lavfi: add an API to synchronize multiple video inputs.

Compared to dualinput, this API can handle more than two
inputs and can generate frames synchronized to any or all
input streams.

1 files changed, 329 insertions, 0 deletions

diff --git a/libavfilter/framesync.c b/libavfilter/framesync.c
new file mode 100644
index 0000000000..12db50cb77
--- /dev/null
+++ b/libavfilter/framesync.c
@@ -0,0 +1,329 @@
+/*
+ * Copyright (c) 2013 Nicolas George
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg 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.
+ *
+ * FFmpeg 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 FFmpeg; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/avassert.h"
+#include "avfilter.h"
+#include "bufferqueue.h"
+#include "framesync.h"
+#include "internal.h"
+
+#define OFFSET(member) offsetof(FFFrameSync, member)
+
+static const char *framesync_name(void *ptr)
+{
+    return "framesync";
+}
+
+static const AVClass framesync_class = {
+    .version                   = LIBAVUTIL_VERSION_INT,
+    .class_name                = "framesync",
+    .item_name                 = framesync_name,
+    .category                  = AV_CLASS_CATEGORY_FILTER,
+    .option                    = NULL,
+    .parent_log_context_offset = OFFSET(parent),
+};
+
+enum {
+    STATE_BOF,
+    STATE_RUN,
+    STATE_EOF,
+};
+
+void ff_framesync_init(FFFrameSync *fs, void *parent, unsigned nb_in)
+{
+    fs->class  = &framesync_class;
+    fs->parent = parent;
+    fs->nb_in  = nb_in;
+}
+
+static void framesync_sync_level_update(FFFrameSync *fs)
+{
+    unsigned i, level = 0;
+
+    for (i = 0; i < fs->nb_in; i++)
+        if (fs->in[i].state != STATE_EOF)
+            level = FFMAX(level, fs->in[i].sync);
+    av_assert0(level <= fs->sync_level);
+    if (level < fs->sync_level)
+        av_log(fs, AV_LOG_VERBOSE, "Sync level %u\n", level);
+    if (level)
+        fs->sync_level = level;
+    else
+        fs->eof = 1;
+}
+
+int ff_framesync_configure(FFFrameSync *fs)
+{
+    unsigned i;
+    int64_t gcd, lcm;
+
+    if (!fs->time_base.num) {
+        for (i = 0; i < fs->nb_in; i++) {
+            if (fs->in[i].sync) {
+                if (fs->time_base.num) {
+                    gcd = av_gcd(fs->time_base.den, fs->in[i].time_base.den);
+                    lcm = (fs->time_base.den / gcd) * fs->in[i].time_base.den;
+                    if (lcm < AV_TIME_BASE / 2) {
+                        fs->time_base.den = lcm;
+                        fs->time_base.num = av_gcd(fs->time_base.num,
+                                                   fs->in[i].time_base.num);
+                    } else {
+                        fs->time_base.num = 1;
+                        fs->time_base.den = AV_TIME_BASE;
+                        break;
+                    }
+                } else {
+                    fs->time_base = fs->in[i].time_base;
+                }
+            }
+        }
+        if (!fs->time_base.num) {
+            av_log(fs, AV_LOG_ERROR, "Impossible to set time base\n");
+            return AVERROR(EINVAL);
+        }
+        av_log(fs, AV_LOG_VERBOSE, "Selected %d/%d time base\n",
+               fs->time_base.num, fs->time_base.den);
+    }
+
+    for (i = 0; i < fs->nb_in; i++)
+        fs->in[i].pts = fs->in[i].pts_next = AV_NOPTS_VALUE;
+    fs->sync_level = UINT_MAX;
+    framesync_sync_level_update(fs);
+
+    return 0;
+}
+
+static void framesync_advance(FFFrameSync *fs)
+{
+    int latest;
+    unsigned i;
+    int64_t pts;
+
+    if (fs->eof)
+        return;
+    while (!fs->frame_ready) {
+        latest = -1;
+        for (i = 0; i < fs->nb_in; i++) {
+            if (!fs->in[i].have_next) {
+                if (latest < 0 || fs->in[i].pts < fs->in[latest].pts)
+                    latest = i;
+            }
+        }
+        if (latest >= 0) {
+            fs->in_request = latest;
+            break;
+        }
+
+        pts = fs->in[0].pts_next;
+        for (i = 1; i < fs->nb_in; i++)
+            if (fs->in[i].pts_next < pts)
+                pts = fs->in[i].pts_next;
+        if (pts == INT64_MAX) {
+            fs->eof = 1;
+            break;
+        }
+        for (i = 0; i < fs->nb_in; i++) {
+            if (fs->in[i].pts_next == pts ||
+                (fs->in[i].before == EXT_INFINITY &&
+                 fs->in[i].state == STATE_BOF)) {
+                av_frame_free(&fs->in[i].frame);
+                fs->in[i].frame      = fs->in[i].frame_next;
+                fs->in[i].pts        = fs->in[i].pts_next;
+                fs->in[i].frame_next = NULL;
+                fs->in[i].pts_next   = AV_NOPTS_VALUE;
+                fs->in[i].have_next  = 0;
+                fs->in[i].state      = fs->in[i].frame ? STATE_RUN : STATE_EOF;
+                if (fs->in[i].sync == fs->sync_level && fs->in[i].frame)
+                    fs->frame_ready = 1;
+                if (fs->in[i].state == STATE_EOF &&
