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• How Many Default Languages ?

  26 janvier 2012, par Multimedia Mike — Programming

  I was thinking back to my childhood, when my family first owned a computer. It was an MS-DOS-powered IBM PC. The default OS came with 2 programming environments, such as they were : GW-BASIC and batch files. It was a start, I suppose. I guess most any microcomputer you can name from that era came with some kind of BASIC interpreter. That defined the computer’s “out of the box” programmability.

  Then I started wondering how this compares to computers (operating systems/distributions, really) these days. So I installed a fresh version of the latest Ubuntu Linux version (11.10 as of this writing ; x86_32) and looked for programmability (without installing anything else). This is what I came up with :

  1. gcc/C (only the C compiler ; other components of the GNU compiler collection are installed separately)
  2. Perl
  3. Python
  4. C#, as furnished by Mono
  5. Bash — can’t forget about the shell as a full-featured programming language (sh is also present, but not t/csh)
  6. JavaScript — since Firefox is installed per default, JS counts
  7. GNU Assember — thanks to Reimar for the reminder that if gcc is present, gas necessarily needs to be there as well

  I checked on C++, Objective C, Java, Ada, Fortran, Go, Lua, Ruby, Tcl, PHP, R and other languages I could think of, but the above items were the only ones present by default. At the same time, I checked my Mac OS X (10.6) box and it also has Ruby and PHP installed. It has a bunch of other languages, courtesy of Xcode, so I can’t certify anything about its out of the box programmability.

  Still, I think “embarrassment of riches” pretty well sums it up. I try not to be crotchety old fogey complaining that kids these days don’t know how good they have it ; rather, I’m genuinely excited for anyone who wants to leap into computer programming in this day and age.

• FFmpeg streaming UDP

  2 octobre 2020, par xKedar

  I'm trying to stream, using FFmpeg, my webcam and audio to a PC in another LAN that connects to mine.

  


  I basically wait for incoming connection in order to acquire IP and port of the other side

  


      import socket

    localPort   = 1234
    bufferSize  = 1024

    UDPServerSocket = socket.socket(family=socket.AF_INET, type=socket.SOCK_DGRAM)
    UDPServerSocket.bind(("", localPort)) # Bind to address and port

    while(True):
        bytesAddressPair = UDPServerSocket.recvfrom(bufferSize)
        message = bytesAddressPair[0].decode("utf-8")
        address = bytesAddressPair[1]
        # Sending a reply to client
        UDPServerSocket.sendto(str.encode("Hello"), address)
        break

    UDPServerSocket.close()


  


  Then I try to send the stream with FFmpeg using the same port number both for server(localPort) and client(the one I acquired from address)

  


      import re
    from threading import Thread
    from subprocess import Popen, PIPE

    def detect_devices():
            list_cmd = 'ffmpeg -list_devices true -f dshow -i dummy'.split()
            p = Popen(list_cmd, stderr=PIPE)
            flagcam = flagmic = False
            for line in iter(p.stderr.readline,''):
                if flagcam:
                    cam = re.search('".*"',line.decode(encoding='UTF-8')).group(0)
                    cam = cam if cam else ''
                    flagcam = False
                if flagmic:
                    mic = re.search('".*"',line.decode(encoding='UTF-8')).group(0)
                    mic = mic if mic else ''
                    flagmic = False
                elif 'DirectShow video devices'.encode(encoding='UTF-8') in line:
                    flagcam = True
                elif 'DirectShow audio devices'.encode(encoding='UTF-8') in line:
                    flagmic = True
                elif 'Immediate exit requested'.encode(encoding='UTF-8') in line:
                    break
            return cam, mic   


    class ffmpegThread (Thread):
        def __init__(self, address):
            Thread.__init__(self)
            self.address = address

        def run(self):
            cam, mic = detect_devices()
            command = 'ffmpeg -f dshow -i video='+cam+':audio='+mic+' -profile:v high -pix_fmt yuvj420p -level:v 4.1 -preset ultrafast -tune zerolatency -vcodec libx264 -r 10 -b:v 512k -s 240x160 -acodec aac -ac 2 -ab 32k -ar 44100 -f mpegts -flush_packets 0 -t 40 udp://'+self.address+'?pkt_size=1316?localport='+str(localPort)
            p = Popen(command , stderr=PIPE)
            for line in iter(p.stderr.readline,''):
                if len(line) <5: break
            p.terminate()

    thread1 = ffmpegThread(address[0]+":"+str(address[1]))
    thread1.start()


  


  While on the other side I have :

  


      from threading import Thread
    import tkinter as tk
    import vlc

    class myframe(tk.Frame):
        def __init__(self, width=240, height=160):
            self.root = tk.Tk()
            super(myframe, self).__init__(self.root)
            self.root.geometry("%dx%d" % (width, height))
            self.root.wm_attributes("-topmost", 1)
            self.grid()
            self.frame = tk.Frame(self, width=240, height=160)
            self.frame.configure(bg="black")
            self.frame.grid(row=0, column=0, columnspan=2)
            self.play()
            self.root.mainloop()

        def play(self):
            self.player = vlc.Instance().media_player_new()
            self.player.set_mrl('udp://@0.0.0.0:5000')
            self.player.set_hwnd(self.frame.winfo_id())
            self.player.play()

    class guiThread (Thread):
        def __init__(self, nome):
            Thread.__init__(self)
            self.nome = nome

        def run(self):
            app = myframe()


  


  and :

  


      import socket

    msgFromClient       = "Hello UDP Server"
    bytesToSend         = str.encode(msgFromClient)
    serverAddressPort   = ("MYglobal_IPaddress", 1234)
    bufferSize          = 1024
    localPort   = 5000

    # Create a UDP socket at client side
    UDPClientSocket = socket.socket(family=socket.AF_INET, type=socket.SOCK_DGRAM) 
    UDPClientSocket.bind(("", localPort))

    UDPClientSocket.sendto(bytesToSend, serverAddressPort)

    msgFromServer = UDPClientSocket.recvfrom(bufferSize)
    msg = msgFromServer[0].decode("utf-8")
    print(msg)
    UDPClientSocket.close()
    gui = guiThread("ThreadGUI")
    gui.start()


  


  I'm not able to reach the client with the stream. I tested everything else so the problem should be in the way I try to reach the client

  


• fftools/ffmpeg_filter : simplify choose_pix_fmts

  25 octobre 2023, par Niklas Haas

  fftools/ffmpeg_filter : simplify choose_pix_fmts
  The only meaningful difference between choose_pix_fmts and the default
  
  code was the inclusion of an extra branch for `keep_pix_fmt` being true.
  However, in this case, we either :
  
  1. Force the specific `ofp->format` that we inherited from
  
     ofilter_bind_ost, or if no format was set :
  
  2. Print an empty format list
  Both of these goals can be accomplished by simply moving the decision
  
  logic to ofilter_bind_ost, to avoid setting any format list when
  
  keep_pix_fmt is enabled. This is arguably cleaner as it moves format
  
  selection logic to a single function. In the case of branch 1, nothing
  
  else needs to be done as we already force the format provided in
  
  ofp->format, if any is set. Add an assertion to verify this assumption
  
  just in case.
  (Side note : The "choose_*" family of functions are arguably misnomers,
  
  as they should really be called "print_*" - their current behavior is to
  
  print the relevant format lists to the `vf/af_format` filter arguments)
  Signed-off-by : Anton Khirnov <anton@khirnov.net>
  
  Signed-off-by : Niklas Haas <git@haasn.dev>
  

  • [DH] fftools/ffmpeg_filter.c