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Comcast MPEG-4 transition [1080i down-converted to 720p!]
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Author:  Chris [ Sat Sep 17, 2016 12:45 pm ]
Post subject:  Comcast MPEG-4 transition [1080i down-converted to 720p!]
Just curious, has anyone out there already transitioned to MPEG-4 in your area? What files sizes are you getting? And most importantly, how has the image quality held up?

Near Seattle where I live, we still have another month before Comcast transitions to MPEG-4 (October 13, I think). So far I've heard files sizes less than 2GB/hour in other states which is quite a drop from the usual 4-5GB/hour we've been getting. Haven't heard anything about how much this might affect image quality though.
Author:  loki0522 [ Mon Oct 03, 2016 11:45 pm ]
Post subject:  Re: Comcast MPEG-4 transition
FYI,

My Comcast area switched to h264 starting 2-1-16 if I'm not mistaken.

I capture from my Comcast box using a desktop running Linux and connected via firewire. After capturing a roughly 5min 44 sec clip, then copying the the audio and video streams to an mp4 container using ffmpeg, I get the following:

Name Duration (hh:mm:ss) File size

test.mp4 00:05:44 126.1Mb

From the above almost 6min clip I suppose one can extrapolate what the file size of an hour clip might be. Looks like a rough estimate would be a little over 1Gb for about an hour.
Author:  Chris [ Fri Oct 07, 2016 9:51 am ]
Post subject:  Re: Comcast MPEG-4 transition
Wow! They transitioned you way early. Still I'm curious if there's any noticeable loss in image quality. In my area sometime in 2012 (I think) we got our bitrate cut and files went from 5GB/hour to 4GB/hour. The quality loss was definitely noticeable, especially in fast moving scenes. I get that H.264 is different than just a simple drop in bitrate but still I'm worried.

Either way I won't have a choice. At least the small file sizes means I can get away with buying 1 hard drive a year instead of 3 or 4. Saves me a bunch of money. :mrgreen:

I still got less than a week before the switch...
Author:  Chris [ Thu Oct 13, 2016 5:06 pm ]
Post subject:  Re: Comcast MPEG-4 transition
Update.

Channels are now H.264. And I was right to be worried; image quality has noticeably dropped even further. Even worse, channels that were 1080i are now 720p! What the hell were they thinking? This sucks. :evil: :evil: :evil:

If you're using a tuner, file sizes are consistently 1.66GB/hour on every recording so far. Before they were as low as 3.5 to as high as 5GB/hour.
Author:  loki0522 [ Thu Oct 13, 2016 7:08 pm ]
Post subject:  Re: Comcast MPEG-4 transition
Which channels have you seen downgraded to 720p?

Just curious...
Author:  Chris [ Thu Oct 13, 2016 7:19 pm ]
Post subject:  Re: Comcast MPEG-4 transition
Haven't recorded any other channel today except CNN so I'm not sure. I'll update in the next few days.

EDIT: Found the answer! http://forums.xfinity.com/t5/Non-X1-Ser ... 08#M183323

It is indeed an intentional move by Comcast.

Quote:
In regards to 720p delivery, some of your HD channels have transitioned from 1080i to 720p60. As part of our ongoing work to improve and modernize the way we deliver HD channels, we are transitioning all of our HD streams to “progressive” format. We are making this change in conjunction with the transition to MPEG-4. This means that some channels that were delivered in 1080i will now be delivered in 720p60.

H.264 already compresses the files to a reasonable size. Why not 1080p instead of taking us back 10 years to 720p? I don't get it... :?
Author:  loki0522 [ Thu Oct 13, 2016 8:30 pm ]
Post subject:  Re: Comcast MPEG-4 transition
Thanks for the link...

Well, that sucks. This means I'm down to the local OTA channels as the only ones I'm able to receive in original source format.

Unfortunately, in my area there's really no other alternative to Comcast.

Too bad FIOS never made it here. I would've gladly switched.
Author:  Chris [ Thu Oct 13, 2016 8:33 pm ]
Post subject:  Re: Comcast MPEG-4 transition
Was thinking exactly the same thing. I'd love to switch to FIOS but unfortunately I live a few miles too far... :x
Author:  Chris [ Sat Oct 15, 2016 10:22 am ]
Post subject:  Re: Comcast MPEG-4 transition
loki0522 wrote:
Which channels have you seen downgraded to 720p?

Just curious...

Quick update: I count 15-20 channels that were originally 1080i have been downconverted to 720p. Don't know if more of them will be downconverted, but I do find it odd that CNN is now 720p/H.264 but HLN is still 1080i/MPEG-2. :?

I can not tell you how pissed I am about this. The picture quality is now less than a live web stream. I can say for sure CNNgo is sharper than live TV right now. It is that bad! :x

I also noticed by midday Friday, my recordings had a strange black mark over their thumbnails and they were no longer showing metadata. The file size even dropped to 1.65GB/hour instead of the previous (and consistent) 1.66GB/hour. Guess they didn't want me to see how horrendously low the bitrate is. FYI, it's under 4000kbps! :Bang

I'm really considering switching to Direct TV and buying a Blackmagic Intensity Shuttle to capture.
Author:  loki0522 [ Sat Oct 15, 2016 2:59 pm ]
Post subject:  Re: Comcast MPEG-4 transition
Starting to wonder if Comcast is really planning to convert all channels versus a subset.

