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• Best ffmpeg options for creating TikTok-like app ? [closed]

  27 août 2022, par nickcoding

  My app is essentially vertical videos, so I'd like the videos to more or less be cropped to that dimension (especially in the case they are 'landscape mode' videos. In the below picture, if the video is that horizontal black rectangle, we should just crop the video to that dimension of the phone (the red vertical rectangle). I've tried messing around with aspect ratios, but can't seem to get it to work right (where the video is essentially cropped to the correct aspect ratio), but not necessarily hard-coding the dimensions (this would look bad on different size devices).

  


  I'm using this module : https://www.npmjs.com/package/fluent-ffmpeg

  


  How should I do this ?

  


  https://i.stack.imgur.com/bb8qR.png

  


  var ffmpeg = require('fluent-ffmpeg');

  ffmpeg('./original.mp4')
    .fps(25)
    .videoCodec('libx264')
    // here, I've tried .withAspectRatio('16:9') and playing around with .size(), but that seems to do nothing.
    .save('./new.mp4');


  


• ffmpeg how to add pcm codec tag to output

  27 septembre 2021, par Alex

  In Python script I want to convert bytes from ogg to wav without coping any data on hard disk. I do it in such a way :

  


  args = (
        ffmpeg
        .input('pipe:')
        .output('pipe:', format='s16le', acodec='pcm_s16le')
        .get_args()
       )
p = subprocess.Popen(['ffmpeg'] + args, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
wav = p.communicate(input=bindata)[0]


  


  it works, but produce result different from what ffmpeg -i sample.ogg sample.wav does. The difference can be found in ffmpeg's otput in Metadata section :

  


  ffmpeg -i sample.ogg sample.wav

  


  Metadata:
    ...
    Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, mono, s16, 768 kb/s
    ...


  


  Python

  


  Metadata:
    ...
    Stream #0:0: Audio: pcm_s16le, 48000 Hz, mono, s16, 768 kb/s
    ...


  


  So, I wonder, how to add this ([1][0][0][0] / 0x0001) tag to Python variant

  


• Opening video from file using OpenCV in Python

  7 septembre 2022, par Noise in the street

  I am trying to use OpenCV2 with my Conda environment for Python 2.7.

  



  My installation was basically the same as what was described in 
this question.

  



  I retrieved OpenCV like so :

  



  conda install --channel https://conda.anaconda.org/menpo opencv3


  



  I can import the library cv2 and print the version, which is 3.1.0. So far so good. I can even load an image and display it :

  



  import cv2

img = cv2.imread('desertfloor.jpg')
cv2.imshow('foo',img)
cv2.waitKey(0)
cv2.destroyAllWindows()


  



  This works just fine. But when I go to load a video in the same directory :

  



  vid = cv2.VideoCapture('bbb.avi') # Big Buck Bunny
returnval,frame = vid.read()
print returnval


  



  The returned value is False, which tells me that the frame wasn't returned correctly. When I check vid.isOpened(), it is False as well. Since it doesn't return an error, it's really hard to tell what's going on. I've heard that ffmpeg can cause some issues if it's not installed properly (whatever that means), but I can't tell if that's what's going on here.

  



  Can anyone tell me why the video isn't opening properly ?