[mythtv] DVB-S with no SDT / NIT tables

Steven Ellis steven at openmedia.co.nz
Mon Oct 29 02:21:01 UTC 2007

On Mon, October 29, 2007 2:23 pm, Manu Abraham wrote:
> Bill Williamson wrote:
>> On 10/26/07, Manu Abraham <abraham.manu at gmail.com> wrote:
>>> Steven Ellis wrote:
>>>> On Wed, October 24, 2007 12:47 am, Janne Grunau wrote:
>>>>> On Tuesday 23 October 2007 07:26:25 Steven Ellis wrote:
>>>>>> There are some DVB-S services on Optus D1 that don't have any SDT or
>>>>>> NIT entries on their TS stream. For details see 12643V at
>>>>>> http://www.lyngsat.com/optusd1.html.
>>>>>> Now is there any way to specify Audio and Video PIDs for a channel
>>>>>> when the SDT information doesn't exist?
>>>>> The PIDs are defined in the in the PMT.
>>>>>> These channels can be loaded onto generic DVB-S STBs where you can
>>>>>> manually add the A/V PID details, and it would be great if we could
>>>>>> get them with MythTV. I've asked on the Users list, but after
>>>>>> looking
>>>>>> at the code i'm wondering if it will need a patch.
>>>>> As long as there is no NIT+SDT and valid PAT+PMT on the transponder
>>>>> the
>>>>> scanner should find them.
>>>> Sadly there is no PMT either.
>>>> All that the DVB-S transponder is carrying are the Audio and Video
>>>> PIDs,
>>>> there are no other information streams present.
>>> If there are is no valid PAT/PMT, then it is not a valid MPEG2 TS
>>> (which are
>>> mandatory, not optional)
>> While that's true, the fact is:
>> -Commercial (but non-propriatary) set top boxes pick up the channel
>> without issue
>> -Other linux based solutions pick up the channel without issue
>> -If this were happening in the US it'd be a "no brainer" fix
> With these solutions that you mentioned, one needs to explicitly tell the
> application
> about the only 2 PID's (Audio and Video) that is mentioned here.


> No PCR also ?

If the STB requires a PCR they usually just enter the Video PID.

> But it sounds quite weird that a TS is generated the way it is mentioned.

Yes it is a little odd. You occasionally see this on some DVB-S
transponders that are used for feeds.

I was hoping that there was some way to use the atscsrcid or some other
field in the channel table to force a/v pids. I'm open to other
suggestions in terms of producing a solution.


Steven Ellis - Technical Director
OpenMedia Limited - The Home of myPVR
email   - steven at openmedia.co.nz
sales   - sales at openmedia.co.nz
support - support at openmedia.co.nz
website - http://www.openmedia.co.nz

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