MPEG-TS
Russel Winder
russel at winder.org.uk
Tue Jul 9 10:20:11 UTC 2019
On Mon, 2019-07-08 at 19:27 +0200, Mathieu Duponchelle wrote:
> Section 6.2.15 of
> https://www.etsi.org/deliver/etsi_en/300400_300499/300468/01.13.01_40/en_300468v011301o.pdf
> does
> get into some details on these two fields, basically items is a dictionary
> of metadata
> (eg: {"Producer": "Some Guy In Hollywood"}), and text is a simple string,
> could be the summary of the program, no
> example is provided for that field however.
After having bashed my head against the documentation, I spotted the "this is
a dictionary implemented in C" bit. To have your confirmation of this
interpretation is most useful so thanks for that confirmation.
I then found a "parsing the original byte sequence" example on the Web that
shows that the text is just a partial text (implying the dictionary is
potentially just a partial dictionary due to the fixed byte length of a
packet) and that you have to process the full sequence of extended event
descriptors to get the full text (and dictionary). Now I have to worry about
how to do this, options being a state machine or making assumptions about the
sequence of packets.
My current problem is though whether fields of type *gchar are actually nul
terminate C strings or not. I believe they should be but CStr::from_ptr is
failing to terminate indicating they are not. This would seem bad design of
the parsing in the library if it is the case. I cannot believe the parsing
algorithm would be bad, that nul terminated string would not be what is there.
So I am in a circle of frustration. :-(
Of course this is all based on test data rather than actual real packets, I
guess I should just get some real packets from Freeview and see what the
result is.
--
Russel.
===========================================
Dr Russel Winder t: +44 20 7585 2200
41 Buckmaster Road m: +44 7770 465 077
London SW11 1EN, UK w: www.russel.org.uk
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