[FFmpeg-devel] [PATCH] avfilter/vf_xcam: add xcam video filter

[Paul B Mahol]

On 7/31/20, Zong, Wei <wei.zong at intel.com> wrote:
> Thank you for the comments on this patch, I want to make some explanation on
> your comments.
>
> 1. the purpose of this patch
>      We got some requirements from users who are trying libxcam stitching or
> developers who showing interests. Many of them want an easy way to construct
> an end 2 end pipeline of high quality immersive media application.
>     The key points are high resolution and low latency, FFMpeg provides high
> quality video codec framework, if we implement video stitching as a video
> filter in FFMpeg,
> they will get benefits.
>
> 2. 3rd party dependency
>     The functions exposed by xcam filter only depends on essential build
> tool-chain.
> According to hardware configuration, user can get performance improvement by
> install OCL, GLES or Vulkan.
> These libraries are not necessary for video stitching, user can build a CPU
> version without these libraries.
>     Beside these, stitching and DVS function depend on feature match
> algorithm from OpenCV library to get better quality, I posted demo link in
> commit message.
> User can run stitching without install OpenCV, the side effect is the
> quality will decrease.
>
> 3. Immersive media standard
>     Normally the camera manufactures provide video stitching software, they
> defined private camera calibration parameters, these are very critical to
> stitching quality. I know MPEG is making proposal on transfer these
> meta-data in video stream, this will help compose immersive media on cloud
> or edge server. I think it's a good idea to
> create such a video filter in FFMpeg pipeline.
>
> 4. Why not implement stitching inside FFMpeg video filter
>     The algorithms are complexity and the performance are also important,
> the stitching function manage computing resource for example thread
> handling, image data block dispatching. Personally I think we don't need to
> construct a wheel from the beginning.

Number of supported pixel formats are rather very low.