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• lavfi/dnn : Async Support for TensorFlow Backend

  8 août 2021, par Shubhanshu Saxena

  lavfi/dnn : Async Support for TensorFlow Backend
  This commit enables async execution in the TensorFlow backend
  
  and adds function to flush extra frames.
  The async execution mechanism executes the TFInferRequests on
  
  a separate thread which is joined before the next execution of
  
  same TFRequestItem/while freeing the model.
  The following is the comparison of this mechanism with the existing
  
  sync mechanism on TensorFlow C API 2.5 CPU variant.
  Async Mode : 4m32.846s
  
  Sync Mode : 5m17.582s
  The above was performed on super resolution filter using SRCNN model.
  Signed-off-by : Shubhanshu Saxena <shubhanshu.e01@gmail.com>
  

  • [DH] libavfilter/dnn/dnn_backend_tf.c
  • [DH] libavfilter/dnn/dnn_backend_tf.h
  • [DH] libavfilter/dnn/dnn_interface.c

• Python video player using ffpyplayer.player with audio repeated cracking at end of clip

  18 janvier 2021, par sunyaer

  I am using the codes below to do a video player. For video clips cut using this command : "ffmpeg -i PrideAndPrejudice.mp4 -ss 00:50:31 -t 00:03:30 OutPutPP.mp4", there is audio crack that keeps repeating a couple of times when the picture stops at the end of the video. I suspect there may be some issues with the codes of QTimer, but as I am quite new to Python and ffmpeg, and can't figure out what exactly the problem is, not to mention how to fix it. Your help would be greatly appreciated.

  


      self.timer = QTimer()
    self.timer.setInterval(50)
    self.timer.start()
    self.timer.timeout.connect(self.showFrame)


  


  This is the whole codes :

  


   from ffpyplayer.player import MediaPlayer
 import sys
 from PyQt5.QtWidgets import *
 from PyQt5.QtGui import QPixmap, QImage, QImageReader
 from PyQt5.QtCore import QTimer

class MyApp(QWidget):
    def __init__(self, name, parent=None):
        super(MyApp, self).__init__(parent)
        self.label = QLabel()
        self.qimg = QImage()
        self.val = ''

        self.player = MediaPlayer("PrideAndPrejudice005030.mp4")
        self.timer = QTimer()
        self.timer.setInterval(50)
        self.timer.start()
        self.timer.timeout.connect(self.showFrame)

        layout = QVBoxLayout()
        layout.addWidget(self.label)
        self.setLayout(layout)
        self.setWindowTitle(name)

        # self.showFullScreen()

    def showFrame(self):
        frame, self.val = self.player.get_frame()
        if frame is not None:
            img, t = frame
            self.qimg = QImage(bytes(img.to_bytearray()[0]), img.get_size()[0], img.get_size()[1],
                               QImage.Format_RGB888)
            self.label.setPixmap(QPixmap.fromImage(self.qimg))


if __name__ == '__main__':
    app = QApplication(sys.argv)
    t = MyApp(sys.argv[0])
    t.show()
    sys.exit(app.exec_())


  


• FFMpeg transcoding for realtime videochat via UDP

  4 septembre 2018, par Lloyd Corfex

  My problem is that I can’t find settings matching my needs.
  I know there is a tradeoff between : Speed, Quality and Size.

  (I am using a wrapper, so I can’t tell you the exact ffmpeg string but it should be comprehensible.)

  Input is always a raw video (bitmaps provided by webcam).

  CustomInputArgs = string.Format(" -pix_fmt bgr24 -video_size {0}x{1}", bitmapSize.Width, bitmapSize.Height),
  
  CustomOutputArgs = string.Format(" -vf scale=-1:{0} -maxrate 3000k -bufsize 4500k -preset ultrafast -tune zerolatency -movflags faststart", scale)

  Format : H.264

  • Speed -> ok
  • Size -> ok
  • Quality -> Not okay - Result gets "blocky" / "pixelchaos"

  
  [https://www.pic-upload.de/view-35890878/HalloPixel.jpg.html
  ]

  Format : H.265 and AVI

  • Speed -> Way too slow

  Format : FLV

  • Results in only a black screen (even if i set one of the following to the encoder)
    [https://stackoverflow.com/a/12290903/10144526]

    CustomOutputArgs = " -pix_fmt yuv420p"

    CustomOutputArgs = " -pix_fmt yuyv422"

  • As long as i have any string in the encoder outputArgs i get the following error in ffmpeg : [flv @ 03c27e40] Packet mismatch 1239459658 55255 55450

  Format MJPEG

  • Quality -> Super
  • Speed -> Ok
  • Size -> Gigantic

  Format M4V

  • Quality -> Not good
  • Speed -> Ok
  • Size -> Ok

  Format MP4

  • Conversion failed

  Does anyone has an idea about good settings ? Or can advice me in a good direction ?