[FFmpeg-devel] [PATCH v2] Change cube faces order to match Youtube's

Hazem Ashmawy hazem.s.ashmawy at gmail.com
Sun Apr 1 23:54:53 EEST 2018


Please find another implementation for bilinear
https://github.com/HazemSamir/FFmpeg/commit/6a62f6db30bed37323d70eb7d66d6c33fa8f00c3

Please let me know your thoughts.

On 3/14/18, Paul B Mahol <onemda at gmail.com> wrote:
> On 3/14/18, Hazem Ashmawy <hazem.s.ashmawy at gmail.com> wrote:
>> So I'm still looking into using bilinear instead of nearest. Most of
>> the online discussions are in the context of computer graphics and
>> using things like openGL shaders.
>>
>> One solution I found and may try to implement is to add padding pixels
>> around each face tile in the input frame. This should help in handling
>> sampling near cube edges and corners. However, I'm not sure about the
>> complexity of this or its effect on the performance. WDYT?
>
> Either that or doing it hard way, by picking different pixels for each face.
> Anyway that (padding) solution doesn't sound that bad, and is much simpler
> than
> above mentioned alternative.
>
>>
>> Meanwhile this is a hacky/lazy way to use bilinear, but I can barely
>> notice any improvements
>> over using nearest by my bare eyes, are there any systematic way to
>> evaluate the quality?
>
> Not realy. One could compare with another projection conversion utility,
> there are at least two freely available AFAIK.
>
>> https://github.com/HazemSamir/FFmpeg/commit/fcd82b9782b5f32072d9b0516b275fe3d4f4a163
>>
>> On 3/12/18, Paul B Mahol <onemda at gmail.com> wrote:
>>> On 3/12/18, Hazem Ashmawy <hazem.s.ashmawy at gmail.com> wrote:
>>>> On 3/12/18, Paul B Mahol <onemda at gmail.com> wrote:
>>>>> On 3/12/18, Hazem Ashmawy <hazem.s.ashmawy at gmail.com> wrote:
>>>>>> Sorry about that! Here is github branch
>>>>>>
>>>>>> https://github.com/FFmpeg/FFmpeg/compare/master...HazemSamir:panorama_youtube
>>>>>
>>>>> Good, now can you look at how to use bilinear instead of nearest
>>>>> interpolation
>>>>> for cubemap to equirectangular conversion.
>>>>>
>>>>> Nearest is extremly ugly.
>>>>>
>>>> Sure, will look into that. Just to take that into my consideration,
>>>> why didn't you use it at the first place? Were there any obstacles?
>>>
>>> It was non-trivial to do.
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