HTTP =perfect UDP/RTP= Horrible

[lanman]

I guys

im a bit of a noob but have learnt heaps with streaming lately....

I can stream over wifi live tv or video to a bunch of phones and ipads and laptops and screens around the house or office with HTTP in PERFECT quality (5 devices at a time easily)

but i switched to doing a multicast ( as im told the http is unicast) using RTP and UDP....and i cant even get one phone to play the network stream without being a blur of nonsense on the screen just very pixelated and eventually freezes.

why can my wifi router successfully serve 5 machines a clear image on http ....but not even serve one on RTP or UDP?


If http streaming is perfect....how many people can watch the live video ? and what will be the first bottle neck?

so far ive had 5 devices watching perfectly off a crappy old dlink

[nobody.loopback]

UDP has no handshake, and wireless lan is not a switched network, and is has a high latency compared to Ethernet.
Even if a multicast reaches not other networks, it is broadcasted across all addresses in your home network.

If you send a high bitrate stream with udp/multicast over a wired or wireless network there will be some package loss, less with a wired network, more with a wireless network, and, since there is no error correction and no retransmission, your picture will be distorted.
From my experience udp/multicast is only good for a low-bitrate stream.

How many users you are able to connect using http unicast depends on the bitrate. A wireless network is always worse then a wired. Wireless networks also do not deliver the advertised datarate in most environments. Even if you are only a few meters away but, in a different room, the actual link rate might be a fraction of what you hoped to get.

[Rémi Denis-Courmont]

Most wireless access points are, by design limitation, unable to multicast at more than token bandwidth. If you want to use UDP over 802.11, use unicast.

[lanman]

thanks for the awesome replies

If i am using the http unicast method the wireless side has been going great....5 machines in different rooms all receiving the stream perfectly! and all on the same address for example 192.168.5.16 (just pointing the vlc on each machine to that address)

lets say i wanted to do 20 machines receiving the stream....what would die first? the wifi to the machines or the ethernet cable from the streaming computer to the router?

am i right in thinking for every extra machine that connects the serving computer would be sending another copy of the stream to the router with http streaming?

[nobody.loopback]

You have to try this out yourself, it is not possible to guess a number of users because this depends on the bitrate, your network topolgy and the cpu of the machine which does the streaming.
But, your WiFi will most likely crap out first.

[lanman]

so being that http is perfect and at 400kbs i can get a fair few machines viewing

and multicast being --please stay polite-- over wifi.....seems as though http is the winner