TiVo Community
TiVo Community
TiVo Community
Go Back   TiVo Community > Main TiVo Forums > TiVo Series3 HDTV DVRs
TiVo Community
Reply
Forum Jump
 
Thread Tools
Old 12-21-2007, 04:56 AM   #841
bicker
Gruff
 
Join Date: Nov 2003
Location: Burlington, MA
Posts: 9,064
Quote:
Originally Posted by lrhorer View Post
Quote:
SDV is based on reasonable projections of usage.
Not fundamentally it isn't no.
Of course it is. Look: You and I disagree. You can type in your drivel all day long and it isn't going to get any more convincing. I think you're wrong. Get over it. You've had your say; I've had mine. Time to move on.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
bicker is offline   Reply With Quote
Old 12-21-2007, 07:21 AM   #842
mikeyts
Wireless Wiseguy
 
Join Date: Jul 2004
Location: San Diego, CA, USA
Posts: 2,121
Quote:
Originally Posted by bicker View Post
Of course it is. Look: You and I disagree. You can type in your drivel all day long and it isn't going to get any more convincing. I think you're wrong. Get over it. You've had your say; I've had mine. Time to move on.
What either of you thinks is irrelevant. The cable providers and the companies developing SDV system have done research and they're convinced. Real, hard data acquisition and analysis--no armchair BS. They pumping many tens of millions of dollars into this and imposing it on us all. It's a gamble, but their only alternative is pumping many billions of dollars into running FTTH to a hundred million households.
__________________
Mike Scott

"
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
" -- hookbill
mikeyts is offline   Reply With Quote
Old 12-21-2007, 07:22 AM   #843
bicker
Gruff
 
Join Date: Nov 2003
Location: Burlington, MA
Posts: 9,064
Quote:
Originally Posted by mikeyts View Post
What either of you thinks is irrelevant. The cable providers and the companies developing SDV system have done research and they're convinced. Real, hard data acquisition and analysis--no armchair BS. They pumping many tens of millions of dollars into this and imposing it on us all;
Abso-friggen-lutely.
__________________

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
bicker is offline   Reply With Quote
Old 12-21-2007, 07:24 AM   #844
dswallow
Save the Moderatоr
 
dswallow's Avatar
 
Join Date: Dec 2000
Location: Long Branch, NJ, USA
Posts: 48,517
TC CLUB MEMBER
Quote:
Originally Posted by Luke M View Post
Theoretically, a rich guy could set up a monster DVR (or multiple DVRs) to record every single channel. In that case, switched video doesn't save any bandwidth regardless of service area size.

In general, if one atypical user can consume as much resources as a large number of typical users, then it creates some tension for a flat rate pricing system.
Except that there'd be sufficient additional outlet charges involved that the cable company would certainly be getting compensated for it. And considering just how many it'd require there may be an upper limit on the number of additional outlets they even allow for one account.
__________________
¯\_(ツ)_/¯****************
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
dswallow is offline   Reply With Quote
Old 12-21-2007, 11:46 AM   #845
morac
Cat God
 
morac's Avatar
 
Join Date: Mar 2003
Location: NJ
Posts: 6,177
Quote:
Originally Posted by lrhorer View Post
Yes, but encoding HD content is not trivial or cheap, adn neither is recording it. It's going to be a while before every source will be capable of delivering HD content.
It can't be all that expensive if Joe Consumer can get a HD camcorder for less than $1000. Yes I know the industry uses more expensive cameras, but even if you're talking a $30,000 camera that should still be affordable to most content providers. As for encoding HD, my desktop PC can do that (albeit slowly) so I don't think that's an issue either.

By the way the current list of HD channels is impressive and it's only going to get bigger. How cable companies will be able to provide all these channels is the big question. I personally think that SDV is not the ultimate solution and that the only way this can be done is by switching to MPEG-4 encoding.
morac is offline   Reply With Quote
Old 12-21-2007, 03:58 PM   #846
lrhorer
Registered User
 
