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• ffmpeg demux concat video output blinks/stuttering between joined clips

  11 juin 2024, par hieroshima

  I'm experiencing a strange issue with FFmpeg after partially joining a few MP4 clips into one output file (output.mp4). The problem is that the video between clips randomly blinks or stutters, showing frames from the previous scene in the next scene. This happens in a completely random manner.

  


  All my MP4 clips have the same FPS, TBR, and TBN values, except for the bitrate (bolded below), which varies for each clip. These clips were prepared and encoded using AWS MediaConvert to ensure they have consistent parameters.

  


  Here’s the ffprobe result for one of the clips :

  


  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661),
yuv420p(progressive), 640x360 [SAR 1:1 DAR 16:9], **84 kb/s**, 29.97 fps,
29.97 tbr, 30k tbn (default)


  


  Below is my input.txt file for concatenation :

  


  file 'clip1_360.mp4' 
outpoint 00:00:04.00
file 'clip2_360.mp4' 
outpoint 00:00:03.00
file 'clip3_360.mp4' 
outpoint 00:00:04.00


  


  The FFmpeg command I'm using to concatenate the clips is :

  


  ffmpeg -y -f concat -safe 0 -protocol_whitelist
file,http,https,tcp,tls -fflags +igndts -i input.txt -c copy output/output.mp4


  


  I use the -fflags +igndts flag because I receive warnings about non-monotonic DTS. I’m employing the concat demuxer to avoid re-encoding the video, as the time required to generate the output is crucial. This is why I have prepared and encoded all clips in advance to have consistent values.

  


  Here is screen recording from my video player to see this problem :

  


  https://youtu.be/SfWnCbMeOfw

  


  Any assistance or suggestions on how to resolve this issue would be greatly appreciated. Because I don't have any more idea what I can do with this. If you need some more details which I didn't provide, please let me know.

  


• ffmpeg - I want to concat multiple videos (front / rear) with overlay and one second delay

  12 mai 2024, par Andrej Florjančič

  I try to write bash script to concat front and rear video files with delay 1 second at start and overlay rear over front.

  


  I wrote the following bash script :

  


  # Define the output file
output_file="${VIDEO}/final_output_${choice}.mp4"

# Collect and sort the video files
front_files=( $(ls *_F.MP4 | sort) )
rear_files=( $(ls *_R.MP4 | sort) )

# Create a file to hold ffmpeg input commands and filter scripts
input_list="input_files.txt"
filter_script="filter_complex.txt"
inputs=""

# Clear the input list and filter script files
echo "" > "$input_list"
echo "" > "$filter_script"

# Number of files
num_files=${#front_files[@]}

# Iterate through the sorted files to build the filter script
for i in "${!front_files[@]}"; do
    echo "file '${front_files[$i]}'" >> "$input_list"
    echo "file '${rear_files[$i]}'" >> "$input_list"
    
    echo "[$((2*i)):v]trim=start=1,scale=1920:1080,setpts=PTS-STARTPTS[f_$i]; [$((2*i)):a]atrim=start=1,asetpts=PTS-STARTPTS[a_$i];" >> "$filter_script"
    echo "[$((2*i+1)):v]trim=start=1,scale=640:360,setpts=PTS-STARTPTS[r_$i];" >> "$filter_script"  # Rear video only
    echo "[f_$i][r_$i]overlay=x=(main_w-overlay_w-10):y=(main_h-overlay_h-10)[mix_$i];" >> "$filter_script"

    input+="[mix_$i][a_$i]"
done

# Concatenate all combined labels
echo "${input}concat=n=${#front_files[@]}:v=1:a=1[v][a]" >> "$filter_script"

# Run FFmpeg with filter script
ffmpeg -f concat -safe 0 -i "$input_list" \
    -filter_complex_script "$filter_script" \
    -map "[v]" -map "[a]" \
    -y "$output_file"


  


  This script generates two files input_list.txt :

  


  file '20200826_084407_F.MP4'
file '20200826_084407_R.MP4'
file '20200826_084708_F.MP4'
file '20200826_084708_R.MP4'
file '20200826_084910_F.MP4'
file '20200826_084910_R.MP4'


  


  filter_script.txt :

  


