Ignore audio streams that fall too far behind (#2101).

diff --git a/src/lib/player.cc b/src/lib/player.cc
index b93bf3f4a7c2756643e47b4cc8e8f0d2a9bcc6b1..dcc89bab95e927b184d28b0a1e9e0b4db91efe89 100644 (file)
--- a/src/lib/player.cc
+++ b/src/lib/player.cc
@@ -743,10 +743,38 @@ Player::pass ()
        /* Emit any audio that is ready */
 
        /* Work out the time before which the audio is definitely all here.  This is the earliest last_push_end of one
-          of our streams, or the position of the _silent.
+          of our streams, or the position of the _silent.  First, though we choose only streams that are less than
+          ignore_streams_behind seconds behind the furthest ahead (we assume that if a stream has fallen that far
+          behind it has finished).  This is so that we don't withhold audio indefinitely awaiting data from a stream
+          that will never come, causing bugs like #2101.
        */
-       auto pull_to = _playback_length;
+       constexpr int ignore_streams_behind = 5;
+
+       using state_pair = std::pair<AudioStreamPtr, StreamState>;
+
+       /* Find the 'leading' stream (i.e. the one that pushed data most recently) */
+       auto latest_last_push_end = std::max_element(
+               _stream_states.begin(),
+               _stream_states.end(),
+               [](state_pair const& a, state_pair const& b) { return a.second.last_push_end < b.second.last_push_end; }
+               );
+
+       if (latest_last_push_end != _stream_states.end()) {
+               LOG_DEBUG_PLAYER("Leading stream is in %1 at %2", latest_last_push_end->second.piece->content->path(0), to_string(latest_last_push_end->second.last_push_end));
+       }
+
+       /* Now make a list of those streams that are less than ignore_streams_behind behind the leader */
+       std::map<AudioStreamPtr, StreamState> alive_stream_states;
        for (auto const& i: _stream_states) {
+               if ((latest_last_push_end->second.last_push_end - i.second.last_push_end) < dcpomatic::DCPTime::from_seconds(ignore_streams_behind)) {
+                       alive_stream_states.insert(i);
+               } else {
+                       LOG_DEBUG_PLAYER("Ignoring stream %1 because it is too far behind", i.second.piece->content->path(0));
+               }
+       }
+
+       auto pull_to = _playback_length;
+       for (auto const& i: alive_stream_states) {
                if (!i.second.piece->done && i.second.last_push_end < pull_to) {
                        pull_to = i.second.last_push_end;
                }