[streaming] Re: How to stream high-def video over a LAN?

[Mark Moriarty]

You may have a problem due to, quite simply, too many packets requiring
processing at the client.  
MPEG TS is chopping things up into 188 byte packets.  Each packet has a 4
byte header, possibly an adaptation field (e.g. PCR), and 184 bytes of AV
data (maximum, depending on the Adaptation Field).

That means your 19Mbps source is turning into roughly 13000 MPEG TS packets
per second.

Seven of these MPEG TS packets get put into one Ethernet packet.  That means
you're getting roughly 2000 Ethernet packets per second, which get moved off
the card, to the OS, and the OS is passing them to VLC for action.

The result is that you're trying to service a LOT of things.

If your server end is a decent machine, you might want to try recoding to
mpeg4, cut your video bitrate down to 3Mbps or 4 Mbps, see if the quality is
sufficient for your application.  Cutting down by a factor of 5 to 6 on the
number of things coming in from the network should be very helpful to the
client.

-----Original Message-----
From: streaming-bounce at videolan.org [mailto:streaming-bounce at videolan.org]
On Behalf Of Chhaya, Harshal
Sent: Tuesday, March 01, 2005 9:37 AM
To: streaming at videolan.org
Subject: [streaming] How to stream high-def video over a LAN?


Hi,

I am trying to stream a high-definition file (MPEG2 transport stream @ ~19
Mbps) over a LAN and would like your advice on the best way to do this.

I can stream using vlc (over unicast UDP) and play it on the other PC using
vlc but the video is choppy. I suspect that this is because the CPU is fully
utilized (100% usage) and vlc cannot decode all the frames in time. If I
dump the received video stream to file and play it layer, it plays back
smoothly which confirms the 'not enough CPU' hypothesis. 
This is a 2.4 Ghz Pentium 4 and I don't have a faster PC.

So I assumed that I could buy one of the DxVA (DirectX video
acceleration) enabled MPEG decoders and offload some of the video decoding
to the video card (ATI Radeon 9000). I know that VLC cannot use these
decoders but Windows Media Player can. However, from what I have read
streaming from vlc to WMP means that I have to transcode the file to a lower
bitrate which defeats the purpose. 

Is there a way to stream to WMP without transcoding? I read some mentions of
a plug-in that allows WMP to decode MPEG-TS over UDP but I can't find any
such plugin. Does such a plugin exist?

Is there any other way I can stream these high-definition files? Are there
other players that can decode MPEG-TS over UDP?

Thanks for any ideas and suggestions you can provide.

- Harshal

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