I found a bug in x264 2-pass conversion if Chinese is used in output filename.
I tried to convert the video, and the output name is "鋼之éŠ金術師 嘆æ¯之丘的èÂâ€"星.mp4". It seem that the first pass ran without problems, but it fails when the second pass starts. The problem seems to be related to unicode file name handling by looking at log file at the line "[setPassAndLogFile] Initializing pass 2" near the end of the log. (see attachment admlog.zip)
BTW, I seem to found a display bug in conversion dialog. The audio codec seems to show the input encoding rather than output encoding . (not sure if same problem appears too for video codec, since the input video is H.264 too).The phase shows "None", while it should be the second pass. Quantiser always shows 0, while it shows the actual quantiser being used in 2.5.x. (see attachment encoding.png)
i have no clean way to fix that
The proper solution would be to modify libx264, trying to find another way