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• Getting h264 stream of DJI Action 2 with ffmpeg (Raspberry Pi)

  8 juin 2022, par ErAzOr

  I have a DJI Action 2 cam which is connected to my Raspberry Pi in webcam mode.
My goal is to save the h264 stream to a local file.

  


  H264 should be a valid format :

  


  root@raspberrypi:/home/pi# v4l2-ctl -d /dev/video0 --list-formats-ext
    ioctl: VIDIOC_ENUM_FMT
    Type: Video Capture

    [0]: 'MJPG' (Motion-JPEG, compressed)
            Size: Discrete 1280x720
                    Interval: Discrete 0.033s (30.000 fps)
            Size: Discrete 1920x1080
                    Interval: Discrete 0.033s (30.000 fps)
    [1]: 'H264' (H.264, compressed)
            Size: Discrete 1280x720
                    Interval: Discrete 0.033s (30.000 fps)
            Size: Discrete 1920x1080
                    Interval: Discrete 0.033s (30.000 fps)


ffmpeg -f video4linux2 -list_formats all -i /dev/video0
.
.
.
[video4linux2,v4l2 @ 0x7021c0] Compressed:       mjpeg :          Motion-JPEG : 1280x720 1920x1080
[video4linux2,v4l2 @ 0x7021c0] Compressed:        h264 :                H.264 : 1280x720 1920x1080


  


  When I now try to save a file in h264, I get an error :

  


  .
.
.
ffmpeg -f v4l2 -input_format h264 -i /dev/video0 -c:v copy output.mkv
[video4linux2,v4l2 @ 0x1b7a1e0] ioctl(MJPG): Invalid argument
/dev/video0: Invalid argument


  


  With mjpg as -input_format it works.

  


  Any ideas, why h264 is not possible ?

  


• How do I get ffmpeg to encode all files in one directory to another directory ? My directory names and filenames all have spaces and periods in them

  26 avril 2023, par Vihung

  I am using the Terminal on a Mac.

  


  Per another question, I am doing

  


  for i in ./01.\ Original\ Recording/*.m4a; do ffmpeg -i "$i" -b:a 64k ./02.\ Compressed/"$(basename $i)"; done


  


  (as you can see, there are spaces in the directory names as well as in the filenames)

  


  The output files are being put in the right directory (02.\ Compressed).

  


  Unfortunately, they come out named as 01.?Original?.m4a (first part of directory name and rest of file name with spaces substituted by ?)

  


• Compress video like whatsapp

  10 juillet 2021, par user1079425

  I'm not an expert in Video Editing but what I want to understand the logic of Whatsapp video processing.

  



  First of all I have noticed that whatever the file is, Whatsapp sets the limit of Uploaded videos to 16MB, after which whatsapp crops the video to not exceed the limit. is this a convention or it's a personal choice ?

  



  Secondly, When a video is recorded using the Camera it's not compressed by default, so whatsapp compresses it using FFMPEG I guess, and it takes no time. (tried for a video of 1min 1920x1080 with 125MB of size, becomes 640x360 with 5MB of size in no time, and the upload starts automatically).. how may they do this ? and why the choice of 640x360, It seems to me very fast for 2 asynchronous tasks : Compression + Upload.

  



  When I run the compression command ffmpeg -y -i in.mp4 -codec:v libx264 -crf 23 -preset medium -codec:a libfdk_aac -vbr 4 -vf scale=-1:640,format=yuv420p out.mp4 it takes approximatively 1 min and the video is being rotated !! :D

  



  Finally, when we download a video from Youtube it's already compressed (I guess) and whatsapp doesn't even try to compress it. So I think that it automatically detects thats the video is compressed. How can we detect this ?

  



  Thank you.