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Re: bttv driver bug: VIDIOC_ENUMSTD returns wrong NTSC value

Trent Piepho wrote:

On Sun, 27 Jan 2008, Mauro Carvalho Chehab wrote:

On Sat, 26 Jan 2008 22:30:07 -0300
Cláudio da Silveira Pinheiro <taupter@xxxxxxxxx> wrote:

I'd like to know if this is an invalid bug or if it will be fixed upstream, or
if I should send a patch.
bttv reports NTSC as 36864  0x9000  1001000000000000
( V4L2_STD_NTSC_M | V4L2_STD_NTSC_M_KR )

videodev2.h says NTSC is 45056  0xB000  1011000000000000
( V4L2_STD_NTSC_M |  V4L2_STD_NTSC_M_JP | V4L2_STD_NTSC_M_KR )

ENUMSTD returns a bit mask of the supported video standards. In this case, bttv is known to
work with both American (V4L2_STD_NTSC_M) and Korean NTSC versions (V4L2_STD_NTSC_M_KR).


AFAIK, the only difference in Korean NTSC is the encoding of stereo audio.
I don't think adding a norm for it was the correct thing to do.


Probably, it would also work with NTSC/M format in Japan (V4L2_STD_NTSC_M_JP),
but maybe some special configuration would be needed for the audio decoder
chips. For us to add also V4L2_STD_NTSC_M_JP, we would need a positive feedback


This isn't the case.  I know I've said this before, but NTSC-JP has a
different black level.  American (and I think everyone else's) NTSC has a
7.5 IRE pedestal, but not in Japan.

The bt848 chip does support NTSC-JP, I guess no one has bothered to add it.
It could even be usefull outside of Japan.  I've read that most DV cameras'
analog outputs don't have the proper black level and use 0 instead of 7.5.
I have a lot of Japanese laserdiscs, not DVDs, but laserdiscs. You know, the big LP sized things.... Would NTSC-JP support give me better video for capturing these? 

Thank you.

Regards,

Rob

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