Very clear explanations.
Thanks very much to all of you. Nico On Fri, 18 Jul 2003, Robert Schlabbach wrote: > From: "Nico" <[EMAIL PROTECTED]> > > 1) read the PAT to find the list of programs ids > > 2) read the PMT to find the list of ES streams > (audio/video/teletext/subs) > > associated to a given program id > > > > Is it correct? > > Yes, but this is only ISO-MPEG2. > > > Now I wonder > > 3) what's the use of NIT and SDT? > > Those are the extensions that DVB makes to ISO-MPEG2. It defines additional > tables and "abstracts" the information from MPEG-2. While MPEG-2 only knows > "programs" and refers to them by "program numbers", DVB calls these things > "services" and refers to them by service identifiers (SIDs). MPEG-2 has no > means to specify a transport stream (multiplex), DVB introduces the > Original Network Identifier (ONID) and the Transport Stream Identifier > (TSID) to address a stream. > > So in DVB you can fully address a service with an ONID:TSID:SID triple. > ONID:TSID uniquely identifies a transport stream. The required tuning > information for each ONID:TSID is transmitted in the DVB NIT (Network > Information Tables). The services (SIDs) for each transport stream are > described in the SDTs, including e.g. broadcaster, network and channel > name. AFAIK, MPEG-2 has no means to transmit such information. > > Consider MPEG-2 as only a _base_ for a digital broadcasting system, which > _needs_ to be extended to become a fully functional system. Two such > extensions are ATSC (North America) and DVB (Europe), of which DVB appears > to be the more complex and powerful one. > > Regards, > -- > Robert Schlabbach > e-mail: [EMAIL PROTECTED] > Berlin, Germany > > -- Info: To unsubscribe send a mail to [EMAIL PROTECTED] with "unsubscribe linux-dvb" as subject.