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

James Almer jamrial at gmail.com
Fri Mar 9 17:38:56 EET 2018

On 3/9/2018 12:30 PM, Paul B Mahol wrote:
> On 3/9/18, James Almer <jamrial at gmail.com> wrote:
>> On 3/9/2018 12:12 PM, James Almer wrote:
>>> 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
>>> https://github.com/google/spatial-media/blob/master/docs/spherical-video-v2-rfc.md
>>> to write the current Matroska and mov implementations, and by extension
>>> the AVSphericalMapping API. Specifically the Equirectangular and Cubemap
>>> projections.
>>> 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...
>> The h264/mp4 version has this unknown "ytmp" box, but the vp9/webm one
>> has a ProjectionType element with a value of 3, plus some binary data in
>> the ProjectionPrivate element, which according to the spec means a Mesh
>> projection. We don't currently support that one.
>> Weird, seeing mp4 supposedly has the "mshp" box for this.
> Do you know of any video sample that have "standard" cubemap layout?

https://0x0.st/smIJ.mp4 (file is called
motherboard-cube-v2-metadata.mp4). Contains a cbmp box, as defined in
the document above for Cubemap projection.

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