test: add default track selection testing

The amount of options we have that are related track selection is insane
and touching any of this stuff is scary. Add some track selection
testing to the CI to hopefully make it slightly less scary to touch any
of that. Since trying to work in media files from some outside source
would be a pain and need to live in some repo somewhere, it's nicer to
just generate dummy files on the fly with ffmpeg during the ci runs and
use that. Obviously, the actual tests themselves could be even more
thorough (external tracks were not even considered), but this is more
than a good enough start for now.

test/libmpv_common.h

@@ -85,6 +85,7 @@ static inline void check_api_error(int status)
 static inline void initialize(void)
 {
     check_api_error(mpv_set_option_string(ctx, "vo", "null"));
+    check_api_error(mpv_set_option_string(ctx, "ao", "null"));
     check_api_error(mpv_request_log_messages(ctx, "debug"));
     check_api_error(mpv_initialize(ctx));
 }

test/libmpv_test_track_selection.c

@@ -0,0 +1,194 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * mpv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <unistd.h>
+#include "libmpv_common.h"
+
+static void check_string(const char *property, const char *expect)
+{
+    char *result_string;
+    check_api_error(mpv_get_property(ctx, property, MPV_FORMAT_STRING, &result_string));
+    if (strcmp(expect, result_string) != 0)
+        fail("String: expected '%s' but got '%s'!\n", expect, result_string);
+    mpv_free(result_string);
+}
+
+static void wait_for_file_load(void)
+{
+    bool loaded = false;
+    while (!loaded) {
+        mpv_event *event = wrap_wait_event();
+        switch (event->event_id) {
+        case MPV_EVENT_FILE_LOADED:
+            loaded = true;
+            break;
+        }
+    }
+}
+
+static void test_track_selection(char *file, char *path)
+{
+    int ret = access(path, F_OK);
+    if (ret)
+        fail("Test file, '%s', was not found!\n", path);
+
+    const char *cmd[] = {"loadfile", path, NULL};
+    if (strcmp(file, "eng_default.mkv") == 0) {
+        // --no-config
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/sub/selected", "yes");
+
+        // --subs-falback=no
+        check_api_error(mpv_set_property_string(ctx, "subs-fallback", "no"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("track-list/2/selected", "no");
+
+        // reset options to defaults
+        check_api_error(mpv_set_property_string(ctx, "subs-fallback", "default"));
+    } else if (strcmp(file, "eng_default_forced.mkv") == 0) {
+        // --subs-fallback-forced=no
+        check_api_error(mpv_set_property_string(ctx, "subs-fallback-forced", "no"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/sub/selected", "yes");
+
+        // reset options to defaults
+        check_api_error(mpv_set_property_string(ctx, "subs-fallback-forced", "yes"));
+    } else if (strcmp(file, "eng_forced_matching_audio.mkv") == 0) {
+        // select forced track
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/sub/selected", "yes");
+    } else if (strcmp(file, "eng_forced_no_matching_audio.mkv") == 0) {
+        // forced track should not be selected
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("track-list/2/selected", "no");
+    } else if (strcmp(file, "eng_forced_always_audio.mkv") == 0) {
+        // forced track should be selected anyway despite no matching audio
+        check_api_error(mpv_set_property_string(ctx, "subs-fallback-forced", "always"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/sub/selected", "yes");
+    } else if (strcmp(file, "eng_no_default.mkv") == 0) {
+        // track should not be selected
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("track-list/2/selected", "no");
+
+        // --subs-fallback=yes
+        check_api_error(mpv_set_property_string(ctx, "subs-fallback", "yes"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/sub/selected", "yes");