Join Date: Aug 2003
Location: San Antonio, Texas, USA
Posts: 6,849
Quote:
Originally Posted by mikeyts View Post
What either of you thinks is irrelevant. The cable providers and the companies developing SDV system have done research and they're convinced. Real, hard data acquisition and analysis--no armchair BS. They pumping many tens of millions of dollars into this and imposing it on us all. It's a gamble, but their only alternative is pumping many billions of dollars into running FTTH to a hundred million households.
That's correct, and I was a fairly significant contributor to that effort until a while back. As a CATV engineer helping to implement the Pegasus system and SDV I had to understand how SDV works and what the implications were for useage, and I still have some inside views on what's going on with the CATV company. The point is, however, they aren't spending a dime worrying about TiVo Suggestions because there isn't anything to worry about. The simple fact - not an opinion but a cold, hard fact - is TiVo suggestions do not add any significant load to the SDV system as a whole. They add nothing at all to the server farm's peak load, and additions to off-peak loads are not relevant in any case. They do potentially add network congestion issues to the local node, but once again this is hardest felt during peak load hours and the additional load is as well represented by any DVR, including the ones provided by the CATV system, not just a TiVo with suggestions.

Last edited by lrhorer : 12-21-2007 at 04:32 PM.
lrhorer is offline   Reply With Quote
Old 12-21-2007, 04:27 PM   #847
lrhorer
Registered User
 
Join Date: Aug 2003
Location: San Antonio, Texas, USA
Posts: 6,849
News for you

Quote:
Originally Posted by morac View Post
It can't be all that expensive if Joe Consumer can get a HD camcorder for less than $1000. Yes I know the industry uses more expensive cameras, but even if you're talking a $30,000 camera that should still be affordable to most content providers.
I have news for you. $30,000 is cheap for an SD commercial camera, let alone an HD. The big networks don't blink an eye at six figures for a camera. The thing is, there aren't hundreds of national networks out there. Most of the content comes from small concerns, down to and including public access where Joe Bob and Cindy create a Merry Christmas video for distribution on the Public Access channel. The cameras the CATV company loans out to those folks cost less than $5000, and that's not liable to change.

Quote:
Originally Posted by morac View Post
As for encoding HD, my desktop PC can do that (albeit slowly) so I don't think that's an issue either.
That's the point, and it is an issue. Anything close to "slowly" is not acceptable for a live broadcast. Of course movie channels and the like have the luxury of taking all the time they want, and they don't use a camera, at all.

The computing horsepower to encode compressed HD video from a live uncompressed stream is phenomenal. Your computer just re-encodes already compressed video, which is much different. The last time I saw a benchmark (although this was several years ago), it took the fastest supercomputer in the world an hour to compress a 60 second commercial into a 1.544Mbps stream without visible artifacts. Of course now chipsets have been developed to handle the compression natively, and computing horsepower is growing at an exponential rate, but it still isn't quite dirt cheap.

Quote:
Originally Posted by morac View Post
By the way the current list of HD channels is impressive and it's only going to get bigger. How cable companies will be able to provide all these channels is the big question. I personally think that SDV is not the ultimate solution and that the only way this can be done is by switching to MPEG-4 encoding.
Well, yes, and no. The number of channels deliverable via SDV is virtualy without bound. In order to increase the number of channels, the CATV company merely needs to decrease the number of houses served by a node. The end limit for node expansion is reached when the number of receivers in every node is less than the number of channel slots on the node, at which point the number of deliverable channels is infinite as far as the distribution system is concerned. Therefore SDV alone is quite sufficient to deliver any number of channels one might wish. The wrinkle is MPEG-4 allows more channels in the same bandwidth, which means the node size doesn't have to be as small. This translates into more channels for less money for the CATV provider, so I have no doubt whatsoever they will be moving to MPEG-4 or some similar protocol in the not too distant future. It won't eliminate SDV, though. What's more, SDV allows for much more than just ungodly numbers of channels. It allows for essentially unlimited venues of interactive services from banking online to interactive classrooms with a live lecturer (rather than what passes for "interactive tutoring" today) to videoconferencing to voting online.
lrhorer is offline   Reply With Quote
Old 12-21-2007, 04:37 PM   #848
cableguy763
Registered User
 
Join Date: Oct 2006
Location: Austin
Posts: 525
If a cable co goes to mpeg 4, they would have to have all new boxes. Pretty expensive option.
cableguy763 is offline   Reply With Quote
Old 12-21-2007, 04:54 PM   #849
lrhorer
Registered User
 
Join Date: Aug 2003
Location: San Antonio, Texas, USA
Posts: 6,849
Quote:
Originally Posted by bicker View Post
Of course it is. Look: You and I disagree. You can type in your drivel all day long and it isn't going to get any more convincing. I think you're wrong. Get over it. You've had your say; I've had mine. Time to move on.
Yes, but I am a qualified expert in the field and you are not. Yet once again you resort to ad-hominem retorts rather than real, physical data.

