X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=futatabi%2Fplayer.cpp;h=b905be0f82a1b35dfcf8d0a3bb20c0825bf72afb;hb=refs%2Fheads%2Fmaster;hp=d168a9dfc051b76339fccbabc7c38dc2acf0ac12;hpb=8919e39eca6caa673bb7cde70dbd34fd1e484010;p=nageru diff --git a/futatabi/player.cpp b/futatabi/player.cpp index d168a9d..b905be0 100644 --- a/futatabi/player.cpp +++ b/futatabi/player.cpp @@ -125,6 +125,7 @@ public: TimelineTracker(double master_speed, int64_t out_pts_origin) : master_speed(master_speed), last_out_pts(out_pts_origin) { origin.out_pts = out_pts_origin; + master_speed_ease_target = master_speed; // Keeps GCC happy. } void new_clip(steady_clock::time_point wallclock_origin, const Clip *clip, int64_t start_pts_offset) @@ -141,35 +142,79 @@ public: int64_t get_in_pts_origin() const { return origin.in_pts; } bool playing_at_normal_speed() const { + if (in_easing) return false; + const double effective_speed = clip->speed * master_speed; return effective_speed >= 0.999 && effective_speed <= 1.001; } void snap_by(int64_t offset) { + if (in_easing) { + // Easing will normally aim for a snap at the very end, + // so don't disturb it by jittering during the ease. + return; + } origin.in_pts += offset; } void change_master_speed(double new_master_speed, Instant now); + float in_master_speed(float speed) const { + return (!in_easing && fabs(master_speed - speed) < 1e-6); + } + + // Instead of changing the speed instantly, change it over the course of + // about 200 ms. This is a simple linear ramp; I tried various forms of + // Bézier curves for more elegant/dramatic changing, but it seemed linear + // looked just as good in practical video. + void start_easing(double new_master_speed, int64_t length_out_pts, Instant now); + + int64_t find_easing_length(double master_speed_target, int64_t length_out_pts, const vector &frames, Instant now); + private: + // Find out how far we are into the easing curve (0..1). + // We use this to adjust the input pts. + double find_ease_t(double out_pts) const; + double easing_out_pts_adjustment(double out_pts) const; + double master_speed; const Clip *clip = nullptr; Instant origin; int64_t last_out_pts; + + // If easing between new and old master speeds. + bool in_easing = false; + int64_t ease_started_pts = 0; + double master_speed_ease_target; + int64_t ease_length_out_pts = 0; }; TimelineTracker::Instant TimelineTracker::advance_to_frame(int64_t frameno) { Instant ret; double in_pts_double = origin.in_pts + TIMEBASE * clip->speed * (frameno - origin.frameno) * master_speed / global_flags.output_framerate; - ret.in_pts = lrint(in_pts_double); double out_pts_double = origin.out_pts + TIMEBASE * (frameno - origin.frameno) / global_flags.output_framerate; + + if (in_easing) { + double in_pts_adjustment = easing_out_pts_adjustment(out_pts_double) * clip->speed; + in_pts_double += in_pts_adjustment; + } + + ret.in_pts = lrint(in_pts_double); ret.out_pts = lrint(out_pts_double); ret.wallclock_time = origin.wallclock_time + microseconds(lrint((out_pts_double - origin.out_pts) * 1e6 / TIMEBASE)); ret.frameno = frameno; last_out_pts = ret.out_pts; + if (in_easing && ret.out_pts >= ease_started_pts + ease_length_out_pts) { + // We have ended easing. Add what we need for the entire easing period, + // then _actually_ change the speed as we go back into normal mode. + origin.out_pts += easing_out_pts_adjustment(out_pts_double); + change_master_speed(master_speed_ease_target, ret); + in_easing = false; + } + return ret; } @@ -182,6 +227,115 @@ void TimelineTracker::change_master_speed(double new_master_speed, Instant now) origin = now; } +void TimelineTracker::start_easing(double new_master_speed, int64_t length_out_pts, Instant now) +{ + if (in_easing) { + // Apply whatever we managed to complete of the previous easing. + origin.out_pts += easing_out_pts_adjustment(now.out_pts); + double reached_speed = master_speed + (master_speed_ease_target - master_speed) * find_ease_t(now.out_pts); + change_master_speed(reached_speed, now); + } + in_easing = true; + ease_started_pts = now.out_pts; + master_speed_ease_target = new_master_speed; + ease_length_out_pts = length_out_pts; +} + +double TimelineTracker::find_ease_t(double out_pts) const +{ + return (out_pts - ease_started_pts) / double(ease_length_out_pts); +} + +double TimelineTracker::easing_out_pts_adjustment(double out_pts) const +{ + double t = find_ease_t(out_pts); + double area_factor = (master_speed_ease_target - master_speed) * ease_length_out_pts; + double val = 0.5 * min(t, 1.0) * min(t, 1.0) * area_factor; + if (t > 1.0) { + val += area_factor * (t - 1.0); + } + return val; +} + +int64_t TimelineTracker::find_easing_length(double