[RFC] Add subrandr SRV3 and WebVTT subtitle renderer

DOCS/man/input.rst

@@ -3951,6 +3951,12 @@ Property list
     somewhat weird form (apparently "hex BCD"), indicating the release version
     of the libass library linked to mpv.
 
+``subrandr-version``
+    The value of ``sbr_library_version()`` as a string in the format
+    ``<major>.<minor>.<patch>``, indicating the release version of the subrandr
+    library at runtime. This property is unavailable if mpv is not compiled
+    with subrandr enabled.
+
 ``platform``
     Returns a string describing what target platform mpv was built for. The value
     of this is dependent on what the underlying build system detects. Some of the

ci/build-common.sh

@@ -3,4 +3,14 @@ common_args="--werror \
 -Dtests=true \
 "
 
+build_subrandr() {
+    local target="$2"
+    local prefix="$1"
+
+    git clone --depth=1 https://github.com/afishhh/subrandr.git
+    pushd subrandr
+    cargo xtask install ${target:+--target} $target --prefix "$prefix"
+    popd
+}
+
 export CFLAGS="$CFLAGS -Wno-error=deprecated -Wno-error=deprecated-declarations -U_FORTIFY_SOURCE -D_FORTIFY_SOURCE=3"

ci/build-mingw64.sh

@@ -286,6 +286,11 @@ _luajit () {
 }
 _luajit_mark=lib/libluajit-5.1.a
 
+_subrandr () {
+    RUSTFLAGS="-L$prefix_dir/lib" build_subrandr "$prefix_dir" "$RUST_TARGET"
+}
+_subrandr_mark=lib/libsubrandr.dll.a
+
 for x in iconv zlib shaderc spirv-cross nv-headers dav1d lcms2; do
     build_if_missing $x
 done
@@ -296,6 +301,9 @@ fi
 for x in ffmpeg libplacebo freetype fribidi harfbuzz libass luajit; do
     build_if_missing $x
 done
+if [[ "$TARGET" != "i686-"* ]]; then
+    build_if_missing subrandr
+fi
 
 ## mpv
 
@@ -330,7 +338,7 @@ if [ "$2" = pack ]; then
     pushd artifact/tmp
     dlls=(
         libgcc_*.dll lib{ssp,stdc++,winpthread}-[0-9]*.dll # compiler runtime
-        av*.dll sw*.dll postproc-[0-9]*.dll lib{ass,freetype,fribidi,harfbuzz,iconv,placebo}-[0-9]*.dll
+        av*.dll sw*.dll {postproc,subrandr}-[0-9]*.dll lib{ass,freetype,fribidi,harfbuzz,iconv,placebo}-[0-9]*.dll
         lib{shaderc_shared,spirv-cross-c-shared,dav1d,lcms2}.dll zlib1.dll
     )
     if [[ -f vulkan-1.dll ]]; then

ci/build-msys2.sh

@@ -8,9 +8,18 @@ args=(
   -D{egl-angle-lib,egl-angle-win32,pdf-build,rubberband,win32-smtc}=enabled
 )
 
-[[ "$SYS" == "clang64" ]] && args+=(
-  -Db_sanitize=address,undefined
-)
+if [[ "$SYS" == "clang64" ]]; then
+    args+=(
+      -Db_sanitize=address,undefined
+    )
+else
+    # currently building with subrandr on clang64+asan
+    # causes a weird crash (https://github.com/msys2/MINGW-packages/issues/25267)
+    echo "::group::Building subrandr"
+    build_subrandr "/$SYS"
+    echo "::endgroup::"
+    args+=(-Dsubrandr=enabled)
+fi
 
 meson setup build $common_args "${args[@]}"
 meson compile -C build

ci/build-tumbleweed.sh

@@ -11,6 +11,7 @@ meson setup build $common_args $@ \
   -Dlibarchive=enabled \
   -Dmanpage-build=enabled \
   -Dpipewire=enabled \
+  -Dsubrandr=enabled \
   -Dvulkan=enabled
 meson compile -C build
 ./build/mpv -v --no-config

