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• How to save a DShow input on a file and simultaneously publish it on rtst stream ?

  18 novembre 2020, par user2586476

  Piping command does not work properly when your input is coming from a device (e.g. a webcam) so you cannot work with 2 output. I need to save the webcam stream on a file (.mkv) and, at the same time, publish it on a rtst server. I tried the following :

  


  ffmpeg -y -f dshow -loglevel info -rtbufsize 2147.48M -i "video=my_camera" -vf hflip,rotate=PI ^
-c:v libx264 -preset fast -crf 25 -pix_fmt yuv420p ^
-minrate 2M -maxrate 4M -bufsize 3.5M -s 1920x1080 -f tee "[f=mkv]'C :\test.mkv'|[f=rtsp]rtsp ://localhost:8554/mystream]"

  


• avcodec/mpeg4videodec : Use union to save space

  21 mai, par Andreas Rheinhardt

  avcodec/mpeg4videodec : Use union to save space
  At most one of block32 and dpcm_macroblock is used at any given time.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] libavcodec/mpeg4videodec.h

• Save a partial video file locally using NodeJS

  25 octobre 2017, par Sami

  I have a serverless web application that is deployed on AWS and I have to take a screenshot from an uploaded video to S3. I am using ffmpeg to extract the screenshot but the only drawback is that I have to download the video file first in order to let ffmpeg work with it.
  Knowing the fact I am using AWS Lambda and I don’t have limits for video length users might upload large files which makes AWS Lambda to hit the storage limit.
  To overcome this I thought of downloading a small chunk of the video and use it with ffmpeg to extract the thumbnail so using the S3.getOjbect method with range params I was able to download a chunk of the file but ffmpeg couldn’t understand it.
  Here is my code :

  s3.getObject({
  
    Bucket: bucketName,
  
    Key: key,
  
    Range: 'bytes=0-1048576'
  
  }, (err, data) => {
  
    fs.writeFile(fileName, data.Body, error => {
  
      if (error)
  
        console.log(error)
  
      else
  
        console.log('File saved');
  
    })
  
  })

  And the code to extract the thumbnail :

  const ffmpeg = require('fluent-ffmpeg');
  
  new ffmpeg(fileName).screenshots({
  
    timestamps: [0],
  
    filename: 'thumb.png',
  
    folder: '.'
  
  })

  And I am getting this error from ffmpeg

  Error: ffmpeg exited with code 1: ./test.mp4: Invalid data found when processing input

  I know there is a problem in saving the file like this but I couldn’t find any solution that solves my problem. If anybody has one that would be much appreciated.

  UPDATE :
  It turns out that ffmpeg does this for me, I just gave it the url and it downloaded what it needs to render the screenshot without the need to download the file locally and the code looks like this :

  const ffmpeg = require('fluent-ffmpeg');
  
  new ffmpeg(url).screenshots({
  
    timestamps: [0],
  
    filename: 'thumb.png',
  
    folder: '.'
  
  })