Re: RTSP Problems
- From: "Neil Smith [MVP Digital Media]" <neil@xxxxxxxxxx>
- Date: Thu, 19 Mar 2009 23:29:36 GMT
On Tue, 17 Mar 2009 03:20:05 -0700, Elena Garrido <Elena
Garrido@xxxxxxxxxxxxxxxxxxxxxxxxx> wrote:
We?re working with a consortium on a research project where we have to
stream videos to client devices. Out first intention is to develop the user
interface using Windows Presentation Foundation.
What sort of Devices ? Unless they're windows PCs, I'm not sure WPF
will help you out - it's a windows-only, desktop-only presentation
system.
If you considered Silverlight instead, at least you'd have some
portability across OS and browsers (Mac OSX is also supported, and
Novell Moonlight is available for Linux PCs).
It should have enough of the WPF features to be useful, and can now
(as of Silverlight 3 beta) be run in disconnected mode as a desktop
application - though still with the browser sandbox in place.
For the moment we?re using
Windows Vista Ultimate 32 bits. For out test we?re using a simple application
that uses the Windows Media Player activeX.
Our original idea was to stream video with MPG-4 H.264 with RTSP protocol
from the server to the client.
Right, so to deliver that using a packaged solution, you'd need
Darwin/Quicktime streaming server or similar.
Windows media services cannot and probably never will deliver H264, it
is setup to only stream ASF content (most usually WMV/WMA) and the
RTSP implementation is non-standard to the extent it only works
properly with WMP and VideoLAN players and maybe a couple of other
obscure players.
In several forums we?ve found that Windows Media Player doesn?t accept H.264.
WMP is extensible using DirectShow plugins. FFDShow and some other
H264 decoders are available, if your clients are willing and able to
install those - that depends on corporate policy of course. So, yes it
can playback H264 and many other formats with the right decoder.
The streaming side OTOH is more of a problem - WMP doesnt implement
standard RTSP and relies on the WMS extensions to work properly.
Orban have implemented shoutcast and other transports in their AAC+
(audio only) plugin for WMP, so it's possible to extend the transport
layer with enough know-how :http://www.orban.com/plugin/
We transcoded the test video to WMV9 (on ASF) and tried to stream it to the
client by using the Microsoft-RTSP protocol (rtsp from Microsofot is not
standard-rfc2326 compilant).
Agreed ;-)
We are using a server developed within the project.
I am always amazed that people go off and develope homebrew media
servers when there are so many other available choices that had teams
of top flight engineers* working for years on them <g>
* Except in Ontario where the term software engineering is apparently
prohibited by license from the province engineers society.
Several tests have been performed, namely with different
streams/resolutions, transported through RTP packets over UDP and TCP
scenarios.
Currently Windows Media Player follows all the MS-RTSP negotiation, but as
soon as we start sending the stream, WMP completely ignores the stream, and
timeouts after 60 seconds.
The captured packets show us that the video RTP packets are being sent (and
received), but no rendering happens in the player.
Aren't you also discussing this ATM on the Apple Quicktime lists ?
This all sounds rather familiar now you mention it ;-)
With the same server setup, VLC was also tested, and worked. While WMP stays
in 'Buffering State' for ever.
My questions are:
Any clue about what is happening with Windows Media Player?
Will any H.264 codec available for WMP during 2010?
Silverlight 3 has H.264 decode support, so I'd go with that given your
previous comments about desktop and browser based requirements.
http://on10.net/blogs/benwagg/Silverlight-3-Beta-Whatrsquos-New-for-Media/
Flash also has H264 support and it's got a high install base even at
9.0.115 version required for H264 decode.
There are relatively low cost ways to distribute over RTMP, such as
Wowza media server and Red5 (the Adobe server IMO is still too
expensive until your scale is very large). We've used it very
successfully out on Amazon EC2 to handle over 25000 live streams
across several servers in a cluster.
By the time you've coded up your app in SL (the XAML is similar to
WPF), the release candidate should probably be out.
Have a look too at the Smooth Streaming for IIS which is mentioned on
Alex Zambellis blog, it goes into useful detail and indicates some
useful features over or instead of traditional RTSP/HTTP streaming
(such as moving from bitrate adaptation to progressive enhancement)
http://alexzambelli.com/blog/2009/02/10/smooth-streaming-architecture/
http://www.iis.net/extensions/SmoothStreaming
http://learn.iis.net/page.aspx/568/smooth-streaming-for-iis-70---exploring-bit-rate-changes/
The most recent expression media encoder has the required features to
encode for smooth streaming, chopping up an MBR into the packets
needed and more or less end-to-end workflow.
Most recently it added H264 encode, though only at iPod image
dimensions initially. I guess thats to avoid cannibalising existing
WMP workflow.
HTH
Cheers - Neil
------------------------------------------------
Digital Media MVP : 2004-2009
http://mvp.support.microsoft.com/mvpfaqs
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- RTSP Problems
- From: Elena Garrido
- RTSP Problems
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