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• No Audio recorded with FFMPEG ALSA Loopback

  6 août 2019, par Dhruvin Bhatt

  I am trying to record screen with audio. I played an mp4 file with audio and video in browser and I tried the command specified here, and tried to save output to mp4 as well as mkv files. But the screen records with no audio. I have installed Alsa loopback with

  sudo apt-get install linux-image-extra-virtual

  modprobe snd-aloop

  The outputs of arecord -l and aplay -l are arecord -l aplay -l

  I have tried all hw devices like hw:0, hw:2, hw:0,1, hw:0,1,0

  I am using Ubuntu 18.04 with FFMPEG version 4.0.3-1 18.04.york0

  I have faced same issue with FFMPEG version 3.4.4-0ubuntu0.18.04.1

  The same issue is also faced in Ubuntu 16.04 with FFMPEG version 4.0.3-1 16.04.york0.

  Please help me solve this. I can not use any other packages like Simple-Screen-Recorder or PulseAudio, as the command which I am trying to run for an application uses only FFMPEG and Alsa Loopback, and is not changeable.

• How to open anullsrc input ?

  5 mai 2022, par dgsgsdgsgdhddhg

  I'm trying :

  


      avformat_open_input(
        &input_context,
        "anullsrc",       
        NULL,
        NULL
    );


  


  That however does not work and input_context remains NULL.

  


  The 3rd argument, NULL, is an optional AVInputFormat.
https://ffmpeg.org/doxygen/trunk/group__lavf__decoding.html#gac05d61a2b492ae3985c658f34622c19d

  


  fmt    If non-NULL, this parameter forces a specific input format. Otherwise the format is autodetected.

  


  I wanted to supply it by first creating the AVInputFormat with av_find_input_format - that however fails to find the format (lavfi), because it seems not to be registered in file ./libavformat/allformats.c even though it exists in ./libavdevice/lavfi.c.

  


  Edit

  


  I might have found an issue. When I do :

  


  $ ffmpeg -v 0 -demuxers | grep lavfi


  


  The output is :

  


   D  lavfi           Libavfilter virtual input device



  


  However, when I do :

  


  main | grep lavfi


  


  Where main is my program which includes :

  


      while ((fmt = av_demuxer_iterate(&i)))                                      
        printf("%s\n", fmt->name);  


  


  I get no output (I confirm that some demuxers are listed if I don't grep for lavfi).

  


  So it seems then, that libavformat.h does not know about lavfi demuxer, whereas ffmpeg does. So it seems I need to fix this issue now.

  


• How do I read an mp4 file directly into moviepy from S3 ?

  9 novembre 2022, par racket99

  Any idea how to read an S3 mp4 file directly into moviepy ?

  



  I have tried,

  



  import boto3
from io import BytesIO
from moviepy.editor import *

client = boto3.client('s3')
obj =  client.get_object(Bucket='some-bucket', Key='some-file')
VideoFileClip(BytesIO(obj['Body'].read())) 


  



  but I am getting,

  



  Traceback (most recent call last):&#xA;File "<stdin>", line 1, in <module>&#xA;File "/<path>/lib/python3.6/site-packages/moviepy/video/io/VideoFileClip.py", line 91, in __init__&#xA;fps_source=fps_source)&#xA;File "/<path>/lib/python3.6/site-packages/moviepy/video/io/ffmpeg_reader.py", line 33, in __init__&#xA;fps_source)&#xA;File "/<path>/lib/python3.6/site-packages/moviepy/video/io/ffmpeg_reader.py", line 243, in ffmpeg_parse_infos&#xA;is_GIF = filename.endswith(&#x27;.gif&#x27;)&#xA;AttributeError: &#x27;_io.BytesIO&#x27; object has no attribute &#x27;endswith&#x27;&#xA;</path></path></path></module></stdin>

  



  where path is my virtual environment