[vdr] Transfer Buffer Overflow

Reinhard Nissl rnissl at gmx.de
Fri Feb 2 23:59:39 CET 2007


Hi,

Thomas Lagemann wrote:

> Just another thought about the timing: MPEG-2 defines rules for a system
> target decoder, thats in charge for decoding and presenting the media at
> the right time, using the PTS-stamps in the PES packets.
> Is this usually done by the driver or is there a VDR instance that deals
> with this.

It's done in the driver / xine.

But it shouldn't be to complicated to extract the PTS value from a TS
packet. The PTS value is very near to the beginning of a PES packet and
a bit in the TS packet tells you that a new PES packet starts in this TS
packet.

When you extract PTS for each PID and calculate the difference to the
first seen PTS for each PID, then you evaluate, how much time should
have passed since the beginning of the TS file. If you put this
information in relation to the time passed in reality since opening the
TS file, you can throttle the TS stream so that it doesn't overflow the
buffers any more.

BTW: keep in mind, that video PTS jump back and forth as the images are
broadcast in decoding order while the PTS time stamps describe
presentation order.

Bye.
-- 
Dipl.-Inform. (FH) Reinhard Nissl
mailto:rnissl at gmx.de



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