Le 2012-02-07 04:16, Invisible a écrit :
>>> Damn. How do you ever get anything done?! o_O
>>
>> I use Google Reader so I don't have to visit all those sites to see
>> what's new. Takes me about an hour in the evening to go through the
>> day's posts and see what's new.
>
> It used to take me about 4 hours in the evening (i.e., my entire
> evening) just to read this newsgroup. (Although it seems a lot quieter
> lately...)
>
>>>> Yes, it is the connection that determines the picture quality.
>>>
>>> Erm, no. It's the quality that the file is transcoded at.
>>
>> A connection that isn't fast enough isn't going to show you the full
>> definition. I defy you to demonstrate a high quality video over a slow
>> connection.
>
> If the bitrate of the source is higher than the available bandwidth, it
> just won't play in realtime. It'll constantly stall to rebuffer. So
> presumably the guys behind iPlayer (and every other Internet video
> system) have to transcode to a low enough bitrate that it will actually
> play in realtime. The result is obviously poor image quality.

Once again, you presumed wrong, since other people are able to see the 
full image!


>
> Consider, for example, that it took me 3 days to download Star Wreck,
> which is only about an hour long. OK, that was only using a 2 Mbit
> connection, but I don't suppose you can download almost 4GB of data over
> an 8 Mbit connection in one hour flat either.
>

Bad example.  Assuming you downloaded it via bit-torrent from other 
users, you were constrained by their very limited upload speeds.  If you 
downloaded it from an FTP server, you were also porbably constrained by 
the number of connections clobbering said server.

Netflix, and other streaming sites have banks of high performance 
servers connected to very large internet pipes, in multiple sites that 
are close to the users.  This way, there are fewer bottlenecks and 
little to no latency issues that can interfere with the stream.

>> <sigh>
>>
>> https://lh6.googleusercontent.com/-UJGO-U7Whto/TzAdp1huWOI/
>> AAAAAAAABbs/1IPtFRGNv6Q/s912/2012-02-06.jpg
>>
>> Now consider that's a quick photo of a 10' screen streaming realtime at 3
>> Mbps. The bluriness you see there is an artifact of the camera used, not
>> the actual image on the screen.
>>
>> Obviously the necessary bandwidth exists.
>
> Yes, the picture looks fine. I still don't understand how that can be
> possible though. The Internet isn't fast enough. I don't see how you can
> get the data from A to B fast enough for realtime playback.

Which part of the Internet isn't fast enough?

Is HD tv available in the UK, from cable tv providers?  Stop and think 
for a few nanoseconds how that signal is delivered to your cablebox. 
Netflix and co. are the same thing, except the source server is just a 
few 10Gbps hops further away on the Internet backbone.

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>> Consider, for example, that it took me 3 days to download Star Wreck,
>> which is only about an hour long. OK, that was only using a 2 Mbit
>> connection, but I don't suppose you can download almost 4GB of data over
>> an 8 Mbit connection in one hour flat either.
>
> Bad example. Assuming you downloaded it via bit-torrent from other
> users, you were constrained by their very limited upload speeds.

Except that you're downloading it from dozens of clients at once, should 
should counteract that problem.

>> Yes, the picture looks fine. I still don't understand how that can be
>> possible though. The Internet isn't fast enough. I don't see how you can
>> get the data from A to B fast enough for realtime playback.
>
> Which part of the Internet isn't fast enough?

The last mile, as always.

> Is HD tv available in the UK, from cable tv providers? Stop and think
> for a few nanoseconds how that signal is delivered to your cablebox.
> Netflix and co. are the same thing, except the source server is just a
> few 10Gbps hops further away on the Internet backbone.

I have no idea what "cable" is. I do know you can receive HD TV with an 
aerial; presumably this uses higher bandwidth than a normal Internet 
connection.

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> > Is HD tv available in the UK, from cable tv providers? Stop and think
> > for a few nanoseconds how that signal is delivered to your cablebox.
> > Netflix and co. are the same thing, except the source server is just a
> > few 10Gbps hops further away on the Internet backbone.
>
> I have no idea what "cable" is. I do know you can receive HD TV with an
> aerial; presumably this uses higher bandwidth than a normal Internet
> connection.

it's also far cheaper, since it's broadcast, i.e. all users receive the very
same stream, not a stream per millions of users...

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On Tue, 07 Feb 2012 09:16:33 +0000, Invisible wrote:

>>> Damn. How do you ever get anything done?! o_O
>>
>> I use Google Reader so I don't have to visit all those sites to see
>> what's new.  Takes me about an hour in the evening to go through the
>> day's posts and see what's new.
> 
> It used to take me about 4 hours in the evening (i.e., my entire
> evening) just to read this newsgroup. (Although it seems a lot quieter
> lately...)

I probably spend a couple hours a day reading my 200+ newsgroups.  Again 
usually just skimming subjects for things that are interesting.

