Local DTV broadcast data rates

[gopheralex]

I thought some of you might be interested, so I'm posting this for reference. I captured brief clips from local OTA DTV with an Elgato EyeTV 500 and opened them up in MPEG Streamclip. I'm not sure if any of these stations use variable bit-rate encoding, which would affect the results substantially. In addition, the networks may adjust these rates however frequently, by whatever amount.

3/2 = Dolby Digital 5.0 or 5.1, 2/0 = DD 2.0.

HDNet from TWC Milwaukee included at the bottom as a reference.

Code Select Expand


Video Audio
4-1 15.24Mbps 384Kbps 3/2
4-2 2.14Mbps 192Kbps 2/0

6-1 15.00Mbps 192Kbps 2/0 *

10-1 2.41Mbps 192Kbps 2/0
10-2 5.76Mbps 192Kbps 2/0
10-3 4.00Mbps 192Kbps 2/0
10-4 4.56Mbps 192Kbps 2/0

12-1 14.66Mbps 384Kbps 3/2

18-1 18.50Mbps 448Kbps 2/0 *

24-1 14.64Mbps 448Kbps 2/0 *
24-2 3.80Mbps 320Kbps 2/0

36-1 18.23Mbps 384Kbps 3/2

58-1 15.81Mbps 384Kbps 3/2
58-2 3.22Mbps 192Kbps 2/0

HDNet 19.98Mbps 384Kbps 3/2



* = SD programming broadcasting stereo audio


[StarvingForHDTV]

Thanks for posting that information.  In the past I was told that 36-1 was not the source of a problem, and that it was coming from the national PBS-HD feed.  Your data helps to confirm that to me.

HDNet must look nice on TWC.

[Bebop]

Same here. I always thought the pixilation on 36 was due to low bandwidth.
if the above data are correct. The problem is somewhere else.

[Gregg Lengling]

I always thought the pixilation on 36 was due to low bandwidth.
if the above data are correct. The problem is somewhere else.

I've had very few problems OTA with them, more via TWC than OTA....however I'm willing to bet the errors are creeping in on the PBS feed not on the OTA feed.

BTW...rush out and buy "The Fast and The Furious, Tokyo Drift" as it's out on HD-DVD.....

[Bebop]

It's only pixilation from fast moving scenes. The signal is stable for me.

Unfortunately, it's not my type of movie. Grand Prix and Dirty Dozen will be out next week.

I still do not own any HD DVD movie yet. Nothing worth collecting. I rent all mine from Netflix.  

[kevbeck122]

I thought somewhere here somebody said that it was because the source was also 19.3 Mbps and through the local re-encode, we get the pixelation.  Other locals get a higher bitrate source.. somewhere close to 50 Mbps is what I heard.

[Gregg Lengling]

I thought somewhere here somebody said that it was because the source was also 19.3 Mbps and through the local re-encode, we get the pixelation.  Other locals get a higher bitrate source.. somewhere close to 50 Mbps is what I heard.

The sat feeds to the stations are usually 45Mbps.

[gopheralex]

I thought somewhere here somebody said that it was because the source was also 19.3 Mbps and through the local re-encode, we get the pixelation.  Other locals get a higher bitrate source.. somewhere close to 50 Mbps is what I heard.

OTA DTV is limited to 19.4 Mbps video+audio combined.

[VoidXero]

So is TW 510 the same as OTA 36.1? I am amazed at how bad 510 can look at times. It's not always bad but at times it is the most pixelated HD feed on TW.

[borghe]

hmmm.. I am definitely noticing a difference in encoders then. WTMJ IMHO looks MUCH better than WDJT. Heroes last night was gorgeous, whereas CSI usually has a bit of pixelation. of course I don't look at the exact bandwidth of either show, but I didn't think that WTMJ dropped 4-1 down below 16Mbps. Very impressive WTMJ. And not really a knock against WDJT. Who knows why they chose the encoder they chose, but I'll cut them some slack with it probably being a nice chunk of change (not to mention time and effort) to change their encoder out.

Wish there was a way to grab MPEG4 bitrates from D* for comparison.

[kevbeck122]

You might be able to find bitrates for the satellite services at satelliteguys.us or another satellite forum.

[gopheralex]

So is TW 510 the same as OTA 36.1? I am amazed at how bad 510 can look at times. It's not always bad but at times it is the most pixelated HD feed on TW.

510 is looking pretty bad on OTA sometimes too. Ocean Adventures tonight was blocky and looked overcompressed. The data rates I posted don't necessarily correspond to video quality. There are lots of different settings in the various encoders and decoders that are used throughout the signal path, from its origin to its destination. An overcompressed or maladjusted signal could still go over the air at the same bitrate as a properly compressed video stream would. I don't know if the problem is with WMVT or PBS, because this channel should theoretically look gorgeous.