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• ffmpeg split by silence (with logic to achieve 12 split segments)

  14 mars 2023, par Martin

  https://github.com/MartinBarker/split_by_silence

  


  I am trying to automate the process of splitting a single audio file into 12 tracks. you can see in the below image that this 35:62 length mp3 file has 11 visible split points (where the audio more quiet), which means 12 distinct segments.


  


  I'd like to be able to run a script to automatically find these split points and split my file, my first split point should be around 159 seconds, and second around 360, third around 540, 4th around 780, 5th around 960, and so on for a total of 11 split points :

  


  1 159
2 360
3 540
4 780
5 960
6 1129
7 1309
8 1500
9 1680
10 1832
11 1980


  


  but my test results have not been working so good :

  


  - Goal:
11 split points found
12 tracks rendered

- Test 1
SD_PARAMS="-24dB"
MIN_FRAGMENT_DURATION="3"
5 split points found: 361.212,785.811,790.943,969.402,2150.24`
6 tracks rendered

-Test 2
SD_PARAMS="-24dB"
MIN_FRAGMENT_DURATION="3"
10 split points found: 151.422,155.026,158.526,361.212,534.254,783.667,967.253,1128.91,2150.2
11 tracks rendered


  


  

  • Test 2 Problem :
Even though 12 tracks were rendered, some split points are very close

leading to tracks being exported that are very short, such as 3, 5, and 2 seconds. as well as one long track being 16 minutes


  


  


  So I added a variable MIN_SEGMENT_LENGTH and ran another test

  


  - Test 3
SD_PARAMS="-18dB"
MIN_FRAGMENT_DURATION="3"
MIN_SEGMENT_LENGTH=120 (02:00)

log:
_______________________
Determining split points...
split points list= 150.482,155.026,158.526,361.212,530.019,534.254,783.667,967.245,1127.67,2144.57,2150.2
1. The difference between 150.482 and 155.026 is 4.544
       diff is less than MIN_SEGMENT_LENGTH=120
2. The difference between 155.026 and 158.526 is 3.500
       diff is less than MIN_SEGMENT_LENGTH=120
3. The difference between 158.526 and 361.212 is 202.686
4. The difference between 361.212 and 530.019 is 168.807
5. The difference between 530.019 and 534.254 is 4.235
       diff is less than MIN_SEGMENT_LENGTH=120
6. The difference between 534.254 and 783.667 is 249.413
7. The difference between 783.667 and 967.245 is 183.578
8. The difference between 967.245 and 1127.67 is 160.425
9. The difference between 1127.67 and 2144.57 is 1016.90
10. The difference between 2144.57 and 2150.2 is 5.63
       diff is less than MIN_SEGMENT_LENGTH=120
_______________________
Exporting 12 tracks with ffmpeg...


  


  I'm unsure how to change my script and vars so that by running it, are calculating the split points, if any of them are too short (less then 120 seconds) to regenerate the split point(s) ?

  


  Here is my audio file :
https://filetransfer.io/data-package/HC7GG07k#link

  


  And here is my script, which can be ran by running ./split_by_silence.sh

  


  # -----------------------
# SPLIT BY SILENCE
# Requirements:
#    ffmpeg
#    $ apt-get install bc
# How To Run:
# $ ./split_by_silence.sh "full_lowq.flac" %03d_output.flac

# output title format
OUTPUTTITLE="%03d_output.mp3"
# input audio filepath
IN="/mnt/e/martinradio/rips/vinyl/L.T.D. – Gittin' Down/lowquality_example.mp3"
# output audio filepath
OUTPUTFILEPATH="/mnt/e/folder/rips"
# ffmpeg option: split input audio based on this silencedetect value
SD_PARAMS="-18dB"
# split option: minimum fragment duration
MIN_FRAGMENT_DURATION=3
# minimum segment length
MIN_SEGMENT_LENGTH=120

# -----------------------
# step: ffmpeg
# goal: get comma separated list of split points (use ffmpeg to determine points where audio is at SD_PARAMS [-18db] )

echo "_______________________"
echo "Determining split points..." >& 2
SPLITS=$(
    ffmpeg -v warning -i "$IN" -af silencedetect="$SD_PARAMS",ametadata=mode=print:file=-:key=lavfi.silence_start -vn -sn  -f s16le  -y /dev/null \
    | grep lavfi.silence_start= \
    | cut -f 2-2 -d= \
    | perl -ne '
        our $prev;
        INIT { $prev = 0.0; }
        chomp;
        if (($_ - $prev) >= $ENV{MIN_FRAGMENT_DURATION}) {
            print "$_,";
            $prev = $_;
        }
    ' \
    | sed 's!,$!!'
)
echo "split points list= $SPLITS"
# determine if the difference between any two splits is less than MIN_SEGMENT_LENGTH seconds
IFS=',' read -ra VALUES <<< "$SPLITS"

for (( i=0; i<${#VALUES[@]}-1; i++ )); do
  diff=$(echo "${VALUES[$i+1]} - ${VALUES[$i]}" | bc)
  display_i=$((i+1))
  echo "$display_i. The difference between ${VALUES[$i]} and ${VALUES[$i+1]} is $diff"
  if (( $(echo "$diff < $MIN_SEGMENT_LENGTH" | bc -l) )); then
    echo "       diff is less than MIN_SEGMENT_LENGTH=$MIN_SEGMENT_LENGTH"
  fi
done


# using the split points list, calculate how many output audio files will be created 
num=0
res="${SPLITS//[^,]}"
CHARCOUNT="${#res}"
num=$((CHARCOUNT + 2))
echo "_______________________"
echo "Exporting $num tracks with ffmpeg"

ffmpeg -i "$IN" -c copy -map 0 -f segment -segment_times "$SPLITS" "$OUTPUTFILEPATH/$OUTPUTTITLE"

echo "Done."



  


• Extract final frame from a video using ffmpeg

  14 mai 2020, par Saavestro

  I know how to extract the first frame by using

  



  ffmpeg -ss 00:00:00 -i input.mp4 -vframes 1 -q:v 31 output.png

  



  Here, the option -ss requires to know the exact time of the frame to extract.

  



  I would like to have the final frame of any .mp4 without knowing the exact final time of the video.

  



  Is there a way to achieve this ?

  


• ffmpeg command for create final video from two different videos and two different audios

  16 décembre 2020, par Kashyap Rathod

  I have two videos and two audios

  


  1 :-
video 1 - length :- 60 sec || audio 1 - length :- 15 sec

  


  2 :-
video - length :- 86 sec || audio 2 - length :- 18 sec

  


  Play video1 and audio1 together, if audio1 is ended then restart that audio till video1 end. this will final video 1.

  


  same way,

  


  play video2 and audio2 together, if audio2 is ended then restart that audio till video2 end. this will final video 2.

  


  after that concatenate those final video 1 and final video 2 and create single video as output.

  


  Thank you in advance.