>>>> Yes, it is the connection that determines the picture quality.
>>>
>>> Erm, no. It's the quality that the file is transcoded at.
>>
>> A connection that isn't fast enough isn't going to show you the full
>> definition.  I defy you to demonstrate a high quality video over a slow
>> connection.
> 
> If the bitrate of the source is higher than the available bandwidth, it
> just won't play in realtime. It'll constantly stall to rebuffer. So
> presumably the guys behind iPlayer (and every other Internet video
> system) have to transcode to a low enough bitrate that it will actually
> play in realtime. The result is obviously poor image quality.

Clearly not, as shown in my photo.  In the case of Netflix, they use a 
dynamically adjusting algorithm so it can display lower quality if the 
bandwidth is throttled.  You'll note that I noted to Stephen that Netflix 
shows "Medium/HD" as the quality for that image - that's usually what I 
get.  If I had a slower connection, I get "High/SD" or "Low/HD".  If I 
had a faster connection, I'd get "High/HD".

> Consider, for example, that it took me 3 days to download Star Wreck,
> which is only about an hour long. OK, that was only using a 2 Mbit
> connection, but I don't suppose you can download almost 4GB of data over
> an 8 Mbit connection in one hour flat either.

That was at a fixed quality setting, not being streamed.

>> <sigh>
>>
>> https://lh6.googleusercontent.com/-UJGO-U7Whto/TzAdp1huWOI/
>> AAAAAAAABbs/1IPtFRGNv6Q/s912/2012-02-06.jpg
>>
>> Now consider that's a quick photo of a 10' screen streaming realtime at
>> 3 Mbps.  The bluriness you see there is an artifact of the camera used,
>> not the actual image on the screen.
>>
>> Obviously the necessary bandwidth exists.
> 
> Yes, the picture looks fine. I still don't understand how that can be
> possible though. The Internet isn't fast enough. I don't see how you can
> get the data from A to B fast enough for realtime playback.

Compression.  We've been over this before.

Jim

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> I probably spend a couple hours a day reading my 200+ newsgroups.  Again
> usually just skimming subjects for things that are interesting.

Damn. If I had that much stuff to look at, I'd *never* get any work 
done... Oh, wait.

>> If the bitrate of the source is higher than the available bandwidth, it
>> just won't play in realtime. It'll constantly stall to rebuffer. So
>> presumably the guys behind iPlayer (and every other Internet video
>> system) have to transcode to a low enough bitrate that it will actually
>> play in realtime. The result is obviously poor image quality.
>
> Clearly not, as shown in my photo.  In the case of Netflix, they use a
> dynamically adjusting algorithm so it can display lower quality if the
> bandwidth is throttled.

So they actually offer multiple quality levels? Well, I guess that makes 
good sense. I'm not sure how you'd automatically detect which one to 
use, but I guess with the right client software it ought to be possible.

>> Yes, the picture looks fine. I still don't understand how that can be
>> possible though. The Internet isn't fast enough. I don't see how you can
>> get the data from A to B fast enough for realtime playback.
>
> Compression.  We've been over this before.

Lossy compression allows you to make the file size be anything you want 
it to be. But this does not happen by magic; it happens by degrading the 
picture quality. So while it obviously /is/ possible to reduce a video 
stream to, say, 3KB per second, it wouldn't be worth watching. What I 
can't figure out is how they can shrink it down to realtime download 
speeds without it looking awful.

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Le 2012-02-07 09:06, Invisible a écrit :
>>> Consider, for example, that it took me 3 days to download Star Wreck,
>>> which is only about an hour long. OK, that was only using a 2 Mbit
>>> connection, but I don't suppose you can download almost 4GB of data over
>>> an 8 Mbit connection in one hour flat either.
>>
>> Bad example. Assuming you downloaded it via bit-torrent from other
>> users, you were constrained by their very limited upload speeds.
>
> Except that you're downloading it from dozens of clients at once, should
> should counteract that problem.

Not always.

>
>>> Yes, the picture looks fine. I still don't understand how that can be
>>> possible though. The Internet isn't fast enough. I don't see how you can
>>> get the data from A to B fast enough for realtime playback.
>>
>> Which part of the Internet isn't fast enough?
>
> The last mile, as always.
>

Which varies a lot from place to place.  First, because your DSL speed 
will be affected by the distance or the CO from your house, and by the 
quality of the wires.  On top of that, different carriers have different 
services.  For example, on top of various DSL packages, my telephone 
company offers fibre connections at 7, 10, 16 or 25 Mbps.  My Cable 
provider offers comparable packages as well.

>> Is HD tv available in the UK, from cable tv providers? Stop and think
>> for a few nanoseconds how that signal is delivered to your cablebox.
>> Netflix and co. are the same thing, except the source server is just a
>> few 10Gbps hops further away on the Internet backbone.
>
> I have no idea what "cable" is. I do know you can receive HD TV with an
> aerial; presumably this uses higher bandwidth than a normal Internet
> connection.

Presumably?  Again.  After having been shown 4759483758975 times in this 
thread alone that your assumptions were wrong, you still persevere!!!

Also, http://en.wikipedia.org/wiki/Cable_television

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>>> Bad example. Assuming you downloaded it via bit-torrent from other
>>> users, you were constrained by their very limited upload speeds.
>>
>> Except that you're downloading it from dozens of clients at once, should
>> should counteract that problem.
>
> Not always.

