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• Video concatenation using ffmpeg. Output video length is longer than inputs length

  28 décembre 2022, par Rostyslav Mosorov

  I have a problem with video mp4 concatenation using ffmpeg. I have two the same videos and I want to concatenate them. I created file inputs.txt and then used command :

  


  ffmpeg  -f concat -i inputs.txt -c copy mergedVideo.mp4

  


  Output :

  


  ffmpeg  -f concat -i inputs.txt -c copy mergedVideo.mp4
ffmpeg version 5.0.1 Copyright (c) 2000-2022 the FFmpeg developers
  built with clang version 12.0.1
  configuration: --prefix=/Users/runner/miniforge3/conda-bld/ffmpeg_1649114094397/_h_env_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_placehold_pl --cc=arm64-apple-darwin20.0.0-clang --disable-doc --disable-openssl --enable-demuxer=dash --enable-gnutls --enable-gpl --enable-hardcoded-tables --enable-libfreetype --enable-libopenh264 --enable-neon --enable-libx264 --enable-libx265 --enable-libaom --enable-libsvtav1 --enable-libxml2 --enable-libvpx --enable-pic --enable-pthreads --enable-shared --disable-static --enable-version3 --enable-zlib --enable-libmp3lame --pkg-config=/Users/runner/miniforge3/conda-bld/ffmpeg_1649114094397/_build_env/bin/pkg-config --enable-cross-compile --arch=arm64 --target-os=darwin --cross-prefix=arm64-apple-darwin20.0.0- --host-cc=/Users/runner/miniforge3/conda-bld/ffmpeg_1649114094397/_build_env/bin/x86_64-apple-darwin13.4.0-clang
  libavutil      57. 17.100 / 57. 17.100
  libavcodec     59. 18.100 / 59. 18.100
  libavformat    59. 16.100 / 59. 16.100
  libavdevice    59.  4.100 / 59.  4.100
  libavfilter     8. 24.100 /  8. 24.100
  libswscale      6.  4.100 /  6.  4.100
  libswresample   4.  3.100 /  4.  3.100
  libpostproc    56.  3.100 / 56.  3.100
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x1561044a0] Auto-inserting h264_mp4toannexb bitstream filter
Input #0, concat, from 'inputs.txt':
  Duration: N/A, start: -0.064000, bitrate: 1424 kb/s
  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], 1355 kb/s, 50 fps, 50 tbr, 12800 tbn
    Metadata:
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
  Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 16000 Hz, mono, fltp, 68 kb/s
    Metadata:
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
File 'mergedVideo.mp4' already exists. Overwrite? [y/N] y
Output #0, mp4, to 'mergedVideo.mp4':
  Metadata:
    encoder         : Lavf59.16.100
  Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(progressive), 1920x1080 [SAR 1:1 DAR 16:9], q=2-31, 1355 kb/s, 50 fps, 50 tbr, 12800 tbn
    Metadata:
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
  Stream #0:1(und): Audio: aac (LC) (mp4a / 0x6134706D), 16000 Hz, mono, fltp, 68 kb/s
    Metadata:
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
Stream mapping:
  Stream #0:0 -> #0:0 (copy)
  Stream #0:1 -> #0:1 (copy)
Press [q] to stop, [?] for help
frame=    0 fps=0.0 q=-1.0 size=       0kB time=00:00:00.06 bitrate=   6.0k[mov,mp4,m4a,3gp,3g2,mj2 @ 0x154f28b20] Auto-inserting h264_mp4toannexb bitstream filter
frame=  166 fps=0.0 q=-1.0 Lsize=     583kB time=00:00:03.39 bitrate=1407.4kbits/s speed= 179x    
video:550kB audio:29kB subtitle:0kB other streams:0kB global headers:0kB muxing overhead: 0.737394%


  


  Unfortunately the result is different then I expected :
  
movies comparison

  


  The output is longer than the length of two inputs. Any thoughts ?

  


  Also I tried using different commands :

  


  ffmpeg  -f concat -i inputs.txt -c copy mergedVideo.mp4


  


  or set the framerate :

  


  ffmpeg -r 50 -f concat -i inputs.txt -c copy mergedVideo.mp4


  


  What is also weird that I have the same problem when using moviepy library.

  


  from moviepy.editor import VideoFileClip, concatenate_videoclips
videos = [VideoFileClip("0.mp4"), VideoFileClip("0.mp4")]
concatenate_videoclips(videos).write_videofile('mergedVideo.mp4')


  


  Update
ffprobe command for output file

  


  ffprobe -v error -select_streams v -show_entries stream=codec_name,time_base,start_pts,start_time,duration -of default=noprint_wrappers=1 mergedVideo.mp4 
codec_name=h264
time_base=1/12800
start_pts=0
start_time=0.000000
duration=3.380000


  


  For input :

  


  ffprobe -v error -select_streams v -show_entries stream=codec_name,time_base,start_pts,start_time,duration -of default=noprint_wrappers=1 0.mp4          
codec_name=h264
time_base=1/12800
start_pts=0
start_time=0.000000
duration=1.660000


  


  The duration supposed to be 2*1.66 = 3.32 and but it's 3.38.

