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• How do I properly enable ffmpeg for matplotlib.animation ?

  7 mars 2017, par spanishgum

  I have covered a lot of ground on stack so far trying to get ffmpeg going so I can make a timelapse video.

  I am on a CentOS 7 machine, running python3.7.0a0.

  python3
  
  >>> import numpy as np
  
  >>> np.__version__
  
  '1.12.0'
  
  >>> import matplotlib as mpl
  
  >>> mpl.__version__
  
  '2.0.0'
  
  >>> import mpl_toolkits.basemap as base
  
  >>> base.__version__
  
  '1.0.7'

  I found this github gist on installing ffmpeg. I used the chromium source, and installed without a prefix option (using the default).

  I have confirmed that ffmpeg is installed, although I don’t know anything about testing whether it works.

  which ffmpeg
  
  /usr/local/bin/ffmpeg
  
  
  
  ffmpeg -version
  
  ffmpeg version N-83533-gada281d Copyright (c) 2000-2017 the FFmpeg dev elopers
  
  built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-11
  
  configuration:
  
  libavutil      55. 47.100 / 55. 47.100
  
  libavcodec     57. 80.100 / 57. 80.100
  
  libavformat    57. 66.102 / 57. 66.102
  
  libavdevice    57.  2.100 / 57.  2.100
  
  libavfilter     6. 73.100 /  6. 73.100
  
  libswscale      4.  3.101 /  4.  3.101
  
  libswresample   2.  4.100 /  2.  4.100

  I tried to run a few sample examples I found online :

  [1] http://matplotlib.org/examples/animation/basic_example_writer.html

  [2] http://stackoverflow.com/a/23098090/3454650

  Everything works fine up until I try to save the animation file.

  [1]

   anim.save('basic_animation.mp4', writer = FFwriter, fps=30, extra_args=['-vcodec', 'libx264'])

  [2]

  im_ani.save('im.mp4', writer=writer)

  I found here that explictly setting the path to ffmpeg might be necessary so I added this to the top of the test scripts :

  plt.rcParams['animation.ffmpeg_path'] = '/usr/local/bin/ffmpeg'

  I tried a few more tweaks in the code but always get the same response, which I do not know how to begin deciphering :

  Traceback (most recent call last):
  
    File "testanim.py", line 27, in <module>
  
      writer.grab_frame()
  
    File "/usr/local/lib/python3.7/contextlib.py", line 100, in __exit__
  
      self.gen.throw(type, value, traceback)
  
    File "/usr/local/lib/python3.7/site-packages/matplotlib/animation.py", line 256, in saving
  
      self.finish()
  
    File "/usr/local/lib/python3.7/site-packages/matplotlib/animation.py", line 276, in finish
  
      self.cleanup()
  
    File "/usr/local/lib/python3.7/site-packages/matplotlib/animation.py", line 311, in cleanup
  
      out, err = self._proc.communicate()
  
    File "/usr/local/lib/python3.7/subprocess.py", line 836, in communicate
  
      stdout, stderr = self._communicate(input, endtime, timeout)
  
    File "/usr/local/lib/python3.7/subprocess.py", line 1474, in _communicate
  
      selector.register(self.stdout, selectors.EVENT_READ)
  
    File "/usr/local/lib/python3.7/selectors.py", line 351, in register
  
      key = super().register(fileobj, events, data)
  
    File "/usr/local/lib/python3.7/selectors.py", line 237, in register
  
      key = SelectorKey(fileobj, self._fileobj_lookup(fileobj), events, data)
  
    File "/usr/local/lib/python3.7/selectors.py", line 224, in _fileobj_lookup
  
      return _fileobj_to_fd(fileobj)
  
    File "/usr/local/lib/python3.7/selectors.py", line 39, in _fileobj_to_fd
  
      "{!r}".format(fileobj)) from None
  
  ValueError: Invalid file object: &lt;_io.BufferedReader name=6>
  
  </module>

  Is there something with my configuration that is malformed ? I searched google for this error for some time but never found anything relevant to animations / ffmpeg. Any help would be greatly appreciated.

  ---

  UPDATE :

  @LordNeckBeard pointed me here : https://trac.ffmpeg.org/wiki/CompilationGuide/Centos

  I ran into problems with installing the x264 encoding dependency. Some files in libavcodec/*.c (in the make output) were reporting undefined references to several functions. After a wild goose chase found this : https://mailman.videolan.org/pipermail/x264-devel/2015-February/010971.html

  To fix the x264 installation, I simply added some configure flags :

  ./configure --enable-static --enable-shared --extra-ldflags="-lswresample -llzma"

  ---

  UPDATE :

  So everything installed fine after fixing the libx264 problems. I went ahead and copied the ffmpeg binary from the ffmpeg_build folder into /usr/local/bin/ffmpeg.

