[x264-devel] stats file empty after first pass when mbtree used

[David Henry]

Hello all - I'm working on an application which uses libx264.  When doing 2-pass encodes, if the mbtree option is enabled, the 1st pass doesn't seem to 
put anything into the stats files:
x264_1345845358591.L.mbtree.temp (size of 0)
x264_1345845358591.L.temp

$ cat x264_1345845358591.L.temp 
#options: 288x162 fps=2997/100 timebase=100/2997 bitdepth=8 cabac=0 ref=3 deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=48 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=abr mbtree=1 bitrate=210 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.40 aq=1:1.00

When I do x264_encoder_open() for the 2nd pass, I get the failure message:
x264 [error]: ratecontrol_init: can't open stats file
x264 [error]: x264_encoder_open failed

2pass works fine if I turn off mbtree.  The app sets some options manually from the pre-mbtree versions of x264 & I'm thinking one of those options is incompatible with mbree.  I can run it with presets or tune parameters as long as one of
them turns off mbtree.  Any ideas of what to look for?

- David