VLC player tolerance of timestamp errors

[laduran]

I hope I chose the right forum since this isn't about developing libVLC per se but is more of a development question.

I noticed that VLC player is tolerant of bad timestamp information in an RTP media stream. I am developing a DirectShow based network transcoder that takes as input an MPEG transport stream, transcodes the video from H.264 to MPEG2 (audio is just passthrough) and then serves the resulting stream back out as an RTP stream as well. I use the MainConcept SDK for the heavy video lifting.

Well, I thought I was mostly done with the prototyping and went to testing my output stream. VLC player can play back my stream pretty well. Ditto with a MainConcept RTP client. However, the goal is to use a hardware decoder set top box based on DekTec hardware. That device has a hard time with playback. Video is nice and smooth but Audio is extremely choppy and at times just non-existant.

Checking the stream with WireShark's RTP analyzer, it seems to think my stream has really bad timestamp information. Wireshark claims 95% of timestamps were wrong in a pretty short capture session. I assume it is talking about either PTS or PCR timestamps but it isn't clear.

Anyway, why would VLC player be able to playback a stream if my timestamps are so horribly wrong?

[Rémi Denis-Courmont]

If you stream MPEG-TS over RTP, you should note that VLC uses the MPEG-TS PCR, not the RTP timestamps, for synchronization...