[FFmpeg-devel] [PATCH] avfilter: add panorama filter

James Almer jamrial at gmail.com
Fri Mar 9 17:12:11 EET 2018

On 3/9/2018 12:04 PM, Paul B Mahol wrote:
> On 3/9/18, James Almer <jamrial at gmail.com> wrote:
>> On 3/9/2018 7:05 AM, Paul B Mahol wrote:
>>> On 3/9/18, Paul B Mahol <onemda at gmail.com> wrote:
>>>> On 3/9/18, wm4 <nfxjfg at googlemail.com> wrote:
>>>>> On Fri, 9 Mar 2018 09:15:13 +0100
>>>>> Paul B Mahol <onemda at gmail.com> wrote:
>>>>>> On 3/9/18, wm4 <nfxjfg at googlemail.com> wrote:
>>>>>>> On Thu, 8 Mar 2018 21:53:48 -0300
>>>>>>> James Almer <jamrial at gmail.com> wrote:
>>>>>>>> On 3/8/2018 9:50 PM, Hazem Ashmawy wrote:
>>>>>>>>> [PATCH] avfilter: add panorama filter
>>>>>>>>> Sorry about that! I removed them now.
>>>>>>>>> For the future, any recommendation for a tool for linting /
>>>>>>>>> checking
>>>>>>>>> formating
>>>>>>>>> rules?
>>>>>>>> There's tools/patcheck. Feed it a git format-patch style of patch to
>>>>>>>> find common issues, but keep in mind it can generate a lot of false
>>>>>>>> positives.
>>>>>>>> I don't know if we have documentation about actual formatting rules
>>>>>>>> anywhere.
>>>>>>> Also:
>>>>>>> <_jamrial> shouldn't that panorama filter sent to the ml use the
>>>>>>> spherical
>>>>>>> frame side data?
>>>>>>> I think so.
>>>>>> Are there actual files that have such data?
>>>>> Is that a trick question? I only know the non-standard, Google specific
>>>>> metadata in mkv and mp4 that lavf can read (was any of this
>>>>> standardized yet?).
>>>>> But that doesn't change that we can tag AVFrames with this info, and
>>>>> for files which don't have the metadata, it makes sense to me to set it
>>>>> with a new vf_format argument or some sort of vf_setinfo (if we don't
>>>>> have anything like this yet).
>>>>> The part that is annoying is that vf_panorama still seems to require
>>>>> setting an output projection, which would make the whole thing more
>>>>> annoying instead of less, but even then I'd argue it should default to
>>>>> taking the AVFrame configuration (AV_FRAME_DATA_SPHERICAL) as input by
>>>>> default, even if the filter arguments can override it.
>>>> That frame side data is very specific and thus considered barely useful
>>>> here.
>>>> Is it at all updated to the latest improvements, like new equi-angular
>>>> cubemap projection?
>>> I guess not at all, I get this:
>>> [mov,mp4,m4a,3gp,3g2,mj2 @ 0x21c1740] Unknown projection type
>> Sample? Also, where is this new projection defined?
> https://www.youtube.com/watch?v=qhLExhpXX0E
> It is defined by Google?

Vittorio and I used
to write the current Matroska and mov implementations, and by extension
the AVSphericalMapping API. Specifically the Equirectangular and Cubemap

This sample seems to have a "ytmp" projection box, but it's not defined
in the above document. I guess the name hints at it being a very early
an internal draft? We can't really do much without a spec...

In any case, I insist much like wm4 that a filter like this should use
the metadata stored in the AVFrame if available.

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