[FFmpeg-devel] [PATCH 3/4] fftools/graph/graphprint: load CSS and HTML resources from ffmpeg data directories
softworkz .
softworkz at hotmail.com
Sat May 17 20:22:03 EEST 2025
> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of Marton
> Balint
> Sent: Samstag, 17. Mai 2025 11:14
> To: FFmpeg development discussions and patches <ffmpeg-devel at ffmpeg.org>
> Subject: Re: [FFmpeg-devel] [PATCH 3/4] fftools/graph/graphprint: load CSS and
> HTML resources from ffmpeg data directories
>
>
>
> On Sat, 17 May 2025, softworkz . wrote:
>
> >
> >
> >> -----Original Message-----
> >> From: ffmpeg-devel <ffmpeg-devel-bounces at ffmpeg.org> On Behalf Of Marton
> >> Balint
> >> Sent: Samstag, 17. Mai 2025 01:09
> >> To: ffmpeg-devel at ffmpeg.org
> >> Cc: Marton Balint <cus at passwd.hu>
> >> Subject: [FFmpeg-devel] [PATCH 3/4] fftools/graph/graphprint: load CSS and
> >> HTML resources from ffmpeg data directories
> >>
> >> Similar to how it is done for ffpreset files. This allows the users to
> change
> >> the HTML/CSS templates at will.
> >>
> >> Signed-off-by: Marton Balint <cus at passwd.hu>
> >> ---
> >> Makefile | 2 +-
> >> doc/ffmpeg.texi | 4 ++-
> >> fftools/cmdutils.c | 48 +++++++++++++++++++++++++++++++++
> >> fftools/cmdutils.h | 2 ++
> >> fftools/graph/graphprint.c | 16 ++++++++---
> >> fftools/textformat/tf_mermaid.h | 4 +--
> >> 6 files changed, 68 insertions(+), 8 deletions(-)
> >>
> >> diff --git a/Makefile b/Makefile
> >> index e2250f6bc6..ebc50bb510 100644
> >> --- a/Makefile
> >> +++ b/Makefile
> >> @@ -32,7 +32,7 @@ FFLIBS-$(CONFIG_SWSCALE) += swscale
> >>
> >> FFLIBS := avutil
> >>
> >> -DATA_FILES := $(wildcard $(SRC_PATH)/presets/*.ffpreset)
> >> $(SRC_PATH)/doc/ffprobe.xsd
> >> +DATA_FILES := $(wildcard $(SRC_PATH)/presets/*.ffpreset)
> >> $(SRC_PATH)/doc/ffprobe.xsd $(SRC_PATH)/fftools/resources/graph.css
> >> $(SRC_PATH)/fftools/resources/graph.html
> >>
> >> SKIPHEADERS = compat/w32pthreads.h
> >>
> >> diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
> >> index 35675b5309..8edf188ab9 100644
> >> --- a/doc/ffmpeg.texi
> >> +++ b/doc/ffmpeg.texi
> >> @@ -1402,7 +1402,9 @@ Writes execution graph details to the specified file
> in
> >> the format set via -prin
> >>
> >> @item -print_graphs_format @var{format} (@emph{global})
> >> Sets the output format (available formats are: default, compact, csv,
> flat,
> >> ini, json, xml, mermaid, mermaidhtml)
> >> -The default format is json.
> >> +The default format is json. The mermarid and mermaidhtml formats need
> >> graph.css
> >> +and graph.html resources which are searched in the FFMPEG data
> directories,
> >> +similar to ffpreset files.
> >>
> >> @item -progress @var{url} (@emph{global})
> >> Send program-friendly progress information to @var{url}.