Let me set up a typical scenario:

Moderately large city
100,000 subscribers
2.5 live viewers per household
2 channel DVR per 10 households ignoring any TiVos whatsoever
= 270,000 receivers
500 scheduled channels (no CATV company yet comes close to this, even in the largest cities)

Answer me this: How many of the 500 channels do you estimate are not being viewed by a single receiver peak viewing times? (I'll give you a hint: the answer is less than 1.)

Changing out every single one of the 235,000 receivers to a 5000 channel super-DVR recording every available channel 24 hours a day on 10 times over won't increase the load on the server farm by any amount whatsoever, except to increease the number of broadcast addresses in the headers.
lrhorer is offline   Reply With Quote
Old 12-21-2007, 05:11 PM   #850
lrhorer
Registered User
 
Join Date: Aug 2003
Location: San Antonio, Texas, USA
Posts: 6,849
Expensive option

Quote:
Originally Posted by cableguy763 View Post
If a cable co goes to mpeg 4, they would have to have all new boxes. Pretty expensive option.
'Not if they are already MPEG-4 capable. I don't know the innards of the new boxes all that well, but even if they don't, a staged retrofit coupled with a staged rollout of MPEG-4 would be about the same as the current SDV rollout. At what point it becomes worth it is the question.
lrhorer is offline   Reply With Quote
Old 12-21-2007, 05:58 PM   #851
dswallow
Save the Moderatоr
 
dswallow's Avatar
 
Join Date: Dec 2000
Location: Long Branch, NJ, USA
Posts: 48,517
TC CLUB MEMBER
Quote:
Originally Posted by lrhorer View Post
'Not if they are already MPEG-4 capable. I don't know the innards of the new boxes all that well, but even if they don't, a staged retrofit coupled with a staged rollout of MPEG-4 would be about the same as the current SDV rollout. At what point it becomes worth it is the question.
Not really. The SDV rollout doesn't involve replacing the cable boxes at every household. If those boxes can't handle MPEG-4, an MPEG-4 rollout would only become advantageous when all subscribers to any given channel had MPEG-4 capable receivers.
__________________
¯\_(ツ)_/¯****************
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
dswallow is offline   Reply With Quote
Old 12-21-2007, 06:03 PM   #852
mikeyts
Wireless Wiseguy
 
Join Date: Jul 2004
Location: San Diego, CA, USA
Posts: 2,121
Quote:
Originally Posted by lrhorer View Post
Yes, but I am a qualified expert in the field and you are not. Yet once again you resort to ad-hominem retorts rather than real, physical data.

Let me set up a typical scenario:

Moderately large city
100,000 subscribers
2.5 live viewers per household
2 channel DVR per 10 households ignoring any TiVos whatsoever
= 270,000 receivers
500 scheduled channels (no CATV company yet comes close to this, even in the largest cities)

Answer me this: How many of the 500 channels do you estimate are not being viewed by a single receiver peak viewing times? (I'll give you a hint: the answer is less than 1.)
Interesting. BigBandNetworks have some papers online describing field trials of the technology which would seem to uphold their premise that it does work. There are papers here and here about trials run in 2002 and 2003. In their studies the numbers strongly support the premise that great efficiencies can be fairly easily acheived with SDV in the real world, which seems intuitively reasonable. Indications are that number of channels in demand does not grow very much after a certain point as you add subscribers. Given a fixed population of subscribers, growth of demand as you add channels is also flat after a certain point. I'm not sure against what population of subscribers, but they think that you can support a 500 channel system with 276 active streams (which they calculate to require 28 QAMs, but they're obviously talking about SD channels packed 10 or so to the QAM). With "maximum broadcast bit rate" HD programs, you'd need 138 QAMs for 500 HD channels. Of course, a 500 channel system put together today would probably have no more than about 100 HD channels with the rest being SD.

