"Cannot find a matching stream for unlabeled input pad 2 on filter Parsed_amerge_2" ffmpeg The error I'm getting is in the title.
I want to merge the two audio streams from a video into one (yes, I've checked if there is two and there is). This is the command I'm using:
ffmpeg -i input.mp4 -filter_complex &quot;[0:v]scale=-2:720,format=yuv420p[v];[0:a]amerge=inputs=2[a]&quot; -map &quot;[v]&quot; -map &quot;[a]&quot; -c:v libx264 -crf 23 -preset medium -c:a aac -ar 44100 -ac 2 output.mp4

Any ideas why I could be getting the error?
Inside a filtergraph, each pad is associated with a single stream. And a specifier such as 0:a will match the first stream that qualifies. You need to specify two pads and fully specify the input streams.
[0:a:0][0:a:1]amerge=inputs=2[a]