> >> diff --git a/fftools/cmdutils.c b/fftools/cmdutils.c
> >> index 1de670c2e4..01e57d91e8 100644
> >> --- a/fftools/cmdutils.c
> >> +++ b/fftools/cmdutils.c
> >> @@ -1005,6 +1005,54 @@ FILE *get_preset_file(AVBPrint *filename,
> >> return f;
> >> }
> >>
> >> +int file_read_from_datadir(const char *filename, char **outbuf)
> >> +{
> >> + FILE *f;
> >> + char *buf = NULL;
> >> + long size;
> >> + AVBPrint bp;
> >> +
> >> + av_bprint_init(&bp, 0, AV_BPRINT_SIZE_UNLIMITED);
> >> + f = get_datadir_file_fmt(&bp, "%s", filename);
> >> + if (!f)
> >> + return AVERROR(errno);
> >> +
> >> + if (fseek(f, 0, SEEK_END)) {
> >> + int ret = AVERROR(errno);
> >> + fclose(f);
> >> + return ret;
> >> + }
> >> +
> >> + size = ftell(f);
> >> + if (size < 0 || size >= INT_MAX) {
> >> + fclose(f);
> >> + return AVERROR(EINVAL);
> >> + }
> >> +
> >> + if (fseek(f, 0, SEEK_SET)) {
> >> + int ret = AVERROR(errno);
> >> + fclose(f);
> >> + return ret;
> >> + }
> >> +
> >> + buf = av_malloc(size + 1);
> >> + if (!buf) {
> >> + fclose(f);
> >> + return AVERROR(ENOMEM);
> >> + }
> >> +
> >> + if (fread(buf, 1, size, f) != size) {
> >> + fclose(f);
> >> + return AVERROR(EIO);
> >> + }
> >> + buf[size] = 0;
> >> +
> >> + fclose(f);
> >> +
> >> + *outbuf = buf;
> >> + return 0;
> >> +}
> >> +
> >> int cmdutils_isalnum(char c)
> >> {
> >> return (c >= '0' && c <= '9') ||
> >> diff --git a/fftools/cmdutils.h b/fftools/cmdutils.h
> >> index 216a2bcfe7..b324e5fc65 100644
> >> --- a/fftools/cmdutils.h
> >> +++ b/fftools/cmdutils.h
> >> @@ -504,6 +504,8 @@ int read_yesno(void);
> >> FILE *get_preset_file(AVBPrint *filename,
> >> const char *preset_name, int is_path, const char
> >> *codec_name);
> >>
> >> +int file_read_from_datadir(const char *filename, char **buf);
> >> +
> >> /**
> >> * Realloc array to hold new_size elements of elem_size.
> >> *
> >> diff --git a/fftools/graph/graphprint.c b/fftools/graph/graphprint.c
> >> index fc94a75797..fbcb7f1b75 100644
> >> --- a/fftools/graph/graphprint.c
> >> +++ b/fftools/graph/graphprint.c
> >> @@ -41,7 +41,6 @@
> >> #include "libavutil/hwcontext.h"
> >> #include "fftools/textformat/avtextformat.h"
> >> #include "fftools/textformat/tf_mermaid.h"
> >> -#include "fftools/resources/resman.h"
> >>
> >> typedef enum {
> >> SECTION_ID_ROOT,
> >> @@ -935,10 +934,19 @@ static int init_graphprint(GraphPrintContext **pgpc,
> >> AVBPrint *target_buf)
> >> }
> >>
> >> if (!strcmp(text_formatter->name, "mermaid") ||
> !strcmp(text_formatter-
> >>> name, "mermaidhtml")) {
> >> - gpc->diagram_config.diagram_css =
> >> ff_resman_get_string(FF_RESOURCE_GRAPH_CSS);
> >> + ret = file_read_from_datadir("graph.css", &gpc-
> >>> diagram_config.diagram_css);
> >> + if (ret < 0) {
> >> + av_log(NULL, AV_LOG_ERROR, "graph.css needed for mermaid graph
> >> format cannot be opened: %s\n", av_err2str(ret));
> >> + goto fail;
> >> + }
> >>
> >> - if (!strcmp(text_formatter->name, "mermaidhtml"))
> >> - gpc->diagram_config.html_template =
> >> ff_resman_get_string(FF_RESOURCE_GRAPH_HTML);
> >> + if (!strcmp(text_formatter->name, "mermaidhtml")) {
> >> + ret = file_read_from_datadir("graph.html", &gpc-
> >>> diagram_config.html_template);
> >> + if (ret < 0) {
> >> + av_log(NULL, AV_LOG_ERROR, "graph.html needed for
> >> mermaridhtml graph format cannot be opened: %s\n", av_err2str(ret));
> >> + goto fail;
> >> + }
> >> + }
> >>
> >> av_diagram_init(tfc, &gpc->diagram_config);
> >> }
> >> diff --git a/fftools/textformat/tf_mermaid.h
> b/fftools/textformat/tf_mermaid.h
> >> index 6e8f2a9b42..0b34d8ab20 100644
> >> --- a/fftools/textformat/tf_mermaid.h
> >> +++ b/fftools/textformat/tf_mermaid.h
