vf_vavpp: move frame handling to separate file

Move the handling of the future/past frames and the associated dataflow
rules to a separate source file.

While this on its own seems rather questionable and just inflates the
code, I intend to reuse it for other filters. The logic is annoying
enough that it shouldn't be duplicated a bunch of times.

(I considered other ways of sharing this logic, such as an uber-
deinterlace filter, which would access the hardware deinterlacer via a
different API. Although that sounds like kind of the right approach,
this would have other problems, so let's not, at least for now.)

1 files changed, 153 insertions, 0 deletions

diff --git a/video/filter/refqueue.c b/video/filter/refqueue.c
new file mode 100644
index 0000000000..1103be9afa
--- /dev/null
+++ b/video/filter/refqueue.c
@@ -0,0 +1,153 @@
+/*
+ * This file is part of mpv.
+ *
+ * mpv is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * mpv is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <assert.h>
+
+#include "common/common.h"
+#include "video/mp_image.h"
+
+#include "refqueue.h"
+
+struct mp_refqueue {
+    int needed_past_frames;
+    int needed_future_frames;
+
+    bool eof;
+    double past_pts;
+
+    // Queue of input frames, used to determine past/current/future frames.
+    // queue[0] is the newest frame, queue[num_queue - 1] the oldest.
+    struct mp_image **queue;
+    int num_queue;
+    // queue[pos] is the current frame, unless pos is an invalid index.
+    int pos;
+};
+
+struct mp_refqueue *mp_refqueue_alloc(void)
+{
+    struct mp_refqueue *q = talloc_zero(NULL, struct mp_refqueue);
+    mp_refqueue_flush(q);
+    return q;
+}
+
+void mp_refqueue_free(struct mp_refqueue *q)
+{
+    talloc_free(q);
+}
+
+// The minimum number of frames required before and after the current frame.
+void mp_refqueue_set_refs(struct mp_refqueue *q, int past, int future)
+{
+    assert(past >= 0 && future >= 0);
+    q->needed_past_frames = past;
+    q->needed_future_frames = future;
+}
+
+// Discard all state.
+void mp_refqueue_flush(struct mp_refqueue *q)
+{
+    for (int n = 0; n < q->num_queue; n++)
+        talloc_free(q->queue[n]);
+    q->num_queue = 0;
+    q->pos = -1;
+    q->eof = false;
+    q->past_pts = MP_NOPTS_VALUE;
+}
+
+// Add a new frame to the queue. (Call mp_refqueue_next() to advance the
+// current frame and to discard unneeded past frames.)
+// Ownership goes to the mp_refqueue.
+// Passing NULL means EOF, in which case mp_refqueue_need_input() will return
+// false even if not enough future frames are available.
+void mp_refqueue_add_input(struct mp_refqueue *q, struct mp_image *img)
+{
+    q->eof = !img;
+    if (!img)
+        return;
+
+    MP_TARRAY_INSERT_AT(q, q->queue, q->num_queue, 0, img);
+    q->pos++;
+
+    assert(q->pos >= 0 && q->pos < q->num_queue);
+}
+
+bool mp_refqueue_need_input(struct mp_refqueue *q)
+{
+    return q->pos < q->needed_future_frames && !q->eof;
+}
+
+bool mp_refqueue_has_output(struct mp_refqueue *q)
+{
+    return q->pos >= 0 && !mp_refqueue_need_input(q);
+}
+
+// Advance current frame by 1 (or 2 fields if interlaced).
+void mp_refqueue_next(struct mp_refqueue *q)
+{
+    if (!mp_refqueue_has_output(q))
+        return;
+
+    q->past_pts = q->queue[q->pos]->pts;
+
+    q->pos--;
+
+    assert(q->pos >= -1 && q->pos < q->num_queue);
+
+    // Discard unneeded past frames.
+    while (q->num_queue - (q->pos + 1) > q->needed_past_frames) {
+        assert(q->num_queue > 0);
+        talloc_free(q->queue[q->num_queue - 1]);
+        q->num_queue--;
+    }
+
+    assert(q->pos >= -1 && q->pos < q->num_queue);
+}
+
+// Return a frame by relative position:
+//  -1: first past frame
+//   0: current frame
+//   1: first future frame
+// Caller doesn't get ownership. Return NULL if unavailable.
+struct mp_image *mp_refqueue_get(struct mp_refqueue *q, int pos)
+{
+    int i = q->pos - pos;
+    return i >= 0 && i < q->num_queue ? q->queue[i] : NULL;
+}
+
+// Get the pts of field 0/1 (0 being the first to output).
+double mp_refqueue_get_field_pts(struct mp_refqueue *q, int field)
+{
+    assert(field == 0 || field == 1);
+
+    if (q->pos < 0)
+        return MP_NOPTS_VALUE;
+
+    double pts = q->queue[q->pos]->pts;
+
+    if (field == 0 || pts == MP_NOPTS_VALUE)
+        return pts;
+
+    if (q->past_pts == MP_NOPTS_VALUE)
+        return MP_NOPTS_VALUE;
+
+    double frametime = pts - q->past_pts;
+    if (frametime <= 0.0 || frametime >= 1.0)
+        return MP_NOPTS_VALUE;
+
+    return pts + frametime / 2;
+}
+