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• FFMpeg(Android) av_read_frame or avcodec_decode_video2 returning same colour

  5 décembre 2012, par Cehm

  I've been experimenting FFMpeg for the past 2 weeks and I'm having a bit of trouble...
  First I've been working with a Galaxy S3, which worked super fine, gave me the best pictures ever but I recently switched to a Galaxy NEXUS which gave me a bunch of problems...

  What I'm doing : I just extract frame from a video

  How I'm doing :

  while(av_read_frame(gFormatCtx, &packet)>=0)
  
          {
  
              // Is this a packet from the video stream?
  
              if(packet.stream_index==videoStream)
  
              {
  
                  // Decode video frame
  
                  avcodec_decode_video2(gVideoCodecCtx, pFrame, &frameFinished, &packet);
  
                  // Did we get a video frame?
  
                  if(frameFinished)
  
                  {//and so on... But our problem is already here...

  Ok, now pFrame is holding a YUV representation of my frame... So, in order to check what I'm getting from the avcodec_decode_video2(...) function I'm just writing pFrame to a file so I can see it with any YUV reader on the web.

  char yuvFileName[100];
  
  sprintf(yuvFileName,"/storage/sdcard0/yuv%d.yuv",index);
  
  FILE* fp = fopen(yuvFileName, "wb");
  
  int y;
  
  // Write pixel data
  
  for(y=0; yheight; y++)
  
  {
  
      fwrite(pFrame->data[0]+y*pFrame->linesize[0], 1, gVideoCodecCtx->width, fp);    
  
  }
  
  for(y=0; yheight/2; y++)
  
  {
  
      fwrite(pFrame->data[1]+y*pFrame->linesize[1], 1, gVideoCodecCtx->width/2, fp);
  
  }
  
  for(y=0; yheight/2; y++)
  
  {
  
      fwrite(pFrame->data[2]+y*pFrame->linesize[2], 1, gVideoCodecCtx->width/2, fp);
  
  }
  
  fclose(fp);

  Ok so Here I now have my result on a file store @ /storage/sdcard0/blabla.YUV on my Galaxy Nexus root memory.

  But If I open the file with (for example XnView, which is meant to display YUV type properly) I only see Dark green on the picture.

  What bothers me is that everything worked properly on Galaxy S3 but something failed on GNexus...

  So here's my question : Why doesn't it work on Galaxy Nexus ?

  Compatibility problem between Gnexus and armeabiv7 ?

  I don't know !

  Regards,
  Cehm

• Moviepy python images and text with colour background video

  7 janvier, par sjpatel

  I trying to create video like below using Moviepy python.?

  


  Video -
https://assets.json2video.com/examples/marketing/slide-text-right.mp4

  


  Is this possible using Moviepy python ? I can't use FFMPEG because it not supported on my server.

  


  from moviepy.editor import *

# Load the image
img_clip = ImageClip("your_image.png")

# Set the duration of the image clip
img_clip = img_clip.set_duration(5)

# Resize the image if necessary
img_clip = img_clip.resize(height=1080)  # Keep the height consistent

# Define your text
text = "Your Marketing Message"

# Create a TextClip
txt_clip = TextClip(text, fontsize=70, color='white')

# Set the duration of the text clip
txt_clip = txt_clip.set_duration(5)

# Animate the text to slide in from the right
def slide_in(t):
    return 'center', -1000 + 1500 * t  # Adjust these values based on your needs

txt_clip = txt_clip.set_position(slide_in)

# Set background color
txt_clip = txt_clip.on_color(size=(1920, 1080), color=(0, 0, 0), col_opacity=1)

# Position the image on the left side
img_clip = img_clip.set_position(('left', 'center'))

# Position the text clip on the right side
txt_clip = txt_clip.set_position(('right', 'center'))

# Composite the two clips together
final_clip = CompositeVideoClip([img_clip, txt_clip])

# Set the duration of the final clip
final_clip = final_clip.set_duration(5)

# Save the video
final_clip.write_videofile("image_and_slide_text.mp4", fps=24)


  


• ffmpeg : thumbnail of frame, preserve aspect ratio, apply background / padding / fill colour

  4 juin 2018, par Pistos

  I already have found out how to scale the thumbnail to stay within specified bounding dimensions while maintaining aspect ratio. For example, to get the frame shown at 6 seconds into the input.mp4 video file, and scale it to fit into 96x60 (16:10 aspect ratio) :

  ffmpeg -y -i input.mp4 -ss 6 -vframes 1 -vf scale="'if(gt(a,16/10),96,-1)':'if(gt(a,16/10),-1,60)'" output.png

  This is fine, it works.

  Next, I would like to do the same, but if the video’s aspect ratio is not exactly 16:10, then I would like to force the output image to have an aspect ratio of 16:10 by taking the above transformation, and filling or padding the space with white. That is, I want the output to be as if I took, say, a 96x48 image, and laid it over a 96x60 white background, resulting in white bars above and below the 96x48 image.

  Ideally, I do not want to resort to using another tool or library, such as ImageMagick. It would be best if ffmpeg could do this on its own.