demux/demux.c

@@ -63,6 +63,9 @@ extern const demuxer_desc_t demuxer_desc_directory;
 extern const demuxer_desc_t demuxer_desc_disc;
 extern const demuxer_desc_t demuxer_desc_rar;
 extern const demuxer_desc_t demuxer_desc_libarchive;
+#if HAVE_SUBRANDR
+extern const demuxer_desc_t demuxer_desc_sbr;
+#endif
 extern const demuxer_desc_t demuxer_desc_null;
 extern const demuxer_desc_t demuxer_desc_timeline;
 
@@ -76,6 +79,9 @@ static const demuxer_desc_t *const demuxer_list[] = {
     &demuxer_desc_matroska,
 #if HAVE_LIBARCHIVE
     &demuxer_desc_libarchive,
+#endif
+#if HAVE_SUBRANDR
+    &demuxer_desc_sbr,
 #endif
     &demuxer_desc_lavf,
     &demuxer_desc_mf,

demux/demux_sbr.c

@@ -0,0 +1,173 @@
+/*
+ * 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/>.
+ */
+
+// This demuxer is specific to the `sd_sbr` subtitle driver and exists
+// so that we can take subtitle files like .srv3 or .vtt in their
+// full text form and pass them to subrandr in the subtitle driver.
+//
+// There are two reasons for this:
+// - subrandr doesn't currently support parsing packetized streams like
+//   what is output by ffmpeg for WebVTT.
+// - Demuxing .srv3 is not supported by ffmpeg, it also doesn't really have
+//   a standard packetized representation that ffmpeg could demux it to
+//   (that I know of).
+//
+// Note that for now this demuxer only recognizes srv3, this is to avoid
+// regressing the behavior of other formats that were previously rendered
+// with libass via ffmpeg conversion.
+
+#include <limits.h>
+#include <math.h>
+
+#include <subrandr/subrandr.h>
+
+#include "common/common.h"
+#include "demux/packet.h"
+#include "misc/bstr.h"
+#include "options/m_config.h"
+#include "options/m_option.h"
+#include "stream/stream.h"
+#include "demux.h"
+
+#define OPT_BASE_STRUCT struct demux_sbr_opts
+struct demux_sbr_opts {
+    int probesize;
+};
+
+const struct m_sub_options demux_sbr_conf = {
+    .opts = (const m_option_t[]) {
+        {"probesize", OPT_INT(probesize), M_RANGE(32, INT_MAX)},
+        {0}
+    },
+    .size = sizeof(struct demux_sbr_opts),
+    .defaults = &(const struct demux_sbr_opts){
+        .probesize = 128,
+    },
+    .change_flags = UPDATE_DEMUXER,
+};
+
+struct format_codec_info {
+    const char *codec;
+    const char *codec_desc;
+};
+
+static const struct format_codec_info fmt_to_codec[] = {
+    [SBR_SUBTITLE_FORMAT_UNKNOWN] = {NULL, NULL},
+    [SBR_SUBTITLE_FORMAT_SRV3   ] = {"subrandr/srv3", "srv3"},
+};
+
+struct sub_codec_ext {
+    const char *ext;
+    struct format_codec_info codec_info;
+};
+
+static const struct sub_codec_ext codec_exts[] = {
+    {".srv3", fmt_to_codec[SBR_SUBTITLE_FORMAT_SRV3]},
+    {".ytt",  fmt_to_codec[SBR_SUBTITLE_FORMAT_SRV3]},
+    {NULL}
+};
+
+struct demux_sbr_priv {
+    bstr content;
+    bool exhausted;
+};
+
+static int demux_open_sbr(struct demuxer *demuxer, enum demux_check check)
+{
+    bstr filename = bstr0(demuxer->filename);
+    struct format_codec_info codec_info = {0};
+    struct demux_sbr_opts *opts = mp_get_config_group(demuxer, demuxer->global, &demux_sbr_conf);
+
+    for (const struct sub_codec_ext *ext = codec_exts; ext->ext; ++ext) {
+        if (bstr_endswith0(filename, ext->ext))
+            codec_info = ext->codec_info;
+    }
+
+    if (!codec_info.codec) {
+        int probe_size = stream_peek(demuxer->stream, opts->probesize);
+        uint8_t *probe_buffer = demuxer->stream->buffer;
+
