Converting mp3 and jpg to mp4 with h.264 and aac.

I have over 500 sermons in audio format (.mp3). I want to use FFMPEG because its free and I like the software.

I am trying to combine the .mp3s with a jpg (picture of my church) to create .mp4 for Youtube.

I know that YouTube usually does well with Audio format:aac or mp3 and Video format:AVC with h.264.

here is the code:

FOR %%a IN (audio/*.mp3) DO ( echo Converting: %%a ffmpeg -i image/img.jpg -i "%%a" -c:v copy -c:a -vcodec libx264 -acodec aac -strict -2 videos/%%~na.mp4 ) echo Finished

I have the FFMPEG with a do loop, but I am getting this error, [NULL @ 000002574bea6b40] Unable to find a suitable output format for 'libx264' libx264: Invalid argument

I have the latest version. Anytakers?