[x264-devel] Yet another updated threaded slicetype patch (v14)

[Steven Walters]

> Sorry for the long delay - I was sitting on the beach on holiday for the last week.
>
>>I'm getting the same segfault with my mingw builds.
>> Higher the lookahead, the less bframes it needs to crash?
>
> Hmmm, I have checked and rechecked this under linux, I cannot recreate the crash.  Can you please email me a new backtrace?  Is there a way to get a backtrace of each of the threads under windows?

i don't know how to do this in mingw gdb... but here's another crashing bt.

#0  0x0044ccf8 in x264_slicetype_frame_cost (h=0x23682f0, a=0x262dd60,
    frames=0x262dc50, p0=66, p1=68, b=68, b_intra_penalty=0)
    at encoder/slicetype.c:276
#1  0x0044d252 in x264_slicetype_path_cost (h=0x23682f0, a=0x262dd60,
    frames=0x262dc50, path=0x262c72f "", threshold=268435456)
    at encoder/slicetype.c:380
#2  0x0044d424 in x264_slicetype_path (h=0x23682f0, a=0x262dd60,
    frames=0x262dc50, length=64, max_bframes=16, buffer_size=51,
    best_paths=0x262cbf0) at encoder/slicetype.c:419
#3  0x0044d4eb in x264_slicetype_path_search (h=0x23682f0, a=0x262dd60,
    frames=0x262dc50, length=67, bframes=16, buffer=51)
    at encoder/slicetype.c:436
#4  0x0044d932 in x264_slicetype_analyse (h=0x23682f0)
    at encoder/slicetype.c:529
#5  0x0044dd5c in x264_slicetype_decide (h=0x23682f0)
    at encoder/slicetype.c:615
#6  0x0042ddd4 in x264_stack_align ()
#7  0x004271ea in _x264_lookahead_slicetype_decide (h=<incomplete type>)
    at encoder/lookahead.c:321
#8  0x0042751b in x264_lookahead_thread (h=<incomplete type>)
    at encoder/lookahead.c:413

it seems the value of b reaches a point when it goes beyond the
allocated space that frames has. as when the problem occurs frames[b]
is pointing to the address 0x1
this might be denoted by the fact that path_search is called with
length=67, and yet frame_cost is called with b=68 which would be
beyond the array of frames.

frame_cost w/ b=66 works fine, which would also point to this.
(in my runs there never was a frame_cost call with b=67)

> Also - could you check that it works with --lookahead 0
>
--lookahead 0 works until i pump the thread and bframe count high
enough to get another frame_cost call like above.