> -----Original Message-----
> From: Stefano Sabatini <stefa...@gmail.com>
> Sent: Donnerstag, 8. Mai 2025 23:39
> To: softworkz . <softwo...@hotmail.com>
> Cc: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH v10 06/15] fftools/textformat: Introduce
> AVTextFormatOptions for avtext_context_open()
>
> On date Thursday 2025-05-08 00:25:28 +0000, softworkz . wrote:
> > > -----Original Message-----
> > > From: Stefano Sabatini <stefa...@gmail.com>
> > > Sent: Donnerstag, 8. Mai 2025 02:06
> > > To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
> > > Cc: softworkz <softwo...@hotmail.com>
> > > Subject: Re: [FFmpeg-devel] [PATCH v10 06/15] fftools/textformat:
> Introduce
> > > AVTextFormatOptions for avtext_context_open()
> > >
> > > On date Sunday 2025-05-04 02:57:17 +0000, softworkz wrote:
> > > > From: softworkz <softwo...@hotmail.com>
> > > >
> > > > This allows future addition of options without
> > > > changes to the signature of avtext_context_open().
> > > >
> > > > Reviewed-by: Stefano Sabatini <stefa...@gmail.com>
> > > > Signed-off-by: softworkz <softwo...@hotmail.com>
> > > > ---
> > > > fftools/ffprobe.c | 13 +++++++++----
> > > > fftools/textformat/avtextformat.c | 21 ++++++++-------------
> > > > fftools/textformat/avtextformat.h | 16 +++++++++-------
> > > > 3 files changed, 26 insertions(+), 24 deletions(-)
> > > >
> > > > diff --git a/fftools/ffprobe.c b/fftools/ffprobe.c
> > > > index f5c83925b9..1277b1e4f9 100644
> > > > --- a/fftools/ffprobe.c
> > > > +++ b/fftools/ffprobe.c
> > > > @@ -3168,10 +3168,15 @@ int main(int argc, char **argv)
> > > > if (ret < 0)
> > > > goto end;
> > > >
> > > > - if ((ret = avtext_context_open(&tctx, f, wctx, f_args,
> > > > - sections, FF_ARRAY_ELEMS(sections),
> > > show_value_unit,
> > > > - use_value_prefix,
> use_byte_value_binary_prefix,
> > > use_value_sexagesimal_format,
> > > > - show_optional_fields, show_data_hash)) >=
> 0) {
> > >
> > > > + AVTextFormatOptions tf_options = {
> > > > + .show_optional_fields = show_optional_fields,
> > > > + .show_value_unit = show_value_unit,
> > > > + .use_value_prefix = use_value_prefix,
> > > > + .use_byte_value_binary_prefix = use_byte_value_binary_prefix,
> > > > + .use_value_sexagesimal_format = use_value_sexagesimal_format,
> > > > + };
> > > > +
> > > > + if ((ret = avtext_context_open(&tctx, f, wctx, f_args, sections,
> > > FF_ARRAY_ELEMS(sections), tf_options, show_data_hash)) >= 0) {
> > > > if (f == &avtextformatter_xml)
> > > > tctx->string_validation_utf8_flags |=
> > > AV_UTF8_FLAG_EXCLUDE_XML_INVALID_CONTROL_CODES;
> > > >
> > > > diff --git a/fftools/textformat/avtextformat.c
> > > b/fftools/textformat/avtextformat.c
> > > > index b2c3aa3fc7..91469ef576 100644
> > > > --- a/fftools/textformat/avtextformat.c
> > > > +++ b/fftools/textformat/avtextformat.c
> > > > @@ -125,13 +125,7 @@ void avtext_context_close(AVTextFormatContext
> **ptctx)
> > > >
> > > >
> > > > int avtext_context_open(AVTextFormatContext **ptctx, const
> AVTextFormatter
> > > *formatter, AVTextWriterContext *writer_context, const char *args,
> > > > - const AVTextFormatSection *sections, int
> > > nb_sections,
> > > > - int show_value_unit,
> > > > - int use_value_prefix,
> > > > - int use_byte_value_binary_prefix,
> > > > - int use_value_sexagesimal_format,
> > > > - int show_optional_fields,
> > > > - char *show_data_hash)
> > > > + const AVTextFormatSection *sections, int
> > > nb_sections, AVTextFormatOptions options, char *show_data_hash)
> > > > {
> > > > AVTextFormatContext *tctx;
> > > > int i, ret = 0;
> > > > @@ -154,11 +148,11 @@ int avtext_context_open(AVTextFormatContext
> **ptctx,
> > > const AVTextFormatter *form
> > > > goto fail;
> > > > }
> > > >
> > > > - tctx->show_value_unit = show_value_unit;
> > > > - tctx->use_value_prefix = use_value_prefix;
> > > > - tctx->use_byte_value_binary_prefix = use_byte_value_binary_prefix;
> > > > - tctx->use_value_sexagesimal_format = use_value_sexagesimal_format;
> > > > - tctx->show_optional_fields = show_optional_fields;
> > > > + tctx->show_value_unit = options.show_value_unit;
> > > > + tctx->use_value_prefix = options.use_value_prefix;
> > > > + tctx->use_byte_value_binary_prefix =
> > > options.use_byte_value_binary_prefix;
> > > > + tctx->use_value_sexagesimal_format =
> > > options.use_value_sexagesimal_format;
> > > > + tctx->show_optional_fields = options.show_optional_fields;
> > > >
> > > > if (nb_sections > SECTION_MAX_NB_SECTIONS) {