  After running the script I was getting problems where ffmpeg could not find the libx264 shared object. I think I will have to recompile everything using different prefixes. My intuition tells me there are old files laying around after I have messed with everything, using some configuration that is broken.

  So I decided maybe I should just try to use NUX : http://linoxide.com/linux-how-to/install-ffmpeg-centos-7/
  I installed ffmpeg using the new rpm, but to no avail. I still was not able to run ffmpeg because of a missing shared object.

  Finally, instead of usiong files copied into my /usr/local/bin folder, I ran ffmpeg directly from the build bin directory. Turns out that this does work properly !

  So in essence, if I want to install ffmpeg system wide, I need to manually compile from sources again but using a nonlocal prefix.

• QTableWidget and QProcess - update table based on multiple process results

  9 mars 2017, par Spencer

  I have a python program that runs through a QTableWidget and for each item it runs a QProcess (an FFMPEG process to be exact). What I’m trying to do is update the "parent" cell when the process completes. Right now there is a for loop that goes through each row and launches a process for each, and connects the finished signal of that process to a "finished" function, which updates the QTableWidget cell. I’m just having trouble properly telling the function WHICH sell to update - right now I am passing it the index of the current row (seeing as it is being spawned by the for loop) but what happens is by the time the processes start to finish it will only get the last row in the table... I’m quite new to Python and PyQt so it is possible there is some fundamental thing I have wrong here !

  I tried passing the actual QTabelWidgetItem instead of the index but I got this error : "RuntimeError : wrapped C/C++ object of type QTableWidgetItem has been deleted"

  My code, the function "finished" and line #132 are the relevant ones :

  import sys, os, re
  
  from PyQt4 import QtGui, QtCore
  
  
  
  class BatchTable(QtGui.QTableWidget):
  
      def __init__(self, parent):
  
          super(BatchTable, self).__init__(parent)
  
          self.setAcceptDrops(True)
  
          self.setColumnCount(4)
  
          self.setColumnWidth(1,50)
  
          self.hideColumn(3)
  
          self.horizontalHeader().setStretchLastSection(True)
  
          self.setHorizontalHeaderLabels(QtCore.QString("Status;Alpha;File;Full Path").split(";"))
  
  
  
          self.doubleClicked.connect(self.removeProject)
  
  
  
      def removeProject(self, myItem):
  
          row = myItem.row()
  
          self.removeRow(row)
  
  
  
      def dragEnterEvent(self, e):
  
          if e.mimeData().hasFormat('text/uri-list'):
  
              e.accept()
  
          else:
  
              print "nope"
  
              e.ignore()
  
  
  
      def dragMoveEvent(self, e):
  
          e.accept()
  
  
  
      def dropEvent(self, e):
  
          if e.mimeData().hasUrls:
  
              for url in e.mimeData().urls():
  
                  chkBoxItem = QtGui.QTableWidgetItem()
  
                  chkBoxItem.setFlags(QtCore.Qt.ItemIsUserCheckable | QtCore.Qt.ItemIsEnabled)
  
                  chkBoxItem.setCheckState(QtCore.Qt.Unchecked)
  
  
  
                  rowPosition = self.rowCount()
  
                  self.insertRow(rowPosition)
  
                  self.setItem(rowPosition, 0, QtGui.QTableWidgetItem("Ready"))
  
                  self.setItem(rowPosition, 1, chkBoxItem)
  
                  self.setItem(rowPosition, 2, QtGui.QTableWidgetItem(os.path.split(str(url.toLocalFile()))[1]))
  
                  self.setItem(rowPosition, 3, QtGui.QTableWidgetItem(url.toLocalFile()))
  
                  self.item(rowPosition, 0).setBackgroundColor(QtGui.QColor(80, 180, 30))
  
  
  
  class ffmpegBatch(QtGui.QWidget):
  
      def __init__(self):
  
          super(ffmpegBatch, self).__init__()
  
          self.initUI()
  
  
  
      def initUI(self):
  
  
  
          self.edit = QtGui.QTextEdit()
  
