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• How to set the destination folder of a Node.js fluent-ffmpeg screenshot to your AWS S3 bucket using getSignedUrl() ?

  10 juillet 2017, par Madhavi Mohoni

  I’m writing a program to generate .png thumbnails (with the same name, in the same folder) for a set of .mp4 videos in my Amazon S3 bucket. For this example, I’m going to create a /folder/file.png for a /folder/file.mp4 in the bucket. I’ve managed to set the source URL using the s3 object and getSignedUrl as follows :

  var srcurl = s3.getSignedUrl('getObject', {
  
          Bucket: 'bucket-name',
  
          Key: '/folder/file.mp4'
  
        });

  and

  new ffmpeg({ source: srcurl })
  
       .screenshots({
  
          count: 1, 
  
          filename: '%f'.substr(0, '%f'.indexOf('.')) + '.png', 
  
          /* To shorten the long string that's returned */ 
  
          folder: desturl,
  
          size: MAX_WIDTH + 'x' + MAX_HEIGHT
  
        });

  The destination URL has to be the same folder as the source. So I set it as follows :

  var desturl = s3.getSignedUrl('putObject', {
  
          Bucket: 'bucket-name',
  
          Key: '/folder/file' + '.png'
  
        });

  This combination doesn’t work - is there a way to do this correctly ?

• RGB to YUV422 conversion with ffmpeg, incorrect colors

  22 janvier 2016, par user3578571

  I’m trying to convert an 8bit RGB uncompressed to an mpeg2 mxf file (xdcam 422 HD 1080 50i) which is YUV422. With info from the FFMpeg docs and various websites i made the following command :

  ./ffmpeg -y -i test_lines.mov  -pix_fmt yuv422p -vcodec mpeg2video -non_linear_quant 1 -flags +ildct+ilme -top 1 -dc 10 -intra_vlc 1 -qmax 2 -vtag xd5c -rc_max_vbv_use 1 -rc_min_vbv_use 1 -g 12 -b:v 50000k -minrate 50000k -maxrate 50000k -bufsize 8000k -acodec pcm_s24le -ar 48000 -bf 2 -ac 2 lines_HD.mxf

  This gave me a result with the colors much brighter than the original.

  So i tried adding the options -color_range 1 -colorspace 1 -color_primaries 1 -color_trc 1 but this didn’t seem to do anything.

  After adding colormatrix=bt601:bt709 i got a way better image, but slightly darker than the original and it also feels weird specifying this option cause the source is also in the REC709 colorspace, so why specify it differently ?

  Next i regenerated my source image to an YUV codec (prores) and rerun FFMpeg on it with the colors coming out just fine. Therefore i think it has to be an RGB -> YUV problem.
  Does somebody have an idea how to this properly ? I can provide screenshots of the different results on a videoscope as soon as i’m back at the office, if anybody is interested.

  Last, i know there are various topics touching this subject but either they go way over my head FFmpeg wise or bring me to the stage where i already am.

• How to compile ffmpeg.dll [closed]

  30 mai 2024, par jdauthre

  I would like to compile a ffmpeg.dll dynamic link library which includes the full range of codecs, but when I search for guides I can only find resouces to create ffmpeg.exe. Can anyone point to any resources. Thank you in advance.