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• Auto aspect on stream with ffmpeg

  6 mars 2018, par Felix Bäder

  I currently try to get an image each second from a udp stream with the following configuration :

  ffmpeg -i udp://localhost:1234 -vf "scale=iw*sar:ih , pad=max(iw\,ih*(16/9)):ow/(16/9):(ow-iw)/2:(oh-ih)/2" -aspect 16:9  -update 1 img.jpg
  
  
  
    Metadata:
  
      encoder         : Lavf57.83.100
  
      Stream #0:0: Video: mjpeg, yuvj420p(pc), 1024x576 [SAR 1:1 DAR 16:9], q=2-31, 200 kb/s, 25 fps, 25 tbn, 25 tbc
  
      Metadata:
  
        encoder         : Lavc57.107.100 mjpeg
  
      Side data:
  
        cpb: bitrate max/min/avg: 0/0/200000 buffer size: 0 vbv_delay: -1

  If the first frame of stream is 4:3 black borders are added to the output image. If the aspect is changed in stream from 4:3 to 16:9 the output image still contains the black broder and the aspect of the image between the borders is 4:3.

  If I restart ffmpeg while the aspect is 16:9 the borders are removed from the output and the output image looks fine.

  In the console I get the following log on the aspect change of stream :

  [swscaler @ 0x7fc6b1035600] deprecated pixel format used, make sure you did set range correctly

  Is there any option to fix this issue.

• FFMPEG waveform transparent, background solid color

  11 mai 2016, par user1152226

  I am trying to generate a waveform with ffmpeg, I want the background to be a solid color, and the actual waveform to be transparent. The following achieves partially what i want, except that in has a black background. I would like to be able to change this to any color, but have the waveform be transparent. How can i achieve this with ffmepg ?

  ffmpeg -i input.mp3 -filter_complex \
  
  "[0:a]aformat=channel_layouts=mono,\
  
  compand=gain=-6, \
  
  showwavespic=s=600x120, \
  
  colorchannelmixer=rr=1:gg=0:bb=0:aa=1,\
  
  drawbox=x=(iw-w)/2:y=(ih-h)/2:w=iw:h=1:color=red,\
  
  format=rgba,\
  
  colorkey=#ff0000" \
  
  -vframes 1 output.png

  This generates this waveform : the background is black, the waveform itself is transparent. How do I change the background color to a different color, while still keeping the waveform transparent ?

  

• There is a problem with converting ffmpeg video from hev1 to hvc1

  18 septembre 2024, par sixawnstar

  ffmpeg -i in.mp4 -c:v copy -c:a copy -tag:v hvc1 out.mp4

  


  I used ffmpeg to transcode the videos, but some of the transcoded videos were black screens with audio but no visuals.

  


  enter image description hereenter image description here

  


  By using ffmpeg -i video.mp4 to view the video information, it was found that the information for both videos is consistent. However, the screen in Figure 1 displays a black screen after transcoding, whereas Figure 2 functions normally after transcoding.