Re: DLT for MPEG2-TS

[Guy Martin <gmsoft () tuxicoman be>]

On Sun, 29 Jan 2012 12:58:20 -0800
Guy Harris <guy () alum mit edu> wrote:

> On Jan 29, 2012, at 9:21 AM, Guy Martin wrote:
>
> > I've been working with protocols encapsulated into MPEG2-TS but
> > I can't save the raw stream straight into a pcap file.
> > Those protocols include DOCSIS (cable modem) and DSM-CC (IP packets
> > into DVB streams).
> >
> > Unless I'm mistaken, there is currently no DLT_ value for MPEG2-TS.
>
> So that's "MPEG-2 Transport Stream" as in H.222.0 (which,
> unfortunately, is also an ISO standard, so you have to pay money for
> it...)?

Correct. It's most commonly refered as ISO 13818-1.

> If so, would each packet in the file be a "transport packet", in the
> form as shown in Table 2-2 of section 2.4.3.2 "Transport Stream
> packet layer" of H.222.0 (2006-05)?

Exactly. Each of these packets is 188 bytes long, including the header.

> If so, is the sync byte the first byte, or is the 16-bit field
> containing the transport_error_indicator,
> payload_unit_start_indicator, transport_priority, and PID at the
> beginning of the packet in the file?  (Presumably in big-endian
> order, as "uimsbf" means "unsigned integer, most-significant bit
> first".)- 

The bits are in the order described in the section you refer to.
You have the sync byte first and the rest follows.

Unfortunately, due to the way the bits in the headers are ordered,
there is no easy way to map that into C structures for both big and
small endians.


Let me know if you need more details.

Regards,
  Guy

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