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Older versions of Clang (Xcode 14, llvm.org Clang 13 and 14)
do support and recognize SME, but when enabled through
".arch_extension sme" it fails to transitively enable support
for Streaming SVE; this was fixed in [1].
This issue results in those versions currently detecting support
for SME, but later failing to build cpu_sme.s with errors like
"error: instruction requires: sve or sme" or "error: instruction
requires: streaming-sve or sve", on the "cntb x0" instruction.
Extend the check for this instruction set extension, to test
with two instructions, both specifically a SME instruction
(smstart) and an instruction that is available in Streaming SVE
mode (cntb).
For the configure check, add an extra parameter to
check_archext_insn for an optional second instruction to check.
It would be tempting to just pass both instructions through
the same parameter, as "smstart; cntb x0". However, Darwin
targets use a different token (%%) for starting a new
instruction on the same line - those targets interpret ";"
as the start of a comment. Due to that, such a check would
entirely ignore the second instruction on Darwin targets.
To avoid dealing with the variability in passing multiple
instructions on one line, just pass the optional second
instruction on a separate line.
[1] ff3f3a54e2
FFmpeg README
FFmpeg is a collection of libraries and tools to process multimedia content such as audio, video, subtitles and related metadata.
Libraries
libavcodecprovides implementation of a wider range of codecs.libavformatimplements streaming protocols, container formats and basic I/O access.libavutilincludes hashers, decompressors and miscellaneous utility functions.libavfilterprovides means to alter decoded audio and video through a directed graph of connected filters.libavdeviceprovides an abstraction to access capture and playback devices.libswresampleimplements audio mixing and resampling routines.libswscaleimplements color conversion and scaling routines.
Tools
- ffmpeg is a command line toolbox to manipulate, convert and stream multimedia content.
- ffplay is a minimalistic multimedia player.
- ffprobe is a simple analysis tool to inspect multimedia content.
- Additional small tools such as
aviocat,ismindexandqt-faststart.
Documentation
The offline documentation is available in the doc/ directory.
The online documentation is available in the main website and in the wiki.
Examples
Coding examples are available in the doc/examples directory.
License
FFmpeg codebase is mainly LGPL-licensed with optional components licensed under GPL. Please refer to the LICENSE file for detailed information.
Contributing
Patches should be submitted to the ffmpeg-devel mailing list using
git format-patch or git send-email. Github pull requests should be
avoided because they are not part of our review process and will be ignored.