user3866: I am recording 15-minutes videos with my GoPro Hero 3 Black edition. The camera starts a new file every 10 minutes of recording by default. I do not think I can change this in a setting.
When I do the white-balance and other edits in the GoPro Cineform Studio, I cannot find a function to stitch these videos back together into one continuous clip. 
I was somehow expecting that if GoPro automatically splits these videos that there would be a function to rejoin them, too. Am I missing something? Is there such a function in this software or do I have to get another software to do this? 
If so, what software should I get, assuming that I do not want to do anything else than that?

user4426: Cineform can't join clips together. 
You could use iMovie (free), QuickTime 7 Pro (£30/$20), or something like Final Cut or Premiere (more). 

user3866: The latest version of Cineform can join clips together as I found out recently, so the problem solved itself.

user3037: If you are using PC, you have some great options. Avidemux is great and allows you to join separate clips together losslessy which is great. You simply open the first 10-minute movie clip in Avidemux and then choose "Append" from the File menu. Select your second clip and press OK. It should now simply be added onto the end of your first clip. Rinse and repeat for extra segments you might have. Make sure the audio/video options on the left hand side says "copy" or "stream copy" to ensure you are saving the new output file without re-encoding.
Virtualdub is also capable of this but you might need to install codecs/plugins to be able to open and use your files.
Hope that solves your problem!

user5053: For this purpose I like to use SolveigMM Video Splitter. It's very fast and lossless video tool (no recompression) and it fully supports H.264 video (GoPro records in mp4 files using h.264 compression).

user25027: Used to merge them with GoPro Studio, but it took too much effort and had too many steps.
Made a PowerShell script to quickly merge and convert videos using open source tools MKVTools and Handbrake.
With one command line, I get my files merged and compressed to about one-fifth of the original size, ready to upload using the HandBrake preset "Vimeo YouTube HQ 1440p60 2.5K".
Output file is Encoded-{original filename}-{date of subfolder}
https://github.com/alexandrosk0/GorpoMergeAndEncode
Example
.\goproMergeEncode.ps1 -dir "D:\Video\GoPro\2019-04-21\HERO5 Black 1\"

To run from command line: powershell.exe –ExecutionPolicy Bypass -noexit "& 'D:\goproMergeEncode.ps1' -dir 'D:\Video\GoPro\2019-04-19\HERO5 Black 1\' -test"
Output file for D:\Video\GoPro\2019-04-21\HERO5 Black 1\GOPR2548.MP4 is Encoded-GOPR2548-20190421.mp4
Parameters

-dir Defaults to the current directory
-preset The default preset is "Vimeo YouTube HQ 1440p60 2.5K".
-MKVMergeExtraParam Extra parameters for MKVMerge
-HandbrakeExtraParam Extra parameters for Handbrake
-test Test merge and encode three seconds of each video, without deleting the original files
-delete Delete original files if no error is found. Defaults to true
-mergeAll Ignore file naming and merge all files in the directory
-noEncoding Skip encoding step, only merge

Notes
Based on the file name format GOPR2548.MP4 and multiple files GP012548.MP4, GP022548.MP4,... and folder structure ..\GoPro\2019-04-21\HERO5 Black 1
Note that the script expects an arrangement that works for single videos for the camera models: HD HERO2, HERO3, HERO3+, HERO (2014), HERO Session, HERO4, HERO5 Black, HERO5 Session, HERO (2018)
For HERO6 Black, & HERO7 (White, Silver, Black) or other formats use -mergeAll parameter.
Requirements
Requires MKVmerge and HandBrakeCLI installed in C:/Program Files/MKVToolNix\ and C:\Program Files\HandBrake\ respectively.
Best of all, it's a text-based script, you can change it at will.

