FFMPEG - Batch combination of H.264 video and separate .WAV audio in Windows

Question

I am a first-time ffmpeg user trying to mux h.264 .mp4 video with separate/secondary .wav audio, without re-encoding anything on the video side. Would like the final audio to come out as .aac (same codec as the audio on the h.264 file).

Essentially, I just want to layer an additional audio track (commentary) of equivalent length onto the video. I'm trying to get around Premiere's inability to import h.264 properly by editing the .wav audio separately and combining it with the original file without ever running it through Premiere or any editor. This program seems to be the best way to do it quickly.

I would be doing this in batches, so any suggestions on how to queue up multiple jobs would be appreciated. Only queuing advice I've found used Linux code.

If you have the time to answer, explain it like I'm 5, please. I am an experienced user, but totally new to this command-line-oriented way of working with content. Not sure I'm doing anything right.

Also: I'm using Windows.

Answer 1

The basic FFmpeg command line for your required use is

ffmpeg -i video.mp4 -i audio.wav -map 0 -map 1:a -c:v copy -c:a:0 copy -c:a:1 aac video-new.mp4

-map 0 means include all streams from the first input - FFmpeg index starts from zero. Similarly, map 1:a means include all audio streams from the 2nd input. -map 1 would have sufficed since WAV files contain only audio streams.

-c:v copy means that any and all video streams being included in the output should be copied, so no re-encoding.

-c:a:0 copy means the first audio stream in the output should be copied as well. The order of output streams here is decided by the order of the map arguments. Since -map 0 is placed first, the audio and video streams from that file will be stacked first in the output. So, the first audio stream in the output will be the one from the first input i.e. video.mp4

-c:a:1 aac means encode the second audio stream in the output with the (native) AAC encoder.

---

On Windows, you can use the Avanti GUI front-end to carry out batch operations. Read the link for setup instructions - pretty straightforward.

Your main GUI window settings should look like this:

After you perform a single job from the main window, you can load the Job Control Manager, available from the drop-down menu when you click on the top-left icon.

That should look like this:

For each corresponding video/audio pair you add, make sure to unmark the audio file so that Avanti knows it's part of the same job as the video entry above it. Select your destination path (4th icon at top from left) to be different than the folder containing your source files. Avanti will the name the output file the same as the first input (the video) so you'll be in for a nasty surprise if you don't take care of this.

That pretty much covers it.