+
+        // reset options to defaults
+        check_api_error(mpv_set_property_string(ctx, "subs-fallback", "default"));
+    } else if (strcmp(file, "multilang.mkv") == 0) {
+        // --alang=jpn should select forced jpn subs
+        check_api_error(mpv_set_property_string(ctx, "alang", "jpn"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/audio/lang", "jpn");
+        check_string("current-tracks/sub/lang", "jpn");
+
+        // --alang=pol should select default, non-forced ger subs
+        check_api_error(mpv_set_property_string(ctx, "alang", "pol"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/audio/lang", "pol");
+        check_string("current-tracks/sub/lang", "ger");
+
+        // --slang=eng and --subs-with-matching-audio should not pick any subs
+        check_api_error(mpv_set_property_string(ctx, "alang", "eng"));
+        check_api_error(mpv_set_property_string(ctx, "slang", "eng"));
+        check_api_error(mpv_set_property_string(ctx, "subs-with-matching-audio", "no"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/audio/lang", "eng");
+        check_string("track-list/5/selected", "no");
+        check_string("track-list/6/selected", "no");
+        check_string("track-list/7/selected", "no");
+        check_string("track-list/8/selected", "no");
+
+        // --subs-with-matching-audio=forced checks
+        check_api_error(mpv_set_property_string(ctx, "subs-with-matching-audio", "forced"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/audio/lang", "eng");
+        check_string("current-tracks/sub/lang", "eng");
+
+        // forced jpn subs should be selected
+        check_api_error(mpv_set_property_string(ctx, "alang", "jpn"));
+        check_api_error(mpv_set_property_string(ctx, "slang", "jpn"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/audio/lang", "jpn");
+        check_string("current-tracks/sub/lang", "jpn");
+
+        // default+forced eng subs should be selected
+        check_api_error(mpv_set_property_string(ctx, "alang", "ger"));
+        check_api_error(mpv_set_property_string(ctx, "slang", "ger"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/audio/lang", "ger");
+        check_string("current-tracks/sub/lang", "eng");
+
+        // eng audio and pol subs should be selected
+        check_api_error(mpv_set_property_string(ctx, "alang", "it"));
+        check_api_error(mpv_set_property_string(ctx, "slang", "pt,it,pol,ger"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/audio/lang", "eng");
+        check_string("current-tracks/sub/lang", "pol");
+
+        // forced jpn subs should be selected
+        check_api_error(mpv_set_property_string(ctx, "alang", "ger"));
+        check_api_error(mpv_set_property_string(ctx, "slang", "jpn,pol"));
+        check_api_error(mpv_set_property_string(ctx, "subs-with-matching-audio", "yes"));
+        check_api_error(mpv_set_property_string(ctx, "subs-fallback-forced", "always"));
+        check_api_error(mpv_command(ctx, cmd));
+        wait_for_file_load();
+        check_string("current-tracks/audio/lang", "ger");
+        check_string("current-tracks/sub/lang", "jpn");
+    }
+}
+
+int main(int argc, char *argv[])
+{
+    if (argc < 3)
+        return 1;
+    atexit(exit_cleanup);
+
+    ctx = mpv_create();
+    if (!ctx)
+        return 1;
+
+    initialize();
+
+    const char *fmt = "================ TEST: %s %s ================\n";
+    printf(fmt, "test_track_selection", argv[1]);
+    test_track_selection(argv[1], argv[2]);
+    printf("================ SHUTDOWN ================\n");
+
+    mpv_command_string(ctx, "quit");
+    while (wrap_wait_event()->event_id != MPV_EVENT_SHUTDOWN) {}
+
+    return 0;
+}

test/meson.build

@@ -130,6 +130,15 @@ if get_option('libmpv')
                      include_directories: incdir, link_with: libmpv)
     test('libmpv-test-options', exe, suite: 'libmpv')
 