+        sbr_subtitle_format fmt = sbr_probe_text((const char *)probe_buffer, (size_t)probe_size);
+        if (fmt < MP_ARRAY_SIZE(fmt_to_codec))
+            codec_info = fmt_to_codec[fmt];
+    }
+
+    if (check != DEMUX_CHECK_REQUEST && !codec_info.codec)
+        return -1;
+
+    struct demux_sbr_priv *priv = talloc_zero(demuxer, struct demux_sbr_priv);
+
+    priv->content = stream_read_complete(demuxer->stream, priv, 64 * 1024 * 1024);
+    if (priv->content.start == NULL)
+        return -1;
+    demuxer->priv = priv;
+
+    struct sh_stream *stream = demux_alloc_sh_stream(STREAM_SUB);
+    stream->codec->codec = codec_info.codec;
+    stream->codec->codec_desc = codec_info.codec_desc;
+    demux_add_sh_stream(demuxer, stream);
+
+    // Note that while in practice seeking on this stream is not possible,
+    // if `demuxer->seekable` is `false` then a warning is emitted when one
+    // tries to seek in the player which is undesirable. Therefore we mark
+    // it as seekable and make seeking a no-op instead.
+    demuxer->seekable = true;
+    demuxer->fully_read = true;
+    demux_close_stream(demuxer);
+
+    return 0;
+}
+
+static bool demux_read_packet_sbr(struct demuxer *demuxer, struct demux_packet **packet)
+{
+    struct demux_sbr_priv *priv = demuxer->priv;
+
+    if (priv->exhausted)
+        return false;
+
+    *packet = new_demux_packet_from(demuxer->packet_pool, priv->content.start, priv->content.len);
+    if (!*packet)
+        return true;
+
+    (*packet)->stream = 0;
+    (*packet)->pts = 0.0;
+    (*packet)->sub_duration = INFINITY;
+    priv->exhausted = true;
+
+    return true;
+}
+
+static void demux_seek_sbr(struct demuxer *demuxer, double seek_pts, int flags)
+{
+    // We only ever emit one packet, no seeking needed or possible.
+}
+
+static void demux_switched_tracks_sbr(struct demuxer *demuxer)
+{
+    struct demux_sbr_priv *ctx = demuxer->priv;
+    ctx->exhausted = false;
+}
+
+
+const struct demuxer_desc demuxer_desc_sbr = {
+    .name = "subrandr",
+    .desc = "subrandr text subtitle demuxer",
+    .open = demux_open_sbr,
+    .read_packet = demux_read_packet_sbr,
+    .seek = demux_seek_sbr,
+    .switched_tracks = demux_switched_tracks_sbr
+};

meson.build

@@ -358,6 +358,13 @@ if features['libdl']
     dependencies += libdl
 endif
 
+subrandr = dependency('subrandr', version: '>= 0.1.1', required: get_option('subrandr'))
+features += {'subrandr': subrandr.found()}
+if features['subrandr']
+    sources += files('demux/demux_sbr.c', 'sub/sd_sbr.c')
+    dependencies += subrandr
+endif
+
 # C11 atomics are mandatory but linking to the library is not always required.
 dependencies += cc.find_library('atomic', required: false)
 

meson.options

@@ -30,6 +30,7 @@ option('pthread-debug', type: 'feature', value: 'disabled', description: 'pthrea
 option('rubberband', type: 'feature', value: 'auto', description: 'librubberband support')
 option('sdl2', type: 'feature', value: 'disabled', description: 'SDL2')
 option('sdl2-gamepad', type: 'feature', value: 'auto', description: 'SDL2 gamepad input')
+option('subrandr', type: 'feature', value: 'auto', description: 'subrandr support (SRV3 and WebVTT subtitle renderer)')
 option('uchardet', type: 'feature', value: 'auto', description: 'uchardet support')
 option('uwp', type: 'feature', value: 'disabled', description: 'Universal Windows Platform')
 option('vapoursynth', type: 'feature', value: 'auto', description: 'VapourSynth filter bridge')

