Jump to content

TransEdit: unable to detect second section of SDT

Recommended Posts

I've ran across some issue, which might be interesting to look at.

TransEdit is unable to detect the second section of SDT table in some DVB-T stream.


I'm attaching a sample (full TS).




This is resulting in missing last 3 services names.


Sections length seems to be OK, also CRC32 is fine. Maybe a bit untypical is that second section is starting in the middle of the packet, but I think that this shouldn't be an issue (?)

Link to comment

Ok, I can see the problem. LastSectionNumber is 1 in the SDT, as the Analyzer -> Table Stats function indicates, so there should be two SDT sections, one with SectionNumber = 0 and one with SectionNumber = 1.


However, even with a manual search by using the Analyzer -> Hex View of the SDT packets I can't find a section with SectionNumber = 1. So it is simply missing, as far as I can see. It looks like the broadcaster's fault...


Link to comment

Thanks for verification and help ;)


The issue is that section 1 is present, it's a little bit hidden, but please look at the screenshot - it will help.


Directly after "Rock Radio" name there's a CRC32 of section 0 (marked with red, value is correct) and section 1 is starting (marked with blue) directly right after.



Edited by oleq
Link to comment
vor 42 Minuten schrieb oleq:

The issue is that section 1 is present, it's a little bit hidden, but please look at the screenshot


It seems to present, but it doesn't comply to the basic ISO/IEC 13818-1 specifications for transport streams. See section, Semantics definition of fields in pointer syntax:



pointer_field – This is an 8-bit field whose value shall be the number of bytes, immediately following the pointer_field until the first byte of the first section that is present in the payload of the Transport Stream packet (so a value of 0x00 in the pointer_field indicates that the section starts immediately after the pointer_field). When at least one section begins in a given Transport Stream packet, then the payload_unit_start_indicator (refer to shall be set to 1 and the first byte  of  the  payload  of  that  Transport  Stream  packet  shall  contain  the  pointer.


Your screenshot shows, that neither the payload_unit_start_indicator is set in the packet where the sections starts, nor a pointer field (following the 4 TS header bytes and pointing to the beginning of the section) is present. It's a proprietary (or simply wrong) way of inserting the second section. That's why TransEdit is not able to find it.


  • Thanks 1
Link to comment

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Unfortunately, your content contains terms that we do not allow. Please edit your content to remove the highlighted words below.
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

  • Create New...