[FFmpeg-devel] [PATCH 1/4] dnxhddec: implement slice multithreading

Michael Niedermayer michaelni at gmx.at
Sat Sep 26 01:52:35 CEST 2015

On Fri, Sep 25, 2015 at 11:25:06PM +0200, Christophe Gisquet wrote:
> Around 3x speedup with 4 threads. Maybe more mb lines should be
> batched per thread, but that's good enough for a first try.
> ---
>  libavcodec/dnxhddec.c | 221 ++++++++++++++++++++++++++++++--------------------
>  1 file changed, 133 insertions(+), 88 deletions(-)

This segfaults with http://samples.ffmpeg.org/ffmpeg-bugs/trac/ticket2125/DNxHDtest2.mov

[Switching to Thread 0x7fffddc35700 (LWP 26013)]
0x0000000000745550 in get_bits (s=0x7fffddc34470, n=11) at libavcodec/get_bits.h:265
265         UPDATE_CACHE(re, s);
(gdb) bt
#0  0x0000000000745550 in get_bits (s=0x7fffddc34470, n=11) at libavcodec/get_bits.h:265
#1  0x0000000000746a59 in dnxhd_decode_macroblock (ctx=0x1cb7be0, row=0x7fffddc33c70, frame=0x1ce4080, x=0, y=0) at libavcodec/dnxhddec.c:373
#2  0x00000000007471c6 in dnxhd_decode_row (avctx=0x1ce34e0, data=0x1ce4080, jobnr=0, threadnr=0) at libavcodec/dnxhddec.c:466
#3  0x0000000000af53fd in avcodec_default_execute2 (c=0x1ce34e0, func=0x7470e6 <dnxhd_decode_row>, arg=0x1ce4080, ret=0x0, count=68) at libavcodec/utils.c:959
#4  0x0000000000747284 in dnxhd_decode_macroblocks (ctx=0x1ce42c0, frame=0x1ce4080, buf=0x7fffeae11290 "", buf_size=1834368) at libavcodec/dnxhddec.c:480
#5  0x00000000007475da in dnxhd_decode_frame (avctx=0x1ce3c00, data=0x1ce4080, got_frame=0x1ce22f0, avpkt=0x1ce2298) at libavcodec/dnxhddec.c:541
#6  0x0000000000a3bc76 in frame_worker_thread (arg=0x1ce2198) at libavcodec/pthread_frame.c:154
#7  0x00007fffef83ee9a in start_thread (arg=0x7fffddc35700) at pthread_create.c:308
#8  0x00007fffef56c38d in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:112
#9  0x0000000000000000 in ?? ()

Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

I have never wished to cater to the crowd; for what I know they do not
approve, and what they approve I do not know. -- Epicurus
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