[Icecast] Basics about Videostreaming?

Balint Jacint bjacint at kvark.hu
Fri Jan 19 07:20:28 UTC 2007

As of CPU load, a 3 GHz P4 machine is capable of encoding live video 
realtime with the following parameter: 640x480, 200kbs, 32kbs vorbis 
audio, 10fps.
If I raised any of the parameters, the CPU got overloaded. With the 
mentioned parameters the CPU load is around 90%.
Unfortunately ffmpeg2theora is not multithreaded yet, that would help a 
lot... Does anyone know how to make it support SMP machines?


Chris MacDonald wrote:
> Hi
> While I've personally never done it, I believe you can follow along 
> with a guide here:
> http://www.oddsock.org/guides/video.php
> Streaming video isn't so different from streaming music, you need a 
> supported source format, a source client to arrange and send your 
> stream to the distribution server and they clients connect to that. In 
> this particular case Icecast only supports OGG Theora (I think...) so 
> you'll first need to convert your video, the guide uses ffmpeg2theora 
> for this but I think any tool would do so long as you end up with 
> Theora. Second you'll need a source client capable of sending your 
> stream to Icecast and in this regard the guide makes use of ezstream, 
> this is available on the Icecast website. An example ezstream 
> configuration is in the guide, in it you can see how ezstream is 
> actually set up to match .avi files, use ffmpeg2theora to convert them 
> then send them to Icecast.
> As for compression, resolution and bandwidth requirements someone else 
> will have to step in here, or you'll just have to try it and tweak it 
> yourself. Try the manpage for ffmpeg2theora, in it it does appear to 
> be possible to lock the video and audio bitrate in order to keep the 
> stream a predictable size. I do know that 1024x768 is going to require 
> a lot of bandwidth to run at a respectable frame-rate and quality. 
> Also keep in mind that the conversion to Theora is happening in 
> real-time, your hardware may not be able to re-encode your stream fast 
> enough at that resolution. That said, I've never done this so you'll 
> probably have to test the waters yourself to get a good idea of the 
> settings you'll need.
> Good Luck,
> Chris
> Anatol wrote:
>> Hi All!
>> I've seen, that icecast can stream videos! Great! Audiostreaming with 
>> icecast is well known, but how about videostreaming? Can you tell me 
>> some basics about it?
>> - which software is required? (Icecast, ok ;) what else? - by the 
>> way: my OS is a linux ;) )
>> - I want to stream a live-video with 1024x768 resolution - is it 
>> possible? - is it wise?
>> - what a compression-rate is to use, if the output-device is a beamer 
>> (1024x768) and the images should have a medium or a good quality in 
>> spite of the compression
>> - What a bandwidth is needed for this resolution/compression?
>> - which other points are important to keep in mind?
>> Thanks for your help!
>> Anatol
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