From f76ce9133ddaee988549e9ae0a0df8723392acaa Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Sun, 12 Mar 2023 17:01:12 +0100
Subject: lavfi/framesync: switch ts maps to use pts+timebase

Also, sort the entries.
---
 doc/filters.texi        |  6 +++---
 libavfilter/framesync.c | 44 +++++++++++++++++++++++++++++++++++---------
 libavfilter/framesync.h |  7 ++++++-
 3 files changed, 44 insertions(+), 13 deletions(-)

diff --git a/doc/filters.texi b/doc/filters.texi
index afc6fd3ebf..bd964d4094 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -377,9 +377,9 @@ input frame.
 
 @item ts_map
 Specify an explicit timestamp map. The string should be composed of lines, one
-per each output frame. The line should contain whitespace-separated times in
-microseconds, one for every input. Frames with these timestamps will be matched
-together to produces output events.
+per each output frame. The line should contain whitespace-separated pairs of
+"pts tb_num/tb_den", one for every input. Frames with these timestamps will be
+matched together to produces output events.
 @end table
 
 @c man end OPTIONS FOR FILTERS WITH SEVERAL INPUTS
diff --git a/libavfilter/framesync.c b/libavfilter/framesync.c
index 6e628af647..2042c83a0b 100644
--- a/libavfilter/framesync.c
+++ b/libavfilter/framesync.c
@@ -130,10 +130,17 @@ static void framesync_sync_level_update(FFFrameSync *fs)
         framesync_eof(fs);
 }
 
+static int map_sort(const void *m1, const void *m2)
+{
+    const TSMapEntry *e1 = m1;
+    const TSMapEntry *e2 = m2;
+    return av_compare_ts(e1->pts, e1->tb, e2->pts, e2->tb);
+}
+
 static int ts_map_parse(FFFrameSync *fs, const char *ts_map_str)
 {
     while (*ts_map_str) {
-        int64_t *dst;
+        TSMapEntry *dst;
 
         ts_map_str += strspn(ts_map_str, " \t\r\n");
 
@@ -153,7 +160,7 @@ static int ts_map_parse(FFFrameSync *fs, const char *ts_map_str)
         // read a timestamp for each input
         for (int i = 0; i < fs->nb_in; i++) {
             char *p;
-            dst[i] = strtol(ts_map_str, &p, 0);
+            dst[i].pts = strtol(ts_map_str, &p, 0);
             if (p == ts_map_str) {
                 av_log(fs, AV_LOG_ERROR,
                        "Invalid number in timestamp map on line %zu: %s\n",
@@ -162,14 +169,29 @@ static int ts_map_parse(FFFrameSync *fs, const char *ts_map_str)
             }
             ts_map_str = p;
 
-            if (fs->nb_ts_map > 1 && dst[i - (int)fs->nb_in] > dst[i]) {
-                av_log(fs, AV_LOG_ERROR,
-                       "Timestamp map for input %d, frame %zu goes backwards\n",
-                       i, fs->nb_ts_map - 1);
+            ts_map_str += strspn(ts_map_str, " \t");
+
+            dst[i].tb.num = strtol(ts_map_str, &p, 0);
+            if (p == ts_map_str) {
+                av_log(fs, AV_LOG_ERROR, "Expected timebase numerator, got %s\n", p);
+                return AVERROR_INVALIDDATA;
+            };
+            ts_map_str = p;
+
+            ts_map_str += strspn(ts_map_str, " \t");
+            if (*ts_map_str != '/') {
+                av_log(fs, AV_LOG_ERROR, "Expected '/' as the timebase separator, got %s\n", ts_map_str);
                 return AVERROR_INVALIDDATA;
             }
+            ts_map_str++;
+            dst[i].tb.den = strtol(ts_map_str, &p, 0);
+            if (p == ts_map_str) {
+                av_log(fs, AV_LOG_ERROR, "Expected timebase denominator, got %s\n", p);
+                return AVERROR_INVALIDDATA;
+            }
+            ts_map_str = p;
 
-            ts_map_str += strspn(p, " \t");
+            ts_map_str += strspn(ts_map_str, " \t");
         }
 
         // skip everything after the needed timestamp
@@ -179,6 +201,9 @@ skip_line:
             break;
     }
 
+    if (fs->ts_map)
+        qsort(fs->ts_map, fs->nb_ts_map, sizeof(*fs->ts_map) * fs->nb_in, map_sort);
+
     return 0;
 }
 
@@ -349,8 +374,9 @@ static int framesync_advance(FFFrameSync *fs)
             fs->frame_ready = 1;
             for (i = 0; i < fs->nb_in; i++) {
                 FFFrameSyncIn * const in = &fs->in[i];
-                int64_t next_ts = av_rescale_q(fs->ts_map[fs->nb_events * fs->nb_in + i],
-                                               AV_TIME_BASE_Q, fs->time_base);
+                int64_t next_ts = av_rescale_q(fs->ts_map[fs->nb_events * fs->nb_in + i].pts,
+                                               fs->ts_map[fs->nb_events * fs->nb_in + i].tb,
+                                               fs->time_base);
                 uint64_t delta_cur  = in->frame      ? FFABS(in->pts      - next_ts) : UINT64_MAX;
                 uint64_t delta_next = in->frame_next ? FFABS(in->pts_next - next_ts) : UINT64_MAX;
 
diff --git a/libavfilter/framesync.h b/libavfilter/framesync.h
index 979f54e16e..10b116c925 100644
--- a/libavfilter/framesync.h
+++ b/libavfilter/framesync.h
@@ -162,6 +162,11 @@ typedef struct FFFrameSyncIn {
     enum FFFrameTSSyncMode ts_mode;
 } FFFrameSyncIn;
 
+typedef struct TSMapEntry {
+    int64_t    pts;
+    AVRational tb;
+} TSMapEntry;
+
 /**
  * Frame sync structure.
  */
@@ -237,7 +242,7 @@ typedef struct FFFrameSync {
     char *ts_map_str;
 
     // explicit frame map
-    int64_t        *ts_map;
+    TSMapEntry     *ts_map;
     size_t       nb_ts_map;
     unsigned int    ts_map_allocated;
 } FFFrameSync;
-- 
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