user14040: I have a video of 2 mins length.Now I want to add extra 1 hour to the video.I have done this be changing video duration in composition settings.But video is rendering for about 4 gb.Whereas original video is only 5 mb.
How to render this video in mp4 format with around 10mb size.

user1871: I don't know if the AE encoder can signal duplicate frames (which would keep the size down). You may be better off using ffmpeg, a command-line tool.
Suppose your source video is 1280x720 at 24 fps, then you would run
ffmpeg -i source.mp4 -f lavfi -i "color=black:s=1280x720:r=24:d=3600" -filter_complex "[0][1]concat=n=2:v=1:a=0[v]" -map [v] -c:v libx264 output.mp4 


To combine with text overlay,
ffmpeg -i universal.mp4 -f lavfi -i "color=black:s=1280x720:r=24000/1001:d=20" -filter_complex "[0][1]concat=n=2:v=1:a=0[v];[v]drawtext=fontfile=FreeSerifB‌​old.ttf:text=\'Hello World\':fontcolor=white@1.0:fontsize=16:x=w-tw-10:y=10:box=1:boxcolor=black@0.5[vout]" -map [vout] -map 0:a -c:v libx264 -profile:v main -movflags +faststart output.mp4 2>&1


14040: <p>I have a video of 2 mins length.Now I want to add extra 1 hour to the video.I have done this be changing video duration in composition settings.But video is rendering for about 4 gb.Whereas original video is only 5 mb.</p>

<p>How to render this video in mp4 format with around 10mb size.</p>
 1871: <p>I don't know if the AE encoder can signal duplicate frames (which would keep the size down). You may be better off using <a href="https://ffmpeg.org/download.html" rel="nofollow">ffmpeg</a>, a command-line tool.</p>

<p>Suppose your source video is 1280x720 at 24 fps, then you would run</p>

<pre><code>ffmpeg -i source.mp4 -f lavfi -i "color=black:s=1280x720:r=24:d=3600" -filter_complex "[0][1]concat=n=2:v=1:a=0[v]" -map [v] -c:v libx264 output.mp4 
</code></pre>

<hr>

<p>To combine with text overlay,</p>

<pre><code>ffmpeg -i universal.mp4 -f lavfi -i "color=black:s=1280x720:r=24000/1001:d=20" -filter_complex "[0][1]concat=n=2:v=1:a=0[v];[v]drawtext=fontfile=FreeSerifB‌​old.ttf:text=\'Hello World\':fontcolor=white@1.0:fontsize=16:x=w-tw-10:y=10:box=1:boxcolor=black@0.5[vout]" -map [vout] -map 0:a -c:v libx264 -profile:v main -movflags +faststart output.mp4 2&gt;&amp;1
</code></pre>
