[Live-devel] How about HD streaming?

[Eric Peters]

??? wrote:

> Hi.
>
> I've tried to serve a HD-grade(about 20Mbps) TS stream using 
> testMPEG2TransportStream, testOnDemandRTSPServer, and openRTSP as a 
> client. It works.. but with much loss. It looks like losing much more 
> data when the client system has low processing power.
>
> Is the LiveMedia library capable of the HD streaming?
>
> Thank you.
>
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>
Which OS are you using? Under Linux we have on the client side some 
problems by receiving MPEG videos with bitrates higher than 2 Mbps. For 
playing the video we used mplayer and testMPEG1or2VideoReceiver piped to 
mplayer. There have been many artefacts since you have set the value 
/proc/sys/net/core/rmem_maxsize to a value at least 2MB. But this is 
only allowed to users with root rights.
For testing the possibility of the OS for reading high level MPEG files 
from the network we have written a small client which only read the data 
from the socket. We have added some debug messages for checking which 
packet about which size was sent and received. There was only a loss 
lesser than 2 percent on a 50Mbps MPEG file. So you see it isn't a 
problem by the OS.

Here are the results of our tests:

the streaming server application was testMPEG1or2VideoStreamer. On the 
receiver side (rmem_maxsize = 64k) we tested three scenarios

- scenario 1: a small test application which reads from the socket and 
prints out the sequence numer of the RTP-packet and its size
- scenario 2: an actual mplayer compiled with the actual liveMedia 
version with the same debug messages mentioned above
- scenario 3: testMPEG1or2VideoReceiver piped to mplayer also with the 
debug messages

The debug messages are also included on the server side so you can check 
the differences with diff. So you can see which packets have been 
received and have they been received completely.

For streaming I used three MPEG2 files, a 5.5 Mbps from a DVD, a 9 Mbps 
and a 50 Mbps both recorded by a IVTV card.

scenario 1:
5,5 Mbps: 241116 packets sent, 23 lost => 0% loss
9 Mbps: 176203 packets sent, 158 lost => 0,09% loss
50 Mbps: 90680 packets sent, 1917 lost => 2,11% loss

scenario 2:
5,5 Mbps: 613219 packets sent, 8842 lost => 1,44% loss
9 Mbps: 168987 packets sent, 8749 lost => 5,18% loss
50 Mbps: 203513 packets sent, 59621 lost => 29,30% loss

scenario 3:
5,5 Mbps: 188852 packets sent, 15087 lost => 7,99% loss

The last two tests couldn't be made because mplayer crashed always.

So you can see there are some problems in the network code.

@Ross:
How can we help you to debug this problem? Perhaps we can solve this 
problem together.


Greetings

Eric