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DBS Video Compression

5K views 15 replies 7 participants last post by  thenewdc 
#1 ·
I was wondering if anyone can either tell me or point me in the right direction here. I am looking at comparing Bell Satellite, Fibe, Shaw Direct and Cogeco Cable video quality. I have Direct TV also and the picture quality is by far the best but have not seen any data lately for the Canadian companies. I would like specific data if possible, I found some information on compression techniques but it was several years old. I am fed up with the mosquito noise I am getting with hockey games on CBC and others on Shaw Direct and need better quality, right now Fibe is still not available in my area. Any help would be greatly appreciated.
 
#2 ·
You are not going to get a definitive answer on this question (who has the best quality) because bitrate/compression is only one factor in assessing picture quality. Due to the way the various BDUs handle signals (some change 1080i signals to 720P), some use different compression, MPEG2, MPEG4, etc.

You are far better looking into which BDU provides you with the channels you want and the price you are willing to pay (although price is not very different on different BDUs for similar packages).

Here are several links where I previously discussed formats, bitrates, etc: Others also contributed their views.

http://www.digitalhome.ca/forum/showthread.php?p=2391065#post2391065

http://www.digitalhome.ca/forum/showthread.php?p=2395729#post2395729

What is more important is a proper optimization of all the equipment in the home theatre: For example, mosquito noise is often the result of too high a sharpness level on the TV.

http://www.digitalhome.ca/forum/showthread.php?t=76161
 
#3 ·
A couple more items that can be very important when choosing a BDU are the equipment availability as well as the MMI (man-machine interface/IPG). Some people might want a WHPVR (whole home PVR setup), or access to TiVo IPG, etc.

Another factor is whether you wish to bundle the services of the provider to get a bundle discount for say phone, internet, etc.

Getting back to your original question, you are not going to get consensus on this or any other forum regarding the best picture quality by BDU. There are simply too many variables. In my optimization travels, I have not found a huge difference in picture quality between the BDUs I've encountered (Fibe, Bell Sat, Rogers Cable, Shaw Direct, Cogeco, etc) I would say that Bell Sat/Fibe were typically a bit "softer" due to their use of 720P, but they also seemed to have fewer artifacts, which are more visible in the "harder" 1080i format. So, depending on what "bugs you" one provider may be superior for you, but inferior for someone else.
 
#4 ·
Given the lack of detail in the original post it's difficult to make any determination on the "mosquito" noise. What type of TV is it? What digital receiver? What type of connection is being used? Are the channels SD or HD? Also, compression artifacts are very subjective. Shaw Direct was often noted for having less compression on their SD channels. I found the type of artifacts on their signals to be more objectionable than the often more compressed signals from Bell. As 57 pointed out, the noise could be caused by something other than compression, such as a piece of equipment. It could even be in the original signal from the production source.
 
#5 ·
Nice, thanks for all the information. I have been a Star Choice/Shaw Direct customer for 20 years and have went through all of the HD Receivers landing on the HDPVR 630 right now. My TV is an Epson 6010 HD 3D Projector with a 174" AT Scope Screen, this is why I need the best possible picture, I have no complaints with my Direct TV quality. All receivers are connected HDMI and I only watch HD channels. Without reading all the attached, just yet, I need to know who is doing the least amount of compression, or who is not squeezing 3 HD channels on one transponder. If there are other factors involved then maybe I need to try each ( Bell Satellite and Cogeco) to see if I can see a difference but I was hoping to be able to just pick one. If Direct TV can look awesome I am gambling that a CDN company can too.
 
#8 ·
So after reading some it looks like Bell Satellite uses MPEG-4 and Shaw Direct MPEG-2?, any idea on Cogeco? Not sure of the visual difference between MPEG-2 or 4. If MPEG-4 is cleaner then I would need to find out the bitrates used by each and I can narrow my choices down.
 
#10 ·
57...This may be my answer here, as mosquito noise/artifacts are what bugs me. Thanks. All my signals are fed through a very expensive receiver and I have tried external scalers to no avail.


"I would say that Bell Sat/Fibe were typically a bit "softer" due to their use of 720P, but they also seemed to have fewer artifacts, which are more visible in the "harder" 1080i format. So, depending on what "bugs you" one provider may be superior for you, but inferior for someone else."
 
#12 ·
Bitrates:

OTA: Typically broadcast at 13-19 Mbps, depending on the HD channel and whether they have subchannels, etc.

Cable companies: If they have 2 HD channels per QAM, you typically get the signal uncompressed from OTA or from the "broadcaster" (specialty channels). Some specialty channels may provide an uplink signal to the BDU, which could be as high as 50 Mbps (FTA/BUD quality). This is atypical but I have heard of it being used - say for Astral Movies in the past. I'm not sure if that still happens now that Astral is owned by Bell. I believe Cable companies are not allowed to (further) compress OTA-type channels, so you'll get those at the original bitrate, however, most cable companies put 3 channels per QAM for the specialty/other channels.

Cable Companies: As mentioned above, most channels are now 3 HD channels per QAM, so they are typically 12.5 Mbps MPEG2.

Bell: For MPEG2 signals, they used to use about 10 Mbps or 3 HD channels per Transponder. They used variable bitrate, so there was no fixed rate per channel.

Bell (Fibe & Sat). For MPEG4, the bitrate is usually around 5 Mbps. 1080i channels are also changed to 720P.

Shaw Direct - I don't know.

NetFlix: Bitrate is usually around 3-5 Mbps

As a side note, Rogers new PVR (the 9865 with the latest firmware) now recompresses any recordings when the PVR is not doing anything else (say 6-7AM). The amount of space the recordings take on the HDD is reduced by about 40%, almost doubling the amount of recording time on the HDD. This "recompression" is done after the original recording is finished at some later time. No one has complained about the quality of the picture being reduced by this additional compression step. I do not know what "process" is used for this compression, but it seems to work very well. I would put Rogers' picture quality up against any other provider (having seen all the major Ontario providers).

Again, as I mentioned before, the provider's picture quality does not correlate well with bitrate. Just remember that the "original" bitrate of HD programming is over 1 Gbps, so all signals are compressed by a factor of 50-100+, even OTA.
 
#13 ·
I wouldn't focus solely on the "amount" of compression. MPEG4 can achieve the same quality with half the transponder space and at half the bit rate of MPEG2. Plus, there are other factors such as encoding techniques and the amount of error correction being used. I believe Bell uses MPEG4 for all their HD channels. Shaw uses MPEG2 for some HD channels and MPEG4 for others so it's a mixed bag. Transponder capacity can vary with satellite band so channels per transponder is not always reliable, even if other factors are equal. Cable is usually MPEG2 but they have *lots* more bandwidth so it's not necessary for them to use MPEG4, at least not yet. The bottom line is that it's not easy to tell unless all the stats are known and it can vary from channel to channel. Channels that look good on one provider may look bad on another and visa versa.

I see two issues in the OP. One is finding the source of the whistle. Some investigation will be required to isolate it.

The other is picture quality. I doubt any Canadian provider will be as good as Direct TV. They just don't compete on the same playing field. I would rate cable as the best, followed by a tossup between Bell and Shaw. Bell was, by far, the worst but their switch to MPEG4 reportedly fixed most of their issues. The big issue with Bell is the use of 720p for all channels. Shaw tends to have more technical issues. Rogers has it's share of technical issues as well. Don't know about Cogeco.
 
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