> >> @@ -28,8 +28,8 @@ typedef enum {
> >>
> >> typedef struct AVDiagramConfig {
> >> AVDiagramType diagram_type;
> >> - const char *diagram_css;
> >> - const char *html_template;
> >> + char *diagram_css;
> >> + char *html_template;
> >> } AVDiagramConfig;
> >>
> >>
> >> --
> >
> > NAK - I totally disagree to this change
> >
> >
> > 1. It makes the feature widely unusable. In all those years I've never seen
> > or dealt with an "FFmpeg data folder" and I know that everywhere I would
> > want to use this feature, there's no such folder nor files
>
> Using external folders for resources is quite common, admittedly not in
> ffmpeg, but for other programs it is.
>
> >
> > 2. The html and the CSS are in no way like exchangeable templates. They are
> > part of the implementation of the feature - especially the CSS.
> > Another - yet unsubmitted - feature (data schema graphs) will have its
> > own and different html and css, which is also very specific.
> >
> > 3. Even when considering the files as something different than templates,
> > this will still not fly. The code in FFmpeg is tightly coupled and
> > dependent of the html and css. When the feature gets updated or extended
> > this will almost certainly include changes to the css, which means that
> > it would be incompatible with the css from a different FFmpeg version.
> > There's no logical independence and hence the files cannot be delivered
> > separately
>
> If that is the case, then I am not sure if it is a good idea to maintain
> the styling of these output variants embedded in ffmpeg CLI.
For styling Mermaid diagrams, the CSS must be part of the Mermaid graph
definition - this is what is taken from the CSS resource file. It gets
transformed and escaped into the Mermaid definition.
When you specify -print_graphs_format mermaid, then you get the plain
Mermaid definition as a valid .mmd (or .mermaid) file - all without a
CDN. Then you can open that in an application or just copy/paste it into
a code block in most Markdown system. You might need to care about the
version, though. For example to make it work in the current GitHub Markdown,
you need to specify an extra parameter (until GitHub updates their Mermaid
libs).
So far, this is all offline. In earlier versions, I had the CSS included
in plain C strings, but I thought it would be a better practice to include
it as compressed resource, to optimize the size of the binaries and that
allowed to reduce it to 25% of the size.
This route (mermaid format) is also the way to got when you want to embed
the diagram a custom html document, but then you are responsible for any
compatibility issues.
The mermaidhtml output on the other hand is the reliable and quick way
when you just want to see the diagram that always works without any worries
and without any pre-conditions.
The compressed sizes are about 1k for the html and 2.5k for the CSS, that
really not that big and it doesn't got into any libs, just the ffmpeg
binary. Given the high value of the feature, I do believe that this is
more than justified.
> Considering that you already depend on CDNs, IMHO it would make more sense
> to generate some minimal HTML with the graph data embedded in JSON in it,
> and then generate the required mermarid format via JS also loaded from
> some CDN, or even better, ffmpeg.org.
That doesn't work, because for the Mermaid creation, the AVTextFormat APIs
have a few extension features which are giving some extra information that
is not included in the plain JSON output.
Thanks for your interest in the feature,
sw
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