DStv High-Definition broadcast details

[Smurfatefrog]

So if you need two feeds for existing HD channels, you most probably will need three or four for 1080p?

You only need 1 cable to get an HD feed, the 2nd cable is for recording a 2nd channel (HD or SD), Box Office, DSTV on Demand and the TV Guide

And 4 tuners for 2 recording channels and a dedicated 4th tuner for the latter 3 above

 

[atomcrusher]

In reality, and given a good spec full-HD TV, would the human eye even discern a noticeable picture quality improvement between 1080i/720p, and 1080p? I'm not talking about 3D, just normal Multichoice HD TV broadcasts?

 

[Sinbad]

Never mind the resolution, the compression artifacts are horrendous even on the hd channels.

 

[Azbubu]

DSTV HD is which is why I went back to CRT.

 

[Ricard]

So 720p is the best quality they are going to broadcast in for the foreseeable future.

That is of course until HEVC (H.265) gained traction.

http://9to5mac.com/2012/08/15/mpeg-...-same-quality-in-half-the-bandwidth-of-h-264/

HEVC is primarily for 4k transmissions, but has got good uses everywhere else. The h265 set top box chips are starting from the end of this year for samples so that is a good step. The next bit are the headend encoders, I didn't spot one at IBC a few weeks ago.

 

[T3rminator]

You only need 1 cable to get an HD feed, the 2nd cable is for recording a 2nd channel (HD or SD), Box Office, DSTV on Demand and the TV Guide

And 4 tuners for 2 recording channels and a dedicated 4th tuner for the latter 3 above

Exactly, although you can decrypt and record all channels simultaneously that are broadcast on the same multiplex. The different feeds are just so that they don't have to let users keep track of multiplexes or explain to them how it works that the channel they want to record is dependent on the channel they are watching.

If you are interested: http://en.wikipedia.org/wiki/Multiplexing#Digital_broadcasting

 

[Quantum Theory]

Exactly, although you can decrypt and record all channels simultaneously that are broadcast on the same multiplex. The different feeds are just so that they don't have to let users keep track of multiplexes or explain to them how it works that the channel they want to record is dependent on the channel they are watching.

If you are interested: http://en.wikipedia.org/wiki/Multiplexing#Digital_broadcasting

Multiplexing is not the reason for the 2 cables. DStv broadcasts on 2 polarities. Vertical low and horizontal low. You can't have both on one cable (well you can, but in a basic installation you can't), so if you want to record on vertical low and watch on horizontal low, you need 2 cables. If you want to watch and record channels on different multiplexes/transponders, you can get away with one cable, if they are on the same polarity.

 

[Roman4604]

In reality, and given a good spec full-HD TV, would the human eye even discern a noticeable picture quality improvement between 1080i/720p, and 1080p? I'm not talking about 3D, just normal Multichoice HD TV broadcasts?

More so between 720p50 vs 1080i50 then 1080i50 vs 1080p24 on modern mid-to-high end 1080p HDTVs (at optimal viewing distances with quality content).

Their high-speed signal processors are more competent at rectifying any image/motion anomalies induced by interlacing than masking the difference between 900KP vs 2MP with upscaling.

 

[Roman4604]

Never mind the resolution, the compression artifacts are horrendous even on the hd channels.

You sure you have a perfect signal? Dont see too many funnies on my HDPVR with steady 98% signal strength & 100% signal quality.

DSTV HD is which is why I went back to CRT.

Really? You prefer analogue 576i on a CRT vs digital 1080i on a 1080p flatscreen?

 

[damian24]

Multiplexing is not the reason for the 2 cables. DStv broadcasts on 2 polarities. Vertical low and horizontal low. You can't have both on one cable (well you can, but in a basic installation you can't), so if you want to record on vertical low and watch on horizontal low, you need 2 cables. If you want to watch and record channels on different multiplexes/transponders, you can get away with one cable, if they are on the same polarity.

You can... Well sort of, but I class satcr as basic and even that doesn't give you the whole low or high band,the decoder asks the lnb to 'tune' in the portion of the band it needs and selects either H or V polarity, satcr delivers the correct subband in one of 8 frequency slots on the cable iirc.

D

 

[elvis_presley]

Certainly not the norm, and from what I can see its only for select content e.g. on demand movies ...

Indeed ... Wikipedia (take that as you will) says only PPV http://en.wikipedia.org/wiki/DirecTV - I could dig further, but due to the fact you only see 1080p episodes once it hits bluray, and up to then you get 720p/1080i tvrips is enough evidence that's what they broadcast in.

 

[elvis_presley]

Really? You prefer analogue 576i on a CRT vs digital 1080i on a 1080p flatscreen?

It's the best way to view the photos you took on your analogue camera and digitized with your phone camera, while listening to vinyl on your valve amp.

Don't hate the hipsters, man.