  [0:v]trim=start=1,scale=1920:1080,setpts=PTS-STARTPTS[f_0]; [0:a]atrim=start=1,asetpts=PTS-STARTPTS[a_0];
[1:v]trim=start=1,scale=640:360,setpts=PTS-STARTPTS[r_0];
[f_0][r_0]overlay=x=(main_w-overlay_w-10):y=(main_h-overlay_h-10)[mix_0];
[2:v]trim=start=1,scale=1920:1080,setpts=PTS-STARTPTS[f_1]; [2:a]atrim=start=1,asetpts=PTS-STARTPTS[a_1];
[3:v]trim=start=1,scale=640:360,setpts=PTS-STARTPTS[r_1];
[f_1][r_1]overlay=x=(main_w-overlay_w-10):y=(main_h-overlay_h-10)[mix_1];
[4:v]trim=start=1,scale=1920:1080,setpts=PTS-STARTPTS[f_2]; [4:a]atrim=start=1,asetpts=PTS-STARTPTS[a_2];
[5:v]trim=start=1,scale=640:360,setpts=PTS-STARTPTS[r_2];
[f_2][r_2]overlay=x=(main_w-overlay_w-10):y=(main_h-overlay_h-10)[mix_2];
[mix_0][a_0][mix_1][a_1][mix_2][a_2]concat=n=3:v=1:a=1[v][a]


  


  I'w got error :

  


  Input #0, concat, from 'input_files.txt':
  Duration: N/A, start: 0.000000, bitrate: 11973 kb/s
  Stream #0:0(eng): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1920x1080, 11877 kb/s, 30 fps, 30 tbr, 60k tbn, 60 tbc
    Metadata:
      creation_time   : 2020-08-26T08:47:07.000000Z
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
      encoder         : h264
  Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 32000 Hz, mono, fltp, 96 kb/s
    Metadata:
      creation_time   : 2020-08-26T08:47:07.000000Z
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]
Invalid file index 1 in filtergraph description
[0:v]trim=start=1,scale=1920:1080,setpts=PTS-STARTPTS[f_0]; [0:a]atrim=start=1,asetpts=PTS-STARTPTS[a_0];
[1:v]trim=start=1,scale=640:360,setpts=PTS-STARTPTS[r_0];
[f_0][r_0]overlay=x=(main_w-overlay_w-10):y=(main_h-overlay_h-10)[mix_0];
[2:v]trim=start=1,scale=1920:1080,setpts=PTS-STARTPTS[f_1]; [2:a]atrim=start=1,asetpts=PTS-STARTPTS[a_1];
[3:v]trim=start=1,scale=640:360,setpts=PTS-STARTPTS[r_1];
[f_1][r_1]overlay=x=(main_w-overlay_w-10):y=(main_h-overlay_h-10)[mix_1];
[4:v]trim=start=1,scale=1920:1080,setpts=PTS-STARTPTS[f_2]; [4:a]atrim=start=1,asetpts=PTS-STARTPTS[a_2];
[5:v]trim=start=1,scale=640:360,setpts=PTS-STARTPTS[r_2];
[f_2][r_2]overlay=x=(main_w-overlay_w-10):y=(main_h-overlay_h-10)[mix_2];
[mix_0][a_0][mix_1][a_1][mix_2][a_2]concat=n=3:v=1:a=1[v][a]


  


  What am I doing wrong ?

  


• Is there a way to horizontal flip video captured from flutter front camera

  5 mai 2024, par JoyJoy

  Basically, I'm trying to flip video horizontally after capturing it from flutter front camera. So I start recording, stop recording, flip the video and pass it to another page. I'm fairly new and would appreciate any assistance as my code isn't working

  


  I've tried doing so using the new ffmpeg_kit flutter

  


  Future<void> flipVideo(String inputPath, String outputPath) async{&#xA;final ffmpegCommand = "-i $inputPath -vf hflip $outputPath";&#xA;final session = FFmpegKit.executeAsync(ffmpegCommand);&#xA;await session.then((session) async {&#xA;  final returnCode = await session.getReturnCode();&#xA;  if (ReturnCode.isSuccess(returnCode)) {&#xA;    print(&#x27;Video flipping successful&#x27;);&#xA;  } else {&#xA;    print(&#x27;Video flipping failed: ${session.getAllLogs()}&#x27;);&#xA;  }&#xA;});}&#xA;&#xA;void stopVideoRecording() async {&#xA;XFile videopath = await cameraController.stopVideoRecording();&#xA;&#xA;try {&#xA;  final Directory appDocDir = await &#xA;  getApplicationDocumentsDirectory();&#xA;  final String outputDirectory = appDocDir.path;&#xA;  final String timeStamp = DateTime.now().millisecondsSinceEpoch.toString();&#xA;  final String outputPath = &#x27;$outputDirectory/flipped_video_$timeStamp.mp4&#x27;;&#xA;&#xA;  await flipVideo(videopath.path, outputPath);&#xA;&#xA;  // Once completed,&#xA;   Navigator.push(&#xA;    context,&#xA;    MaterialPageRoute(&#xA;      builder: (builder) => VideoViewPage(&#xA;        path: File(outputPath),&#xA;        fromFrontCamera: iscamerafront,&#xA;        flash: flash,&#xA;      )));&#xA;  print(&#x27;Video flipping completed&#x27;);&#xA;} catch (e) {&#xA;  print(&#x27;Error flipping video: $e&#x27;);&#xA;}&#xA;</void>

  


  }