Re: [dvbtools-devel] No audio, and interlacing problem with Nova-t card and dvbstream

[Dave C. <da...@dc...>]

jng...@gr... wrote:
> Hi there. I'd be extremely grateful if there is anybody out there who 
> could help me with a few simple DVB related problems. I have recently 
> bought a Hauppauge Nova-t card and I am trying to get it working with 
> Linux (it works fine on Windows, but that's no use!).
> 
> By the way, I hope this is a good mailing list / forum for these 
> questions. Please redirect me if there is a more appropriate place.

This list isn't used at all - you are better off posting to the 
linux-dvb list at http://www.linuxtv.org.

> I checked out the latest DVB drivers, and latest dvbstream. I built them 
> without any problems. The problem comes when I try to watch live TV. I'm 
> using mplayer to play the MPEG stream. But I've encountered a few 
> problems:
> 
> 1) Tuning in the card. If I use 'tzap' that comes with the DVB driver, I
> can tune in the card. 'scan' also works fine, and builds me a sensible 
> looking channels.conf. But 'dvbstream' and 'dvbtune' seem to have a 
> problem tuning in the card. I don't know if this is correct but I used 
> some of the settings from my channels.conf for arguments to 'dvbstream'. 
> For example, I have the following line in my channels.conf:
> 
> BBC ONE:641833330:INVERSION_OFF:BANDWIDTH_8_MHZ:FEC_3_4:FEC_NONE:QAM_16:TRANSMISSION_MODE_2K:GUARD_INTERVAL_1_32:HIERARCHY_NONE:600:602
> 
> So I did something like this:
> 
> dvbstream -f 641833330 -qam 16 -cr 3_4 -o 8192 | ts2pes 600 602 | mplayer -

You should use something like:

dvbstream -f 641833 -qam 16 -cr 3_4 -o -ps 600 601 | mplayer -cache 2048 -

The "-ps" option to dvbstream does the "ts2ps" conversion, and it is 
better to make dvbstream just output the two streams you are interested 
in rather than specifying the whole multiplex using the virtual "PID" 8192.

Also, dvbstream only accepts the frequency in KHz, whereas dvbtune can 
accept it in either KHz or Hz.

The "-cache" option may or may not be needed, but I prefer to use it.

> 2) When I get a live picture playing in mplayer, I nearly always don't get
> any sound/audio. On two occasions I have got sound but it wasn't through
> any reasoned method. I found that in the example above I managed to get
> sound by doing the following:
> 
> tzap "BBC ONE"
> ./dvbstream -o 8192 | ./ts2pes 600 601 | mplayer -
> 
> The difference is the arguments to 'ts2pes'. I specified ID 601 instead of 
> 602. This differs to what my channels.conf says. Either there's a bug in 
> 'scan' (which I doubt), or I've misunderstood something?

I don't know how "scan" works, but most of the UK DVB-T channels have 
two audio streams.  In the case of BBC1, it is 601 and 602.  I always 
use the first audio stream - the second is normally silent.  It looks 
like "scan" outputs the last audio PID.

> 3) Finally, when I do get working video, all is fine until there is rapid
> motion in the animation. Under these conditions I get some pretty horrible
> looking interlacing problems. The effect can be seen if somebody waves
> their hands.  Lots of horizontal stripes appear around the fast moving
> hands. It's as though alternate lines are plotted at the wrong horizontal
> offset. It's definitely some kind of interlacing problem - I have seen it
> before on DVD playback when I have got the wrong interlace settings. But I
> don't know how to change the settings in the DVB world. Again any help
> here would be much appreciated?

Read the docs for mplayer.  It supports various post-processing options, 
including de-interlacing.

You may also want to subscribe to the "mplayer-dvb" list at 
http://www.mplayerhq.hu.  Today someone posted a patch to that list 
which allows mplayer to tune and read data directly from a DVB card 
without the need for dvbstream.  The author is looking for people to 
test and debug the DVB-T support.

Regards,

Dave.