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• ffmpeg 4 : Using the stream_loop parameter to loop the audio during a video ends up with an infinite loop

  17 juin 2020, par JarsOfJam-Scheduler

  Summary

  



  

  1. Context

  


  2. The software I use

  


  3. The problem

  


  4. Results
     
4.1. Actual Results

     



     4.2. Expected Results

  


  5. What did I try to fix the bug ?

  


  6. How to reproduce this bug : minimal and testable example with the provided required data

  


  7. The question

  


  8. Sources

  


  



  ---

  



  Context

  



  I would want to set an audio WAV as the background sound of a video WEBM. The video can be shorter or longer than the audio. At the moment I add the audio over the video, I don't know the length of both streams. The audio must repeat until the video ends (the audio can be truncated if the video ends before the end of the last repetition of the audio).

  



  The software I use

  



  I use ffmpeg version 4.2.2-1ubuntu1 18.04.sav0.

  



  The problem

  



  ffmpeg seems to enter in an infinite loop when it proccesses in order to mix the audio and the video. Also, the length of the currently-generating-output-file (which contains both video and audio) is equal to the length of the audio, instead of the length of the video.

  



  The problem seems to be triggered by this command line :

  



  ffmpeg -i directory_1/video.webm -stream_loop -1 -fflags +shortest -max_interleave_delta 50000 -i directory_2/audio.wav directory_3/video_and_audio.webm


  



  Results

  



  Actual Results

  



  Three things :

  



  


  1. The infinite loop of the ffmpeg process : I must manually stop the ffmpeg process

  


  2. The output video file with music (which is currently generating but output anyway) : it contains both audio and video. But the length of the output file is equal to the length of the audio, instead of the length of the video.

  


  3. The following output logs :

  


  



  


  ffmpeg version 4.2.2-1ubuntu1 18.04.sav0 Copyright (c) 2000-2019 the
 FFmpeg developers built with gcc 7 (Ubuntu 7.5.0-3ubuntu1 18.04)
  
 configuration : —prefix=/usr —extra-version='1ubuntu1 18.04.sav0'
 —toolchain=hardened —libdir=/usr/lib/x86_64-linux-gnu —incdir=/usr/include/x86_64-linux-gnu —arch=amd64 —enable-gpl —disable-stripping —enable-avresample —disable-filter=resample —enable-avisynth —enable-gnutls —enable-ladspa —enable-libaom —enable-libass —enable-libbluray —enable-libbs2b —enable-libcaca —enable-libcdio —enable-libcodec2 —enable-libflite —enable-libfontconfig —enable-libfreetype —enable-libfribidi —enable-libgme —enable-libgsm —enable-libjack —enable-libmp3lame —enable-libmysofa —enable-libopenjpeg —enable-libopenmpt —enable-libopus —enable-libpulse —enable-librsvg —enable-librubberband —enable-libshine —enable-libsnappy —enable-libsoxr —enable-libspeex —enable-libssh —enable-libtheora —enable-libtwolame —enable-libvidstab —enable-libvorbis —enable-libvpx —enable-libwavpack —enable-libwebp —enable-libx265 —enable-libxml2 —enable-libxvid —enable-libzmq —enable-libzvbi —enable-lv2 —enable-omx —enable-openal —enable-opencl —enable-opengl —enable-sdl2 —enable-libdc1394 —enable-libdrm —enable-libiec61883 —enable-nvenc —enable-chromaprint —enable-frei0r —enable-libx264 —enable-shared libavutil 56. 31.100 / 56. 31.100 libavcodec 58. 54.100 / 58. 54.100 libavformat 58. 29.100 / 58. 29.100 libavdevice 58. 8.100 /
 58. 8.100 libavfilter 7. 57.100 / 7. 57.100 libavresample 4. 0. 0 / 4. 0. 0 libswscale 5. 5.100 / 5. 5.100 libswresample 3. 5.100 / 3. 5.100 libpostproc 55. 5.100 /
 55. 5.100 Input #0, matroska,webm, from 'youtubed/my_youtube_video.webm' : Metadata :
 encoder : Chrome Duration : N/A, start : 0.000000, bitrate : N/A
 Stream #0:0(eng) : Video : vp8, yuv420p(progressive), 3200x1608, SAR 1:1 DAR 400:201, 1k tbr, 1k tbn, 1k tbc (default)
 Metadata :
 alpha_mode : 1 Guessed Channel Layout for Input Stream #1.0 : stereo Input #1, wav, from 'tmp_music/original_music.wav' :
  