+    # Old versions of ffmpeg are bugged when setting forced tracks and older
+    # versions of meson don't support the custom version checking argument.
+    if meson.version().version_compare('>= 1.5.0')
+        ffmpeg = find_program('ffmpeg', required: false, version: '>= 6.1', version_argument: '-version')
+        if ffmpeg.found()
+            subdir('samples')
+        endif
+    endif
+
     exe = executable('libmpv-encode', 'libmpv_encode.c',
                      include_directories: incdir, link_with: libmpv)
     test('libmpv-encode', exe, suite: 'libmpv')

test/samples/meson.build

@@ -0,0 +1,57 @@
+# Create core video, audio, and subtitle streams to construct files out of.
+video = custom_target('video.mkv',
+    output: 'video.mkv',
+    command: [ffmpeg, '-v', 'error', '-y', '-f', 'lavfi', '-i',
+              'testsrc=duration=2:size=1280x720', '@OUTPUT@'],
+)
+
+audio = custom_target('audio.flac',
+    output: 'audio.flac',
+    command: [ffmpeg, '-v', 'error', '-y', '-f', 'lavfi', '-i',
+              'sine=frequency=1000:duration=2', '@OUTPUT@'],
+)
+
+sub = join_paths(source_root, 'test', 'samples', 'sub.srt')
+
+common_args = ['-v', 'error', '-y', '-i', video, '-i', audio,
+               '-f', 'srt', '-i', sub, '-c', 'copy',
+              '-metadata:s:s:0', 'language=eng']
+
+samples = {
+    'eng_default.mkv':
+        [ffmpeg, common_args, '-disposition:s:0', 'default', '@OUTPUT@'],
+    'eng_default_forced.mkv':
+        [ffmpeg, common_args, '-disposition:s:0', 'default+forced', '@OUTPUT@'],
+    'eng_forced_matching_audio.mkv':
+        [ffmpeg, common_args, '-metadata:s:a:0', 'language=eng',
+         '-disposition:s:0', 'forced', '@OUTPUT@'],
+    'eng_forced_no_matching_audio.mkv':
+        [ffmpeg, common_args, '-disposition:s:0', 'forced', '@OUTPUT@'],
+    'eng_forced_always_audio.mkv':
+        [ffmpeg, common_args, '-metadata:s:a:0', 'language=ger',
+         '-disposition:s:0', 'forced', '@OUTPUT@'],
+    'eng_no_default.mkv':
+        [ffmpeg, common_args, '@OUTPUT@'],
+    'multilang.mkv':
+        [ffmpeg, '-v', 'error', '-y', '-i', video, '-i', audio, '-i', audio, '-i', audio, '-i', audio,
+         '-f', 'srt', '-i', sub, '-i', sub, '-i', sub, '-i', sub, '-c', 'copy', '-map', '0:0',
+         '-map', '1:0', '-map', '2:0', '-map', '3:0', '-map', '4:0', '-map', '5:0',
+         '-map', '6:0', '-map', '7:0', '-map', '8:0', '-metadata:s:a:0', 'language=eng',
+         '-metadata:s:a:1', 'language=jpn', '-metadata:s:a:2', 'language=ger', '-metadata:s:a:3',
+         'language=pol', '-metadata:s:s:0', 'language=eng', '-metadata:s:s:1', 'language=jpn',
+          '-metadata:s:s:2', 'language=ger', '-metadata:s:s:3', 'language=pol', '-disposition:s:0',
+          'default+forced', '-disposition:s:1', 'forced', '-disposition:s:2', 'default', '@OUTPUT@'],
+}
+
+foreach name, cmd: samples
+    target = custom_target(name,
+        output: name,
+        depends: [video, audio],
+        command: cmd,
+    )
+    testname = 'libmpv-test-' + name
+    exe = executable(testname, '../libmpv_test_track_selection.c',
+                     include_directories: incdir, link_with: libmpv)
+    test(testname, exe, args: [name, target.full_path()],
+         depends: target, suite: 'libmpv')
+endforeach

test/samples/sub.srt

@@ -0,0 +1,6 @@
+1
+00:00:00,000 --> 00:00:01,000
+foo
+2
+00:00:01,000 --> 00:00:02,000
+bar