[FFmpeg-user] Difference in fps between ffplay and ffmpeg SDL output

[Alexei Colin]

Hello,

Is a large performance difference between ffplay and ffmpeg -f sdl
expected?  Both use the same SDL backend and (I assume) the same
decoder. However,

    ffplay big_buck_bunny_1080p_h264.mov
yields relatively smooth playback with A-V somewhere within 0-40ms (so
some lateness, but watchable).

    ffmpeg -i big_buck_bunny_1080p_h264.mov -f sdl "SDL Output"
yields fps=12 (utterly unwatchable slow-motion). Also tried, '-vcodec
rawvideo -pix_fmt yuv420p -window_size qcif' as in the example in the
docs: made no difference.

Is this expected? If not, what's a reasonable suspect if one is to
compare the code? The part that calls into SDL or the decoding end?

Platform: Hardkernel Odroid U3 ARMv7 board (1GHz, 4 cores)
SDL version: 1.2.15 (Arch package 1.2.15-7)
Version: ffmpeg 2.5.2 (Arch package 2.5.2-2.1)
ffmpeg version 2.5.2 Copyright (c) 2000-2014 the FFmpeg developers
built on Jan 10 2015 09:19:27 with gcc 4.9.2 (GCC) 20141224 (prerelease)
configuration: --prefix=/usr --disable-debug --disable-static
--disable-stripping --enable-avisynth --enable-avresample
--enable-fontconfig --enable-gnutls --enable-gpl --enable-libass
--enable-libbluray --enable-libfreetype --enable-libfribidi
--enable-libgsm --enable-libmodplug --enable-libmp3lame
--enable-libopencore_amrnb --enable-libopencore_amrwb
--enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp
--enable-libschroedinger --enable-libspeex --enable-libtheora
--enable-libv4l2 --enable-libvorbis --enable-libvpx --enable-libx264
--enable-libx265 --enable-libxvid --enable-runtime-cpudetect
--enable-shared --enable-swresample --enable-vdpau --enable-version3
--enable-x11grab
libavutil      54. 15.100 / 54. 15.100
libavcodec     56. 13.100 / 56. 13.100
libavformat    56. 15.102 / 56. 15.102
libavdevice    56.  3.100 / 56.  3.100
libavfilter     5.  2.103 /  5.  2.103
libavresample   2.  1.  0 /  2.  1.  0
libswscale      3.  1.101 /  3.  1.101
libswresample   1.  1.100 /  1.  1.100
libpostproc    53.  3.100 / 53.  3.100