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nysports4evr
Premium
join:2010-01-23
kudos:1
Reviews:
·Comcast

2 edits

[HD] Comcast broadcasting local ION & FOX at ~5 Mbps bitrate

Comcast is broadcasting the local ION affiliate, WPXP, at a mere 5.5 or so Mbps average bitrate, which causes awful macroblocking and a nearly unwatchable picture with any motion at all. When Psych airs on ION, which has a lot of grain, the picture is reduced to a blurry mess, even the channel logo becomes barely visible.

It shares a QAM with WHDT, an even more "local" station that generally shows nothing but infomercials. I can't imagine why they're giving WHDT 12 Mbps of bitrate and ION only 5, especially considering there's MORE than enough bandwidth on a single QAM to more than double the bitrate of these channels...



nysports4evr
Premium
join:2010-01-23
kudos:1
Reviews:
·Comcast

Update:

Yikes! About the same on Fox HD. Sure, 720p requires less bitrate to look good (compared to 1080i), but to be reducing one of the most watched channels to about 5 Mbps on average is a bit much, don't you think?




gar187er
I do this for a living

join:2006-06-24
Dover, DE
kudos:4

most watched channels? dunno about that

i wonder if it changes in the evening...
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nysports4evr
Premium
join:2010-01-23
kudos:1
Reviews:
·Comcast

said by gar187er:

most watched channels? dunno about that

i wonder if it changes in the evening...

I was talking about Fox, being one of the real major networks... yeah ION is probably not watched that often


markofmayhem
Why not now?
Premium
join:2004-04-08
Pittsburgh, PA
kudos:5

Forward your data to the station and ask them if they are sending out this bitrate to Comcast. Comcast could be violating FCC mandate. If they are compressing the signal further than they are receiving it and it results in lower quality, it stands against the Second Order and Report for digital television. Because of this, it is likely this is the overly-compressed work of the station, but if not, you can be one of the proud people filling out an FCC complaint

Each stations' contact should be found on their website.
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nysports4evr
Premium
join:2010-01-23
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Last I checked (when I had my OTA antenna set up), my local Fox affiliate was sending out a ~16 Mbps signal.



markofmayhem
Why not now?
Premium
join:2004-04-08
Pittsburgh, PA
kudos:5

Doesn't mean anything if they provide Comcast direct feed through uplink.

In addition, you'll need PQ in the complaint. The ruling is that PQ can not be affected, bitrate doesn't prove picture quality, but it could prove WHERE the PQ degradation occurs (station or Comcast).
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nysports4evr
Premium
join:2010-01-23
kudos:1

I can't imagine why they'd be providing Comcast a lower bitrate feed through a fiber uplink, especially something that low... 5 Mbps MPEG-2 is awful, I could certainly take a few screenshots exhibiting how bad this looks.


andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
reply to nysports4evr

Can you compare the bitrate with a a direct broadcast feed from an OTA tuner? Does that ION affiliate have subchannels?

As mentioned, Comcast will typically pass on broadcast as it's received by them. Also, the 256QAM used by Comcast has nearly double the bandwidth of broadcast. You can fit two full broadcast feeds without any real compression needed.


nysports4evr
Premium
join:2010-01-23
kudos:1
Reviews:
·Comcast

Yes, the local ION has subchannels, but the main channel is still a much higher bitrate OTA:

Stream Type: 0x02 MPEG-2 Video PID 49 (0x0031)
MPEG Video: Bitrate 19.393 Mbps Resolution 1280 x 720p
MPEG Video: Framerate 59.94 fps Aspect Ratio 16:9 Chroma Format 4:2:0



markofmayhem
Why not now?
Premium
join:2004-04-08
Pittsburgh, PA
kudos:5

That's too high, you need to scrub the FEC and null bits as well as separate the sub-channels.


andyross
Premium,MVM
join:2003-05-04
Schaumburg, IL
reply to nysports4evr

19Mb is about the max bandwidth of broadcast. 256QAM is 38Mb. It seems like you are showing the full broadcast including all subchannels and other data.


nysports4evr
Premium
join:2010-01-23
kudos:1

Yeah, oops, that was the max bitrate from the MPEG-2 header, this is the actual bitrate for the main station PID:

0x0031 (60.43% - 11.72 Mbps)


moulder3

join:2007-05-21
Boston, MA

This is probably a stupid question, but there isn't any way to determine the HD bitrate of a channel via a Comcast HD or DVR box, is there? I know you can determine signal quality that way, but I'm very anxious to check the bitrate of several HD channels on Comcast in my area (to compare against un-compressed FiOS & even DirecTV--even though I realize it's MPEG4)



JohnInSJ
Premium
join:2003-09-22
San Jose, CA
reply to nysports4evr

Is ION a SD DTV channel?



markofmayhem
Why not now?
Premium
join:2004-04-08
Pittsburgh, PA
kudos:5
reply to moulder3

said by moulder3:

This is probably a stupid question, but there isn't any way to determine the HD bitrate of a channel via a Comcast HD or DVR box, is there? I know you can determine signal quality that way, but I'm very anxious to check the bitrate of several HD channels on Comcast in my area (to compare against un-compressed FiOS & even DirecTV--even though I realize it's MPEG4)

There is no reason to do this. You already think Fios is "uncompressed", you will find the negativity you seek against Comcast without numbers, just make them up in your head and move on.
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nysports4evr
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join:2010-01-23
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reply to JohnInSJ

said by JohnInSJ:

Is ION a SD DTV channel?

It's a 720p HD channel.

nysports4evr
Premium
join:2010-01-23
kudos:1
reply to nysports4evr

As of tonight FOX HD is back at 14 Mbps, haven't gotten the chance to check ION.



cypherstream
Premium,MVM
join:2004-12-02
Reading, PA
kudos:3
reply to nysports4evr

Some programming may not need a large data rate to look good. If its generally low action, talking heads, slow moving content, it won't spike that high.

Heck some systems are putting 4 HD's in one QAM (AMC HD, IFC HD, Fuse HD, We HD). One QAM = 38.8 mbps so do the math.

How it works is not all the stations peak at the same time. One stream may call for a few extra bits while the other two or three are semi-stationary and can lend a few extra bits. Only in 100% full contention will you notice a loss of detail, but the chances of that on all channels sharing the stream at the same time are low if the multiplexed content was chosen right.

QAM used to be 2 HD per 38.8mbps. They started doing statistical variable bit rate multiplexing and now its common for 3 HD per 38.8mbps. And in some cases not so much Comcast, but other providers have gotten away with 4 HD per QAM in very limited channel arrangements. DirecTV is now even starting to do 6 HD's per transponder in MPEG4 as opposed to the usual 5 HD. Time moves on, encoders get better, more efficient and the quality of lower bitrates improve.


nysports4evr
Premium
join:2010-01-23
kudos:1
Reviews:
·Comcast

I am aware that the lower complexity the content is, the lower bitrate is required to look "good," however, just about nothing looks good at ~5 Mbps MPEG-2. Also, I think the only reason systems are putting those 4 channels on one QAM is because that's how they're distributed by AMC Networks in the first place -- all 4 channels on one TP.