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• ffmpeg trim mp3 - determine precisely the start and end times of section to be trimmed

  4 février 2019, par Ahmed Khalil

  I have a long mp3 track of an audio book (more than 9 hours long) that I would like to trim using ffmpeg.

  The sample code below is used to trim an mp3 section by providing the start and end times. However, when I determine the start and end times, then checking the output file, it’s not as precisely as I want, sometimes several minutes ahead/before the desired point.

  import subprocess
  
  file = r'audio book.mp3'
  
  track_name = "trimmed section"
  
  output = r'D:\{0}'.format(track_name)
  
  start = '01:26:04'
  
  end = '01:33:17'
  
  
  
  d = subprocess.getoutput('ffmpeg -i "{0}" -ss {1} -to {2} -c copy {3}.mp3"'
  
                       .format(file, start, end, output))
  
  
  
  print(d)

  Is there a way to determine with accuracy the real start and end time of an mp3 audio track, to be given afterwards as inputs to the code...to trim the desired sections all at once, without the need to adjust/fine-tune the start and end time manually ??

• Enable Subtitle on FFmpeg Stream

  14 janvier 2020, par A Person

  I am trying to enable subtitle on my streams.

  The problem is that I do not have a subtitle track.

  The original IP stream that is coming has subtitles and I need to know how to enable it.

  I have looked at Set a subtitle language using ffmpeg

  and also read that I need to assign some sort of PID to the FFmpeg tag to enable it. However, I have been googling this and cannot seem to dins it.

  My code is :

  /c ffmpeg -hwaccel cuvid -y -i {udp} -vf "drawtext=fontfile={font}: fontsize=25:text='{ChannelName} %{localtime}': x=10: y=10: fontcolor=white: box=1: boxcolor=0x000000" -pix_fmt yuv420p -vsync 1 -crf 10 -c:v h264_nvenc -r 25 -threads 0  -b:v 1M -profile:v main -minrate 1M -maxrate 1M -bufsize 10M -sc_threshold 0 -c:a aac -b:a 128k -ac 2 -ar 44100 -af "aresample=async=1:min_hard_comp=0.100000:first_pts=0" -bsf:v h264_mp4toannexb -t 00:31:00 {output}\{ChannelName}_{year}_{monthno}_{day}__{Hours}_{Minutes}_{Seconds}.mp4 {FFLog}

  These are the variables :

  {udp} this is the UDP link e.g udp ://239...*:1234

  {font} this just points to the font file

  {ChannelName} holds the name of the stream

  {localtime} current time

  {FLOG} path to a log file to dumb the data

• Web Based Playback of iOS Videos with Orientation Flag

  3 mars 2012, par shanee

  We just recently created an iPhone app for one of our system that allows users to upload picture and video content to our services. The last major hitch we are running into is how to handle videos that are uploaded in an orientation other than Horizontal Right. Apparently if your playback system does not account for the orientation flag sent with the video then it will play upside down or sideways.

  The correct approach appears to be that the playback system should take the orientation flag into account just prior to playback. This is the way Apple handles it directly on the device as well as through Quicktime.

  SO my first hope is that someone is aware of a web based (HTML5 or Flash) player that is capable of rotating a video during playback based on either the video orientation metadata or based on a passed flag (we already have the necessary flag available in the DB if we need to just pass it manually). If you know of any such player then PLEASE SHARE !

  If you aren't aware of such a player, then has anyone had any luck rotating their videos using FFMPEG or MEncoder ? We did a few hours of testing last week and weren't able to get any decent results from the two heavy hitters mentioned there.

  Failing ALL OF THAT, is it possible to have the iPhone upload a video or image in a specified direction ?

  Any of the three will work for me, but I would prefer to do whatever is standard (if one exists).

  Any help is much appreciated !