From a0d394e2f60fd9ff72d6a5f656200abbe94724a7 Mon Sep 17 00:00:00 2001
From: Fuyan Yuan <33221728+TheRainstorm@users.noreply.github.com>
Date: Wed, 3 Jan 2024 22:58:08 +0800
Subject: [PATCH] [FFmpegMerger] Fix merger discard input timestamps

Some website save video-only and audio-only file with non-zero
timestamp. Therefore, when merging them, ffmpeg should keep original
timestamp.

According to ffmpeg doc: https://ffmpeg.org/ffmpeg.html

`-copyts`: Do not process input timestamps, but keep their values
without trying to sanitize them. In particular, do not remove the
initial start time offset value.
---
 yt_dlp/postprocessor/ffmpeg.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/yt_dlp/postprocessor/ffmpeg.py b/yt_dlp/postprocessor/ffmpeg.py
index 7c904417ba..82058a4b9d 100644
--- a/yt_dlp/postprocessor/ffmpeg.py
+++ b/yt_dlp/postprocessor/ffmpeg.py
@@ -822,7 +822,7 @@ class FFmpegMergerPP(FFmpegPostProcessor):
     def run(self, info):
         filename = info['filepath']
         temp_filename = prepend_extension(filename, 'temp')
-        args = ['-c', 'copy']
+        args = ['-c', 'copy', '-copyts']
         audio_streams = 0
         for (i, fmt) in enumerate(info['requested_formats']):
             if fmt.get('acodec') != 'none':