[Kdenlive-devel] Color spaces and MLT

[Simon Eugster]

2010/7/21 Dan Dennedy <dan at dennedy.org>:
> On Wed, Jul 21, 2010 at 12:16 PM, Simon Eugster <simon.eu at gmail.com> wrote:
>> 2010/7/21 Dan Dennedy <dan at dennedy.org>:
>>> On Wed, Jul 21, 2010 at 10:51 AM, Simon Eugster <simon.eu at gmail.com> wrote:
>>>> Dear friends,
>>>>
>>>> I've just added an RGB parade to kdenlive. While testing I found
>>>> something interesting: Although I'm painting on a rect with height 256
>>>> (as atm we're dealing with 8 bits per channel only) and scaling the
>>>> parade afterwards to the target height, I got kind of scanlines.
>>>> Compare these two images:
>>>> http://granjow.net/uploads/kdenlive/kdenlive-mlt-rgbparade-noeffect.png
>>>> http://granjow.net/uploads/kdenlive/kdenlive-mlt-rgbparade-witheffect.png
>>>> With the MLT effect there are scanlines, without it there are none.
>>>>
>>>> This is quite interesting, as this visualizes how color information
>>>> gets lost when converting between different color spaces (according to
>>>> [1], MLT is using YUV422, the input image is RGB).
>>>
>>> It does not operate exclusively in YUV422. The color/image-format
>>> conversion implementation depends on your build and your version of
>>> libswscale (>= 0.7.2) whether MLT uses libswscale or inbuilt routines.
>>> Maybe the problem is in the composite transition.
>>
>> libswscale is at 0..6 here in debian sid.
>
> I do not believe that is correct. Maybe you are looking at a package
> version. What does 'ffmpeg -version' show as the libswscale version?

Something different.
  libswscale     0.11. 0 /  0.11. 0

Simon