PQ of SD channels through HDMI

[hrish88]

I have a toshiba 32av650,which i received on club mahindra membership.i m planning to buy HD DTH service.


can anyone tell me about picture quality of SD channels via HDMI.will there be any difference.there is a significant difference when i connected my ps3.even a 3hr 700mb Hindi movie looks much better via HDMI.also why all these Big tv,tata sky,Dish tv,Sun etc are not showing movie on demand in hd.it will be a huge benefit.as we dont have blu-ray movies on rent in india.

 

[sam9s]

Tata Sky has its showcase event in HD

 

[yrk1969]

I don't see any improvement in PQ of SD channels with HDMI, maybe even a little worse.

 

[hrish88]

thats a sad news. i was thinking of getting tata sky hd as i am a existing tata sky customer.

 

[SaurabhK]

There is a huge improvement in HD via HDMI with TataSky at least!! Killer...startling video and audio both... watching Nat GEo on DTS is amazing..

 

[yrk1969]

There is a huge improvement in HD via HDMI with TataSky at least!! Killer...startling video and audio both... watching Nat GEo on DTS is amazing..

NatGeo is very good but Discovery is so so, looks to have too much DNR.

 

[sam9s]

thats a sad news. i was thinking of getting tata sky hd as i am a existing tata sky customer.

Why are you expecting improvement for SD video over a HD STB. TS HD is for HD channels and its obvious SD channels would be same as what we are getting over a normal STB ... ???

HDMI can do nothing to improve SD signals....

 

[yrk1969]

Why are you expecting improvement for SD video over a HD STB. TS HD is for HD channels and its obvious SD channels would be same as what we are getting over a normal STB ... ???

HDMI can do nothing to improve SD signals....

There would have been improvement if the quality of the picture was limited by composite cable, however in TS case orginal PQ is already seems very limited, so changing to HDMI does not have much/any effect.

With TS over HDMI, the difference comes down mostly to the quality of the scaler in the TS box vs your TV.

 

[SaurabhK]

Why are you expecting improvement for SD video over a HD STB. TS HD is for HD channels and its obvious SD channels would be same as what we are getting over a normal STB ... ???

HDMI can do nothing to improve SD signals....

Your AV receiver I think upscales the regular SD also.

 

[pnredkar]

The actual scenario of SD cable through HDMI is slightly more complicated. The actual transmission of SD signals is at 576i (PAL resolution). However, you have options to set the output resolution of your HD-set-top box to either 720p or 1080i. Hence, the set top box de-interlaces and scales the signal to this resolution. And since TVs are either 768p (HD-ready) or 1080p (Full-HD), the TV further processes this signal to the native resolution. This is the multiple processing that actually degrades the signal. Also, the video processing of your set top box will be at best, mediocre.

When you had the SD set top box, it output the 576i signal (through composite) without applying any processing. The processing was entirely done by your TV. And I assume that most TVs on market will have a better processing than these set top boxes.

This might be the reason for seeing slightly degraded SD picture from your HD set top box. To verify this, you may perform the following test:

- Connect your HD box to TV using composite cable (guaranteed 576i without processing)
- Compare this signal (for SD channels only) with the same signal from HDMI.

I suspect that you may find the composite cable signal better.

Other (better) option would be if your set top box has the ability to set the output based on the input resolution: 480i/576i for SD and 720p/1080i for HD.

- Prasad.

 

[hrish88]

Why are you expecting improvement for SD video over a HD STB. TS HD is for HD channels and its obvious SD channels would be same as what we are getting over a normal STB ... ???

HDMI can do nothing to improve SD signals....

Because i ve read on this forum only that PQ of TS+ is better because of composite cable output.also when i played a 550*320 pixelmovie on ps3 via hdmi and via av the difference was considerable.

 

[hrish88]

There would have been improvement if the quality of the picture was limited by composite cable, however in TS case orginal PQ is already seems very limited, so changing to HDMI does not have much/any effect.

With TS over HDMI, the difference comes down mostly to the quality of the scaler in the TS box vs your TV.

So what you are saying quality is better via composite cable than HDMI

 

[hrish88]

The actual scenario of SD cable through HDMI is slightly more complicated. The actual transmission of SD signals is at 576i (PAL resolution). However, you have options to set the output resolution of your HD-set-top box to either 720p or 1080i. Hence, the set top box de-interlaces and scales the signal to this resolution. And since TVs are either 768p (HD-ready) or 1080p (Full-HD), the TV further processes this signal to the native resolution. This is the multiple processing that actually degrades the signal. Also, the video processing of your set top box will be at best, mediocre.

