fix ffmpeg framerate bug

docs/anime_video_model.md

@@ -81,7 +81,7 @@ ffmpeg -i onepiece_demo.mp4 -qscale:v 1 -qmin 1 -qmax 1 -vsync 0 tmp_frames/fram
 2. Merge frames
 
     ```bash
-    ffmpeg -i out_frames/frame%08d.jpg -c:v libx264 -r 23.98 -pix_fmt yuv420p output.mp4
+    ffmpeg -r 23.98 -i out_frames/frame%08d.jpg -c:v libx264 -r 23.98 -pix_fmt yuv420p output.mp4
     ```
 
     ```console
@@ -95,7 +95,7 @@ ffmpeg -i onepiece_demo.mp4 -qscale:v 1 -qmin 1 -qmax 1 -vsync 0 tmp_frames/fram
     If you also want to copy audio from the input videos, run:
 
      ```bash
-    ffmpeg -i out_frames/frame%08d.jpg -i onepiece_demo.mp4 -map 0:v:0 -map 1:a:0 -c:a copy -c:v libx264 -r 23.98 -pix_fmt yuv420p output_w_audio.mp4
+    ffmpeg -r 23.98 -i out_frames/frame%08d.jpg -i onepiece_demo.mp4 -map 0:v:0 -map 1:a:0 -c:a copy -c:v libx264 -r 23.98 -pix_fmt yuv420p output_w_audio.mp4
     ```
 
     ```console

inference_realesrgan_video.py

@@ -186,7 +186,7 @@ def main():
                 f'ffmpeg -r {args.fps} -i {save_frame_folder}/frame%08d_out.{extension} -i {args.input}'
                 f' -map 0:v:0 -map 1:a:0 -c:a copy -c:v libx264 -r {args.fps} -pix_fmt yuv420p  {video_save_path}')
         else:
-            os.system(f'ffmpeg -i {save_frame_folder}/frame%08d_out.{extension} '
+            os.system(f'ffmpeg -r {args.fps} -i {save_frame_folder}/frame%08d_out.{extension} '
                       f'-c:v libx264 -r {args.fps} -pix_fmt yuv420p {video_save_path}')
 
         # delete tmp file