As in "you're not always downloading from that many clients", or as in 
"downloading from many clients doesn't give you greater bandwidth"?

>>> Which part of the Internet isn't fast enough?
>>
>> The last mile, as always.
>>
>
> Which varies a lot from place to place. First, because your DSL speed
> will be affected by

Yes, but given that 8 Mbit/sec is the maximum speed that current ADSL 
standard allow, we can take it as read that nobody is going faster than 
that.

> For example, on top of various DSL packages, my telephone
> company offers fibre connections at 7, 10, 16 or 25 Mbps.

Oh, really? Well, if you're getting 25 Mbit/sec then yes, streaming 
full-quality video in realtime /should/ work just fine.

(At least, for SD video. Apparently BRD has a transfer rate of 36 
Mbit/sec, so it looks like HD video still wouldn't work.)

>> I have no idea what "cable" is. I do know you can receive HD TV with an
>> aerial; presumably this uses higher bandwidth than a normal Internet
>> connection.
>
> Presumably? Again. After having been shown 4759483758975 times in this
> thread alone that your assumptions were wrong, you still persevere!!!

And to think people tell me I don't persevere enough...

At any rate, a cursory inspection of Wikipedia seems to indicate that, 
yes, digital TV is higher bandwidth.

> Also, http://en.wikipedia.org/wiki/Cable_television

Oh, is /that/ what that means? OK. I didn't know you could use this for 
anything other than analogue TV. Our house used to have this, before 
everything went digital.

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On Wed, 08 Feb 2012 09:06:03 +0000, Invisible wrote:

>> I probably spend a couple hours a day reading my 200+ newsgroups. 
>> Again usually just skimming subjects for things that are interesting.
> 
> Damn. If I had that much stuff to look at, I'd *never* get any work
> done... Oh, wait.

Certainly if you didn't have a way of handling it more quickly, you 
wouldn't.  That's kinda my point.

>> Clearly not, as shown in my photo.  In the case of Netflix, they use a
>> dynamically adjusting algorithm so it can display lower quality if the
>> bandwidth is throttled.
> 
> So they actually offer multiple quality levels? Well, I guess that makes
> good sense. I'm not sure how you'd automatically detect which one to
> use, but I guess with the right client software it ought to be possible.

You start with the lowest quality and increase the quality until you hit 
some sort of limitation.  Buffer enough so it doesn't stutter when you 
hit the limitation, and then back off.

>>> Yes, the picture looks fine. I still don't understand how that can be
>>> possible though. The Internet isn't fast enough. I don't see how you
>>> can get the data from A to B fast enough for realtime playback.
>>
>> Compression.  We've been over this before.
> 
> Lossy compression allows you to make the file size be anything you want
> it to be. But this does not happen by magic; it happens by degrading the
> picture quality. So while it obviously /is/ possible to reduce a video
> stream to, say, 3KB per second, it wouldn't be worth watching. What I
> can't figure out is how they can shrink it down to realtime download
> speeds without it looking awful.

Measuring latency and throughput.  It's not magic.

Jim

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On 2/8/2012 6:08, Invisible wrote:
> Yes, but given that 8 Mbit/sec is the maximum speed that current ADSL
> standard allow, we can take it as read that nobody is going faster than that.

It depends entirely over the distance you are from the head end. I get 
12Mbps on the DSL line that only has to go down to the street from my condo.

> (At least, for SD video. Apparently BRD has a transfer rate of 36 Mbit/sec,
> so it looks like HD video still wouldn't work.)

Have you tried watching an HD youtube video, out of curiosity?


-- 
Darren New, San Diego CA, USA (PST)
   People tell me I am the counter-example.

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On 09/02/2012 03:35 AM, Darren New wrote:
> On 2/8/2012 6:08, Invisible wrote:
>> Yes, but given that 8 Mbit/sec is the maximum speed that current ADSL
>> standard allow, we can take it as read that nobody is going faster
>> than that.
>
> It depends entirely over the distance you are from the head end.

No, it does not.

http://en.wikipedia.org/wiki/ANSI_T1.413_Issue_2

"The maximum achievable downstream data rate is 8.128 Mbit/s."

If you're too far from the exchange, you will get less than 8 Mb, but 
you will never get /more/ than 8 Mb. That's like saying that if you 
connect a USB 1.0 device with a short enough cable, you can make it go 
faster than 12 Mb. Erm, no, no you cannot, because the USB 1.0 standard 
specifies a maximum data rate of 12 Mb.

So, like I said, unless you're using something other than ADSL, you 
cannot go faster than 8 Mbit/sec.

>> (At least, for SD video. Apparently BRD has a transfer rate of 36
>> Mbit/sec, so it looks like HD video still wouldn't work.)
>
> Have you tried watching an HD youtube video, out of curiosity?

I think I've tried flicking the quality switches at some point. From 
what I recall, turning the quality up makes playback a bit less 
reliable, and the picture quality a bit less awful. But it's certainly 
not as good as SD TV picture quality.

(Or rather, certain SD channels. I've noticed that some digital TV 
channels are also fairly heavily compressed...)

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