is over the air HDTV 'compressed'?

[rotuts]

Im new to HDTV and have a DIVCO fusion card in a mac with iTele etc.

Ive noticed that there seems to be very little true HDTV in the SF bay area. KQED at 8pm does have the most spectacular picture on some of their new programing. these they say are filmed with true HDTV cameras, processed digitally and then transmitted over the air.

this just fit my monitor: 1920 x 1200, with no black bands etc. some of their other programing is not a spectacular and seems it might be analog thats convewrted, ie older concerts. still fills the screen.

then some have black bars on the right and left. this seems to be the comercial (CBS, NBC) for there 'prime time' shows ( studio shows) and the ditail does not seem to be the same as the newer PBS shows. they say 'HD widescreen" or something like that.

I have not seen any live sports yet like NFL where Im guessing the comercial networks pull out all the stops.

any references to go to to learn whats really full specturm and whats not? how about whats compressed and whats not? and do cable systems conpress the HD to save bandwith?

thanks rotut

I did not

[pyscrow]

HDTV is broadcast the same as SDTV, in transport streams, which is a variant of mpeg2 compression. HDTV just has a higher bitrate and larger resolution.

"True" HDTV varies depending on locality, in Australia, is is suposed to be at or better than 1080 interlaced vertical resolution, but having said that one of the stations is allowed to claim a lower value of progressive as HDTV.

The black bars are to "fill in" the screen coz they are transmitting in 4x3 mode instead of 16x9, and generally means they might be broadcasting in a HD stream, but the quality if often only good old analog TV quality.

I do not have any knowledge of cable systems offering HDTV, here in Australia the Cable digital is actually a lower quality than normal SDTV

[edDV]

To give you a feel for how compressed ATSC broadcast is vs. studio HD, see below. Even HDCAM SR has some compression.

Studio and field HD recording formats

HDCAM SR - 880/440 Mbps
HDCAM - 144 Mbps
DVCProHD - 100Mbps
HDV - 25Mbps (video only)

ATSC broadcast - 19Mbps (full rate HD) 12-14Mbps allows 1HD+1SD channel
WMV-HD (RC-1) - 6 to 8 Mbps
H.264, MPeg4 (similar to RC-1)

[edDV]

...

any references to go to to learn whats really full specturm and whats not? how about whats compressed and whats not? and do cable systems conpress the HD to save bandwith?

SDTV (US DTV broadcast) comes in several flavors. Most common are

480i 4:3 interlace
480i 16:9 interlace (aka widescreen)
480p 16:9 progressive (aka widescreen - progressive, or EDTV)

HDTV (US DTV broadcast) also comes in several flavors. Most common are

720p ABC, FOX, ESPN-HD
1080i PBS, NBC, CBS, HDNet, InHD, TBS-HD, HBO, Showtime, etc.

Cable systems are mostly passing HDTV at ATSC data rates (~14-19 Mbps) but someday they will adopt RC-1, H.264 or some other compression technology to increase the number of HD channels offered.

Sat DBS (DirecTV and Dish) are in the process of converting to "1000 HDTV channels" in MPeg4 format. Most of the 1000 channels will be the locals.

[redwudz]

I have the DVICO card also. Locally there are 4 channels transmitting and only the PBS station transmits high quality. All the rest are the same quality as the analog channels. Most disappointing are the sporting events. I was hoping the Indy 500 would be in high quality, but I doubt it. I use a 5X8 projection screen so analog quality is hardly worth it.

[edDV]

I have the DVICO card also. Locally there are 4 channels transmitting and only the PBS station transmits high quality. All the rest are the same quality as the analog channels. Most disappointing are the sporting events. I was hoping the Indy 500 would be in high quality, but I doubt it. I use a 5X8 projection screen so analog quality is hardly worth it.

Most locals are passing some network HD programming but they are not required to do so. Best to study the TitanTV listings before you invest in a HDTV set.

[rotuts]

ed

you mentioned that for video only HDV is 25 mbps. so this is the max picture rate for data in the 1920 x 1200 format?

its then compressed into MPEG2?

again trying to figure out why full 'HD' PBS KQED 9 at 8pm sometimes is so much a better picture than commecial nets.

thanks r

[edDV]

ed
you mentioned that for video only HDV is 25 mbps. so this is the max picture rate for data in the 1920 x 1200 format?

its then compressed into MPEG2?

