Fast streaming

[Andster]

Windows Media Services has a function called "Fast streaming". Does it exist similar functionality in Wowza?

The functionality that I am looking for is the possibility to buffer for example 5 seconds of a 128 kbps live audio stream on a streamingserver and when a user connects burst out the buffer during 1-2 seconds and after that stream in 128 kbps in order for the listener to get both a quick start and and good buffer. Is it possible?

/Andster

[charlie]

Wowza does this by default. In Flash the buffer size is controlled by the player. It is controlled using the NetStream.setBufferTime(seconds) API call.

Charlie

[rrlanham]

That is basically how Wowza works by default. If you're interested in lowest possible latency in live streaming, take a look at this post:
http://www.wowzamedia.com/forums/showthread.php?t=6136

Richard

[Andster]

Yes I want low latency but combined with a "large" buffer, which is why I was thinking on a buffer on the serverside that could be bursted out to the player.

Similar to what Microsoft writers
"...If your clients are using Windows Media Player for Windows XP or later, you can use Fast Start to provide data directly to the buffer at speeds higher than the bit rate of the content requested. This enables users to start receiving content more quickly. After the initial buffer requirement is fulfilled, on-demand and broadcast content streams at the bit rate defined by the content stream....Fast Start requires that Windows Media Services continuously maintain a buffer of content to be streamed to new clients. When the Start publishing point when first client connects property is enabled in a live broadcast publishing point, Fast Start can cause an additional rendering delay of 8 to 10 seconds for the first client that connects to the stream because Windows Media Services must first collect a content buffer. ..."

If the buffer is increased in the player, won't also increase the latency at the same time?

[charlie]

Buffering adds latency to live video. There is no way around it. If you want the lowest latency then you have to set a very, very small or zero sized buffer. If you don't care about latency then you can set a larger buffer and there is more room for network fluxations. Buffering requires that you take video/audio from somewhere. The only place to take it from for live video is from the past. If you take video from the past to fill the buffer it increase latency.

I hope that makes sense.

Charlie

[christr]

Buffering adds latency to live video. There is no way around it. If you want the lowest latency then you have to set a very, very small or zero sized buffer. If you don't care about latency then you can set a larger buffer and there is more room for network fluxations. Buffering requires that you take video/audio from somewhere. The only place to take it from for live video is from the past. If you take video from the past to fill the buffer it increase latency.

I hope that makes sense.

Charlie

Just imagine if you guys could develop a buffer that takes the live video from the future. :-) That would be awesome.


--Chris

[Andster]

It definitely makes sense! I’ll try to reformulate my somewhat poor English (mixed up latency and 'wait time')

Yes, buffering equals latency, that’s clear.

Latency is ok but I want to reduce the time a user has to wait for the player to start playing sound.

For example: I need to count with some network fluxations so I want a 6 seconds buffer which gives 6 seconds latency of the live event. But I want the listeners player to start 2 seconds after the play button is pressed. This in my mind would require a buffer on the server side which is sent out to the client in a speed which is 3 times the bitrate for two seconds.

Andster

[charlie]

If you set a 6 second buffer in the player (NetSTream.setBufferTime(6)) and a key frame interval of 2-3 seconds you will get what you want. Wowza will send 6 seconds of video immediately upon connection to fill the client side buffer. It will send this video/audio as fast as it can.

Charlie

[Andster]

Does this mean that the live audio broadcast continuously is buffered on the server as Microsoft describes 'Fast streaming'?

...Fast Start requires that Windows Media Services continuously maintain a buffer of content to be streamed to new clients...

...Wowza will send 6 seconds of video immediately upon connection to fill the client side buffer...

I.e. buffering the live stream on the server side doesn't require configuration on the server/wowza?

Andster

[charlie]

Wowza buffers 8 seconds of video/audio server-side.

Charlie