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Transponder Maps: Domestic & LatinAm ~ Data Refresh 12/17/2014


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#281 OFFLINE   P Smith

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Posted 03 January 2014 - 11:07 AM

Hotat2, when you doing counting discard from your total all channels with same VPID, then the number will be real



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#282 OFFLINE   HoTat2

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Posted 03 January 2014 - 11:54 AM

Hotat2, when you doing counting discard from your total all channels with same VPID, then the number will be real

But aren't PR subscribers actually receiving both sets of channels where even if some of the VPIDs (and associated APIDs too) are the same the receiver is still able to discriminate between them in lieu of their different TID values carried in the packets as well?

 

For instance I notice many local channel markets which have imported locals from other markets into their's as "virtual LiLs" frequently have over-lapping VPIDs and thus I assume use this same principle of differing packet TIDs so the receivers may distinguish among them.   


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#283 OFFLINE   P Smith

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Posted 03 January 2014 - 12:29 PM

umm, TID is not part of packets with A/V data, PIDs are markers of the packets; if a receiver tuned to the mux (by TID, etc from system tables), then different channels of the mux could use same VPID/APID ie same packets with video/audio, etc



#284 OFFLINE   HoTat2

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Posted 03 January 2014 - 12:54 PM

umm, TID is not part of packets with A/V data, PIDs are markers of the packets; if a receiver tuned to the mux (by TID, etc from system tables), then different channels of the mux could use same VPID/APID ie same packets with video/audio, etc

But I still don't see how the receiver would know which PIDs to associate with a given TID in the system tables if there are packets with overlapping PIDs in the same transponder multiplex stream, unless the A/V packets themselves carry a matching TID or maybe some other unique identifier to derive it from. :confused:

 

And do you have any ideas how an MPEG-2 SD channel may be in the same transponder multiplex with MPEG-4 ones?

 

Another oddity for sure ...  


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#285 OFFLINE   P Smith

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Posted 03 January 2014 - 01:04 PM

last q: yes, there is nothing unusual ... have you seen AC-3, DD5.1 , stereo or mono audio on one channel in same mux?

Same for H.262 or H.264 for video compression

 

I'm not sure why you pursuit TID here, as I told you, TID is accounted before tune to the transponder, then tuner pull the  mux with some system data and A/V packets with all channels in it



#286 OFFLINE   HoTat2

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Posted 03 January 2014 - 02:25 PM

last q: yes, there is nothing unusual ... have you seen AC-3, DD5.1 , stereo or mono audio on one channel in same mux?

Same for H.262 or H.264 for video compression

 

OK thanks, still meditating on this example.

... I'm not sure why you pursuit TID here, as I told you, TID is accounted before tune to the transponder, then tuner pull the  mux with some system data and A/V packets with all channels in it

 

 

Well I'm sorry P. Smith, but I'm still stumped on this one.

 

If I drop the issue of TID then what is it which uniquely identifies the A/V packets in a transponder stream when their PIDs overlap?

 

That is, when a receiver tunes to a transponder with multiple program packets sharing the same PIDs, I don't see how it knows which A/V packets to accept or reject for a desired program if the header information for all of them are identical to one another. 


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#287 OFFLINE   P Smith

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Posted 03 January 2014 - 02:39 PM

then lets go back to mux design...

a mux is a stream of packets 131 bytes long for DSS and 188 for DSS-3 [DVB-S2D]

each packet has a header (4 bytes), some of the header's bits [12 or 13] carry PID#

then if you will follow DVB-S/S2 ISO standard you will see how dedicated and variable PIDs define system tables, additional info and video/audio substreams

 

channel's eg service's description by system tables include PIDs what carry a/v/data and belong to the service;

do name/number other channel and point to same PIDs - you'll got 'mirroring' of same a/v to different channels

 

I did short and simplified description, details in that ISO papers


Edited by P Smith, 03 January 2014 - 02:40 PM.


#288 OFFLINE   HoTat2

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Posted 04 January 2014 - 02:22 PM

Well, I'm still giving it the "old college try" in trying to grasp this as the ancient cliche goes P. Smith, by studying a number of MPEG tutorials on other sites. :)

 

But I have to say I'm still largely stuck unfortunately ...   :(

 

I mean I can understand how the various PSI tables, NIT, PAT. PMT, etc. can point a receiver seeking a desired program to the particular transponder which carries it and then ultimately to the program's related streams as specified in the PMT, but that's where my problem comes in.

 

If a given program's associated packet streams for video, audio, and data happen to use the same PID numbers as those of another program's constituent video, audio, and data packet streams multiplexed on the same transponder, then I can't see how a receiver can distinguish between the two program streams.

 

I know I'm missing something here since it's somehow being done as DIRECTV use of duplicate PIDs for packets on the same transponder is an undisputed fact for the LiLs at least.

 

I just can't quite put my finger on specifically how they do it so far though.   


