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• Input FFMPEG subprocess to FFMPEG RTMP stream in python ?

  12 mai 2021, par Guiso

  I managed to stream frames of a video to the RTMP server but I also want to stream the audio - for that I can't use the rawvideo format and now I don't know how many bytes are required for the ffmpeg video to send to the ffmpeg stream.

  


  If there is an easier way to do this I would much prefer it, I tried my best in making comments so that the code is understandable.

  


  WIDTH = 1152
HEIGHT = 720
RTMP = ""
#Returns frame of a video
def read_frame(process1, width, height):
    frame_size = width * height * 3 #<--- I don't know how many bytes should I ask for.
    in_bytes = process1.stdout.read(frame_size)
    if len(in_bytes) == 0:
        return []
    else:
        assert len(in_bytes) == frame_size
        frame = (
            np
            .frombuffer(in_bytes, np.uint8)
            .reshape([height, width, 3])
        )
    return frame


def getVideoOutput(in_filename):
    args = (
        ffmpeg
        .input(in_filename # Path to file
        ,loglevel="quiet"#Don't show ffmpegs logs
        )
        .output('pipe:', format='flv')#Outputs a pipe
        .compile()
    )
    return subprocess.Popen(args, stdout=subprocess.PIPE)

#Start stream
def startStream(width, height):
    args = (
        ffmpeg
        .input('pipe:', #Sats to ffmpeg that the input is a stream
        format='flv'#Format of the video
        ,r="30"#Sets average fps
        ,s='{}x{}'.format(width, height)#Set the width and height of the input
        ,loglevel="quiet" #Don't show ffmpegs logs 
        )
        .output(RTMP,vcodec="libx264",preset="ultrafast",acodec="aac",format="flv")
        .overwrite_output()
        .compile()
    )
    return subprocess.Popen(args, stdin=subprocess.PIPE)

#Writes frame to the stream
def write_frame(process2, frame):
    process2.stdin.write(
        frame
        .astype(np.uint8)
        .tobytes()
    )

#Gets frames from multiple videos
def getBytes():
    for video in os.listdir(".\\Videos"):#Loops through videos in the videos folder 
    #while True:
        #video = os.listdir(".\\Videos")[0]
        videoPath = os.path.join(pathlib.Path().absolute(),"Videos",video)
        pipe = getVideoOutput(videoPath) #Get a stream of bytes from the video
        while True:
            frame = read_frame(pipe,WIDTH,HEIGHT)#Get a frame
            if frame == []:#If the video ends Go to the next one
                break
            yield frame#return the frame


stream = startStream(WIDTH,HEIGHT)#Starts stream to server and outputs a subprocess
FrameGenerator = getBytes()#Start generator

while True:
    write_frame(stream,next(FrameGenerator))#infinite loop writes to the stream a frame


  


• Getting error "WebAssembly.Memory() : could not allocate memory" when running ffmpeg.wasm on android chrome browser

  27 juin 2022, par Ravi Kundu

  Error in detail :

  


  WebAssembly.Memory(): could not allocate memory
at https://*******/ffmpeg-core.js:22:82
at https://*******/ffmpeg.min.js:1:6506
at f (https://*******/ffmpeg.min.js:1:11322)
at Generator._invoke (https://*******/ffmpeg.min.js:1:11110)
at Generator.next (https://*******/ffmpeg.min.js:1:11747)
at i (https://*******/ffmpeg.min.js:1:4295)
at c (https://*******/ffmpeg.min.js:1:4498)


  


  Code for ffmpeg :

  


  const downloadWithFFMPEG = async () =>{
  const sourceBuffer = await fetch(recordingURL).then(r => r.arrayBuffer());
  await ffmpeg.load();
  await ffmpeg.FS(
    "writeFile",
    "input.webm",
    new Uint8Array(sourceBuffer, 0, sourceBuffer.byteLength)
  );
  await ffmpeg.run("-i", "input.webm", "-c", "copy", "output.mp4")
  const output = ffmpeg.FS("readFile", "output.mp4");
  var link = document.createElement('a')
  link.href = URL.createObjectURL(new Blob([output.buffer], { type: 'video/mp4;codecs=H264' }));
  link.download = this.data;
  link.click();
  recording = false;
}


  


  Brief about problem :
The error only comes for android chrome browser. The same code works fine on pc/laptop chrome.
Have also enabled Webassembly-thread on chrome ://flags for android browser as someone suggested me to do it but still same error. Can someone help me ?

  


• Rolling screen capture with ffmpeg on windows

  11 décembre 2020, par gap210

  I have the following code to capture a video stream from my webcam. I use ffmpeg to write to named windows pipe, then read it with python and display with opencv. The thing is that the opencv stream is 'rolling' as shown here https://www.youtube.com/watch?v=H78TRo3DZIo

  


  If I capture the output to a video instead of a pipe, with the command :

  


  ffmpeg -f dshow -video_size 1920x1080 -framerate 60 -i video="USB Video" -c:v copy out.avi

  


  everything looks fine. What should I change to achieve the desired effect ? (non-rolling stream)

  


  My code below :

  


  import cv2
import time
import subprocess
import numpy as np

w, h = 800, 600

# Get frame generator
gen = ffmpegGrab()

# Get start time
start = time.time()

# Read video frames from ffmpeg in loop
nFrames = 0
cmd = 'C:/Users/......./Downloads/ffmpeg-4.3.1-2020-11-19-full_build/bin/ffmpeg.exe -f dshow -framerate 60 -video_size 800x600 -i video="USB Video" -pix_fmt bgr24 -vcodec rawvideo -f image2pipe -'

proc = subprocess.Popen(cmd, stdout=subprocess.PIPE, stderr=subprocess.STDOUT, shell=True, bufsize=10**9)
while True:
    # Read next frame from ffmpeg

    frame = proc.stdout.read(w * h * 3)
    frame = np.frombuffer(frame, dtype=np.uint8).reshape((h, w, 3))
    cv2.imshow('screenshot', frame)

    if cv2.waitKey(1) == ord("q"):
        break

    fps = nFrames / (time.time() - start)
    print(f'FPS: {fps}')

cv2.destroyAllWindows()