Sur d’autres sites (5939)

• How can I open a program using PYTHON with Mutliprocessing, and send it strings from the main process ?

  12 février 2018, par Just Askin

  I have a program that sends frames as strings to FFMPEG using something similar to :

  Working script that streams without using multiprocessing module currently on Ubuntu

  #!/usr/bin/python
  
  import sys, os
  
  import subprocess as sp
  
  import pygame
  
  from pygame.locals import QUIT, KEYUP, K_ESCAPE
  
  import pygame.display
  
  
  
  pygame.init()
  
  os.environ['SDL_VIDEODRIVER'] = 'dummy'
  
  pygame.display.init()
  
  Display_Surface = pygame.display.set_mode([1280,720], 0, 32)
  
  
  
  # FFMPEG command and settings
  
  command = ['ffmpeg', '-framerate', '25', '-s', '1280x720', '-pix_fmt', 'rgba', '-f', 'rawvideo', '-i', '-',
  
             '-f', 'lavfi', '-i', 'anullsrc=cl=mono',
  
             '-pix_fmt', 'yuv420p','-s', 'hd720', '-r', '25', '-g', '50',
  
             '-f', 'flv', 'rtmp://a.rtmp.youtube.com/live2/xxxx-xxxx-xxxx-xxxx']
  
  
  
  pipe = sp.Popen(command, bufsize=0, stdin=sp.PIPE)
  
  
  
  while True:
  
      # Quit event handling
  
      for event in pygame.event.get():
  
          if event.type == QUIT or (event.type == KEYUP and event.key == K_ESCAPE):
  
              pygame.quit()
  
              sys.exit()
  
  
  
      pipe.stdin.write(pygame.image.tostring(Display_Surface, "RGBA"))
  
  
  
  pipe.stdin.close()
  
  pygame.display.quit()
  
  os._exit()

  This works fine, except for the fact that it is killing my CPU, which in turn causes my live stream to freeze often. The stupid GIL won’t let FFMPEG run on another CPU/Core while I have 3 perfectly good cores doing nothing.

  I just whipped up some code to open FFMPEG in another process. (By the way, I’m familiar with threading.Thread, but not Multiprocessing).

  import os
  
  import subprocess as sp
  
  import multiprocessing
  
  
  
  class FFMPEG_Consumer():
  
  
  
      def __init__(self):
  
          proc = multiprocessing.Process(target=self.start_ffmpeg)
  
          proc.start()
  
  
  
      def start_ffmpeg(self):
  
          command = ['ffmpeg','-pix_fmt', 'rgba', '-f', 'rawvideo', '-i', '-',
  
                     '-f, 'lavfi', '-i', 'anullsrc=channel_layout=stereo:sample_rate=44100',
  
                     '-pix_fmt', 'yuv420p','-s', 'hd720', '-f', 'flv', 'rtmp://example.com']
  
  
  
          pipe = sp.Popen(command, bufsize=-1, stdin=sp.PIPE)
  
  
  
      def send_down_the_pipe(self, frame):
  
          pipe.stdin.write(frame)
  
  
  
  ffmpeg = FFMPEG_Consumer()

  For anyone that knows how to use multiprocessing, I’m sure you will immediately see that this does not work because I can’t share variables this way across processes. But, it does open FFMPEG on another core.

  Most online tutorials and resources focus creating pools of workers and queues to send those workers something to be processed until a job is finished. I am however trying to send a new string repeatedly to FFMPEG through each iteration.

  How can I pipe my string to that process/instance of FFMPEG ?

  Or is what I’m trying to do not possible ?

