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• How to build FFmpeg into static libs for MacOS for usage in a C++ application

  29 septembre 2017, par Programist

  How can I build static libs of FFmpeg for MacOS.

  All I need is to make a .mp4 with H264 codecs out of some images using ffmpeg. Dont need the build to be fully loaded with features.

  I built it for iOS using a script from here which was really simple and smooth. It checked out the code & smoothly built the output into include/ & lib/ folders.

  I checked the official FFmpeg site offers excutables for MacOS. But I need static libs to use in my C++ code.

  Question :
  I want to build FFmpeg into static libs for MacOS only for creating .mp4 videos. How can I do it OR
  How can I change this script to do the same for MacOS ?

  PS :
  I am Mac OS Sierra with Xcode9

• How to efficiently store variable frame rate video stream in a pyqt application ?

  1er octobre 2024, par Jeroen De Geeter

  I am developing a PyQT (PySide6) application that needs to display and store multiple camera streams at the same time. The display of the camera streams goes well, however, storing these streams seems to slow down the application significantly up to a point where the GUI doesn't work fluently anymore.

  


  I have a minimal working example using a stub to demonstrate how my code currently works. However, given that it is a minimal working example, it will not visibly slow down.

  


  import sys
from time import sleep

import av
import numpy as np
import pyqtgraph as pg
from PySide6.QtCore import QThread, Signal, Slot, Qt
from PySide6.QtWidgets import QApplication, QHBoxLayout, QWidget, QVBoxLayout, QPushButton, QGroupBox


class RGBCameraStub(QThread):

    newFrame = Signal(np.ndarray)

    def __init__(self):
        super().__init__()
        self.killSwitch = True

    def stop(self):
        self.killSwitch = False
        self.quit()
        self.wait()

    def run(self):
        self.killSwitch = True
        while self.killSwitch:
            self.newFrame.emit((np.random.rand(1456, 1080, 3) * 255).astype(np.uint8))
            sleep((20 + int(np.random.rand() * 30))/ 1000)


class VideoWriter(QThread):

    def __init__(self):
        super().__init__()
        self.output_container = av.open('output_video.mkv', mode='w')
        self.stream = self.output_container.add_stream('ffv1', rate=None)
        self.stream.width = 1456
        self.stream.height = 1080
        self.stream.pix_fmt = 'yuv420p'

    @Slot(np.ndarray)
    def addFrame(self, frame: np.ndarray):
        av_frame = av.VideoFrame.from_ndarray(frame, format='rgb24')
        av_frame.pts = None # Leave emtpy for auto-handling - variable framerate?
        for packet in self.stream.encode(av_frame):
            self.output_container.mux(packet)

    def stop(self):
        self.output_container.close()
        self.quit()
        self.wait()

    def run(self):
        self.exec()


class VideoBox(QGroupBox):

    def __init__(self, title):
        super().__init__(title=title)
        self.createLayout()
        self.videoWidget.setImage((np.random.rand(1456, 1080, 3) * 255).astype(np.uint8))

    def createLayout(self):
        layout = QVBoxLayout()
        self.videoWidget = pg.RawImageWidget()
        layout.addWidget(self.videoWidget)
        self.setLayout(layout)
        self.setStyleSheet("""QGroupBox {
            border: 1px solid #494B4F;
            margin-top: 8px;
            min-width: 180px;
            min-height: 180px;
            padding: 2px 0px 0px 0px;
            }
        QGroupBox::title {
            color: #aeb0b8;
            subcontrol-origin: margin;
            subcontrol-position: top left;
            left: 20px;
            padding: 0 8px;
        }""")

    def setImage(self, data: np.ndarray):
        self.videoWidget.setImage(data)

class MainWindow(QWidget):

    closeSignal = Signal()

    def __init__(self):
        super().__init__()
        self.setGeometry(0, 0, 900, 720)
        self.createLayout()

    def createLayout(self):
        self.vimbaImage = VideoBox("RGB")
        self.info = self.infoLayout()

        layout = QVBoxLayout()
        layout.addWidget(self.vimbaImage)
        layout.addWidget(self.info)
        self.setLayout(layout)

        self.setAttribute(Qt.WA_StyledBackground, True)
        self.setStyleSheet("MainWindow { background-color: #1e1f22; }")

    def infoLayout(self):
        widget = QWidget()
        layout = QVBoxLayout()

        rgbButtonWidget = QWidget()
        buttonLayout = QHBoxLayout()
        self.connectButton = QPushButton('Connect', parent=self)
        self.disconnectButton = QPushButton('Disconnect', parent=self)
        buttonLayout.addWidget(self.connectButton)
        buttonLayout.addWidget(self.disconnectButton)
        buttonLayout.addStretch()
        rgbButtonWidget.setLayout(buttonLayout)
        layout.addWidget(rgbButtonWidget)

        widget.setLayout(layout)
        return widget

    def closeEvent(self, event):
        self.closeSignal.emit()
        event.accept()



if __name__ == "__main__":
    app = QApplication(sys.argv)

    rgbCamera = RGBCameraStub()
    videoWriter = VideoWriter()
    videoWriter.start()

    main_window = MainWindow()

