From 9049ea676363f113eaaef4dbf21aee7df69a3988 Mon Sep 17 00:00:00 2001 From: Niklas Haas Date: Thu, 15 Jun 2023 17:02:48 +0200 Subject: [PATCH] lavfi/vf_libplacebo: set time_base/frame_rate dynamically Use the gcd of all input timebases to ensure PTS accuracy. For the framerate, just pick the highest of all the inputs, under the assumption that we will render frames with approximately this frequency. Of course, this is not 100% accurate, in particular if the input frames are badly misaligned. But this field is informational to begin with. Importantly, it covers the "common" case of combining high FPS and low FPS streams with aligned frames. --- libavfilter/vf_libplacebo.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/libavfilter/vf_libplacebo.c b/libavfilter/vf_libplacebo.c index 1085b6fdd0..09a24e7c29 100644 --- a/libavfilter/vf_libplacebo.c +++ b/libavfilter/vf_libplacebo.c @@ -1158,6 +1158,11 @@ static int libplacebo_config_input(AVFilterLink *inlink) return 0; } +static inline AVRational max_q(AVRational a, AVRational b) +{ + return av_cmp_q(a, b) < 0 ? b : a; +} + static int libplacebo_config_output(AVFilterLink *outlink) { int err; @@ -1198,6 +1203,16 @@ static int libplacebo_config_output(AVFilterLink *outlink) if (s->fps.num) { outlink->frame_rate = s->fps; outlink->time_base = av_inv_q(s->fps); + } else { + outlink->frame_rate = avctx->inputs[0]->frame_rate; + outlink->time_base = avctx->inputs[0]->time_base; + for (int i = 1; i < s->nb_inputs; i++) { + outlink->frame_rate = max_q(outlink->frame_rate, + avctx->inputs[i]->frame_rate); + outlink->time_base = av_gcd_q(outlink->time_base, + avctx->inputs[i]->time_base, + AV_TIME_BASE / 2, AV_TIME_BASE_Q); + } } /* Static variables */