On Mon, 9 May 2005, Dik Takken wrote:
> Indeed, it's a consumer mini-DV camera.
Ok - that's what I thought. Mine's similar (but I went for the
1/4.7" CCD model - it's somewhat better than the 1/6" one but low
light shooting is still problematic).
> I did see this new syntax after entering 'yuvdenoise -h' but it did not
> seem to work either. The reason turns out to be that I entered:
> ... | yuvdenoise -Y 0 -U 0 -V 0 | ...
> to try it and it crashed on that, so I got the impression that this wasn't
Oops :)
Using "-t" should have failed - turns out that yuvdenoise didn't have
a 'default:' case to catch illegal options. That I have fixed.
> correct either. Maybe yuvdenoise could check it's input parameters and
> print a clear error message when the wrong syntax is used, or when the
I did part of that - if you use an invalid option the program will
not continue on. What was happening was that 'getopt' would emit
the "invalid option" message but yuvdenoise ignored the error return
and continued on. That's been fixed.
> user enters floating point threshold values in stead of integer.
> yuvdenoise crashes on floating point values as well.. :)
I suppose the program could accept floating values and conver to
int.
Definitely need to check for 0 to avoid the crash. If the documentation
is updated to explicitly state the values are integers then I think that
is sufficient.
> > Actually I think those settings are quite mild and not aggressive
> > at all. "-t 2 -z 1" is usually dones as a "finishing" step since it
>
> Ah. Well, the values I had to use for chroma denoising (6 and 5) are
Ah, ok - I overlooked the fact you were using the higher thresholds
for the chroma. For the luma though "-t 2 -z 1" is not aggressive
at all.
> > You might try 'yuvmedianfilter' on the chroma only. To disable luma
> > processing use "-t 0" and then experiment with "-T" values to set the
> > chroma thresholding. There is also a "-f" (fast/averaging) option for
>
> I tried that and it is quite effective indeed.
average/median filtering the chroma is something that I have made
part of my standard pipeline especially when dealing with analog
conversions (from VHS tapes for example - the chroma there is
extremely dirty it seems).
It's good to hear that you found that to be effective.
> This sounds like something that is not very difficult to create for
> MJPEGTools. Is there some sort of 'Hello World' example source out there
> to learn how to program/compile your own MJPEGTools tool? I do have
There is the 'y4m API' that has a man page of sorts.
For a "hello world" type of program there are several simple programs
in mjpegtools that can be used as a guide to see how to use the
YUV4MPEG2 routines and how to deal with the various chroma subsamplings,
etc.
Take a look at the simpler programs like 'y4mshift', 'yuv4mpeg',
'y4mblack' and so on. There are other small programs that can be
used as guides - then you can move up to the more complex filters.
Cheers,
Steven Schultz
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