OK more detail on HDV, the pro-sumer camcorder format.
- the video, unlike DV, is actually recorded at 19 Mbps MPeg2 transport stream but within the DV format specification so that it can record to MiniDV tape or be transfered as DV over IEEE-1394 firewire/ilink.
- native HDV is 1280x720 and can be 60i, 30p, 50i or 25p
- most HDV camcorders will also record normal DV (480i)
- some HDV camcorders also allow 720x480p in 30p,25p or 24p
- many support 1080i converted output in addition to 720p, 480p and 480i (also 576p and 576i)

http://www.hdvinfo.net/

again trying to figure out why full 'HD' PBS KQED 9 at 8pm sometimes is so much a better picture than commecial nets.
thanks r

from 6am to 8pm KQED transmits multiplex channels as follows. All these sub channels share the same 19Mbps DTV channel.
9.1 SDTV or HDTV*
9.2 SDTV
9.3 SDTV or slide
9.4 SDTV or slide
9.5 SDTV or slide
* HDTV on 9.1 requires 9.3, 9.4, 9.5 to show a slide only
Note analog Ch9 is a separate program. DTV 9.1-9.5 are currently being broadcast on UHF Ch30. When analog broadcasting ends, 9.1-9.5 will move back to VHF Ch9.

from 8pm-6am, KQED's transmits only two DTV channels + analog Ch9
9.1 SDTV or HDTV
9.2 SDTV

This is when the bulk of HDTV programming will be transmitted on 9.1 almost all of it retransmitted off the PBS HD satellite feed.

The typical commercial station operates all day similar to KQED in the evening most often with a HD version or upconverted 480p simulcast of the analog channel and often with 5.1 dolby sound.

n.1 1080i/720p HDTV or 480p upconversion
n.2 typ. weather, news, or infomercial (leased)

If anything, the commercial stations should be showing an equal or better HDTV picture at 8pm since 9.2 is a full SDTV separate broadcast.

Maybe you are comparing PBS HDTV to the other channel's 480p upconversion.

[rotuts]

edDV: your the wo(man)! a great help to me today. both this thread and the antenna thead;

one q here one in the antenna thead:

here: on KQED ( I bed your a SF Bayarea wo(man)) some shows must be shot in 'full' HD with the best camera's take the fri PM HD show Chef's a Field. when I get this on my computer, its really the best image Ive seen on HDTV.

the commecial shows ( mostly studio) seem not at fine. Ive read in the past pre DIVCO card that true HD with the best cameras make studio shows look poor, so they chizel a little on these some how to not show the makeup and flaws in the sets.

not so with ChefsaField.

that difference is what I was getting at.

now the antenna q: Ill post here and in the antenna thread incase someone is following that:

Ive been told by an engineer at KCSM by email that their signal and KQED is the same strengh. KQED is oniTele 30.6 I guess that 90.4
when I can't get 30.6/90.4 I can still get KCSM digital 43.1

wouild this frequncey difference make that much dif in the antenna's receptions? KQED doesn't have the $$ or energy to answer my emails on this.

great help today ed!

R

[edDV]

Man here, who lives both in SF Bay and Sierra foothills.
I'm familiar with the SF and Sacramento DTV markets.

...

some shows must be shot in 'full' HD with the best camera's take the fri PM HD show Chef's a Field. when I get this on my computer, its really the best image Ive seen on HDTV.

the commecial shows ( mostly studio) seem not at fine. Ive read in the past pre DIVCO card that true HD with the best cameras make studio shows look poor, so they chizel a little on these some how to not show the makeup and flaws in the sets.

not so with ChefsaField.

that difference is what I was getting at.

now the antenna q: Ill post here and in the antenna thread incase someone is following that:

Ive been told by an engineer at KCSM by email that their signal and KQED is the same strengh. KQED is oniTele 30.6 I guess that 90.4
when I can't get 30.6/90.4 I can still get KCSM digital 43.1

wouild this frequncey difference make that much dif in the antenna's receptions? KQED doesn't have the $$ or energy to answer my emails on this.

great help today ed!

R

Shows will vary in quality. Equipment and operator skill will vary as well. The networks that showcase the HD technology best in my opinion are Discovery HD, InHD and PBS. The big networks seem to do best with sports. Dramas are mostly shot on film and tend to have a softer look.

Very little is produced locally in HD at present.

As for transmission power, usually the higher the UHF channel, the more power is needed for the same reception.

[DeadLamb]

PBS also tends to look better in HD then some other networks being the shows they play are more along the lines of brighter lighting, slower motion and so on.. Ya know, like look at the the artwork, see the big trees and so on with family programing Vs a show like 24 that is shooting everyone in a dark room..

as soon as you start watch more shows in HD you will start see all sorts of range as far as how they look.. Even with in the same network, one tv movie of the week will look perfect, next week it's grainy.. I'm not sure any network is bringing perfect HD all the time, every night and again IMO alot of it has to do with the show you are watching along with all the tech stuff edDV mentioned....

also some networks just sort of suck for HD right now.. FOX is lame unless it's sports or live but almost all their shows are a grainy mess in HD (still way better then analog of course). WB is pretty bad also.. UPN is shockingly good for being a new upstart level network.. ABC, NBC and CBS all sort of tie depending on what they are showing..

If you really want to check your HD rate one can always record a clip and feed it into TSreader lite.. It will tell you the bit rate of the show..

http://www.coolstf.com/tsreader/