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• FFMPEG re-broadcast/proxy MJPEG stream

  10 septembre 2022, par Ollie Pugh

  I have an MJPEG stream coming from an RPI on my home network and have an NGINX acting as a proxy on an EC2.

  


  For the camera access the flow of stream to the user is the following

  


  RPi -> mjpeg-proxy (running on EC2) -> NGINX (running on same EC2) -> user

  


  the point of mjpeg-proxy is to reduce the load on the RPi and only have one stream to the Pi and allow the EC2 to distribute that one stream.

  


  Now this work fine-ish from my PC (on same network as Pi) the streams work perfectly. But when it comes to my phone on roaming data, the stream is super choppy and the latency grows massively (this project needs minimal latency, like sub 300ms).

  


  I can't understand why this would happen ? Because even when running of my local PC its going through the Proxy hosted in the cloud, so its not as if its an advantage to it being local ?

  


  the stream is fine on another device, e.g. my laptop, but thats on the same network as the RPi. But like I said, it shouldn't makea difference as its going through a proxy !

  


  I was wondering if using FFMPEG to re-stream the mjpeg stream would be beneficial as node is notoriously slow. But I don't really want to be writing my own mjpeg-proxy in C++ to speed this all up.

  


  I have looked online for answers to FFMPEG MJPEG proxy and have been very unsuccesful

  


• 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.

  


• ffmpeg video freezes some seconds the output video

  7 septembre 2022, par FreddicMatters

  I'm using the program ffmpeg on windows, I just downloaded the binaries setted the path variable of windows to be able of use it.

  


  I'm ran ffmpeg with python and also just running the command in the cmd

  


  #videos.txt

  


  file C:/Users/freddydev/Videos/video1.mp4
file C:/Users/freddydev/Videos/video2.mp4
file C:/Users/freddydev/Videos/video3.mp4
file C:/Users/freddydev/Videos/video4.mp4


  


  #python script :

  


  import subprocess
import shlex

subprocess.run(shlex.split('ffmpeg -f concat -safe 0  -i videos.txt -c:v libx264 -c copy output.mp4'))


  


  #cmd

  


  ffmpeg -f concat -safe 0  -i videos.txt -c:v libx264 -c copy output.mp4


  


  The output video plays fine the half of the video and after some 5 seconds it freezes and the final seconds of the video there is not sound.

  


  I have downloaded multiple ffmpeg binaries from https://ottverse.com/ffmpeg-builds and I'm getting the same result.

  


  My laptop is a core i5 with 12GB of RAM.
The rendering is very fast only takes 2 seconds, I also used moviepy library with python and it takes more than 20sg to render the video but when I concatenate large videos this give me wrong frames in the video at the end.

  


  What could I do to fix this problem with ffmpeg.
Thanks so much.