 Duration : 00:00:11.78, bitrate : 1411 kb/s
 Stream #1:0 : Audio : pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, stereo, s16, 1411 kb/s Stream mapping : Stream #0:0 -> #0:0 (vp8
 (native) -> vp9 (libvpx-vp9)) Stream #1:0 -> #0:1 (pcm_s16le
 (native) -> opus (libopus)) Press [q] to stop, [?] for help
 [libvpx-vp9 @ 0x5645268aed80] v1.8.2 [libopus @ 0x5645268b09c0] No bit
 rate set. Defaulting to 96000 bps. Output #0, webm, to
 'youtubed/my_youtube_video_with_music.webm' : Metadata :
 encoder : Lavf58.29.100
 Stream #0:0(eng) : Video : vp9 (libvpx-vp9), yuv420p(progressive), 3200x1608 [SAR 1:1 DAR 400:201], q=-1—1, 200 kb/s, 1k fps, 1k tbn, 1k
 tbc (default)
 Metadata :
 alpha_mode : 1
 encoder : Lavc58.54.100 libvpx-vp9
 Side data :
 cpb : bitrate max/min/avg : 0/0/0 buffer size : 0 vbv_delay : -1
 Stream #0:1 : Audio : opus (libopus), 48000 Hz, stereo, s16, 96 kb/s
 Metadata :
 encoder : Lavc58.54.100 libopus

  


  



  Expected Results

  



  


  1. No infinite loop during the ffmpeg process

  


  2. Concerning the output logs, I don't know what it should look.

  


  3. The output file with the audio and the video should :

     



     3.1. If the video is longer than the audio, then the audio is repeated until it exactly fits the video. The audio can be truncated.

     



     3.2. If the video is shorter than the audio, then the audio is truncated and exactly fits the video.

     



     3.3. If both video and audio are of the same length, then the audio exactly fits the video.

  


  



  How to reproduce this bug ? (+ required data)

  



  


  1. Download the following files (resp. audio and video) (I must refresh these download links every 24 hours) :

     



     1.1. https://a.uguu.se/dmgsmItjJMDq_audio.wav

     



     1.2. https://a.uguu.se/w3qHDlGq6mOW_video.webm

  


  2. Move them into the directory/directories of your choice.

  


  3. Open your CLI, move to the adequat directory and copy/paste/execute the instruction given in Part. The Problem (don't forget to eventually modify this instruction by indicating the adequat directories, according to step 2.).

  


  4. You'll face my problem.

  


  



  What did I try to fix the bug ?

  



  Nothing, since I don't even understand why the bug occures.

  



  The question

  



  How to correct my command in order to mix these audio and video streams without any infinite loop during the ffmpeg process, keeping in mind that I don't know their length, and that audio must be repeated in order to fit the video, even if audio must be truncated (in the case of the last repetition of the audio file must be truncated because the video stream has just ended) ?

  



  Sources

  



  The source is the command line you can find in Part. The problem.

  


• Building ffmpeg iOS libraries for armv7, armv7s, arm64, i386 and universal

  4 février 2015, par sandy

  I have seen several scripts to build FFmpeg API for armv7, 7s and i386 but couldn’t find anything which would work for armv64 as well. Some of the answers on other threads of this forum suggested to prepare a separate library for arm64 but it does not work well with rest of the architectures. Hence I need a script which can work for all the supported architectures for iOS including armv7, armv7s, armv64 and i386.

• ffmpeg convert variable framerate .webm to constant framerate video

  4 novembre 2019, par Dashadower

  I have a .webm file of a recording of a game at 16fps. However, upon trying to process the video with OpenCV, it seems the video is recorded with a variable framerate, so when I try to use OpenCV to get a frame every second by getting the every 16th frame, it won’t work since the video stream will end prematurely.

  Therefore, I’m trying to convert a variable-frame .webm video, which claims it has a framerate of 16 fps, to a video with a constant frame, so I can extract one frame for every second. I’ve tried the following ffmpeg command from https://ffmpeg.zeranoe.com/forum/viewtopic.php?t=5518 :

  ffmpeg -i input.webm -c:v copy -b:v copy -r 16 output.webm

  However, the following error will occur :

  [NULL @ 00000272ccbc0c40] [Eval @ 000000bc11bfe2f0] Undefined constant or missing '(' in 'copy'
  
  [NULL @ 00000272ccbc0c40] Unable to parse option value "copy"
  
  [NULL @ 00000272ccbc0c40] Error setting option b to value copy.
  
  
  
  Error setting up codec context options.

  Here’s is the code I’m trying to use to process a frame every second :

  video = cv2.VideoCapture(test_mp4_vod_path)
  
  print("Opened ", test_mp4_vod_path)
  
  print("Processing MP4 frame by frame")
  
  
  
  # forward over to the frames you want to start reading from.
  
  # manually set this, fps * time in seconds you wanna start from
  
  video.set(1, 0)
  
  success, frame = video.read()
  
  #fps = int(video.get(cv2.CAP_PROP_FPS))  # this will return 0!
  
  fps = 16  # hardcode fps
  
  total_frame_count = int(video.get(cv2.CAP_PROP_FRAME_COUNT))
  
  print("Loading video %d seconds long with FPS %d and total frame count %d " % (total_frame_count/fps, fps, total_frame_count))
  
  
  
  count = 1
  
  while video.isOpened():
  
      success, frame = video.read()
  
      if not success:
  
          break
  
  
  
      if count % fps == 0:
  
          print("%dth frame is %d seconds on video"%(count, count/fps))
  
      count += 1

  The code will finish before it gets near the end of the video, since the video isn’t at a constant FPS.
  How can I convert a variable-FPS video to a constant FPS video ?