Bitrate on 10-1 higher OTA than cable?

[rossl]

Somebody commented that 10-1 OTA signal was higher quality because Time-Warner "compressed the he!!" out of HD signals before distribution.

I have a good setup to test this claim.

For some background before I give the results, I am using a MyHD MDP-130 card for the test. This is a computer PCI card. It accepts both an antenna or unencrypted QAM cable on two coax connectors on the rear plate. It will record high definition ATSC or QAM to transport stream files on the hard drive.

I record a few minutes of channel 10-1 from each source.

Then I use a software tool that I have purchased, the excellent MPEG editor VideoReDo. I use it's Quick Stream Fix feature on the raw TS files. This tool strips out the overhead packets from the transport stream and just leaves the MPEG data with video, audio and closed captioning. Gone are extra streams, subchannels, PSIP data and other overhead data.

VideoReDo then will report the video bitrate of the captured MPEG file.

I am using a Channel Master 4221 mounted in the attic of my garage for the OTA test. I am located about 7 miles west of the WBNS facility. I have one splitter in the cable coming down from the attic. The MyHD reports the 10-1 signal strength as 93%. Reception is rock solid with this antenna.

You are probably wondering how I can test both Time-Warner cable QAM and Wide Open West cable QAM. I have both. :D I'm sure that qualifies me as a true HD cable geek... but let me explain.

Last fall I switched my cable TV to WOW with two cablecards. Since the locals are unencrypted, I can use the MyHD on the WOW with a splitter and a coax cable run to the PC. I went to WOW with the cable TV, but I kept the Time-Warner Roadrunner cable modem account.

Someone on AVS forum commented that he could get his unencrypted locals on his TW Roadrunner coax cable without paying for cable TV. So I tried it by wiring in a splitter and yet another cable run. Buying that coax crimping tool has really paid off! It works. :D I get unencrypted QAM locals but no analog TV or other digital TV from TimeWarner with just a $44.99 Roadrunner account.

The MyHD reports the OTA 10-1 signal strength as 93%
The MyHD reports the Time-Warner QAM 10-1 signal strength as 75%
The MyHD reports the WOW 10-1 QAM signal strength as 69%

All of these are sufficient strengths. I get no dropouts on any of them.

Now the results from tonights' Wheel of Fortune:

AIR: 18.02 megabits per second.
Time Warner QAM: 17.92 megabits per second.
WOW QAM: 17.64 megabits per second.

I plan on doing another measurment during tomorrow's March Madness final 4, second game. I'll be watching the first game intently and won't have time to worry about this stuff.

As a comparison, the OSU/Michigan football game broadcast by one of the local Sinclair stations in November was 13.13 megabits/sec. :eek:

Draw your own conclusions, but I think most people wouldn't notice the difference between the several options for viewing 10-1, but they will notice the loss of signal when viewing one of the Sinclair stations.

I would like to thank the good folks at WBNS for having us over Thursday night. I certainly didn't expect the extensive tour led by engineer Marvin Born that lasted until after 10PM and I would like to thank him profusely for showing the bunch of us around.

[Robbiee19]

rossl,

If you get the time can you do it for all the locals and give the results. I would love to see like NBC who has a sub ch and bitrates for them.

Thanks

[rossl]

Some numbers from tonight.

First, the measurements from the other locals with subchannels.

At 8:30 the movie "The Rookie" was on 6-1 in 720p. I measured 13.18 mb/sec OTA on 6-1 and then measured 3.42 mb/sec OTA on the 6-2 subchannel. That was a pro wrestling program.
6-1 on Time-Warner cable measured 13.17 mb/sec.

At about 8:45, Cops was on 28-1 in 720p and only measured 14.00 mb/sec OTA. They no longer have a subchannel but WTTE still doesn't have a good bitrate. Luzers!

WOSU was showing something in 1080i on 38-1 and I measured only 9.28 mb/sec OTA. I didn't bother measuring their two subchannels.

At 9:10, 4-1 was showing "Law and Order" in 1080i. I measured 15.92 mb/sec OTA and then I measured 1.95 mb/sec OTA on the weather subchannel.

Now for the March Madness NCAA Basketball. The UCLA-Florida game measured:

OTA: 18.00 mb/sec
TW: 17.98 mb/sec
WOW: 17.68 mb/sec

Congrats to the Buckeyes on the victory and the NCAA title game appearance... and congrats to WBNS on their technical excellence.

[Robbiee19]

Yep OTA for CBS is the best. Thanks for the results. On WTTE I stilll pick up 28-2, but it only is showing the same program. I guess they can't be borther to turn it off.
I like WOSU with all the ch they give, but with the low bitrate I see why 38-1 doesn't provedi a great picture.

[willcail]

I guess that WOSU is dedicating ther bit rate for thier WOSU HD feed than their Ohio Channel and Create. Most of their programming on 34.3 was recorded in 480i, like the Ohio Channel as well.

[rossl]

I guess that WOSU is dedicating ther bit rate for thier WOSU HD feed than their Ohio Channel and Create. Most of their programming on 34.3 was recorded in 480i, like the Ohio Channel as well.


Last time I checked, WOSU was giving about half of their bandwidth to WOSU-HD and about a quarter of their bandwidth to each of the two subchannels.

It seems to work OK for the slow moving scenery programming on WOSU-HD, but it's not so good when they show something faster, like the concerts on Austin City Limits. I tried recording a recent broadcast of Eric Claptons' Crossroads Blues Festival, and it was disappointing. The sound volume is really low and the picture quality wasn't much better than SD.