From efe442362794abe3cef43eea6b4071919b0b2866 Mon Sep 17 00:00:00 2001
From: Anton Khirnov <anton@khirnov.net>
Date: Thu, 17 Nov 2022 12:55:47 +0100
Subject: [PATCH] fftools/ffmpeg: store forced keyframe pts in AV_TIME_BASE_Q

Rather than the encoder timebase. Since the times are parsed as
microseconds, this will not reduce precision, except possibly when
chapter times are used and the chapter timebase happens to be better
aligned with the encoder timebase, which is unlikely.

This will allow parsing the keyframe times earlier (before encoder
timebase is known) in future commits.
---
 fftools/ffmpeg.c | 15 +++++----------
 fftools/ffmpeg.h |  1 +
 2 files changed, 6 insertions(+), 10 deletions(-)

diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 3d10ffc3b2..5d39d8f69b 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -1052,7 +1052,7 @@ static enum AVPictureType forced_kf_apply(KeyframeForceCtx *kf, AVRational tb,
 
     pts_time = (in_picture->pts - kf->ref_pts) * av_q2d(tb);
     if (kf->index < kf->nb_pts &&
-        in_picture->pts >= kf->pts[kf->index]) {
+        av_compare_ts(in_picture->pts, tb, kf->pts[kf->index], AV_TIME_BASE_Q) >= 0) {
         kf->index++;
         goto force_keyframe;
     } else if (kf->pexpr) {
@@ -2748,8 +2748,7 @@ static void set_encoder_id(OutputFile *of, OutputStream *ost)
                 AV_DICT_DONT_STRDUP_VAL | AV_DICT_DONT_OVERWRITE);
 }
 
-static void parse_forced_key_frames(KeyframeForceCtx *kf, OutputFile *of,
-                                    AVCodecContext *avctx)
+static void parse_forced_key_frames(KeyframeForceCtx *kf, OutputFile *of)
 {
     const char *p;
     int n = 1, i, size, index = 0;
@@ -2782,21 +2781,17 @@ static void parse_forced_key_frames(KeyframeForceCtx *kf, OutputFile *of,
                                      sizeof(*pts))))
                 report_and_exit(AVERROR(ENOMEM));
             t = p[8] ? parse_time_or_die("force_key_frames", p + 8, 1) : 0;
-            t = av_rescale_q(t, AV_TIME_BASE_Q, avctx->time_base);
 
             for (j = 0; j < nb_ch; j++) {
                 const AVChapter *c = ch[j];
                 av_assert1(index < size);
                 pts[index++] = av_rescale_q(c->start, c->time_base,
-                                            avctx->time_base) + t;
+                                            AV_TIME_BASE_Q) + t;
             }
 
         } else {
-
-            t = parse_time_or_die("force_key_frames", p, 1);
             av_assert1(index < size);
-            pts[index++] = av_rescale_q(t, AV_TIME_BASE_Q, avctx->time_base);
-
+            pts[index++] = parse_time_or_die("force_key_frames", p, 1);
         }
 
         p = next;
@@ -2971,7 +2966,7 @@ static int init_output_stream_encode(OutputStream *ost, AVFrame *frame)
                 // Don't parse the 'forced_keyframes' in case of 'keep-source-keyframes',
                 // parse it only for static kf timings
             } else if(strncmp(ost->kf.forced_keyframes, "source", 6)) {
-                parse_forced_key_frames(&ost->kf, of, ost->enc_ctx);
+                parse_forced_key_frames(&ost->kf, of);
             }
         }
         break;
diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index db1f00b259..f5d51b90ec 100644
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -492,6 +492,7 @@ typedef struct KeyframeForceCtx {
 
     int64_t      ref_pts;
 
+    // timestamps of the forced keyframes, in AV_TIME_BASE_Q
     int64_t     *pts;
     int       nb_pts;
     int          index;