]> git.sesse.net Git - nageru/blobdiff - futatabi/player.cpp
Fix a minor unneeded unlock/lock.
[nageru] / futatabi / player.cpp
index c4ed8972135e24df4e817f47dcd001ac77cffdec..b7ceb0359968567d9bdc36ef69966768281a5f27 100644 (file)
@@ -8,6 +8,7 @@
 #include "frame_on_disk.h"
 #include "shared/httpd.h"
 #include "jpeg_frame_view.h"
+#include "shared/metrics.h"
 #include "shared/mux.h"
 #include "shared/timebase.h"
 #include "video_stream.h"
@@ -48,27 +49,29 @@ void Player::thread_func(Player::StreamOutput stream_output, AVFormatContext *fi
        check_error();
 
        int64_t pts = 0;
-       Clip next_clip;
-       size_t next_clip_idx = size_t(-1);
-       bool got_next_clip = false;
-       double next_clip_fade_time = -1.0;
-
        while (!should_quit) {
 wait_for_clip:
+               vector<Clip> clip_list;
                bool clip_ready;
                steady_clock::time_point before_sleep = steady_clock::now();
 
                // Wait until we're supposed to play something.
                {
                        unique_lock<mutex> lock(queue_state_mu);
+                       playing = false;
                        clip_ready = new_clip_changed.wait_for(lock, milliseconds(100), [this] {
-                               return should_quit || (new_clip_ready && current_clip.pts_in != -1);
+                               return should_quit || new_clip_ready;
                        });
                        if (should_quit) {
                                return;
                        }
-                       new_clip_ready = false;
-                       playing = true;
+                       if (clip_ready) {
+                               new_clip_ready = false;
+                               playing = true;
+                               clip_list = move(queued_clip_list);
+                               queued_clip_list.clear();
+                               assert(!clip_list.empty());
+                       }
                }
 
                steady_clock::duration time_slept = steady_clock::now() - before_sleep;
@@ -76,307 +79,295 @@ wait_for_clip:
 
                if (!clip_ready) {
                        if (video_stream != nullptr) {
+                               ++metric_refresh_frame;
                                video_stream->schedule_refresh_frame(steady_clock::now(), pts, /*display_func=*/nullptr, QueueSpotHolder());
                        }
                        continue;
                }
 
-               Clip clip;
-               size_t clip_idx;
-               unsigned stream_idx;
-               {
-                       lock_guard<mutex> lock(mu);
-                       clip = current_clip;
-                       clip_idx = current_clip_idx;
-                       stream_idx = current_stream_idx;
-               }
                steady_clock::time_point origin = steady_clock::now();  // TODO: Add a 100 ms buffer for ramp-up?
-               int64_t in_pts_origin = clip.pts_in;
-got_clip:
-               int64_t out_pts_origin = pts;
-
-               // Start playing exactly at a frame.
-               // TODO: Snap secondary (fade-to) clips in the same fashion
-               // so that we don't get jank here).
-               {
-                       lock_guard<mutex> lock(frame_mu);
-
-                       // Find the first frame such that frame.pts <= in_pts.
-                       auto it = find_last_frame_before(frames[stream_idx], in_pts_origin);
-                       if (it != frames[stream_idx].end()) {
-                               in_pts_origin = it->pts;
+               int64_t in_pts_origin = clip_list[0].pts_in;
+               for (size_t clip_idx = 0; clip_idx < clip_list.size(); ++clip_idx) {
+                       const Clip &clip = clip_list[clip_idx];
+                       const Clip *next_clip = (clip_idx + 1 < clip_list.size()) ? &clip_list[clip_idx + 1] : nullptr;
+                       int64_t out_pts_origin = pts;
+
+                       double next_clip_fade_time = -1.0;
+                       if (next_clip != nullptr) {
+                               double duration_this_clip = double(clip.pts_out - in_pts_origin) / TIMEBASE / clip.speed;
+                               double duration_next_clip = double(next_clip->pts_out - next_clip->pts_in) / TIMEBASE / clip.speed;
+                               next_clip_fade_time = min(min(duration_this_clip, duration_next_clip), clip.fade_time_seconds);
                        }
-               }
 
