[linux-dvb] Re: video pts differences on dvb-t in the uk

["Robert Schlabbach" <robert_s@gmx.net>]

From: "Ragnar Sundblad" <ragge@nada.kth.se>
> In VDR recordings recorded from DVB-T in Sweden, the video pts
> is often between 250 and 350 ms ahead of the audio pts.

FWIW, I have been toying with writing a simple TS-to-PS converter which
simply outputs a pack_header() each time a PCR is received (with the PCR
time stamp as the SCR one) and then simply outputs PES packets whenever one
has been completely received.

When I run the result through the BBINFO tool, it always complains that the
time stamps on the audio PES packets are earlier than the pack_header() SCR
stamps, e.g.:

PACK #6, pack_start_code = 000001BA, SCR = 31965722.438889 ms
  stream_id = E0  Video Stream 0, packet #6, PTS = 31966163.755556 ms, DTS
= 31966043.755556 ms
    0 - picture_start_code
    9 - extension_start_code
  stream_id = BD  Private Stream 1, packet #1, PTS = 31965645.888889 ms,
underflow
  stream_id = C0  MPEG Audio Stream 0, packet #1, PTS = 31965678.688889 ms,
underflow
    0 - audio syncword
    576 - audio syncword
    1152 - audio syncword
    1728 - audio syncword
    2304 - audio syncword
    2880 - audio syncword

I'm not sure why, but it seems to be common practice to transmit audio
stream packets seemingly too late...

Regards,
--
Robert Schlabbach
e-mail: robert_s@gmx.net
Berlin, Germany