1 files changed, 25 insertions, 5 deletions

diff --git a/sub/sd_lavc.c b/sub/sd_lavc.c
index 4fbabaf864..56377b213e 100644
--- a/sub/sd_lavc.c
+++ b/sub/sd_lavc.c
@@ -54,6 +54,7 @@ struct seekpoint {
 
 struct sd_lavc_priv {
     AVCodecContext *avctx;
+    AVRational pkt_timebase;
     struct sub subs[MAX_QUEUE]; // most recent event first
     struct sub_bitmap *outbitmaps;
     int64_t displayed_id;
@@ -117,6 +118,22 @@ static int init(struct sd *sd)
     if (!ctx)
         goto error;
     mp_lavc_set_extradata(ctx, sd->codec->extradata, sd->codec->extradata_size);
+    if (cid == AV_CODEC_ID_HDMV_PGS_SUBTITLE) {
+        // We don't always want to set this, because the ridiculously shitty
+        // libavcodec API will mess with certain fields (end_display_time)
+        // when setting it. On the other hand, PGS in particular needs PTS
+        // mangling. While the PGS decoder doesn't modify the timestamps (just
+        // reorder it), the ridiculously shitty libavcodec wants a timebase
+        // anyway and for no good reason. It always sets end_display_time to
+        // UINT32_MAX (which is a broken and undocumented way to say "unknown"),
+        // which coincidentally won't be overridden by the ridiculously shitty
+        // pkt_timebase code. also, Libav doesn't have the pkt_timebase field,
+        // because Libav tends to avoid _adding_ ridiculously shitty APIs.
+#if LIBAVCODEC_VERSION_MICRO >= 100
+        priv->pkt_timebase = (AVRational){1, AV_TIME_BASE};
+        ctx->pkt_timebase = priv->pkt_timebase;
+#endif
+    }
     if (avcodec_open2(ctx, sub_codec, NULL) < 0)
         goto error;
     priv->avctx = ctx;
@@ -166,7 +183,9 @@ static void decode(struct sd *sd, struct demux_packet *packet)
     AVSubtitle sub;
     AVPacket pkt;
 
-    // libavformat sets duration==0, even if the duration is unknown.
+    // libavformat sets duration==0, even if the duration is unknown. Some files
+    // also have actually subtitle packets with duration explicitly set to 0
+    // (yes, at least some of such mkv files were muxed by libavformat).
     // Assume there are no bitmap subs that actually use duration==0 for
     // hidden subtitle events.
     if (duration == 0)
@@ -175,14 +194,15 @@ static void decode(struct sd *sd, struct demux_packet *packet)
     if (pts == MP_NOPTS_VALUE)
         MP_WARN(sd, "Subtitle with unknown start time.\n");
 
-    av_init_packet(&pkt);
-    pkt.data = packet->buffer;
-    pkt.size = packet->len;
+    mp_set_av_packet(&pkt, packet, &priv->pkt_timebase);
     int got_sub;
     int res = avcodec_decode_subtitle2(ctx, &sub, &got_sub, &pkt);
     if (res < 0 || !got_sub)
         return;
 
+    if (sub.pts != AV_NOPTS_VALUE)
+        pts = sub.pts / (double)AV_TIME_BASE;
+
     if (pts != MP_NOPTS_VALUE) {
         if (sub.end_display_time > sub.start_display_time &&
             sub.end_display_time != UINT32_MAX)
@@ -284,7 +304,7 @@ static void get_bitmaps(struct sd *sd, struct mp_osd_res d, double pts,
     priv->current_pts = pts;
 
     struct sub *current = NULL;
-    for (int n = MAX_QUEUE - 1; n >= 0; n--) {
+    for (int n = 0; n < MAX_QUEUE; n++) {
         struct sub *sub = &priv->subs[n];
         if (!sub->valid)
             continue;