-               int64_t in_pts_start_next_clip = -1;
-               steady_clock::time_point next_frame_start;
-               for (int frameno = 0; !should_quit; ++frameno) {  // Ends when the clip ends.
-                       double out_pts = out_pts_origin + TIMEBASE * frameno / global_flags.output_framerate;
-                       next_frame_start =
-                               origin + microseconds(lrint((out_pts - out_pts_origin) * 1e6 / TIMEBASE));
-                       int64_t in_pts = lrint(in_pts_origin + TIMEBASE * frameno * clip.speed / global_flags.output_framerate);
-                       pts = lrint(out_pts);
-
-                       if (in_pts >= clip.pts_out) {
-                               break;
-                       }
+                       int stream_idx = clip.stream_idx;
 
-                       steady_clock::duration time_behind = steady_clock::now() - next_frame_start;
-                       if (stream_output != FILE_STREAM_OUTPUT && time_behind >= milliseconds(200)) {
-                               fprintf(stderr, "WARNING: %ld ms behind, dropping a frame (no matter the type).\n",
-                                       lrint(1e3 * duration<double>(time_behind).count()));
-                               continue;
-                       }
-
-                       double time_left_this_clip = double(clip.pts_out - in_pts) / TIMEBASE / clip.speed;
-                       if (!got_next_clip && next_clip_callback != nullptr && time_left_this_clip <= clip.fade_time_seconds) {
-                               // Find the next clip so that we can begin a fade.
-                               tie(next_clip, next_clip_idx) = next_clip_callback();
-                               if (next_clip.pts_in != -1) {
-                                       got_next_clip = true;
+                       // Start playing exactly at a frame.
+                       // TODO: Snap secondary (fade-to) clips in the same fashion
+                       // so that we don't get jank here).
+                       {
+                               lock_guard<mutex> lock(frame_mu);
 
-                                       double duration_next_clip = double(next_clip.pts_out - next_clip.pts_in) / TIMEBASE / clip.speed;
-                                       next_clip_fade_time = std::min(time_left_this_clip, duration_next_clip);
-                                       in_pts_start_next_clip = next_clip.pts_in + lrint(next_clip_fade_time * TIMEBASE * clip.speed);
+                               // Find the first frame such that frame.pts <= in_pts.
+                               auto it = find_last_frame_before(frames[stream_idx], in_pts_origin);
+                               if (it != frames[stream_idx].end()) {
+                                       in_pts_origin = it->pts;
                                }
                        }
 
-                       // pts not affected by the swapping below.
-                       int64_t in_pts_for_progress = in_pts, in_pts_secondary_for_progress = -1;
-
-                       int primary_stream_idx = stream_idx;
-                       FrameOnDisk secondary_frame;
-                       int secondary_stream_idx = -1;
-                       float fade_alpha = 0.0f;
-                       if (got_next_clip && time_left_this_clip <= next_clip_fade_time) {
-                               secondary_stream_idx = next_clip.stream_idx;
-                               int64_t in_pts_secondary = lrint(next_clip.pts_in + (next_clip_fade_time - time_left_this_clip) * TIMEBASE * clip.speed);
-                               in_pts_secondary_for_progress = in_pts_secondary;
-                               fade_alpha = 1.0f - time_left_this_clip / next_clip_fade_time;
-
-                               // If more than half-way through the fade, interpolate the next clip
-                               // instead of the current one, since it's more visible.
-                               if (fade_alpha >= 0.5f) {
-                                       swap(primary_stream_idx, secondary_stream_idx);
-                                       swap(in_pts, in_pts_secondary);
-                                       fade_alpha = 1.0f - fade_alpha;
+                       steady_clock::time_point next_frame_start;
+                       for (int frameno = 0; !should_quit; ++frameno) {  // Ends when the clip ends.
+                               double out_pts = out_pts_origin + TIMEBASE * frameno / global_flags.output_framerate;
+                               next_frame_start =
+                                       origin + microseconds(lrint((out_pts - out_pts_origin) * 1e6 / TIMEBASE));
+                               int64_t in_pts = lrint(in_pts_origin + TIMEBASE * frameno * clip.speed / global_flags.output_framerate);
+                               pts = lrint(out_pts);
+
+                               if (in_pts >= clip.pts_out) {
+                                       break;
                                }
 
