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• Apply sound effects on a video file

  31 mars 2013, par talhamalik22

  I am a little miss guided here and it seems i am totally lost. I am developing an android app and its core idea is to develop a video recorder and video player that applies some sound effects on the voice of the people or any sound that it records. Sound effect means that if i make a video of a person who is giving some speech then there should be no effect on video but his/her voice should appear like voice in talking tom cat app. I hope you understand the idea. Similar app is Helium Booth you can check it here. I am trying to use libraries like libSonic, libpd and tried to use XUGGLE too.
  Read somewhere that Xuggle is not really developed for mobile devices so left it. Now what i want is that it should apply this effect on voice on the run time i.e while recording the pitch of the sound should be alterd and saved immediately. And what i am getting with these libraries is that i can apply sound effect after video is recorded. So it means i need to rip the audio from the video and then apply the change in pitch and frequency and again concatenate this audio file with the old video file. And i have no idea how to do it.
  Please show me the right approach and tools if possible.

  Regards

• How can I stream images from a remote server to a mobile app in real-time ? [closed]

  1er mars 2024, par Tharunkumar Ampolu

  I have a setup where I connect to a remote server via SSH to retrieve images captured by a robot. Currently, I am using scp to transfer these images to my local system, where I then use FFmpeg to convert them into a video for storage.

  


  However, I would like to explore the possibility of converting these images into a video on-the-fly as they are added to the remote server folder, with the goal of streaming this video feed to a mobile app.

  


  My requirements are as follows :

  


  The image stream needs to be transmitted to the mobile app in real-time.
I would prefer to avoid storing the images locally and instead stream them directly from the remote server to the mobile app.
The streaming solution should be scalable and support a high frame rate (30fps).
Could anyone suggest an approach or provide guidance on how to achieve this ? Specifically, I'm interested in methods for continuously converting images into a video stream on the remote server and then streaming this video feed to a mobile app in real-time.

  


  Any insights, code examples, or recommendations for tools and libraries that could help accomplish this task would be greatly appreciated.

  


• How to use ffmpeg in flask server to convert between audio formats without writing files to disk ?

  14 avril 2020, par Athwulf

  I have successfully managed to use ffmpeg in python to convert the format of some audio files like this :

  



  command = "ffmpeg -i audio.wav -vn -acodec pcm_s16le output.wav"
subprocess.call(command, shell=True)


  



  However I want to do this in memory and avoid saving the input and output files to disk.

  



  I have found the follwing code to do such a thing (Passing python’s file like object to ffmpeg via subprocess) :

  



  command = ['ffmpeg', '-y', '-i', '-', '-f', 'wav', '-']
process = subprocess.Popen(command, stdin=subprocess.PIPE)
wav, errordata = process.communicate(file)


  



  But I am struggeling to use this in my context.

  



  I am receiving the file on a server as part of a multipart/form-data request.

  



  @server.route("/api/getText", methods=["POST"])
def api():
    if "multipart/form-data" not in request.content_type:
        return Response("invalid content type: {}".format(request.content_type))
    # check file format
    file = request.files['file']
    if file:
        print('**found file', file.filename)


  



  Now I have the file as a FileStorage Object (https://tedboy.github.io/flask/generated/generated/werkzeug.FileStorage.html). This object has a stream, which can be accessed by using the read method. So I thought I might be able to use this as input for ffmpeg like so :

  



  f = file.read()
command = ['ffmpeg', '-y', '-i', '-', '-f', 'wav', '-']
process = subprocess.Popen(command, stdin=subprocess.PIPE)
wav, errordata = process.communicate(f)


  



  However this yields the the following error :

  



  AssertionError: Given audio file must be a filename string or a file-like object


  



  I have also tried another approach which I found online, using io.BytesIO, to which I can't find the source anymore :

  



  memfile = io.BytesIO()  # create file-object
memfile.write(file.read())  # write in file-object
memfile.seek(0)  # move to beginning so it will read from beginning


  



  And then trying this again :

  



  command = ['ffmpeg', '-y', '-i', '-', '-f', 'wav', '-']
process = subprocess.Popen(command, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
wav, errordata = process.communicate(memfile)


  



  This gets me the following error :

  



  TypeError: a bytes-like object is required, not '_io.BytesIO'


  



  Does anyone have an idea of how to do this ?

  



  Update

  



  The first error message is actually not a error message thrown by ffmpeg. As v25 pointed out correctly in his answer the first approach also returns a bytes object and is also a valid solution.

  



  The error message got thrown by a library (speech_recognition) when trying to work with the modified file. In the unlikely case of someone coming across the same problem here the solution :

  



  The bytes objected returned by ffmpeg (variable wav) has to be turned into a file-like object as the error message implies. This can easily be done like this :

  



  memfileOutput = io.BytesIO(wav)