BigBand did do these studies, but they're trying to sell the technology which no doubt colors their conclusions. What evidence do you cite to back your assertions?
__________________
Mike Scott

"
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
" -- hookbill
mikeyts is offline   Reply With Quote
Old 12-21-2007, 11:04 PM   #853
mikeyts
Wireless Wiseguy
 
Join Date: Jul 2004
Location: San Diego, CA, USA
Posts: 2,121
TWC Austin rolled out SDV over a year ago. I wondered if they'd published anything about their experiences. There are a few tidbits in the following Multichannel News articles:
The Switch Is On To Boost Channels
How Time Warner Austin Did Switched Digital
Apparently, at the time of the second article, they were switching 175 SD channels and 8 HD ones on 8 QAMs (normally about enough bandwidth for 80 SD channels or 16 HD ones). Impressive.

EDIT: I just noticed that the entired second article (which was published first) is included as a sidebar in the first piece.
__________________
Mike Scott

"
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
" -- hookbill
mikeyts is offline   Reply With Quote
Old 12-22-2007, 08:27 AM   #854
ah30k
Registered User
 
Join Date: Jan 2006
Posts: 2,206
Quote:
Originally Posted by lrhorer View Post
Yes, but I am a qualified expert in the field and you are not. Yet once again you resort to ad-hominem retorts rather than real, physical data.

Let me set up a typical scenario:

Moderately large city
100,000 subscribers
2.5 live viewers per household
2 channel DVR per 10 households ignoring any TiVos whatsoever
= 270,000 receivers
500 scheduled channels (no CATV company yet comes close to this, even in the largest cities)

Answer me this: How many of the 500 channels do you estimate are not being viewed by a single receiver peak viewing times? (I'll give you a hint: the answer is less than 1.)

Changing out every single one of the 235,000 receivers to a 5000 channel super-DVR recording every available channel 24 hours a day on 10 times over won't increase the load on the server farm by any amount whatsoever, except to increease the number of broadcast addresses in the headers.
The fact that you don't understand the 'node' concept with SDV shows you are not much of a qualified expert.
ah30k is offline   Reply With Quote
Old 12-22-2007, 12:02 PM   #855
mikeyts
Wireless Wiseguy
 
Join Date: Jul 2004
Location: San Diego, CA, USA
Posts: 2,121
I also noticed the following at Multichannel News:
SCTE Okays MPEG-4 Video Standard For Cable
Pointed out there as here is the fact that use of it would require distribution of boxes capable of MPEG-4 decoding.
__________________
Mike Scott

"
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
" -- hookbill
mikeyts is offline   Reply With Quote
Old 12-23-2007, 03:57 AM   #856
lrhorer
Registered User
 
Join Date: Aug 2003
Location: San Antonio, Texas, USA
Posts: 6,849
SDV Nodes

Quote:
Originally Posted by ah30k View Post
The fact that you don't understand the 'node' concept with SDV shows you are not much of a qualified expert.
I understand it perfectly well, and if you will re-read my posts, that should be evident. There are two different primary network bottlenecks in SDV. One is the node. The other is the headend. The claim was made the most significant impact by TiVo's running suggestions would be at the headend, and that thousands of TiVos all recording channels 24 hours a day would swamp the headend server farm.

To simplify things, we'll ignore services such as VOD and Video Rewind for the moment, and assume all the channels bear nothing but scheduled content. If the number of receivers on the node is less than or equal to the number of channels on the node, then channel blocking is impossible. Reducing the number of houses to that point is excessive, however, since utilization of channels on the node won't ordinarily reach 100%. First of all, as we all know, every program has a certain popularity, and a single channel may at times garner more than 50% of the viewing public. All those subscribers (or DVRs) viewing the same program receive the very same stream on a single carrier. This cuts down the number of unique receivers drastically and increases the numbe of homes which can be served by a single node. Most MSOs are targeting their network builds to wind up with between 500 and 1000 homes passed per node, which equates to something like 300 - 600 active subscribers and probably 750 - 1500 receivers. The number of active channels will tend to increase fairly rapidly at first with increasing numbers of receivers on the node, but soon the channel utilization begins to flatten out and only increases very slightly as more receivers are added.

