[FFmpeg-user] Blackmagic card issue capturing

Tue Mar 1 15:40:17 CET 2016

I have got the ffmpeg version N-78598-g98a0053  and trying to capturing
from a Blackmagic card, which sometimes works and sometimes doesnt.

ffmpeg.exe -y -f dshow -video_size 1920x1080 -pixel_format uyvy422
-rtbufsize 2100 -framerate 59.94 -i "video=Decklink Video Capture" -codec:v
libx264 -preset ultrafast -an -crf 0 test.mkv

The issue is a not recording at 60 FPS but at  0.. 2...1.3.....0.. and the
file doesnt get big.

After I stop and restart the process, it captures at 60FPS without issues
and the video is great, but I dont get why I need to restart 3-4 times to
get the record working.

this the output that I get when it doesnt work:

ffmpeg.exe -y -f dshow -video_size 1920x1080 -pixel_format uyv
y422 -rtbufsize 2100 -framerate 59.94 -i "video=Decklink Video Capture"
-codec:v
 libx264 -preset ultrafast -an -crf 0 a.mkv
ffmpeg version N-78598-g98a0053 Copyright (c) 2000-2016 the FFmpeg
developers
  built with gcc 5.3.0 (GCC)
  configuration: --enable-gpl --enable-version3 --disable-w32threads
--enable-av
isynth --enable-bzlib --enable-fontconfig --enable-frei0r --enable-gnutls
--enab
le-iconv --enable-libass --enable-libbluray --enable-libbs2b
--enable-libcaca --
enable-libdcadec --enable-libfreetype --enable-libgme --enable-libgsm
--enable-l
ibilbc --enable-libmodplug --enable-libmp3lame --enable-libopencore-amrnb
--enab
le-libopencore-amrwb --enable-libopenjpeg --enable-libopus --enable-librtmp
--en
able-libschroedinger --enable-libsoxr --enable-libspeex --enable-libtheora
--ena
ble-libtwolame --enable-libvidstab --enable-libvo-amrwbenc
--enable-libvorbis --
enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx264
--enable-lib
x265 --enable-libxavs --enable-libxvid --enable-libzimg --enable-lzma
--enable-d
ecklink --enable-zlib
  libavutil      55. 18.100 / 55. 18.100
  libavcodec     57. 24.103 / 57. 24.103
  libavformat    57. 25.101 / 57. 25.101
  libavdevice    57.  0.101 / 57.  0.101
  libavfilter     6. 34.100 /  6. 34.100
  libswscale      4.  0.100 /  4.  0.100
  libswresample   2.  0.101 /  2.  0.101
  libpostproc    54.  0.100 / 54.  0.100
Input #0, dshow, from 'video=Decklink Video Capture':
  Duration: N/A, start: 71654371.100688, bitrate: N/A
    Stream #0:0: Video: rawvideo (HDYC / 0x43594448), uyvy422(tv),
1920x1080, 59
.94 tbr, 10000k tbn, 59.94 tbc
No pixel format specified, yuv422p for H.264 encoding chosen.
Use -pix_fmt yuv420p for compatibility with outdated media players.
[libx264 @ 0000008611052a80] using cpu capabilities: MMX2 SSE2Fast SSSE3
SSE4.2
AVX FMA3 AVX2 LZCNT BMI2
[libx264 @ 0000008611052a80] profile High 4:4:4 Predictive, level 4.2,
4:2:2 8-b
it
[libx264 @ 0000008611052a80] 264 - core 148 r2665 a01e339 - H.264/MPEG-4
AVC cod
ec - Copyleft 2003-2016 - http://www.videolan.org/x264.html - options:
cabac=0 r
ef=1 deblock=0:0:0 analyse=0:0 me=dia subme=0 psy=0 mixed_ref=0 me_range=16
chro
ma_me=1 trellis=0 8x8dct=0 cqm=0 deadzone=21,11 fast_pskip=0
chroma_qp_offset=0
threads=12 lookahead_threads=2 sliced_threads=0 nr=0 decimate=1
interlaced=0 blu
ray_compat=0 constrained_intra=0 bframes=0 weightp=0 keyint=250
keyint_min=25 sc
enecut=0 intra_refresh=0 rc=cqp mbtree=0 qp=0
Output #0, matroska, to 'a.mkv':
  Metadata:
    encoder         : Lavf57.25.101
    Stream #0:0: Video: h264 (libx264) (H264 / 0x34363248), yuv422p,
1920x1080,
q=-1--1, 59.94 fps, 1k tbn, 59.94 tbc
    Metadata:
      encoder         : Lavc57.24.103 libx264
    Side data:
      cpb: bitrate max/min/avg: 0/0/0 buffer size: 0 vbv_delay: -1
Stream mapping:
  Stream #0:0 -> #0:0 (rawvideo (native) -> h264 (libx264))
Press [q] to stop, [?] for help
frame=    2 fps=0.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A
dup=0 dro
frame=    2 fps=2.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A
dup=0 dro
frame=    2 fps=1.3 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A
dup=0 dro
frame=    2 fps=1.0 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A
dup=0 dro
frame=    2 fps=0.8 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A
dup=0 dro
frame=    2 fps=0.7 q=0.0 size=       0kB time=00:00:00.00 bitrate=N/A
dup=0 dro
[dshow @ 000000861104b5a0] real-time buffer [Decklink Video Capture] [video
inpu
t] too full or near too full (197485% of size: 2100 [rtbufsize parameter])!
fram
e dropped!
    Last message repeated 1 times
frame=    2 fps=0.6 q=-1.0 Lsize=    1207kB time=00:00:00.03
bitrate=299661.8kbi
ts/s dup=0 drop=184 speed=0.0106x
video:1206kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB
muxing
overhead: 0.060873%
[libx264 @ 0000008611052a80] frame I:1     Avg QP: 0.00  size:611176
[libx264 @ 0000008611052a80] frame P:1     Avg QP: 0.00  size:623654
[libx264 @ 0000008611052a80] mb I  I16..4: 100.0%  0.0%  0.0%
[libx264 @ 0000008611052a80] mb P  I16..4: 95.1%  0.0%  0.0%  P16..4:  4.9%
 0.0
%  0.0%  0.0%  0.0%    skip: 0.0%
[libx264 @ 0000008611052a80] coded y,uvDC,uvAC intra: 56.9% 99.9% 99.9%
inter: 3
0.3% 100.0% 100.0%
[libx264 @ 0000008611052a80] i16 v,h,dc,p: 60% 39%  1%  0%
[libx264 @ 0000008611052a80] i8c dc,h,v,p:  2%  4% 94%  0%
[libx264 @ 0000008611052a80] kb/s:296063.75
[dshow @ 000000861104b5a0] real-time buffer [Decklink Video Capture] [video
inpu
t] too full or near too full (197485% of size: 2100 [rtbufsize parameter])!
fram
e dropped!

-- 
---------------------------
Hardware & Software Developer
christian at bianchini.ch <christian at biachini.ch>
www.max246.ch