  This was the working solution (with dumbed down FFMPEG settings) :

  #!/usr/bin/python
  
  import sys, os, multiprocessing
  
  import subprocess as sp
  
  import pygame
  
  from pygame.locals import QUIT, KEYUP, K_ESCAPE
  
  import pygame.display
  
  
  
  pygame.init()
  
  os.environ['SDL_VIDEODRIVER'] = 'dummy'
  
  pygame.display.init()
  
  Display_Surface = pygame.display.set_mode([1280,720], 0, 32)
  
  
  
  class FFMPEGConsumer(object):
  
      def __init__(self):
  
          self._r, self._w = multiprocessing.Pipe()
  
          self.reader = os.fdopen(self._r.fileno(), 'r')
  
          self.writer = os.fdopen(self._w.fileno(), 'w', 0)
  
          self.proc = None
  
  
  
      def start_ffmpeg(self):
  
  
  
          command = ['ffmpeg', '-framerate', '25', '-s', '1280x720', '-pix_fmt', 'rgba', '-f', 'rawvideo', '-i', '-',
  
             '-f', 'lavfi', '-i', 'anullsrc=cl=mono',
  
             '-pix_fmt', 'yuv420p','-s', 'hd720', '-r', '25', '-g', '50',
  
             '-f', 'flv', 'rtmp://a.rtmp.youtube.com/live2/xxxx-xxxx-xxxx-xxxx']
  
  
  
          self.proc = sp.Popen(command, bufsize=-1, stdin=self.reader)
  
  
  
      def send_down_the_pipe(self, frame):
  
          self.writer.write(frame)
  
          #print self._stdin.read()
  
  
  
      def __del__(self):
  
          self.reader.close()
  
          self.writer.close()
  
  
  
  ffmpeg = FFMPEGConsumer()
  
  
  
  while True:
  
      # Quit event handling
  
      for event in pygame.event.get():
  
          if event.type == QUIT or (event.type == KEYUP and event.key == K_ESCAPE):
  
              pygame.quit()
  
              sys.exit()
  
  
  
      ffmpeg.send_down_the_pipe(pygame.image.tostring(Display_Surface, "RGBA"))
  
      proc.join()
  
  
  
  pipe.stdin.close()
  
  pygame.display.quit()
  
  os._exit()

  All cores are firing and no lags so far !!!

• Emscripten compiling multiple main functions

  20 février 2018, par AlexVestin

  I’ve been trying to compile FFmpeg using Emscripten to export to WebAssembly code. I’ve been using the ffmpeg.js Makefile here, with very slight modifications. The compilation works fine without any errors, and generates a ffmpeg.bc, however if I try to compile the file along with another C file containing a main function I get the error

  error: Linking globals named ´main´: symbol multiply defined!
ERROR:root:Failed to run llvm optimizations:

  The command I’m using is :

  ffmpeg-wasm.js: (FFMPEG_MP4_BC)
  
      emcc test.c $(FFMPEG_MP4_BC) $(MP4_SHARED_DEPS) $(EMCC_COMMON_ARGS)

  where

  EMCC_COMMON_ARGS = \
  
      -s TOTAL_MEMORY=67108864 \
  
      -s OUTLINING_LIMIT=20000 \
  
      -O3 --memory-init-file 0 \
  
      -o $@ \
  
      -s WASM=1 \
  
      -I/usr/local/include

  I have tried using a different snapshot of ffmpeg, which didn’t fix the problem.

  If I run

  llvm-nm $(find . -name *.so) > log.txt && grep -n ./log.txt -e "int main"

  to test if any of the dependencies contain a main, I get nothing, however there is a global main function in the generated ffmpeg.bc.

  So, is there any way to remove the main function from the library, or some flag to set to prevent a global main function from being generated ?

• avcodec/vc1 : add Simple and Main profile to vc1_put_signed_blocks_clamped

  6 juin 2018, par Jerome Borsboom

  avcodec/vc1 : add Simple and Main profile to vc1_put_signed_blocks_clamped
  Simple and Main profile also need unsigned put_pixels_clamped. Add an argument
  
  to choose between signed and unsigned put_pixels and change function name to
  
  vc1_put_blocks_clamped.
  Signed-off-by : Jerome Borsboom <jerome.borsboom@carpalis.nl>
  

  • [DH] libavcodec/vc1_block.c