-                               FrameOnDisk frame_lower, frame_upper;
-                               bool ok = find_surrounding_frames(in_pts_secondary, secondary_stream_idx, &frame_lower, &frame_upper);
-                               if (ok) {
-                                       secondary_frame = frame_lower;
+                               steady_clock::duration time_behind = steady_clock::now() - next_frame_start;
+                               if (stream_output != FILE_STREAM_OUTPUT && time_behind >= milliseconds(200)) {
+                                       fprintf(stderr, "WARNING: %ld ms behind, dropping a frame (no matter the type).\n",
+                                               lrint(1e3 * duration<double>(time_behind).count()));
+                                       ++metric_dropped_unconditional_frame;
+                                       continue;
                                }
-                       }
 
-                       if (progress_callback != nullptr) {
-                               // NOTE: None of this will take into account any snapping done below.
-                               double played_this_clip = double(in_pts_for_progress - clip.pts_in) / TIMEBASE / clip.speed;
-                               double total_length = double(clip.pts_out - clip.pts_in) / TIMEBASE / clip.speed;
-                               map<size_t, double> progress{{ clip_idx, played_this_clip / total_length }};
 
-                               if (got_next_clip && time_left_this_clip <= next_clip_fade_time) {
-                                       double played_next_clip = double(in_pts_secondary_for_progress - next_clip.pts_in) / TIMEBASE / next_clip.speed;
-                                       double total_next_length = double(next_clip.pts_out - next_clip.pts_in) / TIMEBASE / next_clip.speed;
-                                       progress[next_clip_idx] = played_next_clip / total_next_length;
+                               // pts not affected by the swapping below.
+                               int64_t in_pts_for_progress = in_pts, in_pts_secondary_for_progress = -1;
+
+                               int primary_stream_idx = stream_idx;
+                               FrameOnDisk secondary_frame;
+                               int secondary_stream_idx = -1;
+                               float fade_alpha = 0.0f;
+                               double time_left_this_clip = double(clip.pts_out - in_pts) / TIMEBASE / clip.speed;
+                               if (next_clip != nullptr && time_left_this_clip <= next_clip_fade_time) {
+                                       // We're in a fade to the next clip.
+                                       secondary_stream_idx = next_clip->stream_idx;
+                                       int64_t in_pts_secondary = lrint(next_clip->pts_in + (next_clip_fade_time - time_left_this_clip) * TIMEBASE * clip.speed);
+                                       in_pts_secondary_for_progress = in_pts_secondary;
+                                       fade_alpha = 1.0f - time_left_this_clip / next_clip_fade_time;
+
+                                       // If more than half-way through the fade, interpolate the next clip
+                                       // instead of the current one, since it's more visible.
+                                       if (fade_alpha >= 0.5f) {
+                                               swap(primary_stream_idx, secondary_stream_idx);
+                                               swap(in_pts, in_pts_secondary);
+                                               fade_alpha = 1.0f - fade_alpha;
+                                       }
+
+                                       FrameOnDisk frame_lower, frame_upper;
+                                       bool ok = find_surrounding_frames(in_pts_secondary, secondary_stream_idx, &frame_lower, &frame_upper);
+                                       if (ok) {
+                                               secondary_frame = frame_lower;
+                                       }
                                }
-                               progress_callback(progress);
-                       }
 
-                       FrameOnDisk frame_lower, frame_upper;
-                       bool ok = find_surrounding_frames(in_pts, primary_stream_idx, &frame_lower, &frame_upper);
-                       if (!ok) {
-                               break;
-                       }
+                               if (progress_callback != nullptr) {
+                                       // NOTE: None of this will take into account any snapping done below.
+                                       double played_this_clip = double(in_pts_for_progress - clip.pts_in) / TIMEBASE / clip.speed;
+                                       double total_length = double(clip.pts_out - clip.pts_in) / TIMEBASE / clip.speed;
+                                       map<size_t, double> progress{{ clip_idx, played_this_clip / total_length }};
 