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#289 OFFLINE   P Smith

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Posted 04 January 2014 - 07:09 PM

easy :)

 

by user's guidenance

if the user select particular channel, then PMT will tell the IRD what PIDs to select

for other channel - same process

if two/three/four/etc different channels on same tpn/mux point to same A/V PIDs then be it - IRD will show SAME content for different channels :)



#290 OFFLINE   P Smith

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Posted 04 January 2014 - 07:14 PM

RollTide,

 

Here we are:

our data today still shows your locals on SW1 TPN 3

your Signal Strength Display clearly shows that TPN 3 is not correct for your locals

 

There is a problem here we need to resolve.  I will keep you posted with our progress!

 

Thanks Again

We can't accept SS as a point to particular tpn, at least SHEF cmd must be send when IRD tuned to the particular channel and we must see a result of the FA83 cmd



#291 OFFLINE   slice1900

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Posted 04 January 2014 - 08:01 PM

If you sort the LIL tab in different ways you can better see how things fit together. If you look at 101/119, TID=tpn-1 and the same TID/vPID pair is reused over and over in different LIL markets, sometimes 10 times or so. Compare with 99/103, where each LIL market uses a different TID (for the most part - there is a bit of sharing of TIDs, such as WJHG in Panama City, not sure what is going on there) and the vPID generally starts at 1010 and goes up by 10 for each channel.

 

As we know, PR is unique because it is treated as a huge LIL with all available spots on SW1 and SW2 pointed at it. Each spot has one TID, except for tpn 3, which has two. Perhaps because there are so many channels, it is overflowing some limit of vPIDs per TID (32, perhaps?) so it was assigned two of them. While the vPIDs are duplicated, each one still has a unique TID/vPID pairing so I don't see why this should be a problem. Receivers apparently use both to find the program within a transponder.

 

The large number of programs on this tpn is pretty simple to explain. Some of them are placeholder channels for NFLST and UEFA, so they don't really count. There would only be a couple of them active at once most likely, and they can shut down the PPV channel and starve the bits for the others for a few hours to make them fit. There are also many music channels, which require very little bandwidth since they have a static picture that changes once every 3 or 4 minutes. If you strip both of those out, there are 32 channels. In terms of bandwidth, that's equivalent to maybe a dozen MPEG2 channels on a Ku tpn, and we know Directv uses more than that in CONUS.

 

As for the MPEG2/MPEG4 channel mix...how do you know that PPV channel is MPEG2? I thought that was something we couldn't tell from the data provided? Even if it is, there's nothing stopping Directv from mixing MPEG2 and MPEG4 on the same tpn. They don't do it because they choose not to, not because there is some technical reason that prevents it. Either way its just bits.


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#292 OFFLINE   HoTat2

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Posted 04 January 2014 - 08:59 PM

 

 

... As we know, PR is unique because it is treated as a huge LIL with all available spots on SW1 and SW2 pointed at it. Each spot has one TID, except for tpn 3, which has two. Perhaps because there are so many channels, it is overflowing some limit of vPIDs per TID (32, perhaps?) so it was assigned two of them. While the vPIDs are duplicated, each one still has a unique TID/vPID pairing so I don't see why this should be a problem. Receivers apparently use both to find the program within a transponder.

 

 

I suggested this at first, and thus I as well didn't think it would have been a problem either slice, if the various programs' associated audio, video, and data packet headers also carried a record of their originating TID in addition to their PID number to distinguish them from duplicate packets with the same PID.

 

But P. Smith shot down that notion by claiming the A/V/D packet headers do not have a record of their TID, and that's when it "became a problem" trying to understand how this works then with duplicate PIDs for different program streams on the same transponder multiplex. :confused:  

 

... The large number of programs on this tpn is pretty simple to explain. Some of them are placeholder channels for NFLST and UEFA, so they don't really count. There would only be a couple of them active at once most likely, and they can shut down the PPV channel and starve the bits for the others for a few hours to make them fit. There are also many music channels, which require very little bandwidth since they have a static picture that changes once every 3 or 4 minutes. If you strip both of those out, there are 32 channels. In terms of bandwidth, that's equivalent to maybe a dozen MPEG2 channels on a Ku tpn, and we know Directv uses more than that in CONUS.

 

 

Good analysis here, thanks.

 

 ... As for the MPEG2/MPEG4 channel mix...how do you know that PPV channel is MPEG2? I thought that was something we couldn't tell from the data provided? Even if it is, there's nothing stopping Directv from mixing MPEG2 and MPEG4 on the same tpn. They don't do it because they choose not to, not because there is some technical reason that prevents it. Either way its just bits.

 

 

I accept that this must be the case.

 

Also FYI;

 

I understand that the TPN maps can tell the difference between an MPEG-2 and -4 channel, but not the actual picture resolution of the channel being carried. Only its compression type.

 

Besides, the channel in question is not shaded and has a VPID is "00FA" which is a standard Hex number for an MPEG-2 SD channel.  


Edited by HoTat2, 04 January 2014 - 09:03 PM.