  


  Content of the inputs.txt

  


  file '0.mp4'
file '0.mp4'


  


• ffmpeg segment command flac output broken 'length' metadata

  7 février 2023, par Martin

  I am trying to use this ffmpeg command :

  


  ffmpeg -i "full_lowq.flac" -c copy -map 0 -f segment -segment_times "302.825,552.017" "%03d_output.flac"


  


  to take my flac file input "full_lowq.flac" and split it at specific points 302.825,552.017 into output audio files like so :

  


  %01d_output.flac
%02d_output.flac
%03d_output.flac


  


  And this command does work at the moment, except that my three outputted flac files display the wrong 'length' metadata number when viewed in the win10 file browser. like in this example every outputted file has the same length as 11:16


  


  But if i view the audio files in audacity i can see the correct file length such as file 0 have a length of 05:02

  


  Is it possible my input file (https://file.io/oof3eykKwXiI) is corrupted ? or my command is making a mistake here ? wrong codec ?

  


• ffmpeg command exports flac with wrong 'length' metadata, works fine for mp3

  21 juillet 2023, par Martin

  I have some audio recorded in Audacity 3.2.3 that I have exported as an mp3 and a flac. Then I have this file split_by_silence.sh

  


  Which has hardcoded input path values that take an input file, split it by detecting silence, and then finally run an ffmpeg command to split the files. If you save the below code into a file split.sh, you can call it with the command $ ./split_by_silence.sh "value1" "value2"

  


  # ./split_by_silence.sh "full_lowq.flac" %03d_output.flac
#IN=$1
#OUT=$2

OUT="%03d_output.flac"
IN="/mnt/e/martinradio/rips/vinyl/WIP/Dogs On Fire (1983, Vinyl)/dog on fire.flac"
OUTPUT_LOCATION="/mnt/e/martinradio/rips/vinyl/WIP/Dogs On Fire (1983, Vinyl)/"

true ${SD_PARAMS:="-18dB"};
true ${MIN_FRAGMENT_DURATION:="20"};
export MIN_FRAGMENT_DURATION
if [ -z "$OUT" ]; then
    echo "Usage: split_by_silence.sh full.mp3 output_template_%03d.mp3"
    echo "Depends on FFmpeg, Bash, Awk, Perl 5. Not tested on Mac or Windows."
    echo ""
    echo "Environment variables (with their current values):"
    echo "    SD_PARAMS=$SD_PARAMS       Parameters for FFmpeg's silencedetect filter: noise tolerance and minimal silence duration"
    echo "    MIN_FRAGMENT_DURATION=$MIN_FRAGMENT_DURATION    Minimal fragment duration"
    exit 1
fi
#
# 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 "SPLITS= $SPLITS"

#
# Add 5 seconds to each of the comma separated numbers
#
# Convert the comma-separated string into an array
arr=($(echo $SPLITS | tr ',' '\n'))
# Initialize a new array to store the results
new_arr=()
# Iterate through each element and add 5 seconds of padding
for i in "${arr[@]}"; do
  result=$(echo "$i + 5" | bc -l)
  new_arr+=("$result")
done
# Convert the array back into a comma-separated string
NEW_SPLITS=$(IFS=,; echo "${new_arr[*]}")
# Print the result
echo "NEW_SPLITS= $NEW_SPLITS"
SPLITS=$NEW_SPLITS

#
# Print how many tracks should be exported
#
res="${SPLITS//[^,]}"
CHARCOUNT="${#res}"
num=$((CHARCOUNT + 2))
echo "Exporting $num tracks"
echo "_______________________"

#
# Split audio into individual tracks
#
current_directory=$(pwd)

cd "$OUTPUT_LOCATION"

echo "Running ffmpeg command: "

ffmpeg -i "$IN" -c copy -map 0 -f segment -segment_times "$SPLITS" "$OUT"
#ffmpeg -i "full_lowq.flac" -c copy -map 0 -f segment -segment_times "302.825,552.017" "%03d_output.flac"


echo "Done."

cd $current_directory

echo "running flac command"
# check flac file intrgrity


  


  If I call this code for my flac file :

  


  OUT="%03d_output.flac"
IN="/mnt/e/martinradio/rips/vinyl/WIP/Dogs On Fire (1983, Vinyl)/dog on fire.flac"


  


  The outputted files have an incorrect metadata for the length. They all report as having the same length, but if i import any of them into audacity, the file has a correct length.

  


  

  


  but if i run this for my mp3 file, we can see the correct length metadata :

  


  OUT="%03d_output.mp3"
IN="/mnt/e/martinradio/rips/vinyl/WIP/Dogs On Fire (1983, Vinyl)/dogs on fire.mp3"


  


  

  


  So there is something with my ffmpeg command that causes it to export flac files with wrong 'length' metadata

  


  ffmpeg -i "$IN" -c copy -map 0 -f segment -segment_times "$SPLITS" "$OUT"



  


  I've tried with the flac example to change -c copy to -c:a flac, but that just gives every output flac file a length of 00:00:00

  


  is it a problem with my ffmpeg command ? Or my files ? https://file.io/tIFsa1l70076
it works for mp3 files just fine, why does it have this issue with flac ?