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• ffmpeg black screen issue for video video generation from a list of frames

  11 mai 2023, par arlaine

  I used a video to generate a list of frames from it, then I wanted to create multiple videos from this list of frames.
I've set starting and ending frames indexes for each "sub video", so for example,
indexes = [[0, 64], [64, 110], [110, 234], [234, 449]], and those indexes will help my code generate 4 videos of various durations. The idea is to decompose the original video into multiple sub videos. My code is working just fine, the video generated.

  


  But every sub video start with multiple seconds of black screen, only the first generated video (so the one using indexes[0] for starting and ending frames) is generated without this black screen part. I've tried changing the frame rate for each sub_video, according to the number of frames and things like that, but I didn't work. You can find my code below

  


  for i, (start_idx, end_idx) in enumerate(self.video_frames_indexes):
    if end_idx - start_idx > 10:
        shape = cv2.imread(f'output/video_reconstitution/{video_name}/final/frame_{start_idx}.jpg').shape
        os.system(f'ffmpeg -r 30 -s {shape[0]}x{shape[1]} -i output/video_reconstitution/{video_name}/final/frame_%d.JPG'
              f' -vf "select=between(n\,{start_idx}\,{end_idx})" -vcodec libx264 -crf 25'
              f' output/video_reconstitution/IMG_7303/sub_videos/serrage_{i}.mp4')


  


  Just the ffmpeg command

  


  ffmpeg -r 30 -s {shape[0]}x{shape[1]} -i output/video_reconstitution/{video_name}/final/frame_%d.JPG -vf "select=between(n\,{start_idx}\,{end_idx})" -vcodec libx264 -crf 25 output/video_reconstitution/IMG_7303/sub_videos/serrage_{i}.mp4


  


• Reading RTMP streams using FFMPEG returns AVERROR_EOF randomly

  9 octobre 2013, par user2628781

  I am using FFMpeg to receive RTMP streams. This logic is placed in a custom video player I am building.

  I managed to successfully connect to the RTMP stream and display the video correctly. However, after a period in time, the stream terminates prematurely with an AVERROR_EOF when I perform av_read_frame().

  This indicates to me that the file has ended so my demux, video and audio threads terminates thinking that the video has ended.
  However, the video playback hasn't yet reached its end (in the case of a file streamed through rtmp) or from a live stream (which runs forever). The EOFs are received very randomly so it may run for say 7 min before this occurs or after 3 mins.

  Is this a characteristic behaviour of RTMP or am I doing something incorrectly ?
  I am also having a similar problem with Http Live Streams using FFMpeg.

  A small snippet of the code is provided below :

   AVPacket packet;
  
  //start timeout timer and timeout
  
  __interrupt_timer.start();
  
  
  
  int ret = av_read_frame(format_context, &packet); //0: ok, <0: error/end
  
  
  
  
  
  //invalidate the timer
  
  __interrupt_timer.invalidate();
  
  
  
  if (ret != 0) {
  
      if (ret == AVERROR_EOF) { //end of file. FIXME: why no eof if replaying by seek(0)?            
  
          if (!eof) {
  
              eof = true;
  
              started_ = false;
  
              pkt->data = QByteArray(); //flush
  
              pkt->markEnd();
  
              qDebug("End of file. %s %d", __FUNCTION__, __LINE__);
  
              emit finished();
  
              return true;
  
          }
  
          pkt->data = QByteArray(); //flush
  
          //return true;
  
          return false; //frames after eof are eof frames
  
      } else if (ret == AVERROR_INVALIDDATA) {
  
          qWarning("AVERROR_INVALIDDATA");
  
      } else if (ret == AVERROR(EAGAIN)) {
  
          return true;
  
      }
  
      qWarning("[AVDemuxer] error: %s", av_err2str(ret));
  
      return false;
  
  }

• os.walk returns file names but when trying to modify the files it says directory not found

  13 avril 2021, par epWILL

  Im trying to walk through music folder and find all sub folders in it and convert the mp4's in all folders to wav. It prints out the correct file name but when it trys to convert it says directory not found.

  


  I would like to us os.walk to go through all folders instead going through 1 folder and changing the name in the code for the other folders

  


  This code works for one folder

  


  import os
import ffmpeg
import time

path = './musicTest/'


os.chdir(path)
aud_files = os.listdir()
count = 0
count2 = 0


    ##convert mp4 to wav
for file in aud_files:
    os.system('ffmpeg -i "{}" -acodec pcm_s16le -ac 1 -ar 16000 output-{}.wav'.format(file, count))
    count = count + 1
    os.remove(file)


  


  this is the code that gives me no directory found when using os.walk but it prints the file name

  


  import os
from pydub import AudioSegment
import ffmpeg

path = "./musicTest/"
count = 0

for i, (root, dirs, files) in enumerate(os.walk(path)):
   if root is not path:
      for file in files:
           print(file)
           os.system('ffmpeg -i "{}" -acodec pcm_s16le -ac 1 -ar 16000 output-{}.wav'.format(file, count))
           count = count + 1