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#293 OFFLINE   P Smith

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Posted 04 January 2014 - 10:14 PM

TID is not a paired other way then presenting itself in SI tables; so NIT is for all sats/tpns & SDT for all channels and PAT/PMT/PIDS for one tpn/mux



#294 OFFLINE   slice1900

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Posted 05 January 2014 - 02:54 AM

I think I got a bit of acronym overload here so I can't quite follow all of that, but if you're saying that TID is not presented in the packet stream on the tpn, and thus cannot be used as one of the selection criteria to choose between streams as suggested I have a couple questions.

 

First, is this conclusion based on DVB-S2, or on DVB-S2D? (Directv's special sauce version) I have no idea how large the difference is between the two, or how well understood/documented DVB-S2D is. If you say you know it is not there and there isn't a possibility it is some undocumented extension for the 'D' part Directv added then I'll accept that, as you clearly know your stuff here.

 

Second, even if is the case that the TID isn't broadcast with an individual program stream, if it is broadcast as part of the overall tpn/mux signal (however one should refer to that) in the form of an 'index' that provides some other method which may be used to link TID to a specific program stream in a unique way (i.e., other than vPID, since that apparently is not unique) then that would serve the same purpose, albeit in a bit of a roundabout way. Is there a chance that is what is happening, or do you feel you are able to rule that out as well?

 

Unless the data shown for PR is inaccurate in some way, it appears conclusive that there are many cases on tpn 3 of two program streams being broadcast with the same vPID. The only way to separate them that is evident in the transponder map data is the TID. Either that must be sufficient (somehow) or there is some other unique identifier that is being used which is currently not shown in the transponder map. Would you agree with that, or do you think that something else is going on and we're just plain misunderstanding what we're seeing in that PR tpn 3 data?


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#295 OFFLINE   HoTat2

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Posted 05 January 2014 - 11:42 AM

I think I got a bit of acronym overload here so I can't quite follow all of that, but if you're saying that TID is not presented in the packet stream on the tpn, and thus cannot be used as one of the selection criteria to choose between streams as suggested I have a couple questions.

 

First, is this conclusion based on DVB-S2, or on DVB-S2D? (Directv's special sauce version) I have no idea how large the difference is between the two, or how well understood/documented DVB-S2D is. If you say you know it is not there and there isn't a possibility it is some undocumented extension for the 'D' part Directv added then I'll accept that, as you clearly know your stuff here.

 

Second, even if is the case that the TID isn't broadcast with an individual program stream, if it is broadcast as part of the overall tpn/mux signal (however one should refer to that) in the form of an 'index' that provides some other method which may be used to link TID to a specific program stream in a unique way (i.e., other than vPID, since that apparently is not unique) then that would serve the same purpose, albeit in a bit of a roundabout way. Is there a chance that is what is happening, or do you feel you are able to rule that out as well?

 

Unless the data shown for PR is inaccurate in some way, it appears conclusive that there are many cases on tpn 3 of two program streams being broadcast with the same vPID. The only way to separate them that is evident in the transponder map data is the TID. Either that must be sufficient (somehow) or there is some other unique identifier that is being used which is currently not shown in the transponder map. Would you agree with that, or do you think that something else is going on and we're just plain misunderstanding what we're seeing in that PR tpn 3 data?

 

+1 here on this as well.


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#296 OFFLINE   egakagoc2xi

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Posted 05 January 2014 - 06:17 PM

I've been reading about this debate and though I don't think I got everything you've said, I wanted to add another example which can help or add more question. In the Latam excel you can see what you talk about PR. You can see it in the channel 1552 and all the HD placeholder events channels, you can see that they TID and first pid is the same, but the second pid is what changes between live and placeholder, but the funny thing is that depending on how you access a particular channel the STB can get it wrong and sometimes in the placeholder channel shows you the live but without audio. Just wanted to add that maybe there more that two or three pids per channels, could be N and perhaps we don't get them all right now and SHEF won't show it either and there could be the difference you're searching.

Edited by egakagoc2xi, 05 January 2014 - 06:18 PM.


#297 OFFLINE   P Smith

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Posted 05 January 2014 - 07:58 PM

yes, you're right - the spreadsheet had only first VID and first APID, if there are more it wouldn't be here, but system tables had all of them



#298 OFFLINE   HoTat2

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Posted 05 January 2014 - 10:47 PM

So a channel's program stream packets (video, audio and data) can vary among a list of PIDs it uses over time, but the spreadsheet only captures the first (with only the video one displayed in the map)? 


Edited by HoTat2, 05 January 2014 - 10:49 PM.

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#299 OFFLINE   P Smith

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Posted 05 January 2014 - 10:53 PM

yes

there is no space to provide full list of A/V/D PIDs, for some channels you can see 8 or more of them, for different languages, IP sub-streams, etc


Edited by P Smith, 05 January 2014 - 10:53 PM.


#300 OFFLINE   HoTat2

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Posted 05 January 2014 - 11:37 PM

yes

there is no space to provide full list of A/V/D PIDs, for some channels you can see 8 or more of them, for different languages, IP sub-streams, etc

So as an example, just because the spreadsheet shows the same video PID for two different channels or even if the SHEF command run on them reports the same as well.

 

That doesn't mean either of those channels are necessarily using those PID numbers for their A/V packets at any given time during a broadcast?   


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