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FFmpeg/libavfilter/framesync.c
Nicolas George 53319d5c93 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.
2013-09-23 09:49:37 +02:00

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/*
* 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;
}
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