[mythtv-users] real format of .nuv from DVB-T card (mpeg2 with no header?)

Jesper Sörensen jesper at datapartner.se
Tue Aug 16 12:45:09 UTC 2005


ffrr skrev:
> Jesper Sörensen wrote:
> 
>> ffrr wrote:
>>
>>> I think you misunderstood.  I know what is required for DVD.  I was 
>>> asking the difference between that, and what comes out of the DVB 
>>> card as a program stream (which is what is in the nuv file myth 
>>> creates).  
>>
>>
>>
>> DVB cards deliver the data in the raw TS format so this is the most 
>> "pure" form you can record in. The TS->PS conversion is performed by 
>> Myth if you're in PS mode, but that code isn't 100% kosher so it might 
>> or might not work depending on what you need.
>>
>>> People keep saying the PS is mpeg 2, and I know it is 720x576 etc 
>>> (haven't checked bitrates yet).  So what is it missing (and if it's 
>>> the header that DVDstyler says is missing, how do you put the header 
>>> on)?
>>
>>
>>
>> It's not a header. TS and PS are different ways to hold the data. It's 
>> possible to convert losslessly between the two, but it's not trivial, 
>> and definitely not as simple as smacking on an extra header or 
>> something...
>> _______________________________________________ 
> 
> 
> 
> No, the file is _already_ in ps format.  It's this ps format file that
> DVDstyler says is missing a header.  Given the new info you have just 
> told me, that the myth TS to PS conversion code isn't '100% kosher', 
> then maybe that's the reason.

You could try to use replex or some other tool to remultiplex it (from 
PS to PS).

> Actually the conversion mustn't be all 
> that hard, as Kaffeine, and also the Windows software that came with my 
> Twinhan card, both offered the PS mode as an alternative recording 
> method.

As I said there are lots of tools for this but their quality vary, and I 
don't know which one is best.

I'm no expert so if you need more info you'll need to read the MPEG-2 
system spec, google or trawl the archives. For your info, this is what 
Marcus Metzler said about it (myth-dev list, 2004-11-25, subject "DVB 
subtitles and TS->PES decoder"):

"AFAIKT the TS to PES conversion uses my routines from the
dvb-mpegtools package. This is good enough for a quick and dirty
transformation, but can not be used for e.g. authoring DVDs where you
have to get the muxing correct and add some more time stamps. That's
why I started dvb-replex (see http://www.metzlerbros.org/dvb/index.html)"


 > Maybe the card itself can output either mode?

Not likely. TS is what comes through the air (or cable if you're on 
DVB-C), so if you get PS from the card there is a converter somewhere in 
the data path (probably in the application). I guess it would be 
possible to put a converter in the card's driver or possibly in the 
card's hardware but I've never heard of such a thing.

> Anyway I could record in ts format and try using the command line ts2ps 
> conversion tool I suppose.

Yup.


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