[vlc-devel] receiving HVDTS MPEG2 strams: UDP makes artifacts, RTP is OK.

[Claudio Allocchio]

On Mon, 14 Dec 2009, Marian Ä~NurkoviÄ~M wrote:

> Hi Claudio,
>
> On Mon, 14 Dec 2009 16:58:49 +0100 (CET), Claudio Allocchio wrote
>> Hello all again,
>>
>> there is an issue when using VLC (any version) to receive an MPEG2
>> stream generated by HDVTS http://www.sfc.wide.ad.jp/DVTS/ both in
>> UNICAST and MULTICAST mode.
>>
>> Even if HDVTS generates a stream which UDP should be able to handle
>> correctly, VLC cannot display correctly the video, generating lots of
>> artifacts.
>>
>> If you tell VLC to use RTP instead for receiving the HDVTS generated
>> stream, the all if OK.
>
>  this is most probably due to packet reordering happening somewhere on the path
> between the server and you. 10G interfaces on Juniper M160 routers are famous
> for this.

it is true that there are plenty of M160 and 10G interfaces between 
Internet2 and GEANT and GARR... but we have the same result over a pure 
LAN connection, too.

It might be related to the amount of packets, of course, as 28Mbps can 
cause packets reordering also in switches.

However, when we use just DVTS to DVTS (DVTS also as receiver) we run UDP 
at 30Mbps, and we never have a single video glitch for hours.

... :-(

  >
>  With RTP headers, the sequence number field allows the receiver to restore
> correct packet order - but with UDP you're lost.
>
>
>    With kind regards,
>
>          M.
>
> --------------------------------------------------------------------------
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>
>
>
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Claudio Allocchio             G   A   R   R          Claudio.Allocchio at garr.it
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