How to convert H264 video file to MP4 file with audio

Hi, I am trying to convert files from a Chinese manufactured birdbox camera which also has a microphone. The camera records files with the extension .h264 and until recently, the only way I had found to convert them to a format I could play on Windows was using software they supplied (videoconver.exe) to convert to mp4 (video and sound). videoconver lacks any documentation and delivers video which runs at double speed. I also really need a way of batching the conversion of all the files which I am sending to an ftp server.

I then discovered ffmpeg and found I could convert these files using

ffmpeg -r 12 -i atest.h264 -c copy ffatest.mp4

...but only the video comes across. I tried the solution above but the audio extraction doesn't work and I get lots of error messages and no output file. The following shows the command and relevant output:

ffmpeg -i atest.h264 -c:a copy -vn -sn ffatest.m4a

[h264 @ 000002218326ce00] Format h264 detected only with low score of 1, misdetection possible!
[extract_extradata @ 0000022183255b00] Invalid NAL unit 0, skipping.
Last message repeated 4 times
[h264 @ 000002218326dd40] Invalid NAL unit 0, skipping.
Last message repeated 36 times
[h264 @ 000002218326ce00] Stream #0: not enough frames to estimate rate; consider increasing probesize
Input #0, h264, from 'atest.h264':
Duration: N/A, bitrate: N/A
Stream #0:0: Video: h264 (Main), yuv420p(progressive), 2288x1288, 24 fps, 24 tbr, 1200k tbn
Output #0, ipod, to 'ffatest.m4a':
Output file #0 does not contain any stream

What I think is going on here is that the format they are using is proprietary (I read somewhere that this could be to avoid licence fees). It definitely contains both video and audio.

Does anyone have any advice on how to convert these files - I suspect that millions of people have these cameras (mine is made or oem'd by Golbong but I suspect others are using this format too judging by a bit of googling).

TIA

Wallport