Here the number of multi-stream receivers such as DVRs does impact the number of active channels on the node, especially if things like suggestions are turned on, but the impact is only minimal. Again, it's not zero, but it's not huge, either, especailly once the number of available channels exceeds a moderate fraction of the total number of receivers. In this part of the network, biker is correct in saying the projections are usage based, but first of all, he was talking about congestion at the headend, not at the node, and secondly, the actual impact on traffic of Suggestions at the node is quite small. How small depends on how many channels are supported by the system, how many receivers are online, and of course the time of day. The thing is, at this point in the network, the Suggestions are going to have their biggest impact during the periods of lowest utilization, when blocking is least likely. That's not to say it can never happen. Since the node is considerably oversubscribed, blocking is indeed possible and in fact does happen from time to time. The odds of it hitting the same customer on a regular basis are exceptionally low, however. Unless the node is far too oversubscribed, no user should see a block network error on his receiver even once a month, and then not on any of the more popular channels. Indeed, the presence of Suggestions on TiVo's would tend to help prevent blocking on the scheduled channels while making it somewhat more common on VOD channels or during Video Rewind attempts.

The headend is the second place where blocking can occur, but here the metric is different. At any node the network only has to be able to provide a sufficient number of streams to deliver all the channels being watched on that node, which could easily be fewer than 100. What happens across town is irrelevant. At the headend, however, there is no useage basis for delivery of service. It doesn't matter if one stream is being watched by 90% of the receivers in town. The load in the servers is dependent upon how many total streams are in service. If only a single viewer anywhere in the city is watching a particular program, it has the same impact on the headend as the one holding 90% of the subscribers. At the node the fact a single program is being viewed by a large fraction of the people on the node means the load on the node is potentially much lower. The impact of TiVos running suggestions at the headend is tiny compared with normal scheduled viewing and in fact is minuscule compared to the traffic generated by impulse traffic such as Video Rewind and VOD. Indeed, the traffic generated by all forms of scheduled viewing (including scheduled pay-per-view) is extremely small compared to the traffic generated by interactive video such as VOD and Video Rewind. The scheduled programs might represent 200 or 300 ir even eventually 500 or more unique data streams at the headend, but interactive services could easily eventually outstrip that by a factor of 100. There are a number of very clever schemes to allow the headends to handle such a vast volume, but the point is, if they can handle that volume, they can easily handle one or two or even ten additional streams required by having suggestions turned on.
lrhorer is offline   Reply With Quote
Old 12-23-2007, 04:21 AM   #857
lrhorer
Registered User
 
Join Date: Aug 2003
Location: San Antonio, Texas, USA
Posts: 6,849
Number of channels

Quote:
Originally Posted by mikeyts View Post
BigBand did do these studies, but they're trying to sell the technology which no doubt colors their conclusions. What evidence do you cite to back your assertions?
Well, first of all the fact the channels here in San Antonio now exceed 1000 in numbering. Of course there are some significant gaps and 150 of those channels are audio stations with minimal picture content (more like screen savers), but still the actual number of channels is well over 500, most being pay-per-view and VOD. 72 are still analog. They have a 750MHz system here (they talked about increasing to 850MHz, but ultimately decided against it a couple of years ago). That leaves them about 230 MHz or 38 streams to deliver more than 400 channels, 20 or so of which are HD. I'm told all of their regularly scheduled digital channels offer Video Rewind, but I can't testify to that personally, because I have TiVos, and I left the company long before Video Rewind came out.

I'm not allowed to give too many details, but we happen to share a number of facilities with them, and you wouldn't believe how much power they're using, or how much bandwidth for data. There's a reason for that.

Last edited by lrhorer : 12-23-2007 at 04:26 AM.
lrhorer is offline   Reply With Quote
Old 12-23-2007, 04:25 AM   #858
lrhorer
Registered User
 
Join Date: Aug 2003
Location: San Antonio, Texas, USA
Posts: 6,849
Huh?

Quote:
Originally Posted by dswallow View Post
Not really. The SDV rollout doesn't involve replacing the cable boxes at every household. If those boxes can't handle MPEG-4, an MPEG-4 rollout would only become advantageous when all subscribers to any given channel had MPEG-4 capable receivers.
Um, isn't that kind of what I said? A staged rollout would prevent their having to replace every cable box which didn't support MPEG-4 or to supply one to every customer without a CableCard device of some sort.
lrhorer is offline   Reply With Quote
Old 12-23-2007, 04:41 AM   #859
mikeyts
Wireless Wiseguy
 
Join Date: Jul 2004
Location: San Diego, CA, USA
Posts: 2,121
Quote:
Originally Posted by lrhorer View Post
I'm not allowed to give too many details, but we happen to share a number of facilities with them, and you wouldn't believe how much power they're using, or how much bandwidth for data. There's a reason for that.
I'm sorry, but I seem to have missed something. Who is "we" and who are "them"?