  
  
          cmdGroup = QtGui.QGroupBox("Commandline arguments")
  
          fpsLbl = QtGui.QLabel("FPS:")
  
          self.fpsCombo = QtGui.QComboBox()
  
          self.fpsCombo.addItem("29.97")
  
          self.fpsCombo.addItem("23.976")
  
          hbox1 = QtGui.QHBoxLayout()
  
          hbox1.addWidget(fpsLbl)
  
          hbox1.addWidget(self.fpsCombo)
  
          cmdGroup.setLayout(hbox1)
  
  
  
          saveGroup = QtGui.QGroupBox("Output")
  
          self.outputLocation = QtGui.QLineEdit()
  
          self.browseBtn = QtGui.QPushButton("Browse")
  
          saveLocationBox = QtGui.QHBoxLayout()
  
          # Todo: add "auto-step up two folders" button
  
          saveLocationBox.addWidget(self.outputLocation)
  
          saveLocationBox.addWidget(self.browseBtn)
  
          saveGroup.setLayout(saveLocationBox)
  
  
  
          runBtn = QtGui.QPushButton("Run Batch Transcode")
  
  
  
          mainBox = QtGui.QVBoxLayout()
  
          self.table = BatchTable(self)
  
          # TODO: add "copy from clipboard" feature
  
          mainBox.addWidget(self.table)
  
          mainBox.addWidget(cmdGroup)
  
          mainBox.addWidget(saveGroup)
  
          mainBox.addWidget(runBtn)
  
          mainBox.addWidget(self.edit)
  
  
  
          self.setLayout(mainBox)
  
          self.setGeometry(300, 300, 600, 500)
  
          self.setWindowTitle('FFMPEG Batch Converter')
  
  
  
          # triggers/events
  
          runBtn.clicked.connect(self.run)
  
  
  
      def RepresentsInt(self, s):
  
          try:
  
              int(s)
  
              return True
  
          except ValueError:
  
              return False
  
  
  
      def run(self):
  
          if (self.outputLocation.text() == ''):
  
              return
  
          for projIndex in range(self.table.rowCount()):
  
              # collect some data
  
              ffmpeg_app = "C:\\Program Files\\ffmpeg-20150702-git-03b2b40-win64-static\\bin\\ffmpeg"
  
              frameRate = self.fpsCombo.currentText()
  
              inputFile = self.table.model().index(projIndex,3).data().toString()
  
              outputPath = self.outputLocation.text()
  
              outputPath = outputPath.replace("/", "\\")
  
  
  
              # format the input for ffmpeg
  
              # find how the exact number range, stored as 'd'
  
              imageName = os.path.split(str(inputFile))[1]
  
              imageName, imageExt = os.path.splitext(imageName)
  
              length = len(imageName)
  
              d = 0
  
              while (self.RepresentsInt(imageName[length-2:length-1]) == True):
  
                  length = length-1
  
                  d = d+1
  
              inputPath = os.path.split(str(inputFile))[0]
  
              inputFile = imageName[0:length-1]
  
              inputFile = inputPath + "/" + inputFile + "%" + str(d+1) + "d" + imageExt
  
              inputFile = inputFile.replace("/", "\\")
  
  
  
              # format the output
  
              outputFile = outputPath + "\\" + imageName[0:length-2] + ".mov"
  
  
  
  
  
              # build the commandline
  
              cmd = '"' + ffmpeg_app + '"' + ' -y -r ' + frameRate + ' -i ' + '"' + inputFile + '"' + ' -vcodec dnxhd -b:v 145M -vf colormatrix=bt601:bt709 -flags +ildct ' + '"' + outputFile + '"'
  
  
  
              # launch the process
  
              proc = QtCore.QProcess(self)
  
              proc.finished.connect(lambda: self.finished(projIndex))
  
              proc.setProcessChannelMode(proc.MergedChannels)
  
              proc.start(cmd)
  
              proc.readyReadStandardOutput.connect(lambda: self.readStdOutput(proc, projIndex, 100))
  
              self.table.setItem(projIndex, 0, QtGui.QTableWidgetItem("Running..."))
  
              self.table.item(projIndex, 0).setBackgroundColor(QtGui.QColor(110, 145, 30))
  
  
  
      def readStdOutput(self, proc, projIndex, total):
  
          currentLine = QtCore.QString(proc.readAllStandardOutput())
  
          currentLine = str(currentLine)
  
          frameEnd = currentLine.find("fps", 0, 15)
  
          if frameEnd != -1:
  
              m = re.search("\d", currentLine)
  
              if m:
  
                  frame = currentLine[m.start():frameEnd]
  
                  percent = (float(frame)/total)*100
  
                  print "Percent: " + str(percent)
  
                  self.edit.append(str(percent))
  
                  self.table.setItem(projIndex, 0, QtGui.QTableWidgetItem("Encoded: " + str(percent) + "%"))
  