    # Button connections
    main_window.connectButton.clicked.connect(rgbCamera.start)
    main_window.disconnectButton.clicked.connect(rgbCamera.stop)
    # main_window.disconnectButton.clicked.connect(videoWriter.stop)

    # Display frames
    rgbCamera.newFrame.connect(main_window.vimbaImage.setImage)

    # Write frame to file
    rgbCamera.newFrame.connect(videoWriter.addFrame)

    # Close application
    main_window.closeSignal.connect(rgbCamera.stop)
    main_window.closeSignal.connect(videoWriter.stop)

    main_window.show()
    sys.exit(app.exec())



  


  My question(s) therefore are :

  


  

  • How can I increase the performance of the VideoWriter ? I am currently adding frame by frame as soon as the camera thread provides a new frame. Maybe this is not the best approach ?

  


  • The frame rate of the camera is not completely stable, I therefore set av_frame.pts = None but maybe this is also not the approach to take ?

  


  • With code as is, the resulting media file quickly blows up in size, is there a way of dealing with this without quality loss ?

  


  


  As a side not, I currently use the PyAV wrapper for the FFmpeg libraries, however I am open to other suggestions.

  


• Cannot link an application with libavcodec

  25 mars 2020, par Igor Evdokimov

  I’m trying to make a simplest app with usage of ffmpeg libs.
  Here is my code :

  main.c :

  #include <libavcodec></libavcodec>avcodec.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  #include <libswscale></libswscale>swscale.h>
  
  
  
  int main()
  
  {
  
  
  
      avformat_network_init();
  
      return 0;
  
  }

  compiler command :

  gcc -o main main.c -Wall  -lavformat -lavcodec -lswresample -lswscale -lavutil -lm -lz -lpthread -L/usr/local/lib/

  leads to :

  /usr/local/lib//libavformat.a(matroskaenc.o) : In function

  get_aac_sample_rates':
 /home/ievdokimov/repos/FFmpeg/libavformat/matroskaenc.c:709: undefined
 reference to

  avpriv_mpeg4audio_get_config2’
  /home/ievdokimov/repos/FFmpeg/libavformat/matroskaenc.c:709 : undefined
  reference to

  avpriv_mpeg4audio_get_config2'
 /usr/local/lib//libavformat.a(mux.o): In function
 

  ff_interleave_add_packet’ :
  /home/ievdokimov/repos/FFmpeg/libavformat/mux.c:936 : undefined
  reference to

  av_packet_make_refcounted'
 /usr/local/lib//libavformat.a(utils.o): In function
 

  ff_packet_list_put’ :
  /home/ievdokimov/repos/FFmpeg/libavformat/utils.c:461 : undefined
  reference to

  av_packet_make_refcounted'
 /usr/local/lib//libavformat.a(utils.o): In function

  parse_packet’ :
  /home/ievdokimov/repos/FFmpeg/libavformat/utils.c:1494 : undefined
  reference to

  av_packet_make_refcounted'
 /usr/local/lib//libavformat.a(utils.o): In function

  ff_read_packet’ :
  /home/ievdokimov/repos/FFmpeg/libavformat/utils.c:876 : undefined
  reference to

  av_packet_make_refcounted'
 /usr/local/lib//libavformat.a(codec2.o): In function
 

  codec2_read_header_common’ :
  /home/ievdokimov/repos/FFmpeg/libavformat/codec2.c:74 : undefined
  reference to

  avpriv_codec2_mode_bit_rate'
 /home/ievdokimov/repos/FFmpeg/libavformat/codec2.c:75: undefined
 reference to

  avpriv_codec2_mode_frame_size’
  /home/ievdokimov/repos/FFmpeg/libavformat/codec2.c:76 : undefined
  reference to

  avpriv_codec2_mode_block_align'
 /home/ievdokimov/repos/FFmpeg/libavformat/codec2.c:74: undefined
 reference to

  avpriv_codec2_mode_bit_rate’
  /home/ievdokimov/repos/FFmpeg/libavformat/codec2.c:75 : undefined
  reference to

  avpriv_codec2_mode_frame_size'
 /home/ievdokimov/repos/FFmpeg/libavformat/codec2.c:76: undefined
 reference to

  avpriv_codec2_mode_block_align’
  /usr/local/lib//libavformat.a(isom.o) : In function

  ff_mp4_read_dec_config_descr':
 /home/ievdokimov/repos/FFmpeg/libavformat/isom.c:552: undefined
 reference to

  avpriv_mpeg4audio_get_config2’
  /usr/local/lib//libavformat.a(latmenc.o) : In function

  latm_decode_extradata':
 /home/ievdokimov/repos/FFmpeg/libavformat/latmenc.c:65: undefined
 reference to

  avpriv_mpeg4audio_get_config2’
  /home/ievdokimov/repos/FFmpeg/libavformat/latmenc.c:65 : undefined
  reference to

  avpriv_mpeg4audio_get_config2'
 /usr/local/lib//libavformat.a(matroskadec.o): In function
 

  matroska_decode_buffer’ :
  /home/ievdokimov/repos/FFmpeg/libavformat/matroskadec.c:1657 :
  undefined reference to