-                       {
-                               unique_lock<mutex> lock(queue_state_mu);
-                               if (video_stream == nullptr) {
-                                       // No queue, just wait until the right time and then show the frame.
-                                       new_clip_changed.wait_until(lock, next_frame_start, [this]{
-                                               return should_quit || new_clip_ready || override_stream_idx != -1;
-                                       });
-                               if (should_quit) {
-                                       return;
-                               }
-                               } else {
-                                       // If the queue is full (which is really the state we'd like to be in),
-                                       // wait until there's room for one more frame (ie., one was output from
-                                       // VideoStream), or until or until there's a new clip we're supposed to play.
-                                       //
-                                       // In this case, we don't sleep until next_frame_start; the displaying is
-                                       // done by the queue.
-                                       new_clip_changed.wait(lock, [this]{
-                                               if (num_queued_frames < max_queued_frames) {
-                                                       return true;
-                                               }
-                                               return should_quit || new_clip_ready || override_stream_idx != -1;
-                                       });
-                               }
-                               if (should_quit) {
-                                       return;
-                               }
-                               if (new_clip_ready) {
-                                       if (video_stream != nullptr) {
-                                               lock.unlock();  // Urg.
-                                               video_stream->clear_queue();
-                                               lock.lock();
+                                       if (next_clip != nullptr && time_left_this_clip <= next_clip_fade_time) {
+                                               double played_next_clip = double(in_pts_secondary_for_progress - next_clip->pts_in) / TIMEBASE / next_clip->speed;
+                                               double total_next_length = double(next_clip->pts_out - next_clip->pts_in) / TIMEBASE / next_clip->speed;
+                                               progress[clip_idx + 1] = played_next_clip / total_next_length;
                                        }
-                                       got_next_clip = false;
-                                       goto wait_for_clip;
+                                       progress_callback(progress);
                                }
-                               if (override_stream_idx != -1) {
-                                       stream_idx = override_stream_idx;
-                                       override_stream_idx = -1;
-                                       continue;
+
+                               FrameOnDisk frame_lower, frame_upper;
+                               bool ok = find_surrounding_frames(in_pts, primary_stream_idx, &frame_lower, &frame_upper);
+                               if (!ok) {
+                                       break;
                                }
-                       }
 
-                       if (frame_lower.pts == frame_upper.pts || global_flags.interpolation_quality == 0) {
-                               auto display_func = [this, primary_stream_idx, frame_lower, secondary_frame, fade_alpha]{
-                                       if (destination != nullptr) {
-                                               destination->setFrame(primary_stream_idx, frame_lower, secondary_frame, fade_alpha);
-                                       }
-                               };
-                               if (video_stream == nullptr) {
-                                       display_func();
-                               } else {
-                                       if (secondary_stream_idx == -1) {
-                                               video_stream->schedule_original_frame(
-                                                       next_frame_start, pts, display_func, QueueSpotHolder(this),
-                                                       frame_lower);
+                               // Wait until we should, or (given buffering) can, output the frame.
+                               {
+                                       unique_lock<mutex> lock(queue_state_mu);
+                                       if (video_stream == nullptr) {
+                                               // No queue, just wait until the right time and then show the frame.
+                                               new_clip_changed.wait_until(lock, next_frame_start, [this]{
+                                                       return should_quit || new_clip_ready || override_stream_idx != -1;
+                                               });
+                                               if (should_quit) {
+                                                       return;
+                                               }
                                        } else {
-                                               assert(secondary_frame.pts != -1);
-                                               video_stream->schedule_faded_frame(next_frame_start, pts, display_func,
-                                                       QueueSpotHolder(this), frame_lower,
-                                                       secondary_frame, fade_alpha);
+                                               // If the queue is full (which is really the state we'd like to be in),
+                                               // wait until there's room for one more frame (ie., one was output from
+                                               // VideoStream), or until or until there's a new clip we're supposed to play.
+                                               //
+                                               // In this case, we don't sleep until next_frame_start; the displaying is
+                                               // done by the queue.
+                                               new_clip_changed.wait(lock, [this]{
+                                                       if (num_queued_frames < max_queued_frames) {
+                                                               return true;
+                                                       }
+                                                       return should_quit || new_clip_ready || override_stream_idx != -1;
+                                               });
+                                       }
+                                       if (should_quit) {
+                                               return;
+                                       }
+                                       if (new_clip_ready) {
+                                               if (video_stream != nullptr) {
+                                                       lock.unlock();  // Urg.
+                                                       video_stream->clear_queue();
+                                                       lock.lock();
+                                               }
+                                               goto wait_for_clip;
+                                       }
+                                       // Honor if we got an override request for the camera.
+                                       if (override_stream_idx != -1) {
+                                               stream_idx = override_stream_idx;
+                                               override_stream_idx = -1;
+                                               continue;
                                        }
                                }
-                               continue;
-                       }
 
