[FFmpeg-devel] [PATCH 38/42] fftools/ffmpeg: add support for multiview video

[James Almer]

On 8/31/2024 4:44 AM, Anton Khirnov wrote:
> Quoting James Almer (2024-08-30 02:40:49)
>> On 8/29/2024 8:26 PM, Michael Niedermayer wrote:
>>> On Tue, Aug 27, 2024 at 05:05:18PM +0200, Anton Khirnov wrote:
>>>> This extends the syntax for specifying input streams in -map and complex
>>>> filtergraph labels, to allow selecting a view by view ID, index, or
>>>> position. The corresponding decoder is then set up to decode the
>>>> appropriate view and send frames for that view to the correct
>>>> filtergraph input(s).
>>>> ---
>>>>    doc/ffmpeg.texi           |  30 +++-
>>>>    fftools/cmdutils.c        |   2 +-
>>>>    fftools/cmdutils.h        |   2 +
>>>>    fftools/ffmpeg.h          |  45 ++++-
>>>>    fftools/ffmpeg_dec.c      | 355 +++++++++++++++++++++++++++++++++++++-
>>>>    fftools/ffmpeg_demux.c    |  24 ++-
>>>>    fftools/ffmpeg_filter.c   |  71 +++++---
>>>>    fftools/ffmpeg_mux_init.c |  29 +++-
>>>>    fftools/ffmpeg_opt.c      |  70 +++++++-
>>>>    9 files changed, 575 insertions(+), 53 deletions(-)
>>>
>>> breaks build on mingw64
>>>
>>> src/fftools/ffmpeg_dec.c: In function ‘packet_decode’:
>>> src/fftools/ffmpeg_dec.c:811:19: error: implicit declaration of function ‘ffs’ [-Werror=implicit-function-declaration]
>>>     811 |             pos = ffs(outputs_mask) - 1;
>>>         |                   ^~~
>>> cc1: some warnings being treated as errors
>>> make: *** [src/ffbuild/common.mak:81: fftools/ffmpeg_dec.o] Error 1
>>> make: *** Waiting for unfinished jobs....
>>>
>>> thx
>>
>> Would ff_clz(outputs_mask) work here?
> 
> In principle yes, but it's private and I'd rather not include a private
> header in ffmpeg CLI.
> 
> We could either make it public, or I could add a ffs() implementation
> for Windows to compat/. Anyone has a preference?

I think i prefer making ff_clz public in common.h. It has an optimized 
version not exclusive to Windows using a gcc/clang builtin, and even one 
specific for riscv.

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