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• Merge commit ’bddd8cbf68551f6405b2bf77cc3e212af9fbe834’

  19 mai 2014, par Michael Niedermayer

  Merge commit ’bddd8cbf68551f6405b2bf77cc3e212af9fbe834’
  * commit ’bddd8cbf68551f6405b2bf77cc3e212af9fbe834’ :
  
    Add transformation matrix API.
  Conflicts :
  
  	libavcodec/avcodec.h
  
  	libavcodec/utils.c
  
  	libavutil/version.h
  Merged-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] Changelog
  • [DH] doc/APIchanges
  • [DH] libavcodec/avcodec.h
  • [DH] libavcodec/utils.c
  • [DH] libavutil/Makefile
  • [DH] libavutil/display.c
  • [DH] libavutil/display.h
  • [DH] libavutil/frame.h
  • [DH] libavutil/version.h

• Python stream H.264 data over socket

  9 janvier 2017, par Ezra Knobloch

  I am creating a H.264 encoded stream on my Raspberry using the tool ’raspivid’ and sending that stream to stdout.
  What i want is sending that stream to another computer and feed it to ffmpeg which in turn feeds it to MPlayer.

  When i do this using netcat and pipes it does work really good, i have a clean stream without any graphic bugs.

  I try to get the raspivid stdout over the subprocess module, see code below. Im more or less sure the problem lies somewhere there cause i did something similar a while back and it worked without many problems, and the only thing i did different now is using subprocess.

  My question is : does someone see what causes my problems ?

  Some Notes :

  • Using streamObj.get_data(pcktSize) did never work until now (MPlayer and ffmpeg cant open the stream)

  • process.stdout.readline() seems to be a bit faster than just read()

  • this code seems to be slower than just piping and netcat, how would i make it faster ? (while still using python)

  i need to write this sentence cause the code formatting below would be corrupted if i would not.

  import subprocess, socket, sys, time
  
  from thread import start_new_thread
  
  
  
  class streamObject:
  
      def __init__(self):
  
          global data
  
          data = ""
  
  
  
      def start_stream(self, rot, t, w, h, fps):
  
          global data
  
  
  
          process = subprocess.Popen(['/usr/bin/raspivid', '-rot', str(rot), '-t', str(t), '-w', str(w), '-h', str(h), '-fps', str(fps), '-o', '-'], stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
  
  
  
          nodata_counter = 0
  
  
  
          while 1:
  
              if process.poll() is None:
  
                  data += process.stdout.readline()
  
                  #data += process.stdout.read(256)
  
  
  
                  sys.stdout.write("buffered %i bytes.     \r" % len(data))
  
                  sys.stdout.flush()
  
              elif nodata_counter < 200:
  
                  nodata_counter += 1
  
  
  
                  time.sleep(0.1)
  
              else:
  
                  break
  
  
  
      def get_alldata(self):
  
          global data
  
  
  
          return data
  
  
  
      def get_data(self, data_len):
  
          global data
  
  
  
          if len(data) > data_len:
  
              temp = data[0:data_len]
  
              data = data[data_len:len(data)]
  
  
  
              return temp
  
          else:
  
              return None
  
  
  
      def clear_cache(self):
  
          global data
  
  
  
          data = ""
  
  
  
      def poll(self):
  
          global data
  
  
  
          try:
  
              if len(data) != 0:
  
                  return None
  
              else:
  
                  return 0
  
          except:
  
              return 0
  
  
  
  def socket_connect(ip, port):
  
      s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  
      s.connect((ip, port))
  
  
  
      return s
  
  
  
  def socket_listen(ip, port):
  
      s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
  
      s.bind((ip, port))
  
      s.listen(1)
  
  
  
      conn, addr = s.accept()
  
  
  
      return conn
  
  
  
  def socket_close(sock):
  
      sock.close()
  
  
  
  def send_stream(sock, streamObj, pcktSize):
  
      timeout = 0
  
  
  
      while 1:
  
          if streamObj.poll() is None:
  
              #data = streamObj.get_data(pcktSize)
  
  
  
              data = streamObj.get_alldata()
  
              streamObj.clear_cache()
  
  
  
              if data is not None:
  
                  sock.send(data)
  
          elif timeout < 200:
  
              timeout += 1
  
  
  
              time.sleep(0.1)
  
          else:
  
              break
  
  
  
  stream = streamObject()
  
  
  
  start_new_thread(stream.start_stream, (180, 0, 1280, 720, 20))
  
  
  
  sock = socket_connect("xxxx.xxxx.xxxx.xxxx", 7777)
  
  
  
  send_stream(sock, stream, 256)

  Here is a short video of the graphic bugs i encounter.

  I am doing this over a direct ethernet connection at this time.

• FFmpeg concat video and audio out of sync

  16 septembre 2016, par Xeoncross

  Joining multiple files using ffmpeg concat seems to result in a mismatch of the timestamps or offsets for the audio. I’ve tried with several videos and noticed the same problem for h.264 / MP4.

  Using concat and encoding the video seems to work fine. The audio stays in sync as ffmpeg does the full conversion calculations and seems to get everything right.

  However, simply concatenating the videos without any transformation or encoding results in a slowly increasing sync issue. Obviously, encoding the videos rather than simply joining them will result in a loss of information/quality so I would rather find a way around this problem.

  I’ve tried several flags to sort out this problem that appears to be based on the timestamps. None of these seem to correct the problem though.

  ffmpeg -f concat -fflags +genpts -async 1 -i segments.txt test.mov
  
  ffmpeg -auto_convert 1 -f concat -fflags +genpts -async 1 -i segments.txt -c copy test2.mov
  
  ffmpeg -f concat -i segments.txt -c copy -fflags +genpts test3.mp4
  
  ffmpeg -f concat -fflags +genpts -async 1 -i segments.txt -copyts test4.mov
  
  ffmpeg -f concat -i segments.txt -copyts test5.mov
  
  ffmpeg -f concat -i segments.txt -copyts -c copy test6.mov
  
  ffmpeg -f concat -fflags +genpts -i segments.txt -copyts -c copy test7.mov

  Note : all other questions that I could find on SO seem to "fix" the problem by simply encoding the videos over again. Not a good solution.

  Update

  I realized the concat wasn’t the problem. The original set of clips had mis-matched timestamps. Somehow concat + encoding fixed the issue, but I don’t want to re-encode the videos and loose quality each time.

  ffmpeg -y -ss 00:00:02.750 -i input.MOV -c copy -t 00:00:05.880 output.MOV

  Which resulted in the following data

  ffprobe -v quiet -show_entries stream=start_time,duration output.MOV
  
  
  
  start_time=-0.247500
  
  duration=6.131125
  
  start_time=-0.257333
  
  duration=6.155333

  Since then I’ve tried to use -tom and -t in different places along with -af apad -c:v copy and I’ve still failed to get the duration to be the same.

  Here is the full ffprobe output

  Here is the original (red) vs the segment (green)

  Detailed Sample Files

  I recorded a sample video, added the commands to chop it up, then concat it. http://davidpennington.me/share/audio_sync_test_video.zip