[FFmpeg-devel] [PATCH 1/2] lavfi: add an API to synchronize multiple video inputs.
Nicolas George
nicolas.george at normalesup.org
Sun Sep 8 17:42:29 CEST 2013
Compared to dualinput, this API can handle more than two
inputs and can generate frames synchronized to any or all
input streams.
Signed-off-by: Nicolas George <nicolas.george at normalesup.org>
---
libavfilter/framesync.c | 329 ++++++++++++++++++++++++++++++++++++++++++++++++
libavfilter/framesync.h | 296 +++++++++++++++++++++++++++++++++++++++++++
2 files changed, 625 insertions(+)
create mode 100644 libavfilter/framesync.c
create mode 100644 libavfilter/framesync.h
diff --git a/libavfilter/framesync.c b/libavfilter/framesync.c
new file mode 100644
index 0000000..12db50c
--- /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;
+}
diff --git a/libavfilter/framesync.h b/libavfilter/framesync.h
new file mode 100644
index 0000000..2072781
--- /dev/null
+++ b/libavfilter/framesync.h
@@ -0,0 +1,296 @@
+/*
+ * 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
+ */
+
+#ifndef AVFILTER_FRAMESYNC_H
+#define AVFILTER_FRAMESYNC_H
+
+#include "bufferqueue.h"
+
+/*
+ * TODO
+ * Callback-based API similar to dualinput.
+ * Export convenient options.
+ */
+
+/**
+ * This API is intended as a helper for filters that have several video
+ * input and need to combine them somehow. If the inputs have different or
+ * variable frame rate, getting the input frames to match requires a rather
+ * complex logic and a few user-tunable options.
+ *
+ * In this API, when a set of synchronized input frames is ready to be
+ * procesed is called a frame event. Frame event can be generated in
+ * response to input frames on any or all inputs and the handling of
+ * situations where some stream extend beyond the beginning or the end of
+ * others can be configured.
+ *
+ * The basic working of this API is the following:
+ *
+ * - When a frame is available on any input, add it using
+ * ff_framesync_add_frame().
+ *
+ * - When a frame event is ready to be processed (i.e. after adding a frame
+ * or when requested on input):
+ * - call ff_framesync_next();
+ * - if fs->frame_ready is true, process the frames;
+ * - call ff_framesync_drop().
+ */
+
+/**
+ * Stream extrapolation mode
+ *
+ * Describe how the frames of a stream are extrapolated before the first one
+ * and after EOF to keep sync with possibly longer other streams.
+ */
+enum FFFrameSyncExtMode {
+
+ /**
+ * Completely stop all streams with this one.
+ */
+ EXT_STOP,
+
+ /**
+ * Ignore this stream and continue processing the other ones.
+ */
+ EXT_NULL,
+
+ /**
+ * Extend the frame to infinity.
+ */
+ EXT_INFINITY,
+};
+
+/**
+ * Input stream structure
+ */
+typedef struct FFFrameSyncIn {
+
+ /**
+ * Queue of incoming AVFrame, and NULL to mark EOF
+ */
+ struct FFBufQueue queue;
+
+ /**
+ * Extrapolation mode for timestamps before the first frame
+ */
+ enum FFFrameSyncExtMode before;
+
+ /**
+ * Extrapolation mode for timestamps after the last frame
+ */
+ enum FFFrameSyncExtMode after;
+
+ /**
+ * Time base for the incoming frames
+ */
+ AVRational time_base;
+
+ /**
+ * Current frame, may be NULL before the first one or after EOF
+ */
+ AVFrame *frame;
+
+ /**
+ * Next frame, for internal use
+ */
+ AVFrame *frame_next;
+
+ /**
+ * PTS of the current frame
+ */
+ int64_t pts;
+
+ /**
+ * PTS of the next frame, for internal use
+ */
+ int64_t pts_next;
+
+ /**
+ * Boolean flagging the next frame, for internal use
+ */
+ uint8_t have_next;
+
+ /**
+ * State: before first, in stream or after EOF, for internal use
+ */
+ uint8_t state;
+
+ /**
+ * Synchronization level: frames on input at the highest sync level will
+ * generate output frame events.