-                       // Snap to input frame: If we can do so with less than 1% jitter
-                       // (ie., move less than 1% of an _output_ frame), do so.
-                       // TODO: Snap secondary (fade-to) clips in the same fashion.
-                       double pts_snap_tolerance = 0.01 * double(TIMEBASE) / global_flags.output_framerate;
-                       bool snapped = false;
-                       for (FrameOnDisk snap_frame : { frame_lower, frame_upper }) {
-                               if (fabs(snap_frame.pts - in_pts) < pts_snap_tolerance) {
-                                       auto display_func = [this, primary_stream_idx, snap_frame, secondary_frame, fade_alpha]{
+                               if (frame_lower.pts == frame_upper.pts || global_flags.interpolation_quality == 0) {
+                                       auto display_func = [this, primary_stream_idx, frame_lower, secondary_frame, fade_alpha]{
                                                if (destination != nullptr) {
-                                                       destination->setFrame(primary_stream_idx, snap_frame, secondary_frame, fade_alpha);
+                                                       destination->setFrame(primary_stream_idx, frame_lower, secondary_frame, fade_alpha);
                                                }
                                        };
                                        if (video_stream == nullptr) {
                                                display_func();
                                        } else {
                                                if (secondary_stream_idx == -1) {
+                                                       ++metric_original_frame;
                                                        video_stream->schedule_original_frame(
-                                                               next_frame_start, pts, display_func,
-                                                               QueueSpotHolder(this), snap_frame);
+                                                               next_frame_start, pts, display_func, QueueSpotHolder(this),
+                                                               frame_lower);
                                                } else {
                                                        assert(secondary_frame.pts != -1);
-                                                       video_stream->schedule_faded_frame(
-                                                               next_frame_start, pts, display_func, QueueSpotHolder(this),
-                                                               snap_frame, secondary_frame, fade_alpha);
+                                                       ++metric_faded_frame;
+                                                       video_stream->schedule_faded_frame(next_frame_start, pts, display_func,
+                                                               QueueSpotHolder(this), frame_lower,
+                                                               secondary_frame, fade_alpha);
                                                }
                                        }
-                                       in_pts_origin += snap_frame.pts - in_pts;
-                                       snapped = true;
-                                       break;
+                                       last_pts_played = frame_lower.pts;
+                                       continue;
                                }
-                       }
-                       if (snapped) {
-                               continue;
-                       }
 
