Re: [Discuss-gnuradio] NTSC Demo

[Martin Dvh]

Prateek Dayal wrote:
> Currently I feel that the best place to start off would be to code the
> monochrome algorithms  in gnuradio frame work .. we need to write the
> python module for the monochrome decoding .... I will send you my
> thesis and code soon and then we can write the code .. the problem is
> that I am not very comfortable in C or python :-(  ....
I would like to be involved too.
A while ago I wrote a very simple tv decoder for gnuradio (monochrome only, no 
synchronisation)

Is there somewhere where I can download the thesis and any other info.

All cpu intensive tasks should go into new cpp gnuradio blocks.
There are already quite some generic blocks so maybe we don't have to write 
much new ones.
I think we would need:
saw_filter (use fir_filter)
synchronous_am_decoder (new)
color_comb_filter (use iir_filter)
audio_filter (use_fir_filter)
y_(comb)_filter (use iir_filter)
color_demodulator (new)
tv_audio_demodulator (use am_detector (abs)for ntsc or fm_demodulator 
(quadrature_demodulator) for pal)
synchronisation_block (new)
streaming_display (new, use SDL)
audio_output (use audio_sink)

Then in python we can add all these blocks together:

fg.connect(usrp_source,saw_filter,synchronous_am_decoder,synchronisation_block)
fg.connect(synchronous_am_decoder,color_comb_filter)
fg.connect(synchronous_am_decoder,y_comb_filter)
fg.connect(color_comb_filter,(color_demodulator,0))
fg.connect(y_comb_filter,(color_demodulator,1))
fg.connect(synchronisation_block,(color_demodulator,2))

fg.connect(color_demodulator,streaming_display)
fg.connect(synchronous_am_decoder,audio_filter,tv_audio_demodulator,audio_sink)


We could also put everything into one block. I think we then should start with 
a  generic monochrome videodecoding block
gr_videodecoder_analog

Then write sublasses for ntsc, pal, secam

There is already code for fm and am audio decoding, Probably we can use this 
for the audio part.
Otherwise we could also write tv_audio decoding blocks

We also wan't to show the decoded video.
So we could make a
gr_streaming_bitmap_display


I think this would be best implemented in a cpp block using SDL (cross-platform)
This shouldn't be too hard.

greetings,
Martin
> i will send you the files soon 
>
> regards
>
> Prateek 
>
> On 6/9/05, Matt Chapman <address@hidden> wrote:
>
> > I'd like to volunteer, I've been trying to decode NTSC to build a vector
> > scope. This seems like the perfect project to get me going in the
> > correct direction.
> >
> > Is there something in particular you need help with?
> >
> >
> >
> >
> >
> >
> > On Thu, 2005-06-09 at 20:32 -0700, Prateek Dayal wrote:
> >
> > > Hi,
> > >
> > > Take a look at
> > >
> > > www.geocities.com/pmd_iitgw/ntsc_final.zip
> > >
> > > This video was extracted from data sampled by the USRP ....
> > >
> > > The code is currently in matlab and I am in the process of porting it
> > > to gnuradio but lack the required python and C experience ...
> > >
> > > I have written a long thesis on the elements involved and basic color
> > > decoding is also working ...  I have attached a jpg file ..  note the
> > > brown color of the wooden stuff hidden below the green tint :)
> > >
> > > things remaining -->
> > >
> > > 1. carrier tracking ... for better comb filter performance
> > > 2. gnuradio code
> > >
> > > I would really appreciate if someone with python experience or
> > > gnuradio experience would like to share his time towards the work ...
> > >
> > > Regards
> > >
> > > Prateek
> > > _______________________________________________
> > > Discuss-gnuradio mailing list
> > > address@hidden
> > > http://lists.gnu.org/mailman/listinfo/discuss-gnuradio
> >
> > --
> > Matt Chapman <address@hidden>