+                    fs->in[i].after == EXT_STOP)
+                    fs->eof = 1;
+            }
+        }
+        if (fs->eof)
+            fs->frame_ready = 0;
+        if (fs->frame_ready)
+            for (i = 0; i < fs->nb_in; i++)
+                if ((fs->in[i].state == STATE_BOF &&
+                     fs->in[i].before == EXT_STOP))
+                    fs->frame_ready = 0;
+        fs->pts = pts;
+    }
+}
+
+static int64_t framesync_pts_extrapolate(FFFrameSync *fs, unsigned in,
+                                         int64_t pts)
+{
+    /* Possible enhancement: use the link's frame rate */
+    return pts + 1;
+}
+
+static void framesync_inject_frame(FFFrameSync *fs, unsigned in, AVFrame *frame)
+{
+    int64_t pts;
+
+    av_assert0(!fs->in[in].have_next);
+    if (frame) {
+        pts = av_rescale_q(frame->pts, fs->in[in].time_base, fs->time_base);
+        frame->pts = pts;
+    } else {
+        pts = fs->in[in].state != STATE_RUN || fs->in[in].after == EXT_INFINITY
+            ? INT64_MAX : framesync_pts_extrapolate(fs, in, fs->in[in].pts);
+        fs->in[in].sync = 0;
+        framesync_sync_level_update(fs);
+    }
+    fs->in[in].frame_next = frame;
+    fs->in[in].pts_next   = pts;
+    fs->in[in].have_next  = 1;
+}
+
+int ff_framesync_add_frame(FFFrameSync *fs, unsigned in, AVFrame *frame)
+{
+    av_assert1(in < fs->nb_in);
+    if (!fs->in[in].have_next)
+        framesync_inject_frame(fs, in, frame);
+    else
+        ff_bufqueue_add(fs, &fs->in[in].queue, frame);
+    return 0;
+}
+
+void ff_framesync_next(FFFrameSync *fs)
+{
+    unsigned i;
+
+    av_assert0(!fs->frame_ready);
+    for (i = 0; i < fs->nb_in; i++)
+        if (!fs->in[i].have_next && fs->in[i].queue.available)
+            framesync_inject_frame(fs, i, ff_bufqueue_get(&fs->in[i].queue));
+    fs->frame_ready = 0;
+    framesync_advance(fs);
+}
+
+void ff_framesync_drop(FFFrameSync *fs)
+{
+    fs->frame_ready = 0;
+}
+
+int ff_framesync_get_frame(FFFrameSync *fs, unsigned in, AVFrame **rframe,
+                           unsigned get)
+{
+    AVFrame *frame;
+    unsigned need_copy = 0, i;
+    int64_t pts_next;
+    int ret;
+
+    if (!fs->in[in].frame) {
+        *rframe = NULL;
+        return 0;
+    }
+    frame = fs->in[in].frame;
+    if (get) {
+        /* Find out if we need to copy the frame: is there another sync
+           stream, and do we know if its current frame will outlast this one? */
+        pts_next = fs->in[in].have_next ? fs->in[in].pts_next : INT64_MAX;
+        for (i = 0; i < fs->nb_in && !need_copy; i++)
+            if (i != in && fs->in[i].sync &&
+                (!fs->in[i].have_next || fs->in[i].pts_next < pts_next))
+                need_copy = 1;
+        if (need_copy) {
+            if (!(frame = av_frame_clone(frame)))
+                return AVERROR(ENOMEM);
+            if ((ret = av_frame_make_writable(frame)) < 0) {
+                av_frame_free(&frame);
+                return ret;
+            }
+        } else {
+            fs->in[in].frame = NULL;
+        }
+        fs->frame_ready = 0;
+    }
+    *rframe = frame;
+    return 0;
+}
+
+void ff_framesync_uninit(FFFrameSync *fs)
+{
+    unsigned i;
+
+    for (i = 0; i < fs->nb_in; i++) {
+        av_frame_free(&fs->in[i].frame);
+        av_frame_free(&fs->in[i].frame_next);
+        ff_bufqueue_discard_all(&fs->in[i].queue);
+    }
+}
+
+int ff_framesync_process_frame(FFFrameSync *fs, unsigned all)
+{
+    int ret, count = 0;
+
+    av_assert0(fs->on_event);
+    while (1) {
+        ff_framesync_next(fs);
+        if (fs->eof || !fs->frame_ready)
+            break;
+        if ((ret = fs->on_event(fs)) < 0)
+            return ret;
+        ff_framesync_drop(fs);
+        count++;
+        if (!all)
+            break;
+    }
+    if (!count && fs->eof)
+        return AVERROR_EOF;
+    return count;
+}
+
+int ff_framesync_filter_frame(FFFrameSync *fs, AVFilterLink *inlink,
+                              AVFrame *in)
+{
+    int ret;
+
+    if ((ret = ff_framesync_process_frame(fs, 1)) < 0)
+        return ret;
+    if ((ret = ff_framesync_add_frame(fs, FF_INLINK_IDX(inlink), in)) < 0)
+        return ret;
+    if ((ret = ff_framesync_process_frame(fs, 0)) < 0)
+        return ret;
+    return 0;
+}
+
+int ff_framesync_request_frame(FFFrameSync *fs, AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    int input, ret;
+
+    if ((ret = ff_framesync_process_frame(fs, 0)) < 0)
+        return ret;
+    if (ret > 0)
+        return 0;
+    if (fs->eof)
+        return AVERROR_EOF;
+    outlink->flags |= FF_LINK_FLAG_REQUEST_LOOP;
+    input = fs->in_request;
+    ret = ff_request_frame(ctx->inputs[input]);
+    if (ret == AVERROR_EOF) {
+        if ((ret = ff_framesync_add_frame(fs, input, NULL)) < 0)
+            return ret;
+        if ((ret = ff_framesync_process_frame(fs, 0)) < 0)
+            return ret;
+        ret = 0;
+    }
+    return ret;
+}