user237: I have two MP4 files that I generated with Camtasia Studio. I need to join them together post rendering with Camtasia (it can't be done during the Camtasia rendering process). Looking for a utility or technique that will work to join these, preferably that doesn't require re-rendering all the video again.
Update: Either Windows (preferred) or Mac. Doesn't need a GUI if it is a good command-line app.

user1871: Avidemux should do the work. 

Load File 
Go to File -> Append and select File 
To the left of the video window, 

set video mode to Copy; 
same for audio mode; 
set format to MP4. 

Go to File -> Save -> Video.


user129: I would suggest using ffmpeg, and the -vcopy switch.  Usually this will work, but it depends on codec support.  
Various builds of it have various codecs.  If one version of it doesn't work, try downloading a copy from a different site.

user4426: i think MPEG Streamclip can do this.  It's free on mac and pc.

user8048: I was encountering audio sync issues when trying to do this with Avidemux, but I came upon a two-step process that keeps the audio in sync:

Concatenate files using MKVToolNix (I used version 7.4.0 for Mac). This results in a Matroska video (.mkv) file.
Remux the .mkv file to MP4 format using Avidemux (I used verison 2.6 for Mac). I chose the MP4v2muxer option in the Output Format section. This results in an MP4 file with audio and video in sync.


user3361: I think the simplest way to this is to use MP4Box.
./MP4Box -add file1.mp4 -cat file2.mp4 -cat file3.mp4 output.mp4


237: <p>I have two MP4 files that I generated with <a href="http://www.techsmith.com/camtasia.html" rel="nofollow">Camtasia Studio</a>. I need to join them together post rendering with Camtasia (it can't be done during the Camtasia rendering process). Looking for a utility or technique that will work to join these, preferably that doesn't require re-rendering all the video again.</p>

<p><strong>Update</strong>: Either Windows (preferred) or Mac. Doesn't need a GUI if it is a good command-line app.</p>
 1871: <p><a href="http://fixounet.free.fr/avidemux/" rel="nofollow">Avidemux</a> should do the work. </p>

<ol>
<li>Load File </li>
<li>Go to File -> Append and select File </li>
<li>To the left of the video window, 
<ul>
<li>set video mode to Copy; </li>
<li>same for audio mode; </li>
<li>set format to MP4. </li>
</ul></li>
<li>Go to File -> Save -> Video.</li>
</ol>
 129: <p>I would suggest using ffmpeg, and the <code>-vcopy</code> switch.  <em>Usually</em> this will work, but it depends on codec support.  </p>

<p>Various builds of it have various codecs.  If one version of it doesn't work, try downloading a copy from a different site.</p>
 4426: <p>i think <a href="http://www.squared5.com/" rel="nofollow">MPEG Streamclip</a> can do this.  It's free on mac and pc.</p>
 8048: <p>I was encountering audio sync issues when trying to do this with Avidemux, but I came upon a two-step process that keeps the audio in sync:</p>

<ol>
<li>Concatenate files using <a href="https://www.bunkus.org/videotools/mkvtoolnix/downloads.html" rel="nofollow">MKVToolNix</a> (I used version 7.4.0 for Mac). This results in a Matroska video (.mkv) file.</li>
<li>Remux the .mkv file to MP4 format using <a href="http://fixounet.free.fr/avidemux/download.html" rel="nofollow">Avidemux</a> (I used verison 2.6 for Mac). I chose the MP4v2muxer option in the Output Format section. This results in an MP4 file with audio and video in sync.</li>
</ol>
 3361: <p>I think the simplest way to this is to use MP4Box.</p>

<pre><code>./MP4Box -add file1.mp4 -cat file2.mp4 -cat file3.mp4 output.mp4
</code></pre>
