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• How to set the length metadata property with fluent-ffmpeg ?

  8 avril 2024, par volume one

  I have transcoded a sample video using fluent-ffpmeg and want to set the length metadata property so that the <video></video> player knows how long the video is going to be.

  


  To get the duration of the video I did this :

  


  import ffmpeg from 'fluent-ffmpeg';

function ffprobePromise() {
            return new Promise((resolve, reject) => {
                ffmpeg.ffprobe('/path/to/file'), function (err, metadata) {
                    FileDuration = metadata.format.duration;
                    resolve()
                });
            })}

  await ffprobePromise();

  ffmpeg('path/to/output')
                    .videoCodec('libx264')
                    .audioCodec('libmp3lame')
                    .duration(FileDuration)   // !! not setting 'length' metadata property in file
                    .size(`960x400`)
                    // Stream output requires manually specifying output formats
                    .format('mp4')
                    .outputOptions(['-movflags dash', `-metadata length=${FileDuration}`]) // also not setting length in metadata


  


  Here is the sample file that was created : https://devxxx001.s3.amazonaws.com/sample_960x400_47sec.mp4

  


  If you download and view the properties of that file, there is no length property in the metadata. Hence when you play the file, the video player is not able to determine the total duration of the video. You'll notice it keeps jumping up as the video plays.

  


  The ffmpeg documentation states that you can use ffmpeg -i in.avi -metadata title="my title" out.flv to set the title for example. But how do you do this with fluent-ffmpeg ?

  


• Revision fb1f6f1db4 : Fix segment feature data type. It has a range of -255,255, so should be int16_t

  7 juin 2013, par Ronald S. Bultje

  Changed Paths :
   Modify /vp9/common/vp9_blockd.h

  
  
  Fix segment feature data type.

  It has a range of -255,255, so should be int16_t, not int8_t.

  Change-Id : I5ef4b6aefb6212b0f35f4754f3c4d73fddbc52a0

• How to batch process a series of video files with powershell and other-transcode/ffmpeg

  7 juin 2022, par DarkDiamond

  TL ;DR

  


  What did I do wrong in the following PowerShell-Script ? It does not work as expected.

  


  ---

  


  I am recording some of my lectures in my university with a photo camera. This works pretty well although I have to split the single lecture into three to four parts because the camera can only record 29 minutes of video in one take. I know that this is a common issue related to some licensensing problem that most photo cameras simply don't have the right license to record longer videos. But it confronts me with the problem that I later have to edit the files together after I did some post processing on them.

  


  With the camera I produce up to four video files with sizes around 3.5 GB which is way to big in order to be of any use because our IT department understandably doesn't want to host so much data, as I produce around 22 GB of video material each week.

  


  Some time ago I came across a very useful tool called "other-video-transcoding" by Don Melton over on GitHub, written in ruby, that allows me to compress the files to a reasonable file size without any visual loss. In addition I crop the videos to remove the part of each frame that is neither the board nor a place where my professor stands in order to decrease the filesize even further and do some privacy protection by cutting out most of the students.

  


  As the tools are accessable via the command line, it is relatively easy to configure and does not cost additional computational power to render a nice gui, so I can edit one of the 29 minute clips in less than 10 minutes.

  


  Now I wanted to optimize my workflow by writing a PowerShell script that only takes the parameters what to crop and which files to work on and then does the rest on its own so I can just start the script and then do something else while my laptop renders the new files.

  


  So far I have the following :

  


  $video_path = Get-ChildItem ..\ -Directory | findstr "SoSe"

Get-ChildItem $video_path -name | findstr ".MP4" | Out-File temp.txt -Append 
Get-Content temp.txt | ForEach-Object {"file " + $_} >> .\files.txt

Get-ChildItem $video_path |
Foreach-Object {
other-transcode --hevc --mp4 --target 3000 --crop 1920:780:0:0 $_.FullName
}

#other-transcode --hevc --mp4 --crop 1920:720:60:0 ..\SoSe22_Theo1_videos_v14_RAW\
ffmpeg -f concat -i files.txt -c copy merged.mp4
Remove-Item .\temp.txt


  


  but it does not quite do what I it expect to do.
This is my file system :

  


  sciebo/
└── SoSe22_Theo1_videos/
    ├── SoSe22_Theo1_videos_v16/
    │   ├── SoSe22_Theo1_videos_v16_KOMPR/
    │   │   ├── C0001.mp4
    │   │   ├── C0002.mp4
    │   │   ├── C0003.mp4
    │   │   ├── C0004.mp4
    │   │   ├── temp.txt
    │   │   ├── files.txt
    │   │   └── merged.mp4
    │   └── SoSe22_Theo1_videos_v16_RAW/
    │       ├── C0001.mp4
    │       ├── C0002.mp4
    │       ├── C0003.mp4
    │       └── C0004.mp4
    └── SoSe22_Theo1_videos_v17/
        ├── SoSe22_Theo1_videos_v17_KOMPR
        └── SoSe22_Theo1_videos_v17_RAW/
            ├── C0006.mp4
            ├── C0007.mp4
            ├── C0008.mp4
            └── C0009.mp4


  


  where the 16th lecture is already processed and the 17th is not. I always have the raw video data in the folders ending on RAW and the edited/compressed output files in the one ending on KOMPR. Note that the video files in the KOMPR folder are the output files of the other-transcode tool.

  


  The real work happens in the line where it says

  


  other-transcode --hevc --mp4 --target 3000 --crop 1920:780:0:0 $_.FullName


  


  and in the line

  


  ffmpeg -f concat -i files.txt -c copy merged.mp4


  


  where I concat the output files into the final version I can upload to our online learning platform.
What is wrong with my script ? In the end I'd like to pass the --crop parameter just to my script, but that is not the primary problem.

  


  ---

  


  A little information on the transcoding script so you don't have to look into the documentation :
  
As the last argument the tool takes the location of the video files to work on, be it relative or absolute file paths. The output is placed in the folder the script is called in, so if I cd into one of the KOMPR directories and then call

  


  other-transcode --mp4 ../SoSe22_Theo1_videos_v16_RAW/C0001.mp4


  


  a new file C0001.mp4 is created in the KOMPR directory and the transcoded video and old audio are written to that new video file.