data in video

[B.J.]

Interesting stuff on the 12095V4340 telarity channel on AMC21. The MPEG4 video is a black screen, except that it has 3 lines (one of which is static) of what appear to be data in the bottom 1/4th of the screen. Looks similar to the VBI CC or teletext type stuff, except it's right in the visible part of the screen. Seems like a really wierd/inefficient way of sending data if in fact that is what this is.

 

[hd fan]

The following was posted a week ago on the AVSForums :

" PBS is transmitting a 1080i Telarity (Mpeg4 H.264) channel now, mirroring the PBS East Mpeg2 transponder. Its quite a bit softer, and there is some noticable scene transition pixellation, but its using a SR of 4340 vs the Mpeg2 transponder which used 30000, for two, or 15000 each. Quite a bandwidth savings.

Im having to use it tonight to record Nova, as the PBS East feed is weak due to the rain and heavy cloud cover and the mpeg4 transponder is kicking in at 97% quality.

Wonder if they plan to use H.264 as a transmission method to the stations in the future, maybe via fiber or internet. I know some change is in works."

 

[hd fan]

Telairity is a manufacturer of video encoders , SD and HD , therefore more likely PBS is testing their equipment and the ability to send HD channels at a much lower bandwith using MPEG4. As you can see that new channel is only 4340 SR compared to 30000 SR that the regular HD tp has , well 15000 per each HD national feed. Almost a 70% reduction of bandwith used therefore money saved.

 

[MikeinBaja]

Interesting stuff on the 12095V4340 telarity channel on AMC21. The MPEG4 video is a black screen, except that it has 3 lines (one of which is static) of what appear to be data in the bottom 1/4th of the screen. Looks similar to the VBI CC or teletext type stuff, except it's right in the visible part of the screen. Seems like a really wierd/inefficient way of sending data if in fact that is what this is.

Holy crap - is that my Direcway/Hughesnet stream?

 

[B.J.]

Telairity is a manufacturer of video encoders , SD and HD , therefore more likely PBS is testing their equipment and the ability to send HD channels at a much lower bandwith using MPEG4. As you can see that new channel is only 4340 SR compared to 30000 SR that the regular HD tp has , well 15000 per each HD national feed. Almost a 70% reduction of bandwith used therefore money saved.

Yeah, I was aware of that. They've been sending a very low quality PBS HD channel on that transponder for quite a while now, although it alternates with another feed that is regular mpeg2. Whenever it's telairity, it's been mpeg4 though. Several weeks ago, I was curious, and googled telarity, and found that like you said, they were the developer of an MPEG4 encoder, and one of their main customers was some state in the southeast, I think it was Alabama, who have adopted that as a cheap way to get HD around the state. So this might be coming from Alabama. However this thing today, wasn't the usual PBS feed, but instead this strange black screen with the lines of little white blocks, like you often see at the top of screens when there is CC info there, except this was in the bottom 1/4th of the screen.

 

[toucan-man]

Regarding PBS in general, what's the deal with the color bars and bouncing gray box? Why is the time frozen in place sometimes? Enquiring mind wants to know.

PBS has changed quite a bit since moving to AMC-21.

 

[skysurfer]

what PBS should do is put the MPEG-4 streams within the 30000 SR signal and get about 5 quaity hd channels, or turn the 30000 SR into a S2 signal and get 8 quality HD channels.

 

[Tron]

Telairity is a manufacturer of video encoders , SD and HD , therefore more likely PBS is testing their equipment and the ability to send HD channels at a much lower bandwith using MPEG4. As you can see that new channel is only 4340 SR compared to 30000 SR that the regular HD tp has , well 15000 per each HD national feed. Almost a 70% reduction of bandwith used therefore money saved.

I hope they do not replace the MPEG-2 streams with this low-quality alternative. Just another example of sacrificing picture quality. If it looks "soft" when we receive it directly from satellite, how is it going to look once it is received by a local affiliate, digitally re-processed and re-compressed, and sent out to local viewers? In the past, there were strict guidelines that governed picture quality in the broadcast industry. I hope these aren't being thrown out in favor of bandwidth conservation. I have had talks with at least a couple of Chief Engineers I know who work at television stations, and they all agree that sacrificing quality in digital streams is a terrible mistake.