  
  
      def finished(self, projIndex):
  
          # TODO: This isn't totally working properly for multiple processes (seems to get confused)
  
          print "A process completed"
  
          print self.sender().readAllStandardOutput()
  
          if self.sender().exitStatus() == 0:
  
              self.table.setItem(projIndex, 0, QtGui.QTableWidgetItem("Encoded"))
  
              self.table.item(projIndex, 0).setBackgroundColor(QtGui.QColor(45, 145, 240))
  
  
  
  
  
  def main():
  
      app = QtGui.QApplication(sys.argv)
  
      ex = ffmpegBatch()
  
      ex.show()
  
      sys.exit(app.exec_())
  
  
  
  if __name__ == '__main__':
  
      main()

  (And yes I do know that my percentage update is totally wrong right now, still working on that...)

• Error decoding a simple audio file using FFmpeg library

  29 mars 2017, par satyres

  After successfuly compiling the latest version of FFmpeg library and generated .a library in Ubuntu I’ve been struggling now for more than a week to decode and play a simple mp3 file in Android without a success !
  I’ve followed this tutorial given by FFmpeg team in Github i’ve tried to use it in Android but no luck !
  here is the Native code.

  void Java_com_example_home_hellondk_MainActivity_audio_1decode_1example(JNIEnv * env, jobject obj, jstring file, jbyteArray array) {
  
      jboolean isfilenameCopy;
  
      const char * filename = ( * env) - > GetStringUTFChars(env, file, &
  
          isfilenameCopy);
  
      jclass cls = ( * env) - > GetObjectClass(env, obj);
  
      jmethodID play = ( * env) - > GetMethodID(env, cls, "playSound", "([BI)V");
  
      AVCodec * codec;
  
      AVCodecContext * c = NULL;
  
      int len;
  
      FILE * f, * outfile;
  
      uint8_t inbuf[AUDIO_INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
  
      AVPacket avpkt;
  
      AVFrame * decoded_frame = NULL;
  
  
  
      av_init_packet( & avpkt);
  
  
  
      printf("Decode audio file %s \n", filename);
  
      LOGE("Decode audio file %s\n", filename);
  
      /* find the MPEG audio decoder */
  
      codec = avcodec_find_decoder(AV_CODEC_ID_MP3);
  
      if (!codec) {
  
          fprintf(stderr, "Codec not found\n");
  
          LOGE("Codec not found\n");
  
          exit(1);
  
      }
  
  
  
      c = avcodec_alloc_context3(codec);
  
      if (!c) {
  
          fprintf(stderr, "Could not allocate audio codec context\n");
  
          LOGE("Could not allocate audio codec context\n");
  
          exit(1);
  
      }
  
  
  
      /* open it */
  
      if (avcodec_open2(c, codec, NULL) < 0) {
  
          fprintf(stderr, "Could not open codec\n");
  
          LOGE("Could not open codec\n");
  
          exit(1);
  
      }
  
  
  
      f = fopen(filename, "rb");
  
      if (!f) {
  
          fprintf(stderr, "Could not open %s\n", filename);
  
          LOGE("Could not open %s\n", filename);
  
          exit(1);
  
      }
  
  
  
  
  
      /* decode until eof */
  
      avpkt.data = inbuf;
  
      avpkt.size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f);
  
  
  
      while (avpkt.size > 0) {
  
          int i, ch;
  
          int got_frame = 0;
  
  
  
          if (!decoded_frame) {
  
              if (!(decoded_frame = av_frame_alloc())) {
  
                  fprintf(stderr, "Could not allocate audio frame\n");
  
                  LOGE("Could not allocate audio frame\n");
  
                  exit(1);
  
              }
  
          }
  
  
  
          len = avcodec_decode_audio4(c, decoded_frame, & got_frame, & avpkt);
  
          if (len < 0) {
  
              fprintf(stderr, "Error while decoding\n");
  
              LOGE("Error while decoding\n");
  
              exit(1);
  
          }
  
          if (got_frame) {
  
              /* if a frame has been decoded, output it */
  
              int data_size = av_get_bytes_per_sample(c - > sample_fmt);
  
              if (data_size < 0) {
  
                  /* This should not occur, checking just for paranoia */
  
                  fprintf(stderr, "Failed to calculate data size\n");
  
