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• using ffmpeg/ffprobe to create a waveform json using php

  7 mai 2022, par edwardsmarkf

  I have many ogg & opus files on my server and need to generate json-waveform numeric arrays on an as-needed basis (example below).

  



  recently i discovered the node based waveform-util which uses ffmpeg/ffprobe for rendering a JSON waveform and it works perfectly. i am undecided if having a node process constantly running is the optimum solution to my issue.

  



  since ffmpeg seems to be able to handle anything i can throw at it, i wish to stick with an ffmpeg solution.

  



  i have three questions :

  



  1) is there a php equivalent ? i have found a couple that generate PNG images but not one that generates JSON-waveform numeric arrays

  



  2) are there any significant advantages of going with the node-based solution rather than a php based solution (assuming there is a php based solution) ?

  



  3) is there a way using CLI ffmpeg/ffprobe to generate a json-waveform ? i saw all the -show_ options (-show_data, -show_streams, -show_frames) but nothing looked like it produced what i am looking for.

  



  the json-waveform needs to be in this format :

  



  [ 0.0002, 0.001, 0.15, 0.14, 0.356 .... ]

  



  thank you all.

  


• avcodec/libsvtav1 : give svtav1-params priority over avctx values

  27 mars 2022, par James Almer

  avcodec/libsvtav1 : give svtav1-params priority over avctx values
  If the svt equivalent option to an avctx AVOption is passed by the user
  
  then it should have priority. The exception are fields like dimensions, bitdepth
  
  and pixel format, which must match what lavc will feed the encoder after init.
  This addresses libsvt-av1 issue #1858.
  Signed-off-by : James Almer <jamrial@gmail.com>
  

  • [DH] libavcodec/libsvtav1.c

• Obtaining frames from IP Camera with low latency

  5 février 2023, par Russ1337

  I am currently using this command to get frames from my RTSP stream and reading frames from stdout :

  


  ffmpeg -nostdin -rtsp_transport tcp -i  -pix_fmt bgr24 -an -vcodec rawvideo -f rawvideo -


  


  However, I would like to get the same latency as when I see it via ffplay :

  


  ffplay -fflags nobuffer -flags low_delay -tune zerolatency -framedrop -rtsp_transport tcp 


  


  or when I play it via VLC Media > Open Network Stream with :network_caching=300ms.

  


  I would like to know what other parameters I can use with my ffmpeg command to get an equivalent (or better) result compared to the ffplay command.

  


  I have made references from : How to dump raw RTSP stream to file ?, Open CV RTSP camera buffer lag, How to pipe output from ffmpeg using python ?, bad ffmpeg performace compared to ffplay and VLC, How to minimize the delay in a live streaming with ffmpeg

  


  My current implmentation :

  


  FFMPEG_CMD = "ffmpeg -nostdin -rtsp_transport tcp -i  -pix_fmt bgr24 -an -vcodec rawvideo -f rawvideo -".split(" ")&#xA;WIDTH = 2560&#xA;HEIGHT = 1440&#xA;&#xA;process = subprocess.Popen(FFMPEG_CMD, stdout=subprocess.PIPE, stderr=subprocess.DEVNULL)&#xA;&#xA;while True:&#xA;    raw_frame = process.stdout.read(WIDTH*HEIGHT*3)&#xA;    frame = np.frombuffer(raw_frame, np.uint8) &#xA;    frame = frame.reshape((HEIGHT, WIDTH, 3))&#xA;&#xA;    <do stuff="stuff" with="with" frame="frame"></do> show frame etc.>&#xA;

  


  Thanks for reading.

  


  ---

  


  ffmpeg command I am now using for < 1s latency.

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  ffmpeg -nostdin -flags low_delay -rtsp_transport tcp -i  -pix_fmt bgr24 -an -vcodec rawvideo -f rawvideo -


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  ---

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  Implementation with suggestion(s) from Answers :

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  import subprocess&#xA;import numpy as np&#xA;&#xA;FFMPEG_CMD = "ffmpeg -nostdin -flags low_delay -rtsp_transport tcp -i  -pix_fmt bgr24 -an -vcodec rawvideo -f rawvideo -".split(" ")&#xA;WIDTH = 2560&#xA;HEIGHT = 1440&#xA;&#xA;process = subprocess.Popen(FFMPEG_CMD, stdout=subprocess.PIPE, stderr=subprocess.DEVNULL)&#xA;&#xA;raw_frame = np.empty((HEIGHT, WIDTH, 3), np.uint8) &#xA;frame_bytes = memoryview(raw_frame).cast("B")&#xA;&#xA;while process.poll() is None:&#xA;    process.stdout.readinto(frame_bytes)&#xA;    frame = raw_frame.reshape((HEIGHT, WIDTH, 3))&#xA;&#xA;    <do stuff="stuff" with="with" frame="frame"></do> show frame etc.>&#xA;

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