  BZ2_bzDecompressInit'
 /home/ievdokimov/repos/FFmpeg/libavformat/matroskadec.c:1672:
 undefined reference to

  BZ2_bzDecompress’
  /home/ievdokimov/repos/FFmpeg/libavformat/matroskadec.c:1665 :
  undefined reference to

  BZ2_bzDecompressEnd'
 /home/ievdokimov/repos/FFmpeg/libavformat/matroskadec.c:1675:
 undefined reference to

  BZ2_bzDecompressEnd’
  /usr/local/lib//libavformat.a(mxfenc.o) : In function

  get_ue_golomb_31':
 /home/ievdokimov/repos/FFmpeg/./libavcodec/golomb.h:140: undefined
 reference to

  ff_ue_golomb_vlc_code’
  /usr/local/lib//libavformat.a(mxfenc.o) : In function

  mxf_parse_dnxhd_frame':
 /home/ievdokimov/repos/FFmpeg/libavformat/mxfenc.c:2030: undefined
 reference to

  avpriv_dnxhd_get_hr_frame_size’
  /usr/local/lib//libavformat.a(rtpenc_vc2hq.o) : In function

  init_get_bits_xe':
 /home/ievdokimov/repos/FFmpeg/./libavcodec/get_bits.h:628: undefined
 reference to

  ff_interleaved_golomb_vlc_len’
  /usr/local/lib//libavformat.a(rtpenc_vc2hq.o) : In function

  get_interleaved_ue_golomb':
 /home/ievdokimov/repos/FFmpeg/./libavcodec/golomb.h:197: undefined
 reference to

  ff_interleaved_dirac_golomb_vlc_code’
  /home/ievdokimov/repos/FFmpeg/./libavcodec/golomb.h:185 : undefined
  reference to

  ff_interleaved_dirac_golomb_vlc_code'
 /home/ievdokimov/repos/FFmpeg/./libavcodec/golomb.h:197: undefined
 reference to

  ff_interleaved_dirac_golomb_vlc_code’
  /home/ievdokimov/repos/FFmpeg/./libavcodec/golomb.h:197 : undefined
  reference to

  ff_interleaved_dirac_golomb_vlc_code'
 /home/ievdokimov/repos/FFmpeg/./libavcodec/golomb.h:185: undefined
 reference to

  ff_interleaved_dirac_golomb_vlc_code’
  /usr/local/lib//libavformat.a(rtpenc_vc2hq.o) :/home/ievdokimov/repos/FFmpeg/./libavcodec/golomb.h:185 :
  more undefined references to

  ff_interleaved_dirac_golomb_vlc_code'
 follow /usr/local/lib//libavformat.a(rtpenc_vc2hq.o): In function
 

  get_interleaved_ue_golomb’ :
  /home/ievdokimov/repos/FFmpeg/./libavcodec/golomb.h:183 : undefined
  reference to

  ff_interleaved_ue_golomb_vlc_code'
 /home/ievdokimov/repos/FFmpeg/./libavcodec/golomb.h:183: undefined
 reference to

  ff_interleaved_ue_golomb_vlc_code’
  /home/ievdokimov/repos/FFmpeg/./libavcodec/golomb.h:183 : undefined
  reference to

  ff_interleaved_ue_golomb_vlc_code'
 /usr/local/lib//libavformat.a(spdifdec.o): In function
 

  spdif_get_offset_and_codec’ :
  /home/ievdokimov/repos/FFmpeg/libavformat/spdifdec.c:63 : undefined
  reference to

  av_adts_header_parse'
 /home/ievdokimov/repos/FFmpeg/libavformat/spdifdec.c:63: undefined
 reference to

  av_adts_header_parse’
  /usr/local/lib//libavformat.a(spdifenc.o) : In function

  spdif_header_aac':
 /home/ievdokimov/repos/FFmpeg/libavformat/spdifenc.c:362: undefined
 reference to

  av_adts_header_parse’
  /usr/local/lib//libavformat.a(ac3dec.o) : In function

  ac3_eac3_probe':
 /home/ievdokimov/repos/FFmpeg/libavformat/ac3dec.c:63: undefined
 reference to

  av_ac3_parse_header’
  /home/ievdokimov/repos/FFmpeg/libavformat/ac3dec.c:60 : undefined
  reference to

  av_ac3_parse_header'
 /usr/local/lib//libavformat.a(adtsenc.o): In function
 

  adts_decode_extradata’ :
  /home/ievdokimov/repos/FFmpeg/libavformat/adtsenc.c:56 : undefined
  reference to `avpriv_mpeg4audio_get_config2’ collect2 : error : ld
  returned 1 exit status

  Is there any way to fix that ?