[linux-dvb] Re: Anybody know what PTS stands for?

["Yu, Jacob" <jyu@opentv.com>]

In MPEG-2, PTS stands for presentation timestamp which is unique within the
transport stream.  The begining of a PES is indicated by the PUSI bit in
transport header.  Whenever this bit is set in a transport packet carrying
PES this means to say the PES packet starts from this tranport packet.

Hope this help.


Jacob

-----Original Message-----
From: Jan Panteltje [mailto:root@panteltje.demon.nl]
Sent: Wednesday, May 02, 2001 5:58 AM
To: linux-dvb
Subject: [linux-dvb] Anybody know what PTS stands for?



I am doing some tests with adding subtitles to a recorded program.
Because it gives atm the best result (atm stands for at the moment hehe),
I am using AV_PES, and driver 0.7.1.
At least on my system this gives the least problems.
I have written a program that uses the on screen display to display
subtitles, without interfering with the program flow.
The subtitles are read from a data base (linked list) with numbers
for the start and end of each text.

I need a time reference, timecode would be great but I think it is not
in AV_PES.
But I found something called PTS when running check_av_pes on a AV_PES
stream.
It shows like:
V_PES Packet:  Video  Number: 0x72 
  length: 2432  prebytes: 0x00   postbytes: 0x00 

AV_PES Packet:  Video  Number: 0x73 
  length: 6132  prebytes: 0x00   postbytes: 0x00    PTS: 0x483abd16 

AV_PES Packet:  Video  Number: 0x74 
  length: 3696  prebytes: 0x00   postbytes: 0x04 



Now what is this PTS, what does it stand for, and is it unique in the
stream?
Is there an easy way to find a true start of frame in AV_PES?
I have an other subtitle system (analog) that syncs on frames.

Could PTS be used as a unique reference, and how often does it occur
relative to frames?
I could not even finds the word 'PTS' in all the etsi docs on DTV I have.
What is this???

Anyone please?
Pegards
Jan



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