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• Using ffmpeg with Python3 subprocess to convert multiple PNGs to a video

  17 décembre 2016, par ylnor

  I am using Python3, subprocess and ffmpeg to convert multiple PNG images into a single video.

  I have 400 PNG numbered as "00001.png".

  This call for one single specific image to a a one-frame-video works :

  subprocess.call(["ffmpeg","-y","-r","24","-i", "00300.png","-vcodec","mpeg4", "-qscale","5", "-r", "24", "video.mp4"])

  However, when I try some methods seen online for calling all of my images formated as "#####.png" using "%05d.png" as below, it does not work anymore :

  subprocess.call(["ffmpeg","-y","-r","24","-i", "%05d.png","-vcodec","mpeg4", "-qscale","5", "-r", "24", "video.mp4"])

  I receive the error : "%05d.png: No such file or directory".

  I have the feelling that the above syntax is proper to Python2 and not working on my python3 but can’t find the correct python3 syntax anywhere.

  Thanks in advance for your help

• checkasm : Add vc1dsp inverse transform tests

  31 mars 2022, par Ben Avison

  checkasm : Add vc1dsp inverse transform tests
  This test deliberately doesn't exercise the full range of inputs described in
  
  the committee draft VC-1 standard. It says :
  input coefficients in frequency domain, D, satisfy   -2048 <= D < 2047
  
  intermediate coefficients, E, satisfy                -4096 <= E < 4095
  
  fully inverse-transformed coefficients, R, satisfy    -512 <= R <  511
  For one thing, the inequalities look odd. Did they mean them to go the
  
  other way round ? That would make more sense because the equations generally
  
  both add and subtract coefficients multiplied by constants, including powers
  
  of 2. Requiring the most-negative values to be valid extends the number of
  
  bits to represent the intermediate values just for the sake of that one case !
  For another thing, the extreme values don't look to occur in real streams -
  
  both in my experience and supported by the following comment in the AArch32
  
  decoder :
      tNhalf is half of the value of tN (as described in vc1_inv_trans_8x8_c).
  
      This is done because sometimes files have input that causes tN + tM to
  
      overflow. To avoid this overflow, we compute tNhalf, then compute
  
      tNhalf + tM (which doesn't overflow), and then we use vhadd to compute
  
      (tNhalf + (tNhalf + tM)) >> 1 which does not overflow because it is
  
      one instruction.
  My AArch64 decoder goes further than this. It calculates tNhalf and tM
  
  then does an SRA (essentially a fused halve and add) to compute
  
  (tN + tM) >> 1 without ever having to hold (tNhalf + tM) in a 16-bit element
  
  without overflowing. It only encounters difficulties if either tNhalf or
  
  tM overflow in isolation.
  I haven't had sight of the final standard, so it's possible that these
  
  issues were dealt with during finalisation, which could explain the lack
  
  of usage of extreme inputs in real streams. Or a preponderance of decoders
  
  that only support 16-bit intermediate values in their inverse transforms
  
  might have caused encoders to steer clear of such cases.
  I have effectively followed this approach in the test, and limited the
  
  scale of the coefficients sufficient that both the existing AArch32 decoder
  
  and my new AArch64 decoder both pass.
  Signed-off-by : Ben Avison <bavison@riscosopen.org>
  
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] tests/checkasm/vc1dsp.c

• Seeking CLI Tool for Creating Text Animations with Easing Curves [closed]

  15 novembre 2023, par anonymous-dev

  I'm working on a video project where I need to animate text using various easing curves for smooth and dynamic transitions with the terminal. Specifically, I'm looking to apply the following easing curves to text animations :

  


  bounceIn
bounceInOut
bounceOut
decelerate
ease
easeIn
easeInBack
easeInCirc
easeInCubic
easeInExpo
easeInOut
easeInOutBack
easeInOutCirc
easeInOutCubic
easeInOutCubicEmphasized
easeInOutExpo
easeInOutQuad
easeInOutQuart
easeInOutQuint
easeInOutSine
easeInQuad
easeInQuart
easeInQuint
easeInSine
easeInToLinear
easeOut
easeOutBack
easeOutCirc
easeOutCubic
easeOutExpo
easeOutQuad
easeOutQuart
easeOutQuint
easeOutSine
elasticIn
elasticInOut
elasticOut
fastEaseInToSlowEaseOut
fastLinearToSlowEaseIn
fastOutSlowIn
linearToEaseOut
slowMiddle


  


  My initial thought was to use ffmpeg for this task, however, it appears that ffmpeg may not support these advanced easing curves for text animation.

  


  I am seeking recommendations for a command-line interface (CLI) tool that can handle these types of animations.

  


  Key requirements include :

  


  

  • Easing Curve Support : The tool should support a wide range of easing curves as listed above.

  


  • Efficiency : Ability to render animations quickly, preferably with performance close to what I can achieve with ffmpeg filters.

  


  • Direct Rendering : Ideally, the tool should render animations in one go, without the need to write each individual frame to disk.

  


  • Should work with transformations such as translate, scale and rotate. For example a text translates from a to b with a basing curve applied to the transition.

  


  


  I looked into ImageMagick, but it seems more suited for frame-by-frame image processing, which is not efficient for my needs.

  


  Could anyone suggest a CLI tool that fits these criteria ? Or is there a way to extend ffmpeg's capabilities to achieve these animations ?