player: add automatic loading of external cover art files

Picks up files like "cover.jpg". It's made part of normal external file
loading, so I'm adding 3 new options that are direct equivalents for the
options that control loading of external subtitle and audio files. Even
though I bet nobody wants them and they just increase confusion... I
guess the world is actually hell, so this outcome should be fine.

It prefers non-specific external files like "cover.jpg" over embedded
cover art. Not sure if that's wanted or unwanted.

There's some pain over explicitly marking such files as external
pictures. This is basically an optimization: in most cases, a heuristic
would treat an image file loaded with --external-file the same (it's a
heuristic because ffmpeg can't tell us whether something is an image or
a video). However, even with this heuristic, it would decode the cover
art picture again on each seek, which would essentially slow down
seeking in audio files. This bothered me greatly, which is why I'm
adding these additional options at all, and bothered with the previous
commit.

Fixes: #3056

3 files changed, 50 insertions, 5 deletions

diff --git a/player/external_files.c b/player/external_files.c
index 69610642d2..40fad916ef 100644
--- a/player/external_files.c
+++ b/player/external_files.c
@@ -42,6 +42,25 @@ static const char *const audio_exts[] = {"mp3", "aac", "mka", "dts", "flac",
                                          "wv",
                                          NULL};
 
+// Stolen from: vlc/-/blob/master/modules/meta_engine/folder.c#L40
+static const char *const cover_files[] = {
+    "Folder.jpg",
+    "Folder.png",
+    "AlbumArtSmall.jpg",
+    "AlbumArt.jpg",
+    "Album.jpg",
+    ".folder.png",
+    "cover.jpg",
+    "cover.png",
+    "cover.gif",
+    "front.jpg",
+    "front.png",
+    "front.gif",
+    "front.bmp",
+    "thumb.jpg",
+    NULL
+};
+
 static bool test_ext_list(bstr ext, const char *const *list)
 {
     for (int n = 0; list[n]; n++) {
@@ -60,6 +79,15 @@ static int test_ext(bstr ext)
     return -1;
 }
 
+static int test_filename(bstr fname)
+{
+    for (int n = 0; cover_files[n]; n++) {
+        if (bstrcasecmp(bstr0(cover_files[n]), fname) == 0)
+            return STREAM_VIDEO;
+    }
+    return -1;
+}
+
 bool mp_might_be_subtitle_file(const char *filename)
 {
     return test_ext(bstr_get_ext(bstr0(filename))) == STREAM_SUB;
@@ -159,6 +187,8 @@ static void append_dir_subtitles(struct mpv_global *global, struct MPOpts *opts,
 
         // check what it is (most likely)
         int type = test_ext(tmp_fname_ext);
+        if (type < 0)
+            type = test_filename(dename);
         char **langs = NULL;
         int fuzz = -1;
         switch (type) {
@@ -170,6 +200,9 @@ static void append_dir_subtitles(struct mpv_global *global, struct MPOpts *opts,
             langs = opts->stream_lang[type];
             fuzz = opts->audiofile_auto;
             break;
+        case STREAM_VIDEO:
+            fuzz = opts->coverart_auto;
+            break;
         }
 
         if (fuzz < 0 || (limit_type >= 0 && limit_type != type))
@@ -210,6 +243,10 @@ static void append_dir_subtitles(struct mpv_global *global, struct MPOpts *opts,
         if (!limit_fuzziness && fuzz >= 2)
             prio |= 1;
 
+        // cover art: just accept it
+        if (type == STREAM_VIDEO && fuzz >= 1)
+            prio |= 1;
+
         mp_dbg(log, "Potential external file: \"%s\"  Priority: %d\n",
                de->d_name, prio);
 
diff --git a/player/external_files.h b/player/external_files.h
index d2de60ee5e..e64f249c6d 100644
--- a/player/external_files.h
+++ b/player/external_files.h
@@ -21,7 +21,7 @@
 #include <stdbool.h>
 
 struct subfn {
-    int type; // STREAM_SUB/STREAM_AUDIO
+    int type; // STREAM_SUB/STREAM_AUDIO/STREAM_VIDEO(coverart)
     int priority;
     char *fname;
     char *lang;
diff --git a/player/loadfile.c b/player/loadfile.c
index b5ae9c0212..cb6c1060d7 100644
--- a/player/loadfile.c
+++ b/player/loadfile.c
@@ -827,6 +827,8 @@ int mp_add_external_file(struct MPContext *mpctx, char *filename,
         t->external_filename = talloc_strdup(t, filename);
         t->no_default = sh->type != filter;
         t->no_auto_select = t->no_default;
+        // filter==STREAM_VIDEO always means cover art.
+        t->attached_picture = t->type == STREAM_VIDEO && filter == STREAM_VIDEO;
         if (first_num < 0 && (filter == STREAM_TYPE_COUNT || sh->type == filter))
             first_num = mpctx->num_tracks - 1;
     }
@@ -859,14 +861,15 @@ static void open_external_files(struct MPContext *mpctx, char **files,
 // See mp_add_external_file() for meaning of cancel parameter.
 void autoload_external_files(struct MPContext *mpctx, struct mp_cancel *cancel)
 {
-    if (mpctx->opts->sub_auto < 0 && mpctx->opts->audiofile_auto < 0)
+    struct MPOpts *opts = mpctx->opts;
+
+    if (opts->sub_auto < 0 && opts->audiofile_auto < 0 && opts->coverart_auto < 0)
         return;
-    if (!mpctx->opts->autoload_files || strcmp(mpctx->filename, "-") == 0)
+    if (!opts->autoload_files || strcmp(mpctx->filename, "-") == 0)
         return;
 
     void *tmp = talloc_new(NULL);
-    struct subfn *list = find_external_files(mpctx->global, mpctx->filename,
-                                             mpctx->opts);
+    struct subfn *list = find_external_files(mpctx->global, mpctx->filename, opts);
     talloc_steal(tmp, list);
 
     int sc[STREAM_TYPE_COUNT] = {0};
@@ -887,6 +890,8 @@ void autoload_external_files(struct MPContext *mpctx, struct mp_cancel *cancel)
             goto skip;
         if (list[i].type == STREAM_AUDIO && !sc[STREAM_VIDEO])
             goto skip;
+        if (list[i].type == STREAM_VIDEO && (sc[STREAM_VIDEO] || !sc[STREAM_AUDIO]))
+            goto skip;
         int first = mp_add_external_file(mpctx, filename, list[i].type, cancel);
         if (first < 0)
             goto skip;
@@ -894,6 +899,8 @@ void autoload_external_files(struct MPContext *mpctx, struct mp_cancel *cancel)
         for (int n = first; n < mpctx->num_tracks; n++) {
             struct track *t = mpctx->tracks[n];
             t->auto_loaded = true;
+            t->attached_picture =
+                t->type == STREAM_VIDEO && list[i].type == STREAM_VIDEO;
             if (!t->lang)
                 t->lang = talloc_strdup(t, lang);
         }
@@ -1364,6 +1371,7 @@ static void load_external_opts_thread(void *p)
     load_chapters(mpctx);
     open_external_files(mpctx, mpctx->opts->audio_files, STREAM_AUDIO);
     open_external_files(mpctx, mpctx->opts->sub_name, STREAM_SUB);
+    open_external_files(mpctx, mpctx->opts->coverart_files, STREAM_VIDEO);
     open_external_files(mpctx, mpctx->opts->external_files, STREAM_TYPE_COUNT);
     autoload_external_files(mpctx, mpctx->playback_abort);