> > > > av_log(tctx, AV_LOG_ERROR, "The number of section definitions
> (%d)
> > > is larger than the maximum allowed (%d)\n", nb_sections,
> > > SECTION_MAX_NB_SECTIONS);
> > > > @@ -201,7 +195,7 @@ int avtext_context_open(AVTextFormatContext **ptctx,
> > > const AVTextFormatter *form
> > > > av_dict_free(&opts);
> > > > }
> > > >
> > > > - if (show_data_hash)
> > > > + if (show_data_hash) {
> > > > if ((ret = av_hash_alloc(&tctx->hash, show_data_hash)) < 0) {
> > > > if (ret == AVERROR(EINVAL)) {
> > > > const char *n;
> > > > @@ -212,6 +206,7 @@ int avtext_context_open(AVTextFormatContext **ptctx,
> > > const AVTextFormatter *form
> > > > }
> > > > goto fail;
> > > > }
> > > > + }
> > > >
> > > > /* validate replace string */
> > > > {
> > > > diff --git a/fftools/textformat/avtextformat.h
> > > b/fftools/textformat/avtextformat.h
> > > > index 8ff503401a..87f57d8c24 100644
> > > > --- a/fftools/textformat/avtextformat.h
> > > > +++ b/fftools/textformat/avtextformat.h
> > > > @@ -117,17 +117,19 @@ struct AVTextFormatContext {
> > > > unsigned int string_validation_utf8_flags;
> > > > };
> > > >
> > > > +typedef struct AVTextFormatOptions {
> > > > + int show_optional_fields;
> > > > + int show_value_unit;
> > > > + int use_value_prefix;
> > > > + int use_byte_value_binary_prefix;
> > > > + int use_value_sexagesimal_format;
> > > > +} AVTextFormatOptions;
> > >
> > > I'm not yet convinced this is needed - why not to use a flags field as
> > > in most other places?
> >
> > Believe it or not, I actually had flags initially, but then I figured
> > how ugly this code:
> >
> > > > + AVTextFormatOptions tf_options = {
> > > > + .show_optional_fields = show_optional_fields,
> > > > + .show_value_unit = show_value_unit,
> > > > + .use_value_prefix = use_value_prefix,
> > > > + .use_byte_value_binary_prefix = use_byte_value_binary_prefix,
> > > > + .use_value_sexagesimal_format = use_value_sexagesimal_format,
> > > > + };
> > > > +
> >
>
> > ..would look like when assembling flags from the settings values and then
> > I changed to this way, which looks much cleaner and nicer.
> > This also allows adding non-bool options in the future without changing the
> > signature of avtextformat_open().
>
> My concern was mostly about this not being very FFmpeg-ish as this is
> a pattern not very much applied in FFmpeg (probably the only
> instance?).
It's the only case where it is called "options", but otherwise it's an
existing pattern to have an *_open() function which takes a struct that
holds configuration data like AVInputFormat in avformat_open_input().
In other cases, we APIs where all settings are specified as function
parameters like avio_alloc_context() - that's more like we had it before
where you said that these are too many parameters for the open function.
Another frequent pattern is to have a separate *_alloc_context() function
without any parameters where the parameters are on the context object
and you do:
- *_alloc_context()
- set params on the context object
_ *_open_context(XXContext *ctx)
We could do that, but with this pattern, it's always unclear which
parts of the struct are meant to be set by the caller and which are
populated by the *_open() function - at least in cases where the
context struct is rather complex like in our case.
Once another way would be to keep AVTextFormatOptions and
avtext_context_open() as I'm proposing but make AVTextFormatOptions
part of AVTextFormatContext - like as 'options' - and the
avtext_context_open() would then set the options to the supplied
ones with a single assignment.
All accesses would need to be changed then like from
tctx->show_value_unit to tctx->options.show_value_unit
We could also call it 'config' and AVTextFormatConfig to
disambiguate from user-supplied (cli) options.
> A more FFmpeg-ish solution would be to have a context with
> options.
I don't think that this is a good idea because that would mean that
you must either expose those options as a child object in some
way to become considered as "receiver" when options are applied
or otherwise, you would need to construct a string first (before
calling avtext_context_open() and have it parsed immediately
afterwards (inside the open function) to get them applied.
> Anyway feel free to consider this an idea for a further
> improvement rather than a blocker.
Yea, I don't see a clearly better way at the moment, but we
can change it any time later once there is one.
Thanks,
sw
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