Static gstreamer_allocators::CAPS_FEATURE_MEMORY_DMABUF

pub static CAPS_FEATURE_MEMORY_DMABUF: &GStr

Constant that defines the caps feature name for DMA buffer sharing.

It has to be used for non-mappable dma-buf only, i.e. when the underlying memory is not mappable to user space. Or when the mapped memory contains non meaningful data. It can be the case for protected content or when the user wants explicitly avoid any software post processing.

In these cases all elements between the exported and the importer has to work in passthrough mode. This is done by adding this caps feature.

When the memory is mappable for read and write requests then it is assumes to be a fast path and so this caps feature should not be used. Though according to the dma-buf protocol, while it is mapped it prevents the exporter to migrate the buffer.

This caps feature should not serve at all the purpose of selecting the ALLOCATOR_DMABUF allocator during caps negotiation. When the exporter is the upstream element from the importer point of view, the exporter should try to map the dma buffer at runtime (preferably during decide_allocation phase). When it succeeds for GST_MAP_READWRITE this caps feature should not be used. This allows scalers, color converts and any image processing filters to work directly on the dma buffer. In this case the importer element should check all incoming memory using [is_dmabuf_memory()][crate::is_dmabuf_memory()].