The VideoLAN Forums

I thought this may be an interesting topic to discuss.

As I stated in another thread, real time streaming over the internet is not possible. Why? Well, it takes some 0.8 seconds to send and receive a package or a consecutive small group of packages over IT using a satilite. After receiving, verification that this fairly small video segment has been recieved is needed before the sender can send any more. In addition, not all package groups are sent via the same path, so the reveiver will need to sort out received segments. All this means is that the received video is jerky and can miss entire segments- this is irrespective of bandwidth and compression. So commercial TV still needs dedicated lines for real time video presentations.

So, real users of video presentations over IT use a preloaded BUFFER. See Apple's on-line video presentations on their web site. In addition, QT,Real, even MS per Windows Media Player always buffer.

Ernie Lee

Hello!

I have to disagree! You can stream real time video/audio content over the Internet. And it's so easy too!
Now, you can stream Live concerts or events, online seminars, broadcast live any event (ex: your wedding). Please enter on the Streaming BASE website and you will be amazed to see how easy it is to do all that you say it can't be done.
Please contact me if you have any more questions.

The harder we work the luckier we get!
Thank you!

Streaming Guru... your reply either sounds borderline spam... or something out of a disney cartoon... where we're all happily living in magical smurf land sniffing ucalyptus and hugging trees.

anyway...

i'd have to disagree with you erniemac...

streams are transported via UDP...

one would have the intellectual capacity of a goldfish if they were sending video signals over TCP... it's simply impractical with the constant acknowledgement packets causing delays in the forward packets... and in the case of "high-bandwidth" videos over the internet... it's a jittery nightmare...

udp on the other hand does not suffer from this problem. that is why you'll see that almost all streams... be it VOD,VOIP,Digital Radio,IPTV etc use udp as the underlying protocol. and the basic reason a buffer is there... is to ensure some sort of smooth playback... without a buffer... your content would be seriously jittery...


now getting to the 0.8 seconds... i'm assuming you're referring to internet via satellite... in which case... assuming the satellite is in geostationary orbit approx. 37000 km from the earth... which means 123ms for the signal to go up... 123ms to come down... so approx 250ms for one packet... and then another 250ms for acknowledgement packet (assuming TCP)... which brings the whole trip to 500ms for a packet... now that's a limitation of the speed of light... but it's not so much the delay that's a factor... it's more to do with the bandwidth.

in regards to dedicated lines... well it all depends on the bitrate of your content... is it going to be in dvb-h format... or some other portable/handheld sizes... or is the content goign to be viewed on high-def 720p+ tvs? bandwidth is the killer factor here.... the more you have... the better your viewing is.

so let me restate that again... the bottleneck lies in the amount of bandwidth you have... and not with "how long" it takes to receive a packet... they're two separate things.

- Asim

Do you guys know of a HOW TO setup internet broadcasting. I'm able to broadcast inside my network, but not outside. I tried udp and http without any success. http, doesn't throw any errors, but udp says:

access_udp error: cannot open socket
main error: no suitable access module for `udp://@my.servername.com:8080'

That sounds like my firewall is blocking udp port 8080, but it is open and i can telnet to it. I was thinking too, that the bit rate might be to high so I went all the way down to 16 on video and audio, but didn't work.

Any help will be appreciated.

Thanks!
Hugo I.

firstly... if it's working in a LAN environment... then u should be able to have it overa WAN environment as well.

I suggest that you should use some higher ports instead of 8080 (it could be your ISP is blocking UDP 8080... although i don't see why )..

i'd say pick a number... such as 65000 and go for it...

also... i'm assuming you are unicasting and not multicasting?

now getting to the 0.8 seconds... i'm assuming you're referring to internet via satellite... in which case... assuming the satellite is in geostationary orbit approx. 37000 km from the earth... which means 123ms for the signal to go up... 123ms to come down... so approx 250ms for one packet... and then another 250ms for acknowledgement packet (assuming TCP)... which brings the whole trip to 500ms for a packet... now that's a limitation of the speed of light... but it's not so much the delay that's a factor... it's more to do with the bandwidth.

So you’re a skin designer huh? Sure, just a skin designer (slash rocket scientist). Ok I’m leaving now.

Post count baby! Yeah!

not a rocket scientist... but close enough... i'm a (tele)communication engineer

lol... that guy's just a spammer...

Do you guys know of a HOW TO setup internet broadcasting. I'm able to broadcast inside my network, but not outside. I tried udp and http without any success. http, doesn't throw any errors, but udp says:

access_udp error: cannot open socket
main error: no suitable access module for `udp://@my.servername.com:8080'

That sounds like my firewall is blocking udp port 8080, but it is open and i can telnet to it. I was thinking too, that the bit rate might be to high so I went all the way down to 16 on video and audio, but didn't work.

Any help will be appreciated.

Thanks!
Hugo I.

Hi ..I can do internet udp ..so, tell us the details of your problem and your setup setup .. may be we can tell u what's wrong...

good luck ...