Satellite, Cable bitrates

[docferdie]

Does anyone know what the bitrate is for program content on satellite TV as well as digital cable? For example ATSC OTA HDTV is either 1920x1080i or 1280x720p with a bitrate of around 19 MBps.
I would like to know what the specs are for satellite and digital cable. I have a feeling that the bitrates are horrendously low for either solution.

 

[djoxygen]

I have no idea, but I suspect it's considered proprietary information, changes without notice, and isn't made available for us mere mortals to use as a feature comparison.

However, bitrate isn't necessarily a good predictor of quality. As an example, with MPEG2 compression on DVDs, 2-pass VBR can almost always give you equivalent picture quality at a lower bitrate than 1-pass CBR. Without knowing what hardware, software, codecs, encoding methods, etc... that Dish or DirecTV are using, a comparison of bitrate and/or bandwidth is relatively meaningless.

You should let your eyes be the judge of what is acceptable for you.

 

[docferdie]

I don't think cable and satellite providers use anything but one pass encoding since they get their feeds from the networks like everybody else and a two pass method would incur a big time delay and screw up the broadcast schedule. They just pass on the satellite feeds from their content providers to their customers--ironic actually how cable companies discourage subscribing to satellite when a sattelite dish is exactly how they get their content, but that is another topic altogether--and do not have the content locally so multipass encoding is definitely not an option for them
So since everbody is 1 pass and MPEG 2 then the actual bitrates would be the major determinant of image quality. I suspect that the companies use rates much lower than DVD which is why they don't post them.

I just realized that people with DVR services for these companies should actually be able to tell us what the file sizes are when they record the bitstream that they receive. From there it would be easy enough to calculate a bitrate.

 

[djoxygen]

It was meant "as an example" of the variables that could come into play. You are probably correct that most digital television feeds are single-pass, especially if they are coming from an analog source. But in the interest of higher quality to attract more dollars, premium and PPV services could be compressed in advance of broadcast using 2-pass systems. But even if we assume most are 1-pass, we still don't know what kind/quality hardware they're using or if the streams are CBR or VBR. Even if they were publishing bitrates, it would be more a marketing tool than a true indicator of quality.

 

[Unregistered]

For NTSC, the channels are 6 MHz apart and I think that hasn't changed for ATSC (Digital TV, including Hi-Def). Obviously uncompressed hi-def content will not fit in a 6 MHz channel which is why it is compressed using MPEG-2.

The FCC allows cable/satellite operators to transmit more than one program in a 6 MHz wide channel so to determine the bandwidth of a given program you would need to know how many programs are transmitted in the same channel. Maybe you could get that info from the cable company. I'm sure it varies between cable companies as well as varies with the time of day.

 

[Cheezmo]

I've been collecting this info for local DFW broadcasters and DirecTV.

The results are posted here.