title: Format h264 detected only with low score of 1, misdetection possible
body: <p>there are a h264 rtp stream passing through server, I catch every rtp packets and extract every nalu by getting rid of rtp header, and then write every nalu to file record.h264 with adding a h264 prefix start code 0x00000001, but file record.h264 cannot be played by ffplay and cannot be parsed by ffprobe, where is wrong? </p>
  
  <p>here is my record file:<a href="https://github.com/sshsu/record_h264_file" rel="nofollow noreferrer">https://github.com/sshsu/record_h264_file</a></p>