[FFmpeg-devel] [PATCH] smptebars filter

[Tim Nicholson]

On 20/06/12 09:19, Thierry Foucu wrote:
> On Wed, Jun 20, 2012 at 9:54 AM, Paul B Mahol <onemda at gmail.com> wrote:
> 
>> Signed-off-by: Paul B Mahol <onemda at gmail.com>
>> ---
>>  doc/filters.texi             |   20 ++++
>>  libavfilter/Makefile         |    1 +
>>  libavfilter/allfilters.c     |    1 +
>>  libavfilter/vsrc_smptebars.c |  215
>> ++++++++++++++++++++++++++++++++++++++++++
>>  4 files changed, 237 insertions(+), 0 deletions(-)
>>  create mode 100644 libavfilter/vsrc_smptebars.c
>>
>> diff --git a/doc/filters.texi b/doc/filters.texi
>> index 566fbfc..0c0c490 100644
>> --- a/doc/filters.texi
>> +++ b/doc/filters.texi
>> @@ -3799,6 +3799,26 @@ the @code{mp=geq} filter:
>>  nullsrc=s=256x256, mp=geq=random(1)*255:128:128
>>  @end example
>>
>> + at section smptebars
>> +
>> +Generate SMPTE color bars.
>>
> 
> 
> Am i correct to assume that this SMPTE color bar is the SD version.
> 
> For HD, I though to remember the SMPTE color bar is different.
> see http://en.wikipedia.org/wiki/File:SMPTE_Color_Bars_16x9.svg
> 
> If so, should we not call this one SMPTE_SD? or add both into the same
> filter?
> 
> 

I think bars should be in the correct format for the colorspace intended
with true black at RGB 16  units and true white at 235. (Those are the
European figures I guess they may differ for 525/60 standards)

ISTR that the blackest black on SMPTE bars is actually 2% below true
black in order to test for black clipping, but that true back on NTSC
was 5% up on true black in PAL back in the analogue days....

As for HD bars being different, they certainly look different in HD on a
waveform monitor, but the different colorspace matrix will do that for
you. I'm not aware of the actual generated RGB levels being different,
but again this may be different outside of Europe...

Time to dig out the specs again....
-- 
Tim