<p>The input is read via the lavfi device, and the tags are inserted by the blackdetect filter inside the filtergraph. So, they are present in the packets emitted by the filtergraph. Then, once decoded, they are also present in the decoded frames.</p>
<p>Use either</p>
<pre><code>-show_entries packet_tags=lavfi.black_start,lavfi.black_end
</code></pre>
<p>or</p>
<pre><code>-show_entries frame_tags=lavfi.black_start,lavfi.black_end
</code></pre>

CC BY-SA 4.0
2021-07-19T04:57:55.020Z
2021-07-19T04:57:55.020Z
Gyan
<p>I'm using ffprobe to detect black frames of a video. However, the output produces duplicate entries for each black_start and black_end. Looking for help in figuring out why it duplicates these results.</p>
<p><code>ffprobe -f lavfi -i &quot;movie=movie.mp4,blackdetect[out0]&quot; -show_entries tags=lavfi.black_start,lavfi.black_end -of default=nw=1 -v quiet</code></p>
<pre><code>TAG:lavfi.black_start=0
TAG:lavfi.black_start=0
TAG:lavfi.black_end=0.4004
TAG:lavfi.black_end=0.4004
TAG:lavfi.black_start=1813.68
TAG:lavfi.black_start=1813.68
TAG:lavfi.black_end=1814.38
TAG:lavfi.black_end=1814.38
TAG:lavfi.black_start=6620.85
TAG:lavfi.black_start=6620.85
TAG:lavfi.black_end=6621.88
TAG:lavfi.black_end=6621.88
TAG:lavfi.black_start=9069.16
TAG:lavfi.black_start=9069.16
TAG:lavfi.black_end=9070.69
TAG:lavfi.black_end=9070.69
TAG:lavfi.black_start=9081.84
TAG:lavfi.black_start=9081.84
</code></pre>

<ffmpeg><mac><ffprobe><libav>
Using ffprobe to detect black frames outputs duplicate results
Grofflesby NPZR
# Using ffprobe to detect black frames outputs duplicate results

(Asked by: username_0 on 2021-07-18)

I'm using ffprobe to detect black frames of a video. However, the output produces duplicate entries for each black_start and black_end. Looking for help in figuring out why it duplicates these results.
ffprobe -f lavfi -i "movie=movie.mp4,blackdetect[out0]" -show_entries tags=lavfi.black_start,lavfi.black_end -of default=nw=1 -v quiet
TAG:lavfi.black_start=0
TAG:lavfi.black_start=0
TAG:lavfi.black_end=0.4004
TAG:lavfi.black_end=0.4004
TAG:lavfi.black_start=1813.68
TAG:lavfi.black_start=1813.68
TAG:lavfi.black_end=1814.38
TAG:lavfi.black_end=1814.38
TAG:lavfi.black_start=6620.85
TAG:lavfi.black_start=6620.85
TAG:lavfi.black_end=6621.88
TAG:lavfi.black_end=6621.88
TAG:lavfi.black_start=9069.16
TAG:lavfi.black_start=9069.16
TAG:lavfi.black_end=9070.69
TAG:lavfi.black_end=9070.69
TAG:lavfi.black_start=9081.84
TAG:lavfi.black_start=9081.84

**Tags:** ffmpeg, mac, ffprobe, libav


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## 1 answers

### Answer by username_1 on 2021-07-19. Score: 1 | Accepted answer

The input is read via the lavfi device, and the tags are inserted by the blackdetect filter inside the filtergraph. So, they are present in the packets emitted by the filtergraph. Then, once decoded, they are also present in the decoded frames.
Use either
-show_entries packet_tags=lavfi.black_start,lavfi.black_end

or
-show_entries frame_tags=lavfi.black_start,lavfi.black_end


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