[vlc-devel] Re: Possible UDP/RTP streaming bug

Dugal Harris dugalh at protoclea.co.za
Fri Apr 13 14:30:23 CEST 2007

Jean-Paul Saman wrote:
> Dugal Harris wrote:
>> Jean-Paul Saman wrote:
>>> Dugal Harris wrote:
>>>> Hi
>>>> I have a problem when trying stream high resolution video over UDP 
>>>> / RTP.  The video is 1600x1200 MJPG and I am streaming in its 
>>>> source MJPG format with no transcoding.  The client gives 
>>>> discontinuity and packet loss messages (see attached log for an 
>>>> example).  The upper part of the client video looks ok but the rest 
>>>> is green / garbage.
>>>> If I take the same source video and transcode it before UDP/RTP 
>>>> streaming or stream it over HTTP, in its source format, then 
>>>> everything works fine.
>>>> I see this behaviour with the most recent vlc code as well as older 
>>>> versions (0.8.6a and 0.8.5).
>>>> Is this a bug or am I doing something wrong?
>>> This is not a bug. What you see is that the network is saturated 
>>> when using MJPEG images of 1600x1200. The network drops UDP/RTP 
>>> packets on the floor when it saturates.
>>> The resolution is to lower the quality of the image by either using 
>>> smaller sized images or transcoding to a lower bitrate.
>>> Gtz,
>>> Jean-Paul Saman.
>> Thanks.  This seems unlikely though - the source MJPG video is about 
>> 15Mbs which I am streaming over an idle 100Mbs network.  Another 
>> thing I found, that suggests a bug, is when I stream over HTTP and 
>> encapsulate with ASF, it works fine but if I stream over HTTP and 
>> encapsulate with TS I get the same problems.  So it seems like it is 
>> a problem with TS encapsulation and not UDP / RTP packet loss.
>> Regards
>> Dugal
> well you sure lose packets and usually that is caused by the network. 
> Although you only send us the logging from the client side. To rule 
> out a problem on the vlc server side (eg: muxer) we need info about 
> your exact commandline, os and vlc logging.
> Gtz,
> Jean-Paul Saman.

Thanks for the help.  Attached are server and client logs for a test run 
exhibiting the described problem.  The server seems quite happy while 
streaming but the client reports errors (the server and client are on 
the same PC).  I am using the GUI with server side streaming options 


PS - Sorry - my OS is Win XP Pro SP2.  My PC is a 3GHz P4 with 1GB RAM.

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