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• Download Partial Video via HTTP (for Remote Thumbnailing)

  13 février 2012, par HuntedC

  I have videos hosted on Amazon S3. I encode them with Zencoder and store a thumbnail for the video then using Zencoder. However, I need a way to generate thumbnails at certain points in the video (i.e. 00:00:03, 00:10:32, 01:40:18) and store them either on S3 or my server.

  ffmpeg allows remote thumbnailing, however it takes a very long time (sometimes several minutes) to get a thumbnail from the middle of a file—I believe this is because it downloads the entire file up to that point to get the thumbnail.

  My plan is to somehow download the header of the video file via HTTP byte-range request, guesstimate the byte range where I should be looking for the thumbnail, download about a second of video from that part of the file via HTTP byte-range request, then save the header and tiny video locally. I pull the thumbnail from that using ffmpeg and delete the temporary video.

  I have no idea on how exactly this would work (I believe the H.264 MP4 files I'm working with have a dynamic length header, for another issue). Any suggestions or better ideas ?

  Edit : To clarify, Zencoder thumbnailing is great, but they only allow thumbnail creation in combination with transcoding. I don't want to transcode my video every time I create a new thumbnail, so I need to do this on my own without Zencoder.

• FFmpeg -filter_complex_script crop & blurbox with time based values

  6 juin 2021, par user1503606

  I am trying to create a script that will move a blur boxed across a video based on x and y cords in a text script.

  


  I can easily create a blur box with the following ffmpeg command.

  


  ffmpeg -y -i pex.mp4 -filter_complex_script cropblur.txt -map "[v]" out_crop.mp4


  


  The cropblur.txt has the following.

  


  [0:v]crop=400:400:300:350,boxblur=10[fg]; [0:v][fg]overlay=300:350:enable='between(t\,0\,5)'[v]


  


  This creates this.

  


  

  


  What I want is the blur box to move across where the lady is running.

  


  

  


  She obviously runs out from where the box is positioned.

  


  I can create a script where I can track the correct x and y positions for the blox using jquery ui or something I just dont understand how to implement this in a filter_complex_script.

  


  I thought it would be a simple as just appending to the script something like this.

  


  [0:v]crop=400:400:300:350,boxblur=10[fg]; [0:v][fg]overlay=300:350:enable='between(t\,0\,2)'[v]
[0:v]crop=200:200:200:360,boxblur=10[fg]; [0:v][fg]overlay=300:350:enable='between(t\,2\,3)'[v]
[0:v]crop=200:200:200:370,boxblur=10[fg]; [0:v][fg]overlay=300:350:enable='between(t\,3\,4)'[v]
[0:v]crop=200:200:200:380,boxblur=10[fg]; [0:v][fg]overlay=300:350:enable='between(t\,4\,5)'[v]


  


  Changing the time and the x position based on the incremented time.

  


  If I run this script I get this error.

  


  No output pad can be associated to link label '0:v'


  


  Obviously I am doing something wrong but I cannot find any documentation that really helps me understand how to do this https://ffmpeg.org/ffmpeg.html the official docs dont really help.

  


  I could do it by running multiple passes like this.

  


  ffmpeg -y -i pex.mp4 -filter_complex "[0:v]crop=400:400:300:350,boxblur=10[fg]; [0:v][fg]overlay=300:350:enable='between(t\,0\,2)'[v]" -map "[v]" out_crop.mp4 && ffmpeg -y -i out_crop.mp4 -filter_complex "[0:v]crop=200:200:200:360,boxblur=10[fg]; [0:v][fg]overlay=300:350:enable='between(t\,2\,3)'[v]" -map "[v]" out_crop2.mp4


  


  I Would just really like to understand how to use the filter complex scripts in this way ?

  


  Any help would be great.

  


  Thanks

  


• how to convert video into multiple fames using FFMPEG ?

  6 août 2021, par Justin Lee

  New programmer here ! I'm trying to convert a video into multiple jpegs (24fps) using FFmpeg.wasm and store it into an array. Honestly, I'm not sure what I'm doing but here's what I've done so far. *I'm writing this in React.

  


  await ffmpeg.run(
  "-i", //? Input file
  `test.mp4`, //? name of = Input file
  "-vf", //? set filter
  "fps=24", //? set frame per sec
  "test-%04d.png" //? Output file
);

//* Read the result
const data = ffmpeg.FS("readFile", `test-0001.png`);


  


  I need to store them in an array so I can do something with it after.
How should I go about it ? Cheers !

  


  Update Manage to find a workaround.*
Not too sure why I can't save it in jpeg though.

  


  await ffmpeg.run(
      "-i", //? Input file
      `test.mp4`, //? name of = Input file
      "-vf", //? set filter
      "fps=24", //? set frame per sec
      "test-%05d.png" //? Output file
    );

    //* List entire directory
    const listDir = ffmpeg.FS("readdir", "/");

    //* Retain target files
    const fileData = (data) => {
      const arr = data.filter((fileName) => /^test-.*.png$/.test(fileName));
      return arr;
    };
    const targetFiles = fileData(listDir);