options/options.c

@@ -70,6 +70,9 @@ extern const struct m_sub_options demux_rawvideo_conf;
 extern const struct m_sub_options demux_playlist_conf;
 extern const struct m_sub_options demux_lavf_conf;
 extern const struct m_sub_options demux_mkv_conf;
+#if HAVE_SUBRANDR
+extern const struct m_sub_options demux_sbr_conf;
+#endif
 extern const struct m_sub_options vd_lavc_conf;
 extern const struct m_sub_options ad_lavc_conf;
 extern const struct m_sub_options hwdec_conf;
@@ -693,6 +696,9 @@ static const m_option_t mp_opts[] = {
     {"demuxer-rawvideo", OPT_SUBSTRUCT(demux_rawvideo, demux_rawvideo_conf)},
     {"", OPT_SUBSTRUCT(demux_playlist, demux_playlist_conf)},
     {"demuxer-mkv", OPT_SUBSTRUCT(demux_mkv, demux_mkv_conf)},
+#if HAVE_SUBRANDR
+    {"demuxer-sbr", OPT_SUBSTRUCT(demux_sbr, demux_sbr_conf)},
+#endif
 
 // ------------------------- subtitles options --------------------
 
@@ -1085,13 +1091,15 @@ static const struct MPOpts mp_default_opts = {
         "scc",
         "smi",
         "srt",
+        "srv3",
         "ssa",
         "sub",
         "sup",
         "utf",
         "utf-8",
         "utf8",
         "vtt",
+        "ytt",
         NULL
     },
 

options/options.h

@@ -365,6 +365,9 @@ typedef struct MPOpts {
     struct demux_playlist_opts *demux_playlist;
     struct demux_lavf_opts *demux_lavf;
     struct demux_mkv_opts *demux_mkv;
+#if HAVE_SUBRANDR
+    struct demux_sbr_opts *demux_sbr;
+#endif
 
     struct demux_opts *demux_opts;
     struct demux_cache_opts *demux_cache_opts;

player/command.c

@@ -25,7 +25,12 @@
 #include <math.h>
 #include <sys/types.h>
 
+#include "config.h" // for HAVE_SUBRANDR
+
 #include <ass/ass.h>
+#if HAVE_SUBRANDR
+#include <subrandr/subrandr.h>
+#endif
 #include <libavutil/avstring.h>
 #include <libavutil/common.h>
 #include <libavutil/timecode.h>
@@ -3748,6 +3753,19 @@ static int mp_property_libass_version(void *ctx, struct m_property *prop,
     return m_property_int64_ro(action, arg, ass_library_version());
 }
 
+static int mp_property_subrandr_version(void *ctx, struct m_property *prop,
+                                      int action, void *arg)
+{
+#if HAVE_SUBRANDR
+    uint32_t major, minor, patch;
+    sbr_library_version(&major, &minor, &patch);
+    const char *result = mp_tprintf(33, "%" PRIu32 ".%" PRIu32 ".%" PRIu32, major, minor, patch);
+    return m_property_strdup_ro(action, arg, result);
+#else
+    return M_PROPERTY_UNAVAILABLE;
+#endif
+}
+
 static int mp_property_platform(void *ctx, struct m_property *prop,
                                 int action, void *arg)
 {
@@ -4531,6 +4549,7 @@ static const struct m_property mp_properties_base[] = {
     {"mpv-configuration", mp_property_configuration},
     {"ffmpeg-version", mp_property_ffmpeg},
     {"libass-version", mp_property_libass_version},
+    {"subrandr-version", mp_property_subrandr_version},
     {"platform", mp_property_platform},
 
     {"options", mp_property_options},