3866: <p>I am recording 15-minutes videos with my GoPro Hero 3 Black edition. The camera starts a new file every 10 minutes of recording by default. I do not think I can change this in a setting.</p>

<p>When I do the white-balance and other edits in the GoPro Cineform Studio, I cannot find a function to stitch these videos back together into one continuous clip. </p>

<p>I was somehow expecting that if GoPro automatically splits these videos that there would be a function to rejoin them, too. Am I missing something? Is there such a function in this software or do I have to get another software to do this? </p>

<p>If so, what software should I get, assuming that I do not want to do anything else than that?</p>
 4426: <p>Cineform can't join clips together. </p>

<p>You could use iMovie (free), QuickTime 7 Pro (£30/$20), or something like Final Cut or Premiere (more). </p>
 3866: <p>The latest version of Cineform can join clips together as I found out recently, so the problem solved itself.</p>
 3037: <p>If you are using PC, you have some great options. <a href="http://fixounet.free.fr/avidemux/" rel="nofollow">Avidemux</a> is great and allows you to join separate clips together losslessy which is great. You simply open the first 10-minute movie clip in Avidemux and then choose "Append" from the File menu. Select your second clip and press OK. It should now simply be added onto the end of your first clip. Rinse and repeat for extra segments you might have. Make sure the audio/video options on the left hand side says "copy" or "stream copy" to ensure you are saving the new output file without re-encoding.</p>

<p><a href="http://www.virtualdub.org/" rel="nofollow">Virtualdub</a> is also capable of this but you might need to install codecs/plugins to be able to open and use your files.</p>

<p>Hope that solves your problem!</p>
 5053: <p>For this purpose I like to use <a href="http://www.solveigmm.com/en/products/video-splitter-gopro" rel="nofollow">SolveigMM Video Splitter</a>. It's very fast and lossless video tool (no recompression) and it fully supports H.264 video (GoPro records in mp4 files using h.264 compression).</p>
 25027: <p>Used to merge them with GoPro Studio, but it took too much effort and had too many steps.</p>

<p>Made a PowerShell script to quickly merge and convert videos using open source tools MKVTools and Handbrake.</p>

<p>With one command line, I get my files merged and compressed to about one-fifth of the original size, ready to upload using the HandBrake preset "Vimeo YouTube HQ 1440p60 2.5K".</p>

<p>Output file is Encoded-{original filename}-{date of subfolder}</p>

<p><a href="https://github.com/alexandrosk0/GorpoMergeAndEncode" rel="nofollow noreferrer">https://github.com/alexandrosk0/GorpoMergeAndEncode</a></p>

<h3>Example</h3>

<pre><code>.\goproMergeEncode.ps1 -dir "D:\Video\GoPro\2019-04-21\HERO5 Black 1\"
</code></pre>

<p>To run from command line: <code>powershell.exe –ExecutionPolicy Bypass -noexit "&amp; 'D:\goproMergeEncode.ps1' -dir 'D:\Video\GoPro\2019-04-19\HERO5 Black 1\' -test"</code></p>

<p>Output file for D:\Video\GoPro\2019-04-21\HERO5 Black 1\GOPR2548.MP4 is Encoded-GOPR2548-20190421.mp4</p>

<h3>Parameters</h3>

<ul>
<li>-dir Defaults to the current directory</li>
<li>-preset The default preset is "Vimeo YouTube HQ 1440p60 2.5K".</li>
<li>-MKVMergeExtraParam Extra parameters for MKVMerge</li>
<li>-HandbrakeExtraParam Extra parameters for Handbrake</li>
<li>-test Test merge and encode three seconds of each video, without deleting the original files</li>
<li>-delete Delete original files if no error is found. Defaults to true</li>
<li>-mergeAll Ignore file naming and merge all files in the directory</li>
<li>-noEncoding Skip encoding step, only merge</li>
</ul>

<h3>Notes</h3>

<p>Based on the file name format GOPR2548.MP4 and multiple files GP012548.MP4, GP022548.MP4,... and folder structure ..\GoPro\2019-04-21\HERO5 Black 1</p>

<p>Note that the script expects an arrangement that works for single videos for the camera models: HD HERO2, HERO3, HERO3+, HERO (2014), HERO Session, HERO4, HERO5 Black, HERO5 Session, HERO (2018)</p>

<p>For HERO6 Black, &amp; HERO7 (White, Silver, Black) or other formats use -mergeAll parameter.</p>

<h3>Requirements</h3>

<p>Requires MKVmerge and HandBrakeCLI installed in C:/Program Files/MKVToolNix\ and C:\Program Files\HandBrake\ respectively.</p>

<p>Best of all, it's a text-based script, you can change it at will.</p>