-                       // The snapping above makes us lock to the input framerate, even in the presence
-                       // of pts drift, for most typical cases where it's needed, like converting 60 → 2x60
-                       // or 60 → 2x59.94. However, there are some corner cases like 25 → 2x59.94, where we'd
-                       // get a snap very rarely (in the given case, once every 24 output frames), and by
-                       // that time, we'd have drifted out. We could have solved this by changing the overall
-                       // speed ever so slightly, but it requires that we know the actual frame rate (which
-                       // is difficult in the presence of jitter and missed frames), or at least do some kind
-                       // of matching/clustering. Instead, we take the opportunity to lock to in-between rational
-                       // points if we can. E.g., if we are converting 60 → 2x60, we would not only snap to
-                       // an original frame every other frame; we would also snap to exactly alpha=0.5 every
-                       // in-between frame. Of course, we will still need to interpolate, but we get a lot
-                       // closer when we actually get close to an original frame. In other words: Snap more
-                       // often, but snap less each time. Unless the input and output frame rates are completely
-                       // decorrelated with no common factor, of course (e.g. 12.345 → 34.567, which we should
-                       // really never see in practice).
-                       for (double fraction : { 1.0 / 2.0, 1.0 / 3.0, 2.0 / 3.0, 1.0 / 4.0, 3.0 / 4.0,
-                                                1.0 / 5.0, 2.0 / 5.0, 3.0 / 5.0, 4.0 / 5.0 }) {
-                               double subsnap_pts = frame_lower.pts + fraction * (frame_upper.pts - frame_lower.pts);
-                               if (fabs(subsnap_pts - in_pts) < pts_snap_tolerance) {
-                                       in_pts_origin += lrint(subsnap_pts) - in_pts;
-                                       in_pts = lrint(subsnap_pts);
-                                       break;
+                               // Snap to input frame: If we can do so with less than 1% jitter
+                               // (ie., move less than 1% of an _output_ frame), do so.
+                               // TODO: Snap secondary (fade-to) clips in the same fashion.
+                               double pts_snap_tolerance = 0.01 * double(TIMEBASE) / global_flags.output_framerate;
+                               bool snapped = false;
+                               for (FrameOnDisk snap_frame : { frame_lower, frame_upper }) {
+                                       if (fabs(snap_frame.pts - in_pts) < pts_snap_tolerance) {
+                                               auto display_func = [this, primary_stream_idx, snap_frame, secondary_frame, fade_alpha]{
+                                                       if (destination != nullptr) {
+                                                               destination->setFrame(primary_stream_idx, snap_frame, secondary_frame, fade_alpha);
+                                                       }
+                                               };
+                                               if (video_stream == nullptr) {
+                                                       display_func();
+                                               } else {
+                                                       if (secondary_stream_idx == -1) {
+                                                               ++metric_original_snapped_frame;
+                                                               video_stream->schedule_original_frame(
+                                                                       next_frame_start, pts, display_func,
+                                                                       QueueSpotHolder(this), snap_frame);
+                                                       } else {
+                                                               assert(secondary_frame.pts != -1);
+                                                               ++metric_faded_snapped_frame;
+                                                               video_stream->schedule_faded_frame(
+                                                                       next_frame_start, pts, display_func, QueueSpotHolder(this),
+                                                                       snap_frame, secondary_frame, fade_alpha);
+                                                       }
+                                               }
+                                               in_pts_origin += snap_frame.pts - in_pts;
+                                               snapped = true;
+                                               last_pts_played = snap_frame.pts;
+                                               break;
+                                       }
+                               }
+                               if (snapped) {
+                                       continue;
                                }
-                       }
-
-                       if (stream_output != FILE_STREAM_OUTPUT && time_behind >= milliseconds(100)) {
-                               fprintf(stderr, "WARNING: %ld ms behind, dropping an interpolated frame.\n",
-                                       lrint(1e3 * duration<double>(time_behind).count()));
-                               continue;
-                       }
 
-                       double alpha = double(in_pts - frame_lower.pts) / (frame_upper.pts - frame_lower.pts);
+                               // The snapping above makes us lock to the input framerate, even in the presence
+                               // of pts drift, for most typical cases where it's needed, like converting 60 → 2x60
+                               // or 60 → 2x59.94. However, there are some corner cases like 25 → 2x59.94, where we'd
+                               // get a snap very rarely (in the given case, once every 24 output frames), and by
+                               // that time, we'd have drifted out. We could have solved this by changing the overall
+                               // speed ever so slightly, but it requires that we know the actual frame rate (which
+                               // is difficult in the presence of jitter and missed frames), or at least do some kind
+                               // of matching/clustering. Instead, we take the opportunity to lock to in-between rational
+                               // points if we can. E.g., if we are converting 60 → 2x60, we would not only snap to
+                               // an original frame every other frame; we would also snap to exactly alpha=0.5 every
+                               // in-between frame. Of course, we will still need to interpolate, but we get a lot
+                               // closer when we actually get close to an original frame. In other words: Snap more
+                               // often, but snap less each time. Unless the input and output frame rates are completely
+                               // decorrelated with no common factor, of course (e.g. 12.345 → 34.567, which we should
+                               // really never see in practice).
+                               for (double fraction : { 1.0 / 2.0, 1.0 / 3.0, 2.0 / 3.0, 1.0 / 4.0, 3.0 / 4.0,
+                                                        1.0 / 5.0, 2.0 / 5.0, 3.0 / 5.0, 4.0 / 5.0 }) {
+                                       double subsnap_pts = frame_lower.pts + fraction * (frame_upper.pts - frame_lower.pts);
+                                       if (fabs(subsnap_pts - in_pts) < pts_snap_tolerance) {
+                                               in_pts_origin += lrint(subsnap_pts) - in_pts;
+                                               in_pts = lrint(subsnap_pts);
+                                               break;
+                                       }
+                               }
 
