Appending 2 video files, the second loses all sound

[Mario]

Hello,

I have 2 videos ,
the first one is an intro with some text , in which I added some free music from youtube via Audio->Select Track->Add Audio Track
If a play this video with a player everything works fine, the music is playing and all is good.
I also have a second video which has recorded gameplay, also full of the game's sound.

But when I add these two files together, the final result is that only the audio of the first intro video is kept,
and the second part with the gameplay has no sound at all.

I cannot understand what I do wrong.
Any help is appreciated...
thank you.

[eumagga0x2a]

The number of audio tracks, the audio codec including codec settings and the channel layout of all tracks in all videos must match.

[Mario]

Thank you for the reply.
After changing the audio output to AAC and appending the video parts again, then all the videos have sound, but it is completely out of sync...
Any ideas?

[fish]

I would make sure the audio of both files matched before appending, so it's a case of saving each clip from Avidemux, with the same audio settings first. Then append them in copy mode, assuming the audio is still in sync in each clip before appending.

[Mario]

that's the problem.
Before appending every single video has synced sound,
after the appending everything goes bad..
I just cand find the solution.

[fish]

Did you load each clip into Avidmux and save them with the same audio settings, before trying to append them?