I wasn't aware that people are including the music services in the "500 channels" number. The bandwidth required for streaming music must be miniscule (and for feeding those screen savers, which I doubt are actual video streams). There are 64 of these channels on my system and I'd be surprised if they consumed more than half a QAM.
__________________
Mike Scott

"
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
" -- hookbill
mikeyts is offline   Reply With Quote
Old 12-23-2007, 08:40 AM   #860
ah30k
Registered User
 
Join Date: Jan 2006
Posts: 2,206
Quote:
Originally Posted by lrhorer View Post
I understand it perfectly well, and if you will re-read my posts, that should be evident. There are two different primary network bottlenecks in SDV. One is the node. The other is the headend. The claim was made the most significant impact by TiVo's running suggestions would be at the headend, and that thousands of TiVos all recording channels 24 hours a day would swamp the headend server farm...................
My oh my, you do like to type a lot. I recall no claim that the bottleneck was in the headend. It may be here somewhere but I don't recall it. You laid out a scenario with 100,000 subscribers, tuners and 500 channels and claimed that SDV won't work because of the probability of more streams being needed was greater than 99%. That is where nodes fix the problem.

I don't know why you are off on the headend bottleneck and 1000 interactive streams killing the system. That is a totally different topic. Perhaps you headend is just poorly designed.
ah30k is offline   Reply With Quote
Old 12-23-2007, 09:23 AM   #861
lew
Registered User
 
Join Date: Mar 2002
Posts: 3,254
I understand how SDV would allow a cable system to add more PPV channels and even VOD. I'm not sure how it lets them add more regular channels. The way I understand it if no customer on the node requests the channel then the channel won't be sent. What is the purpose of offering a channel that literally no one in a given area wants to watch? I guess it might make sense for a very niche channel, perhaps international.
lew is offline   Reply With Quote
Old 12-23-2007, 09:41 AM   #862
dswallow
Save the Moderatоr
 
dswallow's Avatar
 
Join Date: Dec 2000
Location: Long Branch, NJ, USA
Posts: 48,517
TC CLUB MEMBER
Quote:
Originally Posted by lew View Post
I understand how SDV would allow a cable system to add more PPV channels and even VOD. I'm not sure how it lets them add more regular channels. The way I understand it if no customer on the node requests the channel then the channel won't be sent. What is the purpose of offering a channel that literally no one in a given area wants to watch? I guess it might make sense for a very niche channel, perhaps international.
Statistically there's always channels people aren't watching. By only actually sending video for channels that someone is watching, you can offer more channels than you actually have space to carry simultaneously. That's what Switched Digital Video (SDV) is all about. The efficiency exists because of the way subscribers are grouped and serviced in nodes. Every node has a maximum number of subscribers and receivers within it, and it's within each node that what channels are being watched that matters. The smaller the node, the more unwatched channels exist within the node.

You can even think of the system much like a cell phone tower. When all available channels are being used simultaneously on a given cell tower, they break the cell up into smaller nodes, each serviced by their own tower.
__________________
¯\_(ツ)_/¯****************
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
dswallow is offline   Reply With Quote
Old 12-23-2007, 10:00 AM   #863
ah30k
Registered User
 
Join Date: Jan 2006
Posts: 2,206
Quote:
Originally Posted by lew View Post
What is the purpose of offering a channel that literally no one in a given area wants to watch?
The key thing in how you phrase the question. It is NOT "Does anyone ever want to watch this channel?". The question is "Given the number of homes in this node, is someone watching this channel at this given instant?".

Very different questions.

