Playback speed problem after recording by RTMPDump (plays faster or slower)

[karmao]

After recoding a rtmp streaming into flv file, there are some playback problems.
The timestamp didn't work well, it may go from 1:54 to 3:25, or sometimes faster and sometimes slower.

I tried some metadata fixing software like yamdi, it worked partially,
that some of the missing frames showed up.
However, the playback speed still remains a problem. It still speed up sometime during the process.

Anyone has any thought on this issue? Thanks