[FFmpeg-devel] avfilter/image2: Add source file path and basename to each packet side data.

It didn't work. For some reason, when I send the patch, entries like this:

+@item
+Plot special @var{source_basename} metadata, extracted from each input 
frame, or
+the string "NA" if the metadata is not defined.
+@example
+drawtext="fontsize=20:fontcolor=white:fontfile=FreeSans.ttf:text='%{metadata\:source_basename\:NA}':x=10:y=10"
+@end example
+

become this:

+ at item
+Plot special @var{source_basename} metadata, extracted from each input 
frame, or
+the string "NA" if the metadata is not defined.
+ at example
+drawtext="fontsize=20:fontcolor=white:fontfile=FreeSans.ttf:text='%{metadata\:source_basename\:NA}':x=10:y=10"
+ at end example
+

So I'm attaching the patch to make life easier.

Thank you!

Alex.

On 16/12/2019 22:26, Alexandre Heitor Schmidt wrote:
> This is the second time I'm submiting this patch, now modified to be
> less intrusive, as sugested by Marton Balint, and hopefully without git
> send-email messing up with the diff by replacing '@' within
> documentation entries.
>
> The patch modifies image2 filter to make available two special metadata
> entries called source_path and source_file, which represents,
> respectively, the complete path to the source image for the current
> frame and the basename i.e. the file name related to the current frame.
> These can then be used by filters like drawtext and others.
>
> doc/filters: The documentation for drawtext was also updated and an usage
> example was added.
>
> Fixes #2874.
>
> Signed-off-by: Alexandre Heitor Schmidt <alexandre.schmidt@gmail.com>
> ---
>   doc/filters.texi      | 15 +++++++++++++--
>   libavformat/img2.h    |  2 ++
>   libavformat/img2dec.c | 28 ++++++++++++++++++++++++++++
>   3 files changed, 43 insertions(+), 2 deletions(-)
>
> diff --git a/doc/filters.texi b/doc/filters.texi
> index c543203ce3..15498aee0d 100644
> --- a/doc/filters.texi
> +++ b/doc/filters.texi
> @@ -9723,8 +9723,12 @@ Available metadata can be identified by inspecting entries
>   starting with TAG included within each frame section
>   printed by running @code{ffprobe -show_frames}.
>   
> -String metadata generated in filters leading to
> -the drawtext filter are also available.
> +String metadata generated in filters leading to the drawtext filter are also
> +available. For example, image2 filter generates two special metadata fields
> +called @var{source_path} and @var{source_basename} for each input frame
> +generated from a single image. @var{source_path} contains the entire path
> +to input filename, while @var{source_basename} contains the equivalent
> +to @code{basename(source_path)}.
>   
>   @item n, frame_num
>   The frame number, starting from 0.
> @@ -9872,6 +9876,13 @@ drawtext=fontfile=FreeSans.ttf:text=DOG:fontsize=24:x=10:y=20+24-max_glyph_a,
>   drawtext=fontfile=FreeSans.ttf:text=cow:fontsize=24:x=80:y=20+24-max_glyph_a
>   @end example
>   
> +@item
> +Plot special @var{source_basename} metadata, extracted from each input frame, or
> +the string "NA" if the metadata is not defined.
> +@example
> +drawtext="fontsize=20:fontcolor=white:fontfile=FreeSans.ttf:text='%{metadata\:source_basename\:NA}':x=10:y=10"
> +@end example
> +
>   @end itemize
>   
>   For more information about libfreetype, check:
> diff --git a/libavformat/img2.h b/libavformat/img2.h
> index 0e5b374a6b..8208c1f58b 100644
> --- a/libavformat/img2.h
> +++ b/libavformat/img2.h
> @@ -74,5 +74,7 @@ extern const AVOption ff_img_options[];
>   
>   int ff_img_read_header(AVFormatContext *s1);
>   
> +int add_filename_as_pkt_side_data(char *filename, AVPacket *pkt);
> +
>   int ff_img_read_packet(AVFormatContext *s1, AVPacket *pkt);
>   #endif
> diff --git a/libavformat/img2dec.c b/libavformat/img2dec.c
> index f8b4a655a5..3fb7aa7967 100644
> --- a/libavformat/img2dec.c
> +++ b/libavformat/img2dec.c
> @@ -374,6 +374,32 @@ int ff_img_read_header(AVFormatContext *s1)
>       return 0;
>   }
>   
> +/**
> + * Add this frame's source path and basename to packet's sidedata
> + * as a dictionary, so it can be used by filters like 'drawtext'.
> + */
> +int add_filename_as_pkt_side_data(char *filename, AVPacket *pkt) {
> +    uint8_t* metadata;
> +    int metadata_len;
> +    AVDictionary *d = NULL;
> +    char *packed_metadata = NULL;
> +
> +    av_dict_set(&d, "source_path", filename, 0);
> +    av_dict_set(&d, "source_basename", av_basename(filename), 0);
> +
> +    packed_metadata = av_packet_pack_dictionary(d, &metadata_len);
> +    if (!packed_metadata)
> +        return AVERROR(ENOMEM);
> +    if (!(metadata = av_packet_new_side_data(pkt, AV_PKT_DATA_STRINGS_METADATA, metadata_len))) {
> +        av_freep(&packed_metadata);
> +        return AVERROR(ENOMEM);
> +    }
> +    memcpy(metadata, packed_metadata, metadata_len);
> +    av_freep(&packed_metadata);
> +
> +    return 0;
> +}
> +
>   int ff_img_read_packet(AVFormatContext *s1, AVPacket *pkt)
>   {
>       VideoDemuxData *s = s1->priv_data;
> @@ -485,6 +511,8 @@ int ff_img_read_packet(AVFormatContext *s1, AVPacket *pkt)
>   
>       if (s->is_pipe)
>           pkt->pos = avio_tell(f[0]);
> +    else if ( (res = add_filename_as_pkt_side_data(filename, pkt)) != 0 )
> +        goto fail;
>   
>       pkt->size = 0;
>       for (i = 0; i < 3; i++) {