I watch all kinds of channels, but only maybe two at any one time.
ah30k is offline   Reply With Quote
Old 12-23-2007, 11:49 AM   #864
HiDefGator
Registered User
 
Join Date: Oct 2004
Posts: 1,851
Quote:
Originally Posted by lrhorer View Post
Um, isn't that kind of what I said? A staged rollout would prevent their having to replace every cable box which didn't support MPEG-4 or to supply one to every customer without a CableCard device of some sort.
couldn't cable take the same route directv did and only do HD in mpeg4 first? then they wouldn't have to replace every cable box right away.
HiDefGator is offline   Reply With Quote
Old 12-23-2007, 12:50 PM   #865
morac
Cat God
 
morac's Avatar
 
Join Date: Mar 2003
Location: NJ
Posts: 6,177
Quote:
Originally Posted by HiDefGator View Post
couldn't cable take the same route directv did and only do HD in mpeg4 first? then they wouldn't have to replace every cable box right away.
They'd still have to replace all the HD boxes out there. There's also the issue that there are no cable MPEG-4 boxes available currently. They won't be available till early 2008.

I think eventually (years out) all new provided HD channels will be MPEG-4, but the cable companies can only use what's available now which is why HD is MPEG-2.
morac is offline   Reply With Quote
Old 12-23-2007, 11:27 PM   #866
lrhorer
Registered User
 
Join Date: Aug 2003
Location: San Antonio, Texas, USA
Posts: 6,849
Twc

Quote:
Originally Posted by mikeyts View Post
I'm sorry, but I seem to have missed something. Who is "we" and who are "them"?
"We" is the company for which I work. "Them" is Time Warner Cable.

Quote:
Originally Posted by mikeyts View Post
I wasn't aware that people are including the music services in the "500 channels" number.
If you mean in terms of quantifying the performance of SDV, I would think "people" are excluding music channels, or at least they should be - which is why I specifically excluded them from my post. On the other hand, by either excluding the local FM stations in favor of the music stations or else putting the local FM stations on a QAM stream, they could gain back 20MHz or 3 QAM streams. That's a fair bit of content, and I suspect they may do just that as one of the first steps to going all digital.

Quote:
Originally Posted by mikeyts View Post
The bandwidth required for streaming music must be miniscule (and for feeding those screen savers, which I doubt are actual video streams).
Compared to HD video, yeah. Compared to the $250 300 BAUD modem I bought back in 1983, it's downright screaming.

Quote:
Originally Posted by mikeyts View Post
There are 64 of these channels on my system and I'd be surprised if they consumed more than half a QAM.
They're probably 200Kbps or so, so a QAM stream probably handles about 150 of them, so yeah, that's about right.
lrhorer is offline   Reply With Quote
Old 12-23-2007, 11:53 PM   #867
lrhorer
Registered User
 
Join Date: Aug 2003
Location: San Antonio, Texas, USA
Posts: 6,849
Claims

Quote:
Originally Posted by ah30k View Post
My oh my, you do like to type a lot.
'Not particularly, but I'm quite used to it. Writing technical documents including engineering briefs and detailed step-by-step instructions is a significant part of my job.

Quote:
Originally Posted by ah30k View Post
I recall no claim that the bottleneck was in the headend.
See here:
http://www.tivocommunity.com/tivo-vb...01#post5787201

Quote:
Originally Posted by ah30k View Post
It may be here somewhere but I don't recall it. You laid out a scenario with 100,000 subscribers, tuners and 500 channels and claimed that SDV won't work because of the probability of more streams being needed was greater than 99%. That is where nodes fix the problem.
I never claimed any such thing. Quite to the contrary, my entire point during this discussion is SDV will work just fine, even with the tiny impact added by having large numbers of TiVos in the field with Suggestions turned on. The probability of more streams being needed is almost 0. The secenario I laid out is quite reasonable and only demonstrates that TiVo Suggestions won't cause issues at the CATV headend.

Quote:
Originally Posted by ah30k View Post
I don't know why you are off on the headend bottleneck and 1000 interactive streams killing the system. That is a totally different topic. Perhaps you headend is just poorly designed.
I wasn't, and I never said it would, and it's not my headend in any case.
lrhorer is offline   Reply With Quote
Old 12-24-2007, 12:07 AM   #868
lrhorer
Registered User
 
Join Date: Aug 2003
Location: San Antonio, Texas, USA
Posts: 6,849
Quote:
Originally Posted by dswallow View Post
Statistically there's always channels people aren't watching. By only actually sending video for channels that someone is watching, you can offer more channels than you actually have space to carry simultaneously. That's what Switched Digital Video (SDV) is all about.
Well, it's a big part of it, anyway. Another big part is the ability to deliver a myriad of interactive services.

