Re: [FFmpeg-devel] [PATCH 3/4] fftools/graph/graphprint: load CSS and HTML resources from ffmpeg data directories

[Marton Balint <cus@passwd.hu>]

On Sat, 17 May 2025, softworkz . wrote:

>
>
>> -----Original Message-----
>> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of Marton
>> Balint
>> Sent: Samstag, 17. Mai 2025 01:09
>> To: ffmpeg-devel@ffmpeg.org
>> Cc: Marton Balint <cus@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@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.

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.

Thanks,
Marton
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