[MPlayer-advusers] DVB documentation unclear/outdated

[lynx.abraxas at freenet.de]

On 12/02/07 00:05:17, Nico Sabbi wrote:
> lynx.abraxas at freenet.de wrote:
> 
> >
> >I  think  there  is  a  misunderstanding.  I  am  using  transcoding  here 
> >for
> >"transcoding between MPEG-2  and    MPEG-4  (partial  decompression)" 
> 
> there's nothing "partial" here: a full decompression takes place
> 
> >without decoding  to  raw  and then encoding to mpeg4 (as mentioned at the 
> >end of DVB-
> >doc). If I'm not mistaken decoding to raw and  then  encoding  is  called  
> >re-
> >encoding  which  is  not transcoding. I'm though not sure if transrating 
> >would
> >apply here as well since they are both mpeg but not the same video 
> >formats. In
> >the  excerpt  it  states  re-encoding  not  transcoding  and so it is for 
> >sure
> >mencoder's task but not what I am looking for.
> 
> 
> re-encoding == transcoding; in this context the only difference 
> between the transcodings done by mplayer and mencoder is the direction 
> of the output: to file if done by mencoder, to the dvb card if done by 
> mplayer

Why is -dumpstream and co in mplayer?

> 
> >
> >I'm    referring    to    this     email     from     the     thread     
> >here:
> >http://lists.mplayerhq.hu/pipermail/mplayer-dvb/2002-August/000668.html
> >
> 
> unsubstantiated science ficton

OK, that's what I feared...

> 
> >
> >>>What  uses demux_ts: -demuxer lavf or  -demuxer mpegts?
> >>>
> >>
> >>isn't the filename clear enough? demux_ts; anyway -demuxer lavf can be
> >>used to demux dvb streams, too
> >>
> >
> >
> >If  one  is  new and unsure about things concerning DVB, demux_ts is 
> >confusing
> >since  mplayer  -demux  help  yields  mpegts  fitting   to   last   lines  
> >of
> >libmpdemux/demux_ts.c  but  making  not  much sense to google hit for 
> >demux_ts
> >http://www.arcknowledge.com/gmane.comp.video.mplayer.user.dvb/2006-10/msg00031.html
> 
> that mail isn't about trandcoding, but simply about dumping (saving) 
> the dvb stream to file

Yes, but demux_ts is in its title;)

> 
> >So  I'm  still  wondering  if  anyhow  one  can use demux_ts with 
> >DVB-input to
> >achieve transcoding in the way I discribed above? So that I  end  up  with 
> >an
> >mpeg4-file without re-encoding.
> >
> 
> as I wrote, re-encoding/transcoding - however you call it - is still 
> done 100% by your cpu: there's nothing done by the dvb card, not even
> the mpeg2 decoding
> (although it's possible to make the dvb card to the actual decoding 
> and use mencoder to read the uncompressed audio and video streams
> from the card's output: tv://, but I would never bet on the synchrony)
> 
> 
> >>xvidix does accept 'h', 'k' and shows the osd menu. I use it every day
> >
> >
> >Sorry, my mistake. gmplayer -vo xvidix and 'h'  or 'k'  make  mine  crash  
> >but
> >mplayer -vo xvidix does work.
> >Contrary mplayer -vo cvidix and 'h' or 'k' make mplayer change the channel 
> >but
> >when showing the new channel it does not care about any key strokes any  
> >more.
> 
> maybe *during* channel tuning
> 

No, even afterwards when the programme is already displayed and whatever minutes later.
Do You have any idea how I could find out what's wrong there? I don't get any errors. Nor does -v or strace give something suspicious.

> >I  think this is somehow connected to dvb:// since 'h'  or 'k' work 
> >forever if
> >I use them with v4l2 mplayer -vo cvidix tv:// -tv ...
> >
> 

Thanks for all the explanations. It's much clearer now. (except for cvidix + dvb)

Greetings
Lynx