                  LOGE("Failed to calculate data size\n");
  
                  exit(1);
  
              }
  
              if (data_size > 0) {
  
  
  
                  jbyte * bytes = ( * env) - > GetByteArrayElements(env, array, NULL);
  
                  memcpy(bytes, decoded_frame, got_frame); //
  
                  ( * env) - > ReleaseByteArrayElements(env, array, bytes, 0);
  
                  ( * env) - > CallVoidMethod(env, obj, play, array, got_frame);
  
                  LOGE("DECODING ERROR5");
  
              }
  
          }
  
          avpkt.size -= len;
  
          avpkt.data += len;
  
          avpkt.dts =
  
              avpkt.pts = AV_NOPTS_VALUE;
  
          if (avpkt.size < AUDIO_REFILL_THRESH) {
  
              /* Refill the input buffer, to avoid trying to decode
  
               * incomplete frames. Instead of this, one could also use
  
               * a parser, or use a proper container format through
  
               * libavformat. */
  
              memmove(inbuf, avpkt.data, avpkt.size);
  
              avpkt.data = inbuf;
  
              len = fread(avpkt.data + avpkt.size, 1,
  
                  AUDIO_INBUF_SIZE - avpkt.size, f);
  
              if (len > 0)
  
                  avpkt.size += len;
  
          }
  
      }
  
  
  
  
  
      fclose(f);
  
  
  
      avcodec_free_context( & c);
  
      av_frame_free( & decoded_frame);
  
  
  
  }

  The Java code :

  package com.example.home.hellondk;
  
  
  
  import android.media.AudioFormat;
  
  import android.media.AudioManager;
  
  import android.media.AudioTrack;
  
  import android.media.MediaPlayer;
  
  import android.support.v7.app.AppCompatActivity;
  
  import android.os.Bundle;
  
  import android.util.Log;
  
  
  
  import java.io.File;
  
  import java.io.FileNotFoundException;
  
  import java.io.FileOutputStream;
  
  import java.io.IOException;
  
  
  
  public class MainActivity extends AppCompatActivity {
  
      static {
  
          System.loadLibrary("MyLibraryPlayer");
  
      }
  
      public native void createEngine();
  
  
  
      public native void audio_decode_example(String outfilename, byte[] array);
  
  
  
  
  
  
  
      private AudioTrack track;
  
      private FileOutputStream os;
  
  
  
      @Override
  
      protected void onCreate(Bundle savedInstanceState) {
  
          super.onCreate(savedInstanceState);
  
          setContentView(R.layout.activity_main);
  
          createEngine();
  
  
  
   /*        MediaPlayer mp = new MediaPlayer();
  
          mp.start();*/
  
  
  
          int bufSize = AudioTrack.getMinBufferSize(32000,
  
                  AudioFormat.CHANNEL_CONFIGURATION_STEREO,
  
                  AudioFormat.ENCODING_PCM_16BIT);
  
  
  
          track = new AudioTrack(AudioManager.STREAM_MUSIC,
  
                  32000,
  
                  AudioFormat.CHANNEL_CONFIGURATION_STEREO,
  
                  AudioFormat.ENCODING_PCM_16BIT,
  
                  bufSize,
  
                  AudioTrack.MODE_STREAM);
  
  
  
          byte[] bytes = new byte[bufSize];
  
  
  
          try {
  
              os = new FileOutputStream("/storage/emulated/0/Cloud Radio/a.out", false);
  
          } catch (FileNotFoundException e) {
  
              // TODO Auto-generated catch block
  
              e.printStackTrace();
  
          }
  
     audio_decode_example("/storage/emulated/0/Cloud Radio/test.mp3", bytes);
  
  
  
      }
  
  
  
      void playSound(byte[] buf, int size) {
  
          //android.util.Log.v("ROHAUPT", "RAH Playing");
  
          if (track.getPlayState() != AudioTrack.PLAYSTATE_PLAYING)
  
              track.play();
  
          track.write(buf, 0, size);
  
  
  
          try {
  
              os.write(buf, 0, size);
  
          } catch (IOException e) {
  
              // TODO Auto-generated catch block
  
              e.printStackTrace();
  
          }
  
      }
  
  }

  I always got this error : Error while decoding .
  i’ve tried to change the decoder "AV_CODEC_ID_MP3" no sucess !
  Thank you so much for your help.
  Kind regards