On 2019-03-08 2:47 p.m., Venkateswaran.S wrote:
Hi Philippe,
Thanks for your reply. I have got the required output by adding below
function call in my code,
if ((tag = av_dict_get(filt_frame->metadata, "lavfi.black_duration",
tag, AV_DICT_IGNORE_SUFFIX)))
printf("%s=%s\n", tag->key);
and it prints below output,
[blackdetect @ 0x5566fef000c0] black_start:5.46379 black_end:7.29896
black_duration:1.83517
[blackdetect @ 0x5566fef000c0] black_start:82.8328 black_end:84.4594
black_duration:1.62662
[blackdetect @ 0x5566fef000c0] black_start:142.768 black_end:144.019
black_duration:1.25125
I'm using "lavfi.black_duration" because if I use "lavfi.black_start" it
print black_start at 0 second (false detection).
I could not find "lavfi.black_duration" anywhere in the file
libavfilter/vf_blackdetect.c (or the source code at all), so I doubt
it's being set.
If the key doesn't exist in the AVDictionary, av_dict_get returns NULL
(0). You want to check until it returns an actual AVDictionaryEntry,
then check AVDictionaryEntry.value for the time string.
Now, I tried to run the same filter through command line using below
command,
ffmpeg -i SonOfGod.mp4 -vf "blackdetect=d=1:pix_th=0.00" -an -f null -
and it prints below output,
[blackdetect @ 0x5601cbc54c60] black_start:5.46379 black_end:7.007
black_duration:1.54321
[blackdetect @ 0x5601cbc54c60] black_start:82.8745 black_end:84.1674
black_duration:1.29296
above command line tool produces perfect output and exactly matches with
actual video content timing (black start & back end).
How does both the C API and FFmpeg cmd tool give different output? is
there anything I'm missing in C API code
https://ffmpeg.org/doxygen/3.4/filtering__video_8c_source.html (removed
display_frame function).
The black duration log you see is the result of the filter subtracting
black_start from black_end in the check_black_end function.
Testing Video: https://www.youtube.com/watch?v=-Hsl5UG9O_c&t=6s
_______________________________________________
Libav-user mailing list
[email protected]
https://ffmpeg.org/mailman/listinfo/libav-user
To unsubscribe, visit link above, or email
[email protected] with subject "unsubscribe".
You want to get lavfi.black_end and lavfi.black_start, parse the time
strings and find the difference.
--
Philippe Gorley
Free Software Consultant | Montréal, Qc
Savoir-faire Linux
_______________________________________________
Libav-user mailing list
[email protected]
https://ffmpeg.org/mailman/listinfo/libav-user
To unsubscribe, visit link above, or email
[email protected] with subject "unsubscribe".
