Re: [FFmpeg-devel] [FFmpeg-cvslog] lavu/opt: add array options
On Fri, Mar 08, 2024 at 07:06:17AM +0000, Anton Khirnov wrote:
ffmpeg | branch: master | Anton Khirnov <anton@khirnov.net> | Thu Feb 8 08:50:18 2024 +0100| [efe447877811f2f14f814e80ce71383e2f056f36] | committer: Anton Khirnov
lavu/opt: add array options
http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=efe447877811f2f14f...
doc/APIchanges | 3 + libavutil/opt.c | 360 ++++++++++++++++++++++++++++++++++++++++++++------ libavutil/opt.h | 56 +++++++- libavutil/tests/opt.c | 49 +++++++ libavutil/version.h | 2 +- tests/ref/fate/opt | 35 ++++- 6 files changed, 459 insertions(+), 46 deletions(-) [...] --- a/libavutil/opt.h +++ b/libavutil/opt.h @@ -250,6 +250,17 @@ enum AVOptionType{ AV_OPT_TYPE_COLOR, AV_OPT_TYPE_BOOL, AV_OPT_TYPE_CHLAYOUT, + + /** + * May be combined with another regular option type to declare an array + * option. + * + * For array options, @ref AVOption.offset should refer to a pointer + * corresponding to the option type. The pointer should be immediately + * followed by an unsigned int that will store the number of elements in the + * array. + */ + AV_OPT_TYPE_FLAG_ARRAY = (1 << 16),
This sounds like it suggests undefined behavior taking a pointer to a pointer of lets say a array of float and adding 1 and then dereferencing this as int is undefined behavior A pointer created that way may not be aligned correctly. This just happens to work on the major platforms ... Or said differently a int *array ; int array_len in a struct arent guranteed to have the same distance between each other each time. thx [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB He who knows, does not speak. He who speaks, does not know. -- Lao Tsu
On Fri, Jul 5, 2024 at 9:38 PM Michael Niedermayer <michael@niedermayer.cc> wrote:
On Fri, Mar 08, 2024 at 07:06:17AM +0000, Anton Khirnov wrote:
ffmpeg | branch: master | Anton Khirnov <anton@khirnov.net> | Thu Feb 8 08:50:18 2024 +0100| [efe447877811f2f14f814e80ce71383e2f056f36] | committer: Anton Khirnov
lavu/opt: add array options
http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=efe447877811f2f14f... ---
doc/APIchanges | 3 + libavutil/opt.c | 360 ++++++++++++++++++++++++++++++++++++++++++++------ libavutil/opt.h | 56 +++++++- libavutil/tests/opt.c | 49 +++++++ libavutil/version.h | 2 +- tests/ref/fate/opt | 35 ++++- 6 files changed, 459 insertions(+), 46 deletions(-) [...] --- a/libavutil/opt.h +++ b/libavutil/opt.h @@ -250,6 +250,17 @@ enum AVOptionType{ AV_OPT_TYPE_COLOR, AV_OPT_TYPE_BOOL, AV_OPT_TYPE_CHLAYOUT, + + /** + * May be combined with another regular option type to declare an array + * option. + * + * For array options, @ref AVOption.offset should refer to a pointer + * corresponding to the option type. The pointer should be immediately + * followed by an unsigned int that will store the number of elements in the + * array. + */ + AV_OPT_TYPE_FLAG_ARRAY = (1 << 16),
This sounds like it suggests undefined behavior
taking a pointer to a pointer of lets say a array of float and adding 1 and then dereferencing this as int is undefined behavior
A pointer created that way may not be aligned correctly. This just happens to work on the major platforms ...
Or said differently a int *array ; int array_len in a struct arent guranteed to have the same distance between each other each time.
One more reason to replace AVOptions limited API.
thx
[...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB
He who knows, does not speak. He who speaks, does not know. -- Lao Tsu _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel
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participants (2)
-
Michael Niedermayer -
Paul B Mahol