When you had the SD set top box, it output the 576i signal (through composite) without applying any processing. The processing was entirely done by your TV. And I assume that most TVs on market will have a better processing than these set top boxes.

This might be the reason for seeing slightly degraded SD picture from your HD set top box. To verify this, you may perform the following test:

- Connect your HD box to TV using composite cable (guaranteed 576i without processing)
- Compare this signal (for SD channels only) with the same signal from HDMI.

I suspect that you may find the composite cable signal better.

Other (better) option would be if your set top box has the ability to set the output based on the input resolution: 480i/576i for SD and 720p/1080i for HD.

- Prasad.

thank you for such a detailed explanation.can you tell which set top box has this ability.

 

[SMFire]

Am working as a Set Top Box developer & i assure you that there is no such box available. Unless the guy who posted it wants to develop one himself.
But seriously, have u seen the amount of time it takes for a PS3 to change resolutions from 1080p to 720p/480p. It would be the worst user experience ever.
If you are so bothered by the HDMI output, you should consider connecting a composite cable to your TV as well & after changing to an SD channel, you can switch to the composite input.

 

[pnredkar]

thank you for such a detailed explanation.can you tell which set top box has this ability.

AFAIK, no set-top box in India has this ability. There are a few operators in other countries (US for example) which has such boxes. The option is typically called as "source direct".

 

[hrish88]

Am working as a Set Top Box developer & i assure you that there is no such box available. Unless the guy who posted it wants to develop one himself.
But seriously, have u seen the amount of time it takes for a PS3 to change resolutions from 1080p to 720p/480p. It would be the worst user experience ever.
If you are so bothered by the HDMI output, you should consider connecting a composite cable to your TV as well & after changing to an SD channel, you can switch to the composite input.

I m not bothered by HDMI.i was optimistic.recently ive got HDTV.so yet dont know much about this all.

connecting composite cable and changing SD channel well thats a bit too much work at least for me.

i hope more n more HD channels will get added in coming months.

 

[deepakb]

The actual scenario of SD cable through HDMI is slightly more complicated. The actual transmission of SD signals is at 576i (PAL resolution). However, you have options to set the output resolution of your HD-set-top box to either 720p or 1080i. Hence, the set top box de-interlaces and scales the signal to this resolution. And since TVs are either 768p (HD-ready) or 1080p (Full-HD), the TV further processes this signal to the native resolution. This is the multiple processing that actually degrades the signal. Also, the video processing of your set top box will be at best, mediocre.

When you had the SD set top box, it output the 576i signal (through composite) without applying any processing. The processing was entirely done by your TV. And I assume that most TVs on market will have a better processing than these set top boxes.

This might be the reason for seeing slightly degraded SD picture from your HD set top box. To verify this, you may perform the following test:

- Connect your HD box to TV using composite cable (guaranteed 576i without processing)
- Compare this signal (for SD channels only) with the same signal from HDMI.

I suspect that you may find the composite cable signal better.

Other (better) option would be if your set top box has the ability to set the output based on the input resolution: 480i/576i for SD and 720p/1080i for HD.

- Prasad.

Your explanation makes lot of sense.

However, I tried these options

(1) Tried viewing the SD content through Composite cable in TataSky HD box and through HDMI, both the cases the quality of SD was crap and really there was not much comparison

(2) Tried setting the HDMI to 576i, again the quality was crap.

 

[pnredkar]

Your explanation makes lot of sense.

However, I tried these options

(1) Tried viewing the SD content through Composite cable in TataSky HD box and through HDMI, both the cases the quality of SD was crap and really there was not much comparison

(2) Tried setting the HDMI to 576i, again the quality was crap.

Hard luck! Then nothing much can be done about it (unless you get a video processor like DVDO Edge which might marginally improve the quality).

And I see that you are already spoiled by HD :lol:

- Prasad.

 

[dgtl887]

IF anything, PQ of SD channels on Tata Sky HD is a little worse (than my cable guy with a digi box). Weird..

 

[shredder]

One question to existing TATA SKY HD users. I understand that the native HD channels will come in a 16:9 aspect ratio. But is there an option to change the aspect ratio of SD channels into 16:9 ratio?