Data rate measuring Doo-Hicky?

[ChetK]

Is there a third party product that could measure the data rate out of or into a satellite receiver?

Basically, I'd like to test the data rates of specific channels (like DiscoveryHDTheater) coming out of the Voom receiver and also coming out of the Dish Network Receiver. I would document the data rates and decipher, once and for all, if the mpeg-2 data rates are being encoded higher or lower than their competitor. If the data rates are the same between providers, then it might be the receiver(s).

I'm not sure if this data rate could be measured because I am going out of my Voom receiver via component and the same for my Dish Network 6000U. But, I thought I'd ask anyway.

 

[barth2k]

I think people with PC card or recorder of some type and measure this. Unfortunately, though it'll give an indication, measuring the data rates won't settle the debate over PQ since there are many other factors affecting PQ. But yes, I'd be curious to know.

 

[Sean Mota]

Those PC cards are quite expensive in the $800-$1000. I am waiting for a new one to come out.

 

[cameron119]

DirecTV uses the most compression on their HDTV channels of any satellite provider.

DirecTV HDTV is 15.8Mbit, vs 16.9Mbit on Voom. Dish is 19.8, just like the OTA HDTV channels.

(Details compiled by Mike123ABC on DBStalk:

VOOM Runs 8PSK 22msym 5/6 FEC 188/204 RS or 50.69 mbit/sec or 16.9mbit per channel with 3 HDTV channels (minus some because of guide data, etc but not much).

DIRECTV runs QPSK 20msym 6/7 FEC 188/204 RS or 31.6 mbit/sec or 15.8mbit per channel with 2 HDTV channels

Echostar current is 8PSK 21.5msym 2/3 FEC 188/204 RS or 39.6 mbit/sec or 19.8 mbit/channel with 2 HDTV)

(results compiled by Bichon at DSLReports.com)

 

[andrzej]

DirecTV uses the most compression on their HDTV channels of any satellite provider.

DirecTV HDTV is 15.8Mbit, vs 16.9Mbit on Voom. Dish is 19.8, just like the OTA HDTV channels.
...

I am wondering if it is possible to tell (without doing any quantitative measurements) the difference between say 17Mbit and 15Mbit signal delivered by the same provider and received by the same stb and watched on the same display. That would tell me how much the #s matter. This is important because, obviously, there are other factors than the compressions rate that also contribute to the overall impression of PQ.

 

[ChetK]

I realize that there are other factors to video quality, but a 3 mbps difference can be quite a bit. I've authored DVD's that were 3 mbps (constant bit rate) that look pretty darn good. Now I realize that DVD resolution is much lower than that of HD, but a 3 mbps chunk can make or break a good HD video stream when there is a lot of motion (pixel changes) in the video.

I remember watching OTA channels on my HDTV tuner and I did not see macroblocking (it was full bandwidth HD data rates). As soon as that channel began multi-casting (taking 2 or 3 mbps away from the main HD channel) I could see a quality loss on the main HD channel (macro-blocking with a lot of motion).

Also, for the record:
I like Voom. I like their commitment to happy customers. I think they are giving us what the consumer asked for (more HD channels) I applaud them for this. I don't want to cancel Voom because I like their good customer support and I like rooting for companies that make a VALUED attempt at bringing the consumer what they want. I have no doubt that things will get better in regards to picture quality. I'm just hoping it happens sooner than later. Perhaps by taking bandwidth away from SD and giving it to HD???

 

[vurbano]

wm9 applied to SD channels will do this later this year i hope.

 

[vurbano]

I am wondering if it is possible to tell (without doing any quantitative measurements) the difference between say 17Mbit and 15Mbit signal delivered by the same provider and received by the same stb and watched on the same display. That would tell me how much the #s matter. This is important because, obviously, there are other factors than the compressions rate that also contribute to the overall impression of PQ.

15mbps will show a lot of pixelation at 1080i, Thats about what my PBS station was before it went to 720p to fix it. (looks like crap IMO). 17-18mbps looks pretty good.

 

[cameron119]

wm9 applied to SD channels will do this later this year i hope.

I'm thinking WM9 is so efficient and high quality vs. MPEG2 that Voom will be able to gain A LOT of additional bandwidth for their MPEG2 HD channels. Perhaps enough to reduce all channels carrying HD content to 2 per transponder by repositioning current SD content and giving the gained transponders to HD content. Once WM9 is applied to the HD channels, the sky is the limit (well, it's just an expression )

One thing is for certain: Macroblocking is a larger problem on Voom and DirecTV than on Dish Network. Eventually, Chuck will have to add more HD...if he doesn't add capacity or shift capacity then Chuck will actually have a lower bitrate per channel than Voom. In the meantime, it's one of the best places to see the finest quality HD...too bad the selection is TERRIBLY ANEMIC. In this case, since I have Voom it's nice to have a balance of beautiful, clean HD with selection on Voom PLUS pristine, gorgeous full ATSC bit-rate HDNet on Dish.

 

[vurbano]

DirecTV uses the most compression on their HDTV channels of any satellite provider.

