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• FFmpeg.AutoGen decoding an image using av_image_copy_to_buffer

  28 juin 2022, par Steve

  I try to use FFmpeg.AutoGen.av_image_copy_to_buffer to get decoded data into my application defined frame_buffer like so :

  


  bytes_decoded = ffmpeg.av_image_copy_to_buffer(frame_data, buffer_size, frame->data, frame->linesize, 
                                               codCtx->pix_fmt, codCtx->width, codCtx->height, 1);


  


  However the type of the parameter frame->data is of type FFmpeg.AutoGen.byte_ptrArray8, but the interface expects FFmpeg.AutoGen.byte_ptrArray4.
Does anyone know how to convert this parameter, so that I can pass it to the interface ? VS complains with the following error message :
https://docs.microsoft.com/en-us/dotnet/csharp/misc/cs1503?f1url=%3FappId%3Droslyn%26k%3Dk(CS1503)

  


  Thanks in advance for any help on this issue.

  


• Composite 2 video(.mov) files using ffmpeg

  20 octobre 2012, par eco_bach

  Novice user of ffmpeg but going thru whatever docs I can find online.

  For a current project I will need to composite 2 videos together to create a .flv file.

  Does anyone know the commands to do this ?

• If multiple channels, merge then take sample length from audio file and save it to s3

  18 mai 2017, par khinester

  I am using transloadit to extract the audio from a video file, which is then saved to S3.
  This works great, but I wanted to know how to :

  1. check if the file has multiple channels and then squash it inot one as per https://transloadit.com/demos/audio-encoding/merging-multiple-audio-streams/ - do I need to check for this or do i default to use this robot ?

  2. extract a small sample from the audio file - and save this as a separate file.

  For example, I have a 2h audio file from which I want to take 5% of the length and save this as sample.mp3

  In ffmpeg, i can cut :

  ffmpeg -ss 0 -t 30 -i original.mp3 sample.mp3

  but I am unsure how to chain this workflow, here is what i have thus far :

  const opts = {
  
    params: {
  
      notify_url: `${ process.env.SELF }/services/trans/${ jwToken }`,
  
      steps:      {
  
        import: {
  
          robot:  '/s3/import',
  
          use:    ':original',
  
          bucket: process.env.S3_INGEST,
  
          path:   ingest.key,
  
          key:    process.env.AWS_ID,
  
          secret: process.env.AWS_SECRET,
  
        },
  
        encode: {
  
          robot:        '/audio/encode',
  
          use:          'import',
  
          ffmpeg_stack: 'v2.2.3',
  
          preset:       'aac',
  
          ffmpeg:       {
  
            ab:  '128k',
  
          },
  
        },
  
        export: {
  
          robot:   '/s3/store',
  
          use:     'encode',
  
          bucket:  s3Export,
  
          path:    `${ prefix }/${ token }.m4a`,
  
          headers: {
  
            'Content-Type': 'audio/mp4',
  
            'x-amz-server-side-encryption': 'AES256',
  
          },
  
          key:    process.env.AWS_ID,
  
          secret: process.env.AWS_SECRET,
  
        },
  
      },
  
    },
  
  };

  in the docs, https://transloadit.com/docs/conversion-robots/ i can’t see how to do this ?

  any advice is much appreciated.