-                       if (video_stream == nullptr) {
-                               // Previews don't do any interpolation.
-                               assert(secondary_stream_idx == -1);
-                               if (destination != nullptr) {
-                                       destination->setFrame(primary_stream_idx, frame_lower);
+                               if (stream_output != FILE_STREAM_OUTPUT && time_behind >= milliseconds(100)) {
+                                       fprintf(stderr, "WARNING: %ld ms behind, dropping an interpolated frame.\n",
+                                               lrint(1e3 * duration<double>(time_behind).count()));
+                                       ++metric_dropped_interpolated_frame;
+                                       continue;
                                }
-                       } else {
-                               auto display_func = [this](shared_ptr<Frame> frame) {
+
+                               double alpha = double(in_pts - frame_lower.pts) / (frame_upper.pts - frame_lower.pts);
+
+                               if (video_stream == nullptr) {
+                                       // Previews don't do any interpolation.
+                                       assert(secondary_stream_idx == -1);
                                        if (destination != nullptr) {
-                                               destination->setFrame(frame);
+                                               destination->setFrame(primary_stream_idx, frame_lower);
                                        }
-                               };
-                               video_stream->schedule_interpolated_frame(
-                                       next_frame_start, pts, display_func, QueueSpotHolder(this),
-                                       frame_lower, frame_upper, alpha,
-                                       secondary_frame, fade_alpha);
+                                       last_pts_played = frame_lower.pts;
+                               } else {
+                                       auto display_func = [this](shared_ptr<Frame> frame) {
+                                               if (destination != nullptr) {
+                                                       destination->setFrame(frame);
+                                               }
+                                       };
+                                       if (secondary_stream_idx == -1) {
+                                               ++metric_interpolated_frame;
+                                       } else {
+                                               ++metric_interpolated_faded_frame;
+                                       }
+                                       video_stream->schedule_interpolated_frame(
+                                               next_frame_start, pts, display_func, QueueSpotHolder(this),
+                                               frame_lower, frame_upper, alpha,
+                                               secondary_frame, fade_alpha);
+                                       last_pts_played = in_pts;  // Not really needed; only previews use last_pts_played.
+                               }
                        }
-               }
-
-               if (should_quit) {
-                       return;
-               }
-
-               // The clip ended.
 
-               // Last-ditch effort to get the next clip (if e.g. the fade time was zero seconds).
-               if (!got_next_clip && next_clip_callback != nullptr) {
-                       tie(next_clip, next_clip_idx) = next_clip_callback();
-                       if (next_clip.pts_in != -1) {
-                               got_next_clip = true;
-                               in_pts_start_next_clip = next_clip.pts_in;
+                       // The clip ended.
+                       if (should_quit) {
+                               return;
                        }
-               }
-
-               // Switch to next clip if we got it.
-               if (got_next_clip) {
-                       clip = next_clip;
-                       clip_idx = next_clip_idx;
-                       stream_idx = next_clip.stream_idx;  // Override is used for previews only, and next_clip is used for live ony.
                        if (done_callback != nullptr) {
                                done_callback();
                        }
-                       got_next_clip = false;
 
                        // Start the next clip from the point where the fade went out.
-                       origin = next_frame_start;
-                       in_pts_origin = in_pts_start_next_clip;
-                       goto got_clip;
+                       if (next_clip != nullptr) {
+                               origin = next_frame_start;
+                               in_pts_origin = next_clip->pts_in + lrint(next_clip_fade_time * TIMEBASE * clip.speed);
+                       }
                }
 
