ffmpeg -i test1.avi -i test2.avi -vcodec copy -acodec copy \ -vcodec copy -acodec copy test12.avi -newvideo -newaudio
-newvideo, -newaudio, -newsubtitle have been removed from the current version. You have to use the -map option. (which I haven't wrapped my brain around.) If somebody wants to show how to use -map to string together MP4s that would be awesome.
From the ffmpeg man page "Examples" section:
I'm not sure if this question/answer belongs on SuperUser.
In addition to the first video and audio streams, the resulting
output file test12.avi will contain the second video and the second
audio stream found in the input streams list.
Note I'm having videos get corrupted if I concat very long files, so I'm going to try to mp4->mpeg then use simple concat.
The "-newvideo", "-newaudio" and "-newsubtitle" options have to be specified immediately after the name of the output file to which you want to add them.
The concat option in ffmpeg does not require the use of the -map option if you are really just concatenating the input files (e.g. you have two mp4 files, each 2 minutes in duration, and want to create a single mp4 file of 4 minutes duration as the output). The ffmpeg command line in Windows 7 (using bcmpinc's "inputs.txt" file, see above) is: ffmpeg -f concat -i inputs.txt -c copy output.mp4
These docs describe the concat filter and how to use the -map option in that case: ffmpeg.org/trac/ffmpeg/wiki/
You can put many streams of the same type in the output: