[FFmpeg-devel] [V2 08/10] libavutil/hwcontext_vulkan: fix wrong offset of plane

[Chen, Wenbin]

> -----Original Message-----
> From: Lynne <dev at lynne.ee>
> Sent: Wednesday, September 1, 2021 7:33 PM
> To: Chen, Wenbin <wenbin.chen at intel.com>
> Subject: RE: [FFmpeg-devel] [V2 08/10] libavutil/hwcontext_vulkan: fix wrong
> offset of plane
> 
> 1 Sept 2021, 03:40 by wenbin.chen at intel.com:
> 
> >
> >
> >> -----Original Message-----
> >> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of
> >> Lynne
> >> Sent: Tuesday, August 31, 2021 7:42 PM
> >> To: FFmpeg development discussions and patches <ffmpeg-
> >> devel at ffmpeg.org>
> >> Subject: Re: [FFmpeg-devel] [V2 08/10] libavutil/hwcontext_vulkan: fix
> wrong
> >> offset of plane
> >>
> >> 31 Aug 2021, 09:24 by wenbin.chen at intel.com:
> >>
> >> > According to spec, if we use VkBindImagePlaneMemoryInfo to bind
> image
> >> > we mush create image with disjoint flag.
> >> > The offset in subresourcelayout is relative to the base address of
> >> > the plane, but the offset in drm is relative to the drm objectis so
> >> > I think this offset should be 0.
> >> > Also, when I import vaapi frame to vulkan I got broken frame, and
> >> > setting plane_data->offset to 0 makes command works.
> >> >
> >> > Signed-off-by: Wenbin Chen <wenbin.chen at intel.com>
> >> >
> >>
> >> I don't quite get the point of this. Is there some situation where
> >> clients may want to change the modifier of the image they're allocating,
> >> like maybe use a different modifier when allocating images that would
> >> be used as framebuffers to be presented?
> >>
> >
> > Maybe you reply to the wrong patch? I assume you want to reply to the 9th
> patch.
> > " specify the modifier to create VKImage".
> > I tried on the latest intel driver. The log recommend to use linear or
> drmModifier to create image.
> > Also if I use optimal to create image, the export drm modifier is unknown.
> >
> 
> Linear is almost never optimal. Could you post a link to the recommendation?
> The DRM modifier is known for optimal, there's a Vulkan API to retrieve
> image modifiers.

This restriction is for VK_EXTERNAL_MEMORY_HANDLE_TYPE_DMA_BUF_BIT_EXT.

I get recommendation information from here.
https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/intel/vulkan/anv_formats.c#L1412
If I use optimal to create VkImage, the modifier I get from VkGetImageDrmFormatModifierPropertiesExt() 
is DRM_FORMAT_MOD_INVALID.
I tested this on Intel platform, and I see AMD has this restriction as well.
https://gitlab.freedesktop.org/mesa/mesa/-/blob/main/src/amd/vulkan/radv_formats.c#L1530