libavfilter/framesync.c
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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,
 };
 
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 int ff_framesync_init(FFFrameSync *fs, void *parent, unsigned nb_in)
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 {
     fs->class  = &framesync_class;
     fs->parent = parent;
     fs->nb_in  = nb_in;
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     fs->in = av_calloc(nb_in, sizeof(*fs->in));
     if (!fs->in)
         return AVERROR(ENOMEM);
     return 0;
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 }
 
 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);
     }
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     av_freep(&fs->in);
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 }
 
 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;
     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;
 }