FFmpeg transcoding mpeg2 to H264 and compare frames
<p>I have the following mpeg2 source file: <br></p>

<blockquote>
  <p>Stream #0:0[0x900]: Video: mpeg2video (Main) ([2][0][0][0] / 0x0002),
  yuv420p(tv, top first), 720x576 [SAR 16:15 DAR 4:3], 4540 kb/s, 25
  fps, 25 tbr, 90k tbn, 50 tbc</p>
</blockquote>

<p>And transcoding it to H264 with the following command:<br></p>

<blockquote>
  <p>ffmpeg -i source.mpg -vcodec h264_nvenc -r 25 -g 25 -acodec copy
  -copyts -f mpegts  example1.mpg</p>
</blockquote>

<p>After this I want to extract identical frames from the both video files:<br></p>

<blockquote>
  <p>ffmpeg -y -ss 00:44:16 -i source.mpg -frames:v 1 source.png</p>
  
  <p>ffmpeg -y -ss 00:44:16 -i example1.mpg -frames:v 1 example1.png</p>
</blockquote>

<p>But pictures(source.png and example1.png) are different. Please see the source.png:
<a href="https://i.stack.imgur.com/d7YHo.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/d7YHo.png" alt="enter image description here"></a></p>

<p>And the example1.png
<a href="https://i.stack.imgur.com/0obm4.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/0obm4.png" alt="enter image description here"></a></p>

<p><strong>How can I catch the same moment(frame) at the both video</strong>?</p>