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• FFmpeg - video frame cropped after rotating video ?

  20 juin 2021, par Md Yeamin

  I am using following command to rotate video :

  


  ffmpeg -i input.mp4 -c:v h264 -vf rotate=PI/2 -c:a copy output.mp4


  


  After processing the video, the frame get cropped. Please see the attached screenshot of the video for reference.

  


  Screenshot of original video


  


  Screenshot of rotated video


  


• FFMPEG Audio/Video out of sync after transcoding video in segments

  25 mai 2017, par Idan

  My system transcodes videos in a very specific way.

  1. separating the video and the audio
  2. transcoding the audio stream
  3. segmenting the video
  4. transcoding each of the segments of the video
  5. concat all segments back to 1 video
  6. merging the new transcoded video and audio back together

  While at 99% of the times the process works as it should and the result is a valid video+audio file. in 1% of the times, I get the video and audio out of sync.

  When investigated the issue I noticed that the sync issue appears in a specific segment/s. Meaning, if the video was sliced into 100 segments, the sync can be ok for the first 50 segments, then something happens and the audio or video gets an offset and goes out of sync. It can occur in any number of segments in one video.

  I guess it’s something to do with timestamps getting lost in the process and segments changing their length in the process but I have no idea how I can overcome it. Open for suggestions.

  The commands I use for each step (paths were shorten and may not match, not real issue there) :

  Segmenting the video :

  ffmpeg -fflags +genpts -i $INPUT_FILE -c copy -map 0:0 -flags -global_header -segment_time 10 -break_non_keyframes 0 -reset_timestamps 1 -segment_list segments.list -segment_list_type ffconcat -write_empty_segments 0 -segment_format mp4 -f segment seg-%d.mp4

  Transcoding audio :

  ffmpeg -i $INPUT_FILE  -vn -c:a aac -threads 1 -ac 2 -b:a 125588 audio.mp4

  Transcoding each of the segments :

  ffmpeg -y -i $f -an -vcodec libx264 -threads 4 -r 30 -pix_fmt yuv420p -crf 20 -preset:v fast -profile:v main -level:v 4.1 transcoded/$f

  Concat segments :

  ffmpeg -y -f concat -i segments.list  -c copy -movflags +faststart file_video.mp4

  Combine video and audio :

  ffmpeg -y -i file_video.mp4 -i file_audio.mp4 -c copy -shortest file_out.mp4

• How to get video size of compressed video by ffmpeg ?

  14 juillet 2016, par Mani Kandan

  Hi we are using ffmpeg for compressing the video through php script, now what i need is i want to get the video size of compressed image, but am getting an video path so kindly guide me how i need to over come this ?

  Below is the code what i used for compressing the video

  original path

  $path = "sample.mp4";

  Command to compress

  exec("ffmpeg -i sample.mp4 -vcodec h264 -acodec aac -strict -2 compressed_video.mp4);

  The command what i used for getting video size

  $compressed_video_information = exec("ls -h1 compressed_video.mp4);
  
  echo $compressed_video_information;

  I get just file path instaed of getting video file size, so someone help me how to overcome this issue ?