user14036: I have an x265 video file with dual audio tracks in different languages. Obviously one is useless to me and I want to remove it without waiting through a lengthy conversion that will lead to quality loss.
I have been using mkv2mp4 to do this with x264 in the past, but it spits out an error when I try any x265 coded video. Is there a codec I can install? Any other suggestions?

user1871: Use ffmpeg*, a free command-line tool: 
ffmpeg -i input.mkv -c copy -map 0:v -map 0:a:0 singleaudio.mkv

where 0:a:0 is the index of the audio stream you wish to keep. In ffmpeg, numbering starts from zero, so 0:a:0 refers to the first audio stream in the source file. Running ffprobe input.mkv beforehand will show the contents of the input.
*download the latest snapshot/nightly build.

14036: <p>I have an x265 video file with dual audio tracks in different languages. Obviously one is useless to me and I want to remove it without waiting through a lengthy conversion that will lead to quality loss.</p>

<p>I have been using <a href="https://sourceforge.net/projects/mkv2mp4/" rel="nofollow">mkv2mp4</a> to do this with x264 in the past, but it spits out an error when I try any x265 coded video. Is there a codec I can install? Any other suggestions?</p>
 1871: <p>Use <a href="https://ffmpeg.org/download.html" rel="nofollow">ffmpeg</a>*, a free command-line tool: </p>

<pre><code>ffmpeg -i input.mkv -c copy -map 0:v -map 0:a:0 singleaudio.mkv
</code></pre>

<p>where <code>0:a:0</code> is the index of the audio stream you wish to keep. In ffmpeg, numbering starts from zero, so <code>0:a:0</code> refers to the first audio stream in the source file. Running <code>ffprobe input.mkv</code> beforehand will show the contents of the input.</p>

<p>*download the latest snapshot/nightly build.</p>
