From c23c9e22aef88eede0d3a6b3c63e125a9c7ba8e0 Mon Sep 17 00:00:00 2001
From: wm4 <wm4@nowhere>
Date: Fri, 27 Oct 2017 18:40:33 +0200
Subject: lavc_conv: clamp timestamps to positive, fixes idiotic ffmpeg issue

In some cases, demux_mkv will detect a start time slightly above 0, but
there might still be a subtitle starting at exactly 0. When the player
rebases the timestamps to assumed start time, the subtitle will have a
slightly negative timestamp in the end. libavcodec's subtitle converter
turns this into a larger number due to underflow. Fix by clamping
subtitles always to 0, which may or may not be what you want.

At least it fixes #5047.
---
 sub/lavc_conv.c | 2 ++
 1 file changed, 2 insertions(+)

(limited to 'sub')

diff --git a/sub/lavc_conv.c b/sub/lavc_conv.c
index 0f3b18e0fa..843da42ca7 100644
--- a/sub/lavc_conv.c
+++ b/sub/lavc_conv.c
@@ -237,6 +237,8 @@ char **lavc_conv_decode(struct lavc_conv *priv, struct demux_packet *packet)
     avsubtitle_free(&priv->cur);
 
     mp_set_av_packet(&pkt, packet, &avctx->time_base);
+    if (pkt.pts < 0)
+        pkt.pts = 0;
 
     if (strcmp(priv->codec, "webvtt-webm") == 0) {
         if (parse_webvtt(&pkt, &parsed_pkt) < 0) {
-- 
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