user22438: I am using kdenlive to create mp4 files.
How do I indicate which image (or which point on the timeline) that will appear as the mp4 file icon when I display the mp4 file in Microsoft File Explorer?

user18155: Use
ffmpeg -i input.mp4 -i input.png -map 0 -map 1 -c copy -disposition:v:1 attached_pic output.mp4


-map 0 and -map 1 will map all streams from both input files (numbered as 0 and 1) into the output file, 
-c copy will directly copy all streams into the output file (i.e. without transcoding),
-disposition:v:1 attached_pic will tag your picture (the videostream #1) as as the embedded cover / thumbnail.


22438: <p>I am using kdenlive to create mp4 files.</p>

<p>How do I indicate which image (or which point on the timeline) that will appear as the mp4 file icon when I display the mp4 file in Microsoft File Explorer?</p>
 18155: <p>Use</p>

<pre><code>ffmpeg -i input.mp4 -i input.png -map 0 -map 1 -c copy -disposition:v:1 attached_pic output.mp4
</code></pre>

<ul>
<li><code>-map 0</code> and <code>-map 1</code> will map all streams from both input files (numbered as <code>0</code> and <code>1</code>) into the output file, </li>
<li><code>-c copy</code> will directly copy all streams into the output file (i.e. without transcoding),</li>
<li><code>-disposition:v:1 attached_pic</code> will tag your picture (the <strong>v</strong>ideostream #<strong>1</strong>) as as the embedded cover / thumbnail.</li>
</ul>
