user29716: I am using ffmpeg-python to convert an hevc mkv file to an h264 mp4. This is the relevant code:
ffmpeg.input(video_file).output(out_name, vcodec='libx264', **{'pix_fmt': 'yuv420p'}).run()

Yet after converting the file, the resulting mp4 will only play in certain media players. Here is the result of running ffprobe on the mp4:

I know this should be possible, so does anyone have an idea of why it isn't playing in older/more standard media players?

user1871: Legacy media players like Windows Media Player may be finicky about the files they will accept. In this case, it looks like the audio channel count of 6 is too high.
Add the CLI option -ac 2 and check.

29716: <p>I am using <a href="https://kkroening.github.io/ffmpeg-python/" rel="nofollow noreferrer">ffmpeg-python</a> to convert an hevc mkv file to an h264 mp4. This is the relevant code:</p>
<pre><code>ffmpeg.input(video_file).output(out_name, vcodec='libx264', **{'pix_fmt': 'yuv420p'}).run()
</code></pre>
<p>Yet after converting the file, the resulting mp4 will only play in certain media players. Here is the result of running ffprobe on the mp4:</p>
<p><a href="https://i.stack.imgur.com/FHJt1.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/FHJt1.png" alt="ffprobe output" /></a></p>
<p>I know this should be possible, so does anyone have an idea of why it isn't playing in older/more standard media players?</p>
 1871: <p>Legacy media players like Windows Media Player may be finicky about the files they will accept. In this case, it looks like the audio channel count of 6 is too high.</p>
<p>Add the CLI option <code>-ac 2</code> and check.</p>
