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• mp4 generated by moviepy no sound with tweepy

  2 décembre 2020, par Will Rowe

  I'm using MoviePy to edit a mp4 file and then Tweepy to tweet out the video.

  


  Here's what I have currently :

  


  clip = VideoFileClip("c:/users/.../UNIQUENAME2.mp4").subclip(8) #cut off the first 8 seconds of the clip
clip.write_videofile("c:/users/.../UNIQUENAME2-finished.mp4")
clip.close()
highlightz = TweetMachine()
highlightz.makeAVidTweet('c:/users/.../UNIQUENAME2-finished.mp4','audio test')


  


  Here's my TweetMachine :

  


  def makeAVidTweet(self,fileLoc,text):
        upload_result = self.api.media_upload(fileLoc)
        time.sleep(120) #wait just in case things are still processing
        media_ids = [upload_result.media_id_string]
        self.api.update_status(status=text, media_ids=media_ids)


  


  Currently, the video is cut fine and UNIQUENAME2-finished.mp4 is constructed correctly such that if I open the file on my computer, the video is cut correctly and the sound works. However, the video posted on Twitter has no sound.

  


  I'm assuming it's some sort of issue with how MoviePy makes the mp4 file and Twitter not liking something with the sound settings, but I'm pretty unfamiliar with mp4 stuff and I couldn't find anything about it on the MoviePy or Tweepy docs.

  


  Any tips or thoughts would be greatly appreciated !

  


  Stream info from VLC :
Codec : MPEG Audio layer 1/2 (mpga),
Type : Audio,
Channels : Stereo,
Sample Rate : 44100 Hz,
Bits per sample : 32,
Bitrate : 128 kb/s

  


• ffmpeg : md5 of m3u8 playlists generated from same input video with different segment durations (after applying video filter) don't match

  15 juillet 2020, par Saurabh P Bhandari

  Here are a few commands I am using to convert and transize a video in mp4 format to a m3u8 playlist.

  


  For a given input video (mp4 format), generate multiple video only segments with segment duration 30s

  


  ffmpeg -loglevel error -i input.mp4 -dn -sn -an -c:v copy -bsf:v h264_mp4toannexb -copyts -start_at_zero -f segment -segment_time 30 30%03d.mp4 -dn -sn -vn -c:a copy audio.aac


  


  Apply video filter (in this case scaling) on each segment and convert it to a m3u8 format

  


  ls 30*.mp4 | parallel 'ffmpeg -loglevel error -i {} -vf scale=-2:144 -hls_list_size 0 {}.m3u8'


  


  Store the list of m3u8 files generated in list.txt in this format file 'segment-name.m3u8'

  


  for f in 30*.m3u8; do echo "file '$f'" >> list.txt; done


  


  Using concat demuxer, combine all segment files (which are in m3u8 format) and the audio to get one final m3u8 playlist pointing to segments with duration of 10s.

  


  ffmpeg -loglevel error -f concat -i list.txt -i audio.aac -c copy -hls_list_size 0 -hls_time 10 output_30.m3u8


  


  ---

  


  I can change the segment duration in the first step from 30s to 60s, and compare the md5 of the final m3u8 playlist generated in both the cases using this command

  


  ffmpeg -loglevel error -i <input m3u8="m3u8" playlist="playlist" /> -f md5 - &#xA;

  


  The md5 of the output files differ i.e video streams of output_30.m3u8 and output_60.m3u8 are not the same.

  


  Can anyone elaborate on this ?

  


  (I expected the md5 to be the same)

  


• FFProbe generated data don't seem to agree with calculated data using ffmpeg libraries

  18 janvier 2020, par ark1974

  Using ffmpeg library avformat I am trying to check if the ffprobe generated data agrees with the data generated by the library. The code objective is to try to seek to the nearest key frame. When trying to seek at 100 frame or less, the codes returns 0 all the time.
  When trying to seek at 200 frame, the codes returns 4 all the time. But the result ie 4th frame don’t seem to be right. Where am I wrong ? Is my time_base conversion to actual frame faulty ?

  The test result using ffprobe

  Filename = test.mp4  
  
  Duration = 00:00:10.56 
  
  Fps = 25
  
  Total frames = 256   
  
  The key frames pkt_pts_time are at 2.120000  and 0.000000 (using -skip_frame nokey )
  
  Corresponding pkt_duration_time: 0.040000 and 0.040000 (  same, why?)

  Abstract of the code :

  // Objective: seek to the nearest key frame
  
  frameIndex = 200;
  
  int64_t timeBase = (int64_t(pCodecCtx->time_base.num) * AV_TIME_BASE) / int64_t(pCodecCtx->time_base.den);  
  
  int64_t seekTarget = int64_t(frameIndex) * timeBase;
  
  
  
  if (av_seek_frame(pFormatCtx, -1, seekTarget, AVSEEK_FLAG_FRAME | AVSEEK_FLAG_BACKWARD) < 0) return -1;
  
  
  
  //convert the time_base to actual frame
  
  auto time2frame = [&](int64_t tb) {
  
      return tb * int64_t(pCodecCtx->time_base.den) / (int64_t(pCodecCtx->time_base.num) * AV_TIME_BASE);
  
  };
  
  
  
  AVPacket avPacket;
  
  int result = av_read_frame(pFormatCtx, &avPacket);
  
  if (result == 0) {
  
  
  
      auto dts = avPacket.dts;
  
      auto pts = avPacket.pts;
  
      auto idx = avPacket.stream_index;
  
      auto f = time2frame(pts); // expecting the actual frame here
  
      std::cout << dts << pts << idx << f;
  
  }