akirby wrote:I thought DirecTV had more than just 4 sats. I thought it was 6 or 7?
Yes they do. I was referring to the recent announcement of 4 new satellites devoted just to 1650 new HDTV channels to be launched in 2005 and 2007( 150 national HD and 1500 local HD). Since very few DirecTV customers have HD capable receivers, existing customers will not benefit from this expansion unless they upgrade. DirecTV will have to keep their existing SD channels on the existing satellites for a long time for backwards compatibility.
It is a similar situation to an OTA broadcaster putting both a SD and HD channel in the bandwidth. DirecTV will have to essentially duplicate almost every channel in both a SD and a HD version in order to maintain compatibility to all customers - thus the temptation to bit shave. The entire fleet is the available bandwidth and they dynamically share bits. When DirecTv begins to retransmit a local HD station the BEST they can do is the station's bitrate, but DirecTv could easily shave a few bits off that rate. Given past practice which bitrate will they use?
I suppose they could go 100% HD channels and do a free upgrade of millions of SD receivers instead where non HD customers would set output to 480i-unlikely.
Fox has decided to provide a 12-15mb/s feed to their affiliates, along
with the technology to pass it on unaltered to home viewers without a
decode/encode stage at the affiliate. They keep it down under 15mb/s
so that affiliates will have room to add second channel for weather
radar or whatever if they choose. Unfortunately that means that
everyone is limited to under 15mb/s even in markets where there is no
secondary channel.
DirecTV decodes the signals from their providers and reencodes at
anywhere from 6-18mb/s depending on how many channels they are
squeezing on to one transponder, etc. In the case of the Super Bowl,
they decided to up the bitrate they give to Fox in order to lose as
little quality as possible in their decode/encode stage. So the
DirecTV quality is slightly reduced (due to the reencoding) but their
bitrate is higher. Thankfully the bitrate was high enough (17.2mb/s)
that there didn't appear to be much visible difference.
What about the macro blocking on the hood of the red XLR at the end of the game? Is that due to bit shaving? It looked terrible. Also the grass on long shots didn't look right but I can't describe it accurately.
akirby wrote:What about the macro blocking on the hood of the red XLR at the end of the game? Is that due to bit shaving? It looked terrible. Also the grass on long shots didn't look right but I can't describe it accurately.
I don't know if I saw the XLR, but that could be from MPEG compression (or if it was short and really bad, some other breakup of the signal).
The "swimming grass" problem is definitely from too low a bitrate. What happens is that a finely detailed pattern (like grass) "shifts" periodically" as there is movement in other parts of the picture. Another MPEG2 compression artifact. If the bitrate was higher, it wouldn't be an issue.
The grass problem was evident on Fox's OTA feed so is not necessarily DirecTV issue.
No, it wasn't a breakup. It was just on the hood as the camera panned and again visible (but not as bad) on the side shot. The car was a very bright metallic red.
And yes, swimming would be an appropriate word for the grass appearance.
Australian OTA maximum native HDTV bitrate is 14.5mb....it looks sensational on my 19inch PC CRT, LOL, but it macroblocks on pans.
I dled some American 18.5 mb HDTV content and the macroblocking was gone.....also, I've never seen macroblocking on any blu-ray on large HDTV's, but I think the BD bitrate starts at 18mb
