player: add track-list/N/image sub-property

This exposes whether a video track is detected as an image, which is
useful for profile conditions, property expansion and lavfi-complex.

The lavf demuxer sets image to true when the existing check detects an
image.

When the lavf demuxer fails, the mf one guesses if the file is an image
by its extension, so sh->image is set to true when the mf demuxer
succeds and there's only one file.

The mkv demuxer just sets image to true for any attached picture.

The timeline demuxer just copies the value of image from source to
destination. This sets image to true for attached pictures, standalone
images and images added with !new_stream in EDL playlists, but it is
imperfect since you could concatenate multiple images in an EDL playlist
(which should be done with the mf demuxer anyway). This is good enough
anyway since the comment of the modified function already says it is
"Imperfect and arbitrary".

DOCS/interface-changes.rst

@@ -45,6 +45,7 @@ Interface changes
     - make `current-window-scale` writeable and use it in the default input.conf
     - add `--input-builtin-bindings` flag to control loading of built-in key
       bindings during start-up (default: yes).
+    - add ``track-list/N/image`` sub-property
 
  --- mpv 0.33.0 ---
     - add `--d3d11-exclusive-fs` flag to enable D3D11 exclusive fullscreen mode

DOCS/man/input.rst

@@ -2838,11 +2838,15 @@ Property list
     ``track-list/N/lang``
         Track language as identified by the file. Not always available.
 
-    ``track-list/N/albumart``
+    ``track-list/N/image``
         ``yes``/true if this is a video track that consists of a single
-        picture, ``no``/false or unavailable otherwise. This is used for video
-        tracks that are really images embedded in audio files and for external
-        cover art.
+        picture, ``no``/false or unavailable otherwise. The heuristic used to
+        determine if a stream is an image doesn't attempt to detect images in
+        codecs normally used for videos. Otherwise, it is reliable.
+
+    ``track-list/N/albumart``
+        ``yes``/true if this is an image embedded in an audio file or external
+        cover art, ``no``/false or unavailable otherwise.
 
     ``track-list/N/default``
         ``yes``/true if the track has the default flag set in the file,
@@ -2936,6 +2940,7 @@ Property list
                 "src-id"            MPV_FORMAT_INT64
                 "title"             MPV_FORMAT_STRING
                 "lang"              MPV_FORMAT_STRING
+                "image"             MPV_FORMAT_FLAG
                 "albumart"          MPV_FORMAT_FLAG
                 "default"           MPV_FORMAT_FLAG
                 "forced"            MPV_FORMAT_FLAG

demux/demux_lavf.c

@@ -714,6 +714,7 @@ static void handle_new_stream(demuxer_t *demuxer, int i)
                 strcmp(priv->avif->name, "image2pipe") == 0
             )) {
             MP_VERBOSE(demuxer, "Assuming this is an image format.\n");
+            sh->image = true;
             sh->codec->fps = priv->mf_fps;
         }
         sh->codec->par_w = st->sample_aspect_ratio.num;

demux/demux_mf.c

@@ -381,8 +381,12 @@ static int demux_open_mf(demuxer_t *demuxer, enum demux_check check)
 
     // create a new video stream header
     struct sh_stream *sh = demux_alloc_sh_stream(STREAM_VIDEO);
-    struct mp_codec_params *c = sh->codec;
+    if (mf->nr_of_files == 1) {
+        MP_VERBOSE(demuxer, "Assuming this is an image format.\n");
+        sh->image = true;
+    }
 
+    struct mp_codec_params *c = sh->codec;
     c->codec = codec;
     c->disp_w = 0;
     c->disp_h = 0;

demux/demux_mkv.c

@@ -1300,6 +1300,7 @@ static void add_coverart(struct demuxer *demuxer)
             sh->attached_picture->pts = 0;
             talloc_steal(sh, sh->attached_picture);
             sh->attached_picture->keyframe = true;
+            sh->image = true;
         }
         sh->title = att->name;
         demux_add_sh_stream(demuxer, sh);

demux/demux_timeline.c

@@ -525,6 +525,7 @@ static void apply_meta(struct sh_stream *dst, struct sh_stream *src)
     dst->missing_timestamps = src->missing_timestamps;
     if (src->attached_picture)
         dst->attached_picture = src->attached_picture;
+    dst->image = src->image;
 }
 
 // This is mostly for EDL user-defined metadata.

demux/stheader.h

@@ -48,6 +48,7 @@ struct sh_stream {
     bool dependent_track;       // container dependent track flag
     bool visual_impaired_track; // container flag
     bool hearing_impaired_track;// container flag
+    bool image;                 // video stream is an image
     bool still_image;           // video stream contains still images
     int hls_bitrate;
 

player/command.c

@@ -1949,6 +1949,7 @@ static int get_track_entry(int item, int action, void *arg, void *ctx)
                         .unavailable = !track->lang},
         {"audio-channels", SUB_PROP_INT(track_channels(track)),
                         .unavailable = track_channels(track) <= 0},
+        {"image",       SUB_PROP_FLAG(track->image)},
         {"albumart",    SUB_PROP_FLAG(track->attached_picture)},
         {"default",     SUB_PROP_FLAG(track->default_track)},
         {"forced",      SUB_PROP_FLAG(track->forced_track)},

player/core.h

@@ -136,6 +136,7 @@ struct track {
     char *title;
     bool default_track, forced_track, dependent_track;
     bool visual_impaired_track, hearing_impaired_track;
+    bool image;
     bool attached_picture;
     char *lang;
 

player/loadfile.c

@@ -421,6 +421,7 @@ static struct track *add_stream_track(struct MPContext *mpctx,
         .dependent_track = stream->dependent_track,
         .visual_impaired_track = stream->visual_impaired_track,
         .hearing_impaired_track = stream->hearing_impaired_track,
+        .image = stream->image,
         .attached_picture = stream->attached_picture != NULL,
         .lang = stream->lang,
         .demuxer = demuxer,