actually snapped by the camera at a slightly different time (temporally independent). That is why a 1080i signal cannot be said to have "frames" because you do not get one continuous picture if you combine two adjacent fields together.
Your TV takes the stream of fields and buffers them, and carefully examines each field to identify objects that are moving and objects that aren't. It then applies two different algorithms to the fields to create full frames using the information in the current field, as well as information in the previous and subsequent fields. The result is a 1080p signal at 60 frames per second, each frame consisting of half actual pixel information from the 1080i signal, and half algorithm-created information.
The modern scaler/deinterlacer chips in TVs do this job fairly well, although there are wide variations in quality from different manufacturers.
A 1080p signal that you get from Blu-Ray is not 60 frames per second. It is typically 24 frames per second, which matches the film rate. 24 frames per second looks very "juddery" when played back because there is not nearly as much temporal information as a 1080i signal has. (A 1080i/60 signal has 60 updates per second of temporal information, corresponding to the 60 fields. This is more than 2.5x what a 1080p/24 signal has).
Because a 1080p signal has far less temporal information, the bandwidth requirements for 1080p are actually less than what is required for 1080i. So the issue with providers not doing 1080p is not a bandwidth issue. The reason they typically don't do it is because not every HDTV out there can process a 1080p/24 signal. Early HDTVs (typically rear-projection CRT models) could display 1080i signals only, because they actually still use electron beam scanning, which has always been interlaced in consumer equipment.
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longhornsk57
Mentor
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15 Messages
13 years ago
Wow.
Thanks for that explanation, it totally makes sense and I can see I had some confusions about what exactly interlaced vs progressive was 🙂
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skeeterintexas
ACE - Expert
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28.3K Messages
13 years ago
I have no idea what SomeJoe is talking about but, darn, he's smart!
Don't mess with old people. The older we get, the less "Life in Prison" is a deterrent.
*I am not a DIRECTV employee, and the views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
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Anonymous
1.9K Messages
13 years ago
If technology keeps going the way it is, SJ is going to need more RAM and a bigger hard drive. I read that twice and still can't remember everything he just said.
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SomeJoe7777
Expert
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346 Messages
13 years ago
More RAM and a bigger hard drive makes everything better. Kinda like bacon.
Wanna make your computer better? More RAM and a bigger hard drive.
Wanna make your turkey sandwich better? Bacon.
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longhornsk57
Mentor
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15 Messages
13 years ago
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new_dev_iwaanures
Tutor
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5 Messages
13 years ago
Seriously, what method is used to encode/compress each stream? I am actually under the impression that the 1080i hd setting is nothing more than "upconverted" 720p happening at the stb. That is if the method of encode/compress actually even results in true 720p exiting your stb.
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SomeJoe7777
Expert
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346 Messages
13 years ago
AT&T uses H.264 (AVC) to compress/encode their video streams. This is the same encoding used on most Blu-Ray discs, but AT&T uses far lower bitrates. The native bitrate that AT&T is using for HD streams is approximately 5.7 Mbps.
The STB will output whatever resolution is selected in the Menu -> Options -> System Options -> Aspect Ratio screen, regardless of the native resolution of the stream. For example, if you have selected 1080i output, the STB will output 1080i for all channels: incoming streams that are 1080i will be sent natively to the TV, and incoming streams that are 720p will be converted to 1080i, then sent to the TV.
The opposite happens if you've selected 720p output. 720p streams will be sent natively to the TV, 1080i streams will be converted to 720p and then sent to the TV.
Some providers, notably DirecTV, have a selector in their STBs called "Native Mode", where the STB will send the stream to the TV in the native resolution, no matter what it is, and your TV can then handle it. This selection is unfortunately not available on U-Verse.
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oz_1
Master
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85 Messages
13 years ago
I wish Uverse had Native Mode maybe a hope for future STB's.
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morphinapg
Tutor
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7 Messages
12 years ago
The reason for 1080p output is not to receive 1080p channels, it's so that BOTH 1080i and 720p content get scaled properly. If you have 1080i output, then you're losing resolution on 720p channels, and if you use 720p output, then you lose resolution on 1080i channels. With 1080p output, you don't ever lose resolution.
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baseballisback
ACE - Professor
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8.2K Messages
12 years ago
*I am not a DIRECTV employee, and the views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
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JefferMC
ACE - Expert
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36.9K Messages
12 years ago
Perhaps you should re-read the thread above?
The TV has exactly ONE native resolution. It is either 720 or 1080 vertical pixels. If it gets the other resolution, the TV will scale it to the TV's native resolution.
So... if the TV is 1080i and the channel comes in as 1080i, then no scaling occurs. If the TV is 1080 and the channel is 720p, even if this is the "native" format for the content, it will STILL get scaled by the TV.
1080p and 1080i have the same vertical resolution, it's just that on 1080i only frames are "sort of" broken up into fields containing half the lines in each field.
The only thing having the STB lock the resolution at a certain number of pixels does is move the scaling from the TV to the STB. The STB, especially a newer one, has fairly good scaling ability.
*I am not a DIRECTV employee, and the views and opinions expressed on this forum are purely my own. Any product claim, statistic, quote, or other representation about a product or service should be verified with the manufacturer, provider, or party.
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