master_speed_target, int64_t desired_length_out_pts, const vector &frames, Instant now) +{ + // Find out what frame we would have hit (approximately) with the given ease length. + double in_pts_length = 0.5 * (master_speed_target + master_speed) * desired_length_out_pts * clip->speed; + const int input_frame_num = distance( + frames.begin(), + find_first_frame_at_or_after(frames, lrint(now.in_pts + in_pts_length))); + + // Round length_out_pts to the nearest amount of whole frames. + const double frame_length = TIMEBASE / global_flags.output_framerate; + const int length_out_frames = lrint(desired_length_out_pts / frame_length); + + // Time the easing so that we aim at 200 ms (or whatever length_out_pts + // was), but adjust it so that we hit exactly on a frame. Unless we are + // somehow unlucky and run in the middle of a bad fade, this should + // lock us nicely into a cadence where we hit original frames (of course + // assuming the new speed is a reasonable ratio). + // + // Assume for a moment that we are easing into a slowdown, and that + // we're slightly too late to hit the frame we want to. This means that + // we can shorten the ease a bit; this chops some of the total integrated + // velocity and arrive at the frame a bit sooner. Solve for the time + // we want to shorten the ease by (let's call it x, where the original + // length of the ease is called len) such that we hit exactly the in + // pts at the right time: + // + // 0.5 * (mst + ms) * (len - x) * cs + mst * x * cs = desired_len_in_pts + // + // gives + // + // x = (2 * desired_len_in_pts / cs - (mst + ms) * len) / (mst - ms) + // + // Conveniently, this holds even if we are too early; a negative x + // (surprisingly!) gives a lenghtening such that we don't hit the desired + // frame, but hit one slightly later. (x larger than len means that + // it's impossible to hit the desired frame, even if we dropped the ease + // altogether and just changed speeds instantly.) We also have sign invariance, + // so that these properties hold even if we are speeding up, not slowing + // down. Together, these two properties mean that we can cast a fairly + // wide net, trying various input and output frames and seeing which ones + // can be matched up with a minimal change to easing time. (This lets us + // e.g. end the ease close to the midpoint between two endpoint frames + // even if we don't know the frame rate, or deal fairly robustly with + // dropped input frames.) Many of these will give us the same answer, + // but that's fine, because the ease length is the only output. + int64_t best_length_out_pts = TIMEBASE * 10; // Infinite. + for (int output_frame_offset = -2; output_frame_offset <= 2; ++output_frame_offset) { + int64_t aim_length_out_pts = lrint((length_out_frames + output_frame_offset) * frame_length); + if (aim_length_out_pts < 0) { + continue; + } + + for (int input_frame_offset = -2; input_frame_offset <= 2; ++input_frame_offset) { + if (input_frame_num + input_frame_offset < 0 || + input_frame_num + input_frame_offset >= int(frames.size())) { + continue; + } + const int64_t in_pts = frames[input_frame_num + input_frame_offset].pts; + double shorten_by_out_pts = (2.0 * (in_pts - now.in_pts) / clip->speed - (master_speed_target + master_speed) * aim_length_out_pts) / (master_speed_target - master_speed); + int64_t length_out_pts = lrint(aim_length_out_pts - shorten_by_out_pts); + + if (length_out_pts >= 0 && + abs(length_out_pts - desired_length_out_pts) < abs(best_length_out_pts - desired_length_out_pts)) { + best_length_out_pts = length_out_pts; + } + } + } + + // If we need more than two seconds of easing, we give up -- + // this can happen if we're e.g. going from 101% to 100%. + // If so, it would be better to let other mechanisms, such as the switch + // to the next clip, deal with getting us back into sync. + if (best_length_out_pts > TIMEBASE * 2) { + return desired_length_out_pts; + } else { + return best_length_out_pts; + } +} + } // namespace void Player::play_playlist_once() @@ -271,8 +425,10 @@ void Player::play_playlist_once() next_frame_start = instant.wallclock_time; float new_master_speed = change_master_speed.exchange(0.0f / 0.0f); - if (!std::isnan(new_master_speed)) { - timeline.change_master_speed(new_master_speed, instant); + if (!std::isnan(new_master_speed) && !timeline.in_master_speed(new_master_speed)) { + int64_t ease_length_out_pts = TIMEBASE / 5; // 200 ms. + int64_t recommended_pts_length = timeline.find_easing_length(new_master_speed, ease_length_out_pts, frames[clip->stream_idx], instant); + timeline.start_easing(new_master_speed, recommended_pts_length, instant); } if (should_skip_to_next.exchange(false)) { // Test and clear.