Ideally there should be three parts to the filter context - public,
private to the filter, and private to generic code, but only the first
and the last of these exist currently. Until the second is implemented,
this is better than nothing.
Split it into sections that describe in detail
* the components of the transcoding pipeline
* the main features it handles, in order of complexity
* streamcopy
* transcoding
* filtering
Replace the current confusing/misleading diagrams with new ones that
actually reflect the program components and data flow between them.
893f3fde4c made libavcodec link to libshaderc/libglslang, though
no codecs depend on it at this immediate moment.
This was merged largely as a coordination effort to synchronize three
different developers' repositories to allow them to send patches without
overlapping functionality in between.
This line can be removed once the first component to depend on spirv_compiler
lands, but leaving it in is fine too.
We started defauling to nasm 8 years ago.
We are still compatible with yasm 0.8.0, released in 2009. **15 years ago**.
The time has more than come to remove support for it.
Maintaining compatibility started cutting into writing new code long ago.
We still can't have 2-argument instructions, preprocessor booleans, and all
AVX2 code must still be wrapped in ifdefs. Newly added code often breaks this.
This is the same as with libavfilter.
We will need SPIR-V compilation for at least three different things,
like the VC-2 encoder and decoder, AV1 film grain synthesis for
hardware with no support for it, and possibly other codecs.
The code is not currently used by libavutil, its just where our
common Vulkan code is.
Since SPIR-V compilation will be needed by lavc, move it, rather
than having lavc including lavfi.