[FFmpeg-user] Question for using blackdetect video filter

[Wu-bin Zhen]

Hello ffmpeg,

I have a completely black video file and want to use blackdetect filter to
detect it, but no luck. The command below is what I use:
> ./ffmpeg -v info -i ./blackvideo.flv -vf blackdetect=d=2 -t 10 -f null -

No error, but the ffmpeg info mode never reports that there is the black
video with more than 2 seconds. However, from the debug mode ffmpeg shows
that all frames are completely black. (picture_black_ratio:1.000000)
The debug message is shown as below. I will appreciate if there is a way i
can detect black video with the info mode. Btw, the video stream of the flv
file is h264 with yuvj420p (not yuv420p).

Thank you, and have a great weekend.
-w
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...
[Parsed_blackdetect_0 @ 0x2a08840] frame:235 picture_black_ratio:1.000000
pos:1404440 pts:7833 t:7.833 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:236 picture_black_ratio:1.000000
pos:1415621 pts:7866 t:7.866 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:237 picture_black_ratio:1.000000
pos:1421058 pts:7900 t:7.9 type:P
frame:238 picture_black_ratio:1.000000 pos:1432427 pts:7933 t:7.933 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:239 picture_black_ratio:1.000000
pos:1438052 pts:7966 t:7.966 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:240 picture_black_ratio:1.000000
pos:1449609 pts:8000 t:8 type:I
[Parsed_blackdetect_0 @ 0x2a08840] frame:241 picture_black_ratio:1.000000
pos:1460068 pts:8033 t:8.033 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:242 picture_black_ratio:1.000000
pos:1466179 pts:8066 t:8.066 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:243 picture_black_ratio:1.000000
pos:1466545 pts:8100 t:8.1 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:244 picture_black_ratio:1.000000
pos:1472843 pts:8133 t:8.133 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:245 picture_black_ratio:1.000000
pos:1473396 pts:8166 t:8.166 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:246 picture_black_ratio:1.000000
pos:1479881 pts:8200 t:8.2 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:247 picture_black_ratio:1.000000
pos:1480621 pts:8233 t:8.233 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:248 picture_black_ratio:1.000000
pos:1487293 pts:8266 t:8.266 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:249 picture_black_ratio:1.000000
pos:1488221 pts:8300 t:8.3 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:250 picture_black_ratio:1.000000
pos:1495081 pts:8333 t:8.333 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:251 picture_black_ratio:1.000000
pos:1496197 pts:8366 t:8.366 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:252 picture_black_ratio:1.000000
pos:1503245 pts:8400 t:8.4 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:253 picture_black_ratio:1.000000
pos:1504549 pts:8433 t:8.433 type:P
frame:254 picture_black_ratio:1.000000 pos:1511785 pts:8466 t:8.466 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:255 picture_black_ratio:1.000000
pos:1513277 pts:8500 t:8.5 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:256 picture_black_ratio:1.000000
pos:1520701 pts:8533 t:8.533 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:257 picture_black_ratio:1.000000
pos:1522381 pts:8566 t:8.566 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:258 picture_black_ratio:1.000000
pos:1529993 pts:8600 t:8.6 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:259 picture_black_ratio:1.000000
pos:1531861 pts:8633 t:8.633 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:260 picture_black_ratio:1.000000
pos:1539661 pts:8666 t:8.666 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:261 picture_black_ratio:1.000000
pos:1541717 pts:8700 t:8.7 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:262 picture_black_ratio:1.000000
pos:1549705 pts:8733 t:8.733 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:263 picture_black_ratio:1.000000
pos:1551948 pts:8766 t:8.766 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:264 picture_black_ratio:1.000000
pos:1560123 pts:8800 t:8.8 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:265 picture_black_ratio:1.000000
pos:1562554 pts:8833 t:8.833 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:266 picture_black_ratio:1.000000
pos:1570917 pts:8866 t:8.866 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:267 picture_black_ratio:1.000000
pos:1573536 pts:8900 t:8.9 type:P
frame:268 picture_black_ratio:1.000000 pos:1582087 pts:8933 t:8.933 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:269 picture_black_ratio:1.000000
pos:1584894 pts:8966 t:8.966 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:270 picture_black_ratio:1.000000
pos:1593633 pts:9000 t:9 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:271 picture_black_ratio:1.000000
pos:1596628 pts:9033 t:9.033 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:272 picture_black_ratio:1.000000
pos:1605555 pts:9066 t:9.066 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:273 picture_black_ratio:1.000000
pos:1608738 pts:9100 t:9.1 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:274 picture_black_ratio:1.000000
pos:1617853 pts:9133 t:9.133 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:275 picture_black_ratio:1.000000
pos:1621224 pts:9166 t:9.166 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:276 picture_black_ratio:1.000000
pos:1630527 pts:9200 t:9.2 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:277 picture_black_ratio:1.000000
pos:1634086 pts:9233 t:9.233 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:278 picture_black_ratio:1.000000
pos:1643577 pts:9266 t:9.266 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:279 picture_black_ratio:1.000000
pos:1647323 pts:9300 t:9.3 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:280 picture_black_ratio:1.000000
pos:1657001 pts:9333 t:9.333 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:281 picture_black_ratio:1.000000
pos:1660935 pts:9366 t:9.366 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:282 picture_black_ratio:1.000000
pos:1670801 pts:9400 t:9.4 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:283 picture_black_ratio:1.000000
pos:1674923 pts:9433 t:9.433 type:P
frame:284 picture_black_ratio:1.000000 pos:1684977 pts:9466 t:9.466 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:285 picture_black_ratio:1.000000
pos:1689287 pts:9500 t:9.5 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:286 picture_black_ratio:1.000000
pos:1699529 pts:9533 t:9.533 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:287 picture_black_ratio:1.000000
pos:1704027 pts:9566 t:9.566 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:288 picture_black_ratio:1.000000
pos:1714457 pts:9600 t:9.6 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:289 picture_black_ratio:1.000000
pos:1719143 pts:9633 t:9.633 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:290 picture_black_ratio:1.000000
pos:1729761 pts:9666 t:9.666 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:291 picture_black_ratio:1.000000
pos:1734635 pts:9700 t:9.7 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:292 picture_black_ratio:1.000000
pos:1745441 pts:9733 t:9.733 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:293 picture_black_ratio:1.000000
pos:1750503 pts:9766 t:9.766 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:294 picture_black_ratio:1.000000
pos:1761497 pts:9800 t:9.8 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:295 picture_black_ratio:1.000000
pos:1766746 pts:9833 t:9.833 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:296 picture_black_ratio:1.000000
pos:1777927 pts:9866 t:9.866 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:297 picture_black_ratio:1.000000
pos:1783364 pts:9900 t:9.9 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:298 picture_black_ratio:1.000000
pos:1794733 pts:9933 t:9.933 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:299 picture_black_ratio:1.000000
pos:1800358 pts:9966 t:9.966 type:P
frame:300 picture_black_ratio:1.000000 pos:1811915 pts:10000 t:10 type:I
No more output streams to write to, finishing.
[Parsed_blackdetect_0 @ 0x2a08840] frame:301 picture_black_ratio:1.000000
pos:1822374 pts:10033 t:10.033 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:302 picture_black_ratio:1.000000
pos:1828485 pts:10066 t:10.066 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:303 picture_black_ratio:1.000000
pos:1828851 pts:10100 t:10.1 type:P
[Parsed_blackdetect_0 @ 0x2a08840] frame:304 picture_black_ratio:1.000000
pos:1835149 pts:10133 t:10.133 type:P