Quote:
Originally Posted by dswallow View Post
The efficiency exists because of the way subscribers are grouped and serviced in nodes. Every node has a maximum number of subscribers and receivers within it, and it's within each node that what channels are being watched that matters.
Your statement is correct, but I think it could be misconstrued. It's not quite what channels are being watched, per se, but rather that every node can have a potentially different set of channels being watched.

Quote:
Originally Posted by dswallow View Post
The smaller the node, the more unwatched channels exist within the node.
Well, yes, but once again it doesn't matter how many channels are unwatched at the node, as long as the total number of channels requested doesn't exceed the total number available. The CATV provider's greatest dream is that every single channel on every single node would be active 24 hours a day. Anything less than that means some amount of theri investment is laying idle. Unfortunately for them, in order to maintain customer satisfaction, they are going to have to make certain the node utilization does not a number slightly lower than 100% for any significant amount of time during peak watching hours.
lrhorer is offline   Reply With Quote
Old 12-24-2007, 12:28 AM   #869
dswallow
Save the Moderatоr
 
dswallow's Avatar
 
Join Date: Dec 2000
Location: Long Branch, NJ, USA
Posts: 48,517
TC CLUB MEMBER
lrhorer, I think you're maybe just trying too hard in some of these replies.

The cable company isn't looking to have 100% utilization at all. All they want is to never have demand for 100.1% utilization or more. On a system-wide basis, they want to offer the greatest selection (i.e., be competitive to alternative services that may be available to customers). On a node level, they never want to have to tell a customer something isn't available. Every node doesn't have to ever see every available channel watched; certainly the cable company doesn't want to see weeks or months go by with not a single customer viewing any particular channel (as that would mean they could just drop the channel and save the money and nobody would even notice or care)... and with SDV they'll actually know if that ever happens, whereas with analog they'd never know.

That balance is of course always subject to review, but it can be monitored very easily with the tools provided by SDV vendors they're using now. And as needed, they can split off nodes well before utilization reaches dangerous levels where they may face having to deny a customer access to a service they're trying to tune.

As far as interactive services, they're not called Switched Digital services; they're called Interactive services. All that SDV has to do with them is simply efficiently using bandwidth for regular channels so that Interactive services have bandwidth for their own needs. The same goes for PPV or VOD services... no relation to SDV except that SDV enables them to have more bandwidth on the node available for such services.

From many of the papers on SDV statistics it seems somewhere around 70% bandwidth utilization at peak times on a node is the "red flag" to initiate adjusting the node or splitting it completely.
__________________
¯\_(ツ)_/¯****************
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
dswallow is offline   Reply With Quote
Old 12-24-2007, 01:05 AM   #870
ah30k
Registered User
 
Join Date: Jan 2006
Posts: 2,206
Quote:
Originally Posted by lrhorer View Post
I never claimed any such thing. Quite to the contrary, my entire point during this discussion is SDV will work just fine, even with the tiny impact added by having large numbers of TiVos in the field with Suggestions turned on.
Doesn't the following quote mean you think that SDV won't work since only 1 of 500 channels isn't being watched?

Quote:
Let me set up a typical scenario:

Moderately large city
100,000 subscribers
2.5 live viewers per household
2 channel DVR per 10 households ignoring any TiVos whatsoever
= 270,000 receivers
500 scheduled channels (no CATV company yet comes close to this, even in the largest cities)

Answer me this: How many of the 500 channels do you estimate are not being viewed by a single receiver peak viewing times? (I'll give you a hint: the answer is less than 1.)

ah30k is offline   Reply With Quote
Reply
Forum Jump




Thread Tools


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Advertisements

TiVo Community
Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
vBulletin Skins by: Relivo Media

(C) 2013 Magenium Solutions - All Rights Reserved. No information may be posted elsewhere without written permission.
TiVoŽ is a registered trademark of TiVo Inc. This site is not owned or operated by TiVo Inc.
All times are GMT -5. The time now is 09:35 PM.
OUR NETWORK: MyOpenRouter | TechLore | SansaCommunity | RoboCommunity | MediaSmart Home | Explore3DTV | Dijit Community | DVR Playground |