}
}
- // TODO: Lock to a rational multiple of the frame rate if possible.
- double speed = 0.5;
-
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 * speed / global_flags.output_framerate);
+ 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) {
continue;
}
- double time_left_this_clip = double(clip.pts_out - in_pts) / TIMEBASE / speed;
+ 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;
- double duration_next_clip = double(next_clip.pts_out - next_clip.pts_in) / TIMEBASE / speed;
+ 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 * speed);
+ in_pts_start_next_clip = next_clip.pts_in + lrint(next_clip_fade_time * TIMEBASE * clip.speed);
}
}
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 * speed);
+ 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 (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 / speed;
- double total_length = double(clip.pts_out - clip.pts_in) / TIMEBASE / speed;
+ 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 / speed;
- double total_next_length = double(next_clip.pts_out - next_clip.pts_in) / TIMEBASE / speed;
+ 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;
}
progress_callback(progress);
// 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 }) {
- double snap_pts_as_frameno = (snap_frame.pts - in_pts_origin) * global_flags.output_framerate / TIMEBASE / speed;
- if (fabs(snap_pts_as_frameno - frameno) < 0.01) {
+ 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);
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;
+ }
+ }
+
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()));
double last_fade_time_seconds = 0.0;
for (size_t row = last_it->first; row < clips.size(); ++row) {
const Clip &clip = clips[row];
- double clip_length = double(clip.pts_out - clip.pts_in) / TIMEBASE / 0.5; // FIXME: stop hardcoding speed.
+ double clip_length = double(clip.pts_out - clip.pts_in) / TIMEBASE / clip.speed;
if (row == last_it->first) {
// A clip we're playing: Subtract the part we've already played.
remaining = clip_length * (1.0 - last_it->second);