[FFmpeg-devel] [PATCH] smptebars filter

[Paul B Mahol]

On 6/20/12, Tim Nicholson <nichot20 at yahoo.com> wrote:
> 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)

Colors (rainbow and wobnair) are exactly as generated by y4mcolorbars.

Other colors like mentioned in comments are just made up and can not
be really reproduced in RGB or YUV(J) colorspace.

Also drawutils only supports RGB color input.

>
> 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....