[FFmpeg-devel] [PATCH] fftools/ffmpeg: accelerate seeking while reading input at native frame rate

[Linjie Fu]

From: Linjie Fu <linjie.justin.fu at gmail.com>

Skip the logic of frame rate emulation until the input reaches the
specified start time.

Test CMD:
   $ffmpeg -re -ss 30 -i input.mp4 -pix_fmt yuv420p -f sdl2 -

Before the patch:
first time to got frame, it takes 257305 us
After this patch:
first time to got frame, it takes 48879 us

Signed-off-by: Linjie Fu <linjie.justin.fu at gmail.com>
---
 fftools/ffmpeg.c | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index e97d879cb3..851f23ffdb 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -4223,6 +4223,8 @@ static int get_input_packet(InputFile *f, AVPacket **pkt)
         int i;
         for (i = 0; i < f->nb_streams; i++) {
             InputStream *ist = input_streams[f->ist_index + i];
+            if (!ist->got_output)
+                continue;
             int64_t pts = av_rescale(ist->dts, 1000000, AV_TIME_BASE);
             int64_t now = av_gettime_relative() - ist->start;
             if (pts > now)
-- 
2.31.1