As I recall, I was forced to swap my HD box by 01/31/16 because my older box didn't support h264 and I was starting to get only audio and black screen as channels got converted. I suspect they actually started converting my area to h264 much earlier. Given that, I estimate that here we're at least 8-10 months into the h264 migration. However, I just did a quick test capture of a handful of channels. I'm still getting a number of what I consider 'major' channels in mpeg2/1920x1080. CNN and HLN are already h264/1280x720, though, with bitrates of approximately 3500 kb/s.

ABC-HD

Duration: 00:00:51.53, start: 76626.922589, bitrate: 26543 kb/s
Stream #0:0[0x14f5]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), yuv420p(tv), 1280x720 [SAR 1:1 DAR 16:9], Closed Captions, 59.94 fps, 59.94 tbr, 90k tbn, 119.88 tbc

CBS-HD

Duration: 00:00:44.41, start: 76280.270133, bitrate: 26675 kb/s
Stream #0:1[0x1428]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], Closed Captions, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc

CNN-HD

Duration: 00:00:38.14, start: 0.000000, bitrate: 3553 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], Closed Captions, 3174 kb/s, 59.94 fps, 59.94 tbr, 90k tbn, 119.88 tbc (default)

HLN-HD

Duration: 00:00:38.02, start: 0.000000, bitrate: 3560 kb/s
Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], Closed Captions, 3199 kb/s, 59.94 fps, 59.94 tbr, 90k tbn, 119.88 tbc (default)

NBC-HD

Duration: 00:00:48.48, start: 76471.525367, bitrate: 26696 kb/s
Stream #0:1[0x1217]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), yuv420p(tv), 1920x1080 [SAR 1:1 DAR 16:9], Closed Captions, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc

NBCSports-HD

Duration: 00:00:51.11, start: 34665.444300, bitrate: 26692 kb/s
Stream #0:1[0x1012]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), yuv420p(tv), 1920x1080 [SAR 1:1 DAR 16:9], Closed Captions, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc

WGN-HD

Duration: 00:00:52.92, start: 79213.868178, bitrate: 26611 kb/s
Stream #0:1[0x14f2]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002), yuv420p(tv, bt709), 1920x1080 [SAR 1:1 DAR 16:9], Closed Captions, 29.97 fps, 29.97 tbr, 90k tbn, 59.94 tbc
Author:  Chris [ Sat Oct 15, 2016 3:07 pm ]
Post subject:  Re: Comcast MPEG-4 transition
Yep, those numbers are pretty much identical to my old 1080i/MPEG-2 recordings and my current 720p/H.264 recordings.

I've not had any issues with Comcast despite what I've seen so many others say about them. But this is going way too far.

I'm really surprised there isn't more of an uproar about this. There doesn't seem to be much awareness. I can only find TWO places online that are even discussing this:

TiVo Community: https://www.tivocommunity.com/tivo-vb/s ... p?t=542203
DSLReports: https://www.dslreports.com/forum/r30896 ... 0p-w-mpeg4
Author:  Chris [ Mon Nov 07, 2016 9:36 pm ]
Post subject:  Re: Comcast MPEG-4 transition [1080i down-converted to 720p!
OK, let me reset for those who are just now seeing this topic:

If you are a Comcast customer, all of your native 1080i channels have been or will be down-converted to 720p, in addition to sub-optimal compression. Yes, there is a noticeable loss of picture quality---less detail and increased artifacting. This is Comcast's solution to save bandwidth which they will instead use for online streaming to mobile devices.



chris217 wrote:
I'm really surprised there isn't more of an uproar about this.
Took a while for people to take notice, but looks like the uproar is starting:

http://forums.xfinity.com/t5/Channels-a ... d-id/78911
http://forums.xfinity.com/t5/Non-X1-Ser ... -p/2806786

I'm glad more people are taking issue with this, but there's no way this will change anything with Comcast. :(
Author:  altrieneirialx [ Tue Jan 17, 2017 11:33 am ]
Post subject:  Re: Comcast MPEG-4 transition [1080i down-converted to 720p!
4k tvs upscale smooth out. I dont see a problem.
Author:  Chris [ Tue Jan 17, 2017 11:42 am ]
Post subject:  Re: Comcast MPEG-4 transition [1080i down-converted to 720p!
Do you live in any of these locations?

https://support.tivo.com/articles/Features_Use/Comcast-Transitioning-to-MPEG4-in-Select-Markets

If so, you'd have been downconverted to 720p. I've already switched to DirecTV---it's that bad! FYI, I hate to say it, but re-upconverting an already downconverted transmission would just make the picture quality even worse. A lot worse.
Author:  FishOil [ Mon Jan 23, 2017 10:14 pm ]
Post subject:  Re: Comcast MPEG-4 transition
Chris wrote:
H.264 already compresses the files to a reasonable size. Why not 1080p instead of taking us back 10 years to 720p? I don't get it... :?


A message from Comcast (NSFW) -

https://www.youtube.com/watch?v=KMcny_pixDw
Author:  werp121 [ Wed Apr 12, 2017 9:43 am ]
Post subject:  Re: Comcast MPEG-4 transition [1080i down-converted to 720p!
Comcast just flipped my area over and it's awful. Their de-interlacing method isn't even that good. There's a clear loss of sharpness and fine detail with the compression, down-res, and de-interlacing. This is so fornicating stupid. No wonder more people are cutting the cord. Streaming services are moving up to 4K and Comcast is giving us this crap.
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