DirecTV HDTV is 15.8Mbit, vs 16.9Mbit on Voom. Dish is 19.8, just like the OTA HDTV channels.

if this is correct then Voom should be able to engineer a better Picture with their software than D*. AND WM9 should really improve things. We must have terrible software right now?

 

[Ken F]

VOOM Runs 8PSK 22msym 5/6 FEC 188/204 RS or 50.69 mbit/sec or 16.9mbit per channel with 3 HDTV channels (minus some because of guide data, etc but not much).

This is not correct. You're forgetting all those SD channels that share the bandwidth with the HD channels.

VOOM uses 13 transponders, so 13 * 50.69 = 658.97Mbps. It's actually a bit less than that due to overhead. Now divide that by 37 HDTV channels and 84 SD channels @ 2-3Mbps. I don't recall exactly, but I believe SD channels on Dish Network are in the 2.1Mbps to 2.3Mbps range on average. If you assume 2Mbps per SD channel on VOOM (since it doesn't have more bandwidth-hungry RSNs), that leaves about 13Mbps per HD channel with overhead -- with the current channel lineup.

All HD channels do not require 17Mbps. The heavily filtered, film-sourced content on HBOHD and CinemaxHD requires less bandwidth than HD video seen on Discovery Theater. Analysis of the HBO HD bitstream indicates an actual data rate more in the 11-12Mbps range on Dish Network. Starz did announce a 18.2Mbps bit rate for their HD channel in a press release, but I doubt VOOM is passing it at anything close to that.

My hope is that VOOM will reduce the SD capacity its expects to gain from WM9/MPEG-4, and just add use it for the most popular additions, with the remaining bandwidth used to improve both SD and HD picture quality. Right now, SD picture quality on VOOM is what you would expect on a provider (like Dish Network) that markets its service for 25-27" televisions. But VOOM is not selling to customers with 25-27" televisions; they are marketing their service to customers with larger displays. At current quality levels, the SD on Dish, DirecTV, and VOOM is hard for me to watch on my large display.

 

[vurbano]

well then i see bad news. voom has 13 transponders. which would logically mean 3 HD channels per transponder and say at 2.5MBPS for 7 sd channels per transponder as well for a total of 91 SD channels. That would mean (50.69MBPS-(2.5*7))3 = 11 MBPS left for each HD signal? assuming 7 sd's per transponder. Rainbow1 is full already!

 

[Ilya]

I'm not sure if this data rate could be measured because I am going out of my Voom receiver via component and the same for my Dish Network 6000U.

Even over DVI the video signal is sent un-compressed. So, I don't see how one can possibly measure the compressed data rate at the output.

 

[vurbano]

SO i guess the really good PQ we have on some of the HD channels means that that transponder is next for a channel addition? O but thats wrong because we have been assured that voom was already fully loaded since the day it went live. Another reason to combine the exclusives and give us Picture Quality in lieu of repetitive content. LMAO

 

[Sean Mota]

There's still space guys... I have those data and there are still space. Also remember that the encoder at each channels changes the mbps depending on what the channel requires. So when you measure mbps in TP for a given channel, you have to look at it for a long time because it may vary depending on what is needed. I assume that WorldSport is where you can probably see more constant mbps because there's a lot more action there.

 

[ChetK]

Are you saying that Voom uses a variable bit rate Sean?

 

[CraziFuzzy]

I was under the impression that most broadscast systems use a CBR compression rate, which would not vary based on picture requirements. VBR would be great, but it would be hard to use any of the extra bandwidth that the low bitrate portions would free up on a transponder, so in the end, would not really give you anything extra.

 

[Sean Mota]

Are you saying that Voom uses a variable bit rate Sean?

Yes. It changes depending on where the most mbsp is needed. This is why you can't take a snap shot of it and say I caught you (using less mbps ). You need to look at it for a prolong time and then take the average.

 

[cameron119]

I was under the impression that most broadscast systems use a CBR compression rate, which would not vary based on picture requirements. VBR would be great, but it would be hard to use any of the extra bandwidth that the low bitrate portions would free up on a transponder, so in the end, would not really give you anything extra.

I believe Dish is using VBR (or self-adjusting CBR that has normal and maximum allowable bandwidth usage) on the SD content.

By lumping in the SD channels with the HD content and guessing 2-3Mbps, I'm not sure the calculation of 11Mbps is completely accurate. I'm willing to wager it's 14-16Mbps. With all of the high-quality, high-motion HD content on Voom, you'd be screwed with CBR or VBR and such little bandwidth. As in my original post taken from DSLReports, It has to be at least 14Mbps for those high-motion channels...there is no reason it wouldn't approach 16Mbps on a show like MotoPIG. Are any TP's HD and SD content shared? Bandwidth can only be borrowed within the transponder.

 

[Ken F]

Are you saying that Voom uses a variable bit rate Sean?

VOOM uses statistical multiplexing for all its channels, just like Dish does for SD and DirecTV does for SD and HD.

Are any TP's HD and SD content shared?

Yes, on most (if not all) transponders.

I'm not sure the calculation of 11Mbps is completely accurate. I'm willing to wager it's 14-16Mbps.

Once again, VOOM uses 13 transponders @ about 50Mbps each. They've got 37 HDTV channels and 84 SD channels. You do the math.