Video MP4 AVC play failed after merging

[Kelvin]

Hi guys
I downloaded two video from youtube, format mp4 AVC. After I merge them with avidemux,  it cannot play when it gets to the latter video.

Avidemux 2.7 nightly build on Windows 10 64bit.
http://www.avidemux.org/nightly/win64/avidemux_r170623_win64Qt5_438.zip

Two video from youtube:

• https://www.youtube.com/watch?v=56lXwJcBYk8
• https://www.youtube.com/watch?v=haXIeJNyJ_E

You can download by youtube-dl:

command line:

• > youtube-dl -f 138 56lXwJcBYk8
• > youtube-dl -f 266 haXIeJNyJ_E

I attached the project file for more detail.

[eumagga0x2a]

Appending WFM at least with MKV muxer.

[Kelvin]

what does "Appending WFM" mean?

[eumagga0x2a]

Oh, I see now. Only keyframes can be decoded in the appended video after the whole was saved in copy mode.

("WFM" means "works for me", but it really doesn't as I see now).

[eumagga0x2a]

Remarkably, an attempt to join these videos with ffmpeg 3.3.1 results in exactly the same issue (at least when using software decoding). It doesn't matter which video comes first; the second one can't be decoded.

720p versions of the videos doesn't exhibit this problem, btw.

[eumagga0x2a]

Looks like differing stream identifiers (138 vs 266) indicate also different encoding options, which makes videos not mergeable.

[Kelvin]

Yes, the stream 266 has higher quality than 138, that why I choose 266. Hope you find out and fix issue in future version, to make avidemux better and better

[eumagga0x2a]

You can't mix 138 and 266. I guess, there is nothing Avidemux could do about it unless you reencode.