-               {
-                       unique_lock<mutex> lock(queue_state_mu);
-                       playing = false;
-               }
                if (done_callback != nullptr) {
                        done_callback();
                }
@@ -410,6 +401,18 @@ Player::Player(JPEGFrameView *destination, Player::StreamOutput stream_output, A
        : destination(destination)
 {
        player_thread = thread(&Player::thread_func, this, stream_output, file_avctx);
+
+       if (stream_output == HTTPD_STREAM_OUTPUT) {
+               global_metrics.add("http_output_frames", {{ "type", "original" }, { "reason", "edge_frame_or_no_interpolation" }}, &metric_original_frame);
+               global_metrics.add("http_output_frames", {{ "type", "faded" }, { "reason", "edge_frame_or_no_interpolation" }}, &metric_faded_frame);
+               global_metrics.add("http_output_frames", {{ "type", "original" }, { "reason", "snapped" }}, &metric_original_snapped_frame);
+               global_metrics.add("http_output_frames", {{ "type", "faded" }, { "reason", "snapped" }}, &metric_faded_snapped_frame);
+               global_metrics.add("http_output_frames", {{ "type", "interpolated" }}, &metric_interpolated_frame);
+               global_metrics.add("http_output_frames", {{ "type", "interpolated_faded" }}, &metric_interpolated_faded_frame);
+               global_metrics.add("http_output_frames", {{ "type", "refresh" }}, &metric_refresh_frame);
+               global_metrics.add("http_dropped_frames", {{ "type", "interpolated" }}, &metric_dropped_interpolated_frame);
+               global_metrics.add("http_dropped_frames", {{ "type", "unconditional" }}, &metric_dropped_unconditional_frame);
+       }
 }
 
 Player::~Player()
@@ -422,59 +425,47 @@ Player::~Player()
        player_thread.join();
 }
 
-void Player::play_clip(const Clip &clip, size_t clip_idx, unsigned stream_idx)
+void Player::play(const vector<Clip> &clips)
 {
-       {
-               lock_guard<mutex> lock(mu);
-               current_clip = clip;
-               current_stream_idx = stream_idx;
-               current_clip_idx = clip_idx;
-       }
-
-       {
-               lock_guard<mutex> lock(queue_state_mu);
-               new_clip_ready = true;
-               override_stream_idx = -1;
-               new_clip_changed.notify_all();
-       }
+       lock_guard<mutex> lock(queue_state_mu);
+       new_clip_ready = true;
+       queued_clip_list = clips;
+       override_stream_idx = -1;
+       new_clip_changed.notify_all();
 }
 
 void Player::override_angle(unsigned stream_idx)
 {
+       int64_t last_pts;
+
        // Corner case: If a new clip is waiting to be played, change its stream and then we're done.
        {
                unique_lock<mutex> lock(queue_state_mu);
                if (new_clip_ready) {
-                       lock_guard<mutex> lock2(mu);
-                       current_stream_idx = stream_idx;
+                       assert(queued_clip_list.size() == 1);
+                       queued_clip_list[0].stream_idx = stream_idx;
                        return;
                }
-       }
 
-       // If we are playing a clip, set override_stream_idx, and the player thread will
-       // pick it up and change its internal index.
-       {
-               unique_lock<mutex> lock(queue_state_mu);
+               // If we are playing a clip, set override_stream_idx, and the player thread will
+               // pick it up and change its internal index.
                if (playing) {
                        override_stream_idx = stream_idx;
                        new_clip_changed.notify_all();
+                       return;
                }
-       }
 
-       // OK, so we're standing still, presumably at the end of a clip.
-       // Look at the current pts_out (if it exists), and show the closest
-       // thing we've got.
-       int64_t pts_out;
-       {
-               lock_guard<mutex> lock(mu);
-               if (current_clip.pts_out < 0) {
+               // OK, so we're standing still, presumably at the end of a clip.
+               // Look at the last frame played (if it exists), and show the closest
+               // thing we've got.
+               if (last_pts_played < 0) {
                        return;
                }
-               pts_out = current_clip.pts_out;
+               last_pts = last_pts_played;
        }
 
        lock_guard<mutex> lock(frame_mu);
-       auto it = find_first_frame_at_or_after(frames[stream_idx], pts_out);
+       auto it = find_first_frame_at_or_after(frames[stream_idx], last_pts);
        if (it == frames[stream_idx].end()) {
                return;
        }