 

[Smiley_lauf]

Now it makes sense why English Premier League on Ch 176 looks so "faded"--I questioned that when I first got the HD PVR-, but did not get an proper answer from DSTV. Compare that picture with the locally run soccer PSL on now Ch 178--the difference if so obvious; could this be distortion across satellite?

Yet, we pay a premium for this quality..go figure!

 

[Azbubu]

Really? You prefer analogue 576i on a CRT vs digital 1080i on a 1080p flatscreen?

No. I prefer analogue, which I watch 99% of the time, on a CRT over analogue on a 1080p screen.

 

[XRayA4T]

I stand to be corrected but it is my understanding that 1080i50 gets converted to 1080p25. So it is only a transmission standard. The TV still shows the content at progressive as we no longer have the old CRT where interlacing used scan lines. As most movies are shot at 24fps converting to 1080i50 should result in ideal HD reproduction. I know that PAL movies on DVD just take the 24fps and show it at 25fps to match the 576i50 25fps and speed up the sound track. That is why a PAL version is slightly shorter than a NTSC movie which uses the silly 3:2 pull down to convert 24fps to 30fps.

Where the source content is 50/60 fps then 1080p50 would be better but movies at 1080i50->1080p25 should be perfect. BluRay uses 1080p24 to match the source.

 

[Roman4604]

I stand to be corrected but it is my understanding that 1080i50 gets converted to 1080p25.

No 1080i still runs at 50fps, but in each frame half the lines are missing (either odd or even).

Since all flat-screen TVs must display progressively (i.e. 1080p50), the signal processor fills in the missing lines by comparing the freshly received adjacent lines to the stale previously received line to derive (predict) what the line should look like if it were received in that cycle.

As each line is cycled at high speed between accurately derived and real versions, the end result is a picture that would be difficult to discern from genuine 1080p50 (if such a thing commonly existed).

but movies at 1080i50->1080p25 should be perfect.

Movies at 1080i50 are very close to the 1080p24 original. They are sped up by 4% to 25fps and then frame doubled, resulting in the full 1080 lines being shown within one source frame cycle.

 

[XRayA4T]

No 1080i still runs at 50fps, but in each frame half the lines are missing (either odd or even).

Since all flat-screen TVs must display progressively (i.e. 1080p50), the signal processor fills in the missing lines by comparing the freshly received adjacent lines to the stale previously received line to derive (predict) what the line should look like if it were received in that cycle.

As each line is cycled at high speed between accurately derived and real versions, the end result is a picture that would be difficult to discern from genuine 1080p50 (if such a thing commonly existed).

From Wikipedia:

In native or pure 1080i, the two fields of a frame correspond to different instants (points in time). This is true for interlaced video in general and can be easily observed in still images taken from fast motion scenes, as shown in the figure on the right. However, for processing or broadcasting purposes, 1080p material at 25 or 30 frames/second is converted to 1080i at 50 or 60 fields/second, respectively, both fields in a frame do correspond to the same instant.

When the two frames are at different points in time you get the comb effect:

But as we have 1080i50 and movies are at 24fps sped up 4% the two fields are at the same instant so there is no comb effect and it is effectively 1080p25 if I understand the wikipedia article correctly.

 

[R13...]

DSTV HD is which is why I went back to CRT.

I assume you're only referring to SD content on a flat screen TV, because their HD content is very good. Except box office which has horrible artefacts esp. on night scenery.

 

[Sinbad]

I watched India v England t20 at a friend's place in HD. The green of the field was smearing all over the place....

 

[Genghis Khan]

Not sure I entirely agree with you, purely from my observation at my sister-in-law's house.

They have a Samsung 3D tv ( not sure on the model ) and the current DSTV hd pvr. Watching an HD channel on the tv results in a horrible 'almost real-time' picture. You would think it was at 60fps. No matter how much of the artificial processing I had turned off on the tv, the problem was still there; including a horribly cropped back & white border at the top of the screen.

Actually, the black and white border at the top led me to believe the fancy cycle speed up and frame doubling DSTV is doing is resulting in a slightly off aspect ratio.

Comparing this to my SKY setup, I can set the option to receive HD broadcasts in 720p or 1080i on the decoder.

Unfortunately, i don't think we will see true 1080p/24 broadcasting for a long time. The bandwith requirements are just massive.

Blurays play in excess of 30Mbps

No 1080i still runs at 50fps, but in each frame half the lines are missing (either odd or even).

Since all flat-screen TVs must display progressively (i.e. 1080p50), the signal processor fills in the missing lines by comparing the freshly received adjacent lines to the stale previously received line to derive (predict) what the line should look like if it were received in that cycle.

As each line is cycled at high speed between accurately derived and real versions, the end result is a picture that would be difficult to discern from genuine 1080p50 (if such a thing commonly existed).

Movies at 1080i50 are very close to the 1080p24 original. They are sped up by 4% to 25fps and then frame doubled, resulting in the full 1080 lines being shown within one source frame cycle.