+ *
+ * For example, if inputs #0 and #1 have sync level 2 and input #2 has
+ * sync level 1, then a frame on either input #0 or #1 will generate a
+ * frame event, but not a frame on input #2 until both inputs #0 and #1
+ * have reached EOF.
+ *
+ * If sync is 0, no frame event will be generated.
+ */
+ unsigned sync;
+
+} FFFrameSyncIn;
+
+/**
+ * Frame sync structure.
+ */
+typedef struct FFFrameSync {
+ const AVClass *class;
+ void *parent;
+
+ /**
+ * Number of input streams
+ */
+ unsigned nb_in;
+
+ /**
+ * Time base for the output events
+ */
+ AVRational time_base;
+
+ /**
+ * Timestamp of the current event
+ */
+ int64_t pts;
+
+ /**
+ * Callback called when a frame event is ready
+ */
+ int (*on_event)(struct FFFrameSync *fs);
+
+ /**
+ * Opaque pointer, not used by the API
+ */
+ void *opaque;
+
+ /**
+ * Index of the input that requires a request
+ */
+ unsigned in_request;
+
+ /**
+ * Synchronization level: only inputs with the same sync level are sync
+ * sources.
+ */
+ unsigned sync_level;
+
+ /**
+ * Flag indicating that a frame event is ready
+ */
+ uint8_t frame_ready;
+
+ /**
+ * Flag indicating that output has reached EOF.
+ */
+ uint8_t eof;
+
+ /**
+ * Array of inputs; all inputs must be in consecutive memory
+ */
+ FFFrameSyncIn in[1]; /* must be the last field */
+
+} FFFrameSync;
+
+/**
+ * Initialize a frame sync structure.
+ *
+ * The entire structure is expected to be already set to 0.
+ *
+ * @param fs frame sync structure to initialize
+ * @param parent parent object, used for logging
+ * @param nb_in number of inputs
+ */
+void ff_framesync_init(FFFrameSync *fs, void *parent, unsigned nb_in);
+
+/**
+ * Configure a frame sync structure.
+ *
+ * Must be called after all options are set but before all use.
+ *
+ * @return >= 0 for success or a negative error code
+ */
+int ff_framesync_configure(FFFrameSync *fs);
+
+/**
+ * Free all memory currently allocated.
+ */
+void ff_framesync_uninit(FFFrameSync *fs);
+
+/**
+ * Add a frame to an input
+ *
+ * Typically called from the filter_frame() method.
+ *
+ * @param fs frame sync structure
+ * @param in index of the input
+ * @param frame input frame, or NULL for EOF
+ */
+int ff_framesync_add_frame(FFFrameSync *fs, unsigned in, AVFrame *frame);
+
+/**
+ * Prepare the next frame event.
+ *
+ * The status of the operation can be found in fs->frame_ready and fs->eof.
+ */
+void ff_framesync_next(FFFrameSync *fs);
+
+/**
+ * Drop the current frame event.
+ */
+void ff_framesync_drop(FFFrameSync *fs);
+
+/**
+ * Get the current frame in an input.
+ *
+ * @param fs frame sync structure
+ * @param in index of the input
+ * @param rframe used to return the current frame (or NULL)
+ * @param get if not zero, the calling code needs to get ownership of
+ * the returned frame; the current frame will either be
+ * duplicated or removed from the framesync structure
+ */
+int ff_framesync_get_frame(FFFrameSync *fs, unsigned in, AVFrame **rframe,
+ unsigned get);
+
+/**
+ * Process one or several frame using the on_event callback.
+ *
+ * @return number of frames processed or negative error code
+ */
+int ff_framesync_process_frame(FFFrameSync *fs, unsigned all);
+
+
+/**
+ * Accept a frame on a filter input.
+ *
+ * This function can be the complete implementation of all filter_frame
+ * methods of a filter using framesync.
+ */
+int ff_framesync_filter_frame(FFFrameSync *fs, AVFilterLink *inlink,
+ AVFrame *in);
+
+/**
+ * Request a frame on the filter output.
+ *
+ * This function can be the complete implementation of all filter_frame
+ * methods of a filter using framesync if it has only one output.
+ */
+int ff_framesync_request_frame(FFFrameSync *fs, AVFilterLink *outlink);
+
+#endif /* AVFILTER_FRAMESYNC_H */
--
1.8.4.rc3
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