Recherche avancée

Sur d’autres sites (4133)

• Piping the output of ffmpeg directly to Audacity

  21 décembre 2020, par colin baguley

  I'm trying to make a 2 stage process into one CLI command.

  


  First :- I want to extract the audio from a video file

  


  Second :- I want to open up that audio file in Audacity

  


  On the command line at the moment I do this :-

  


  -ffmpeg -i inputfile.mp4 -vn sound.wav ;  audacity sound.wav

  


  which works but involves writing the sound.wav to my disc ( I don't want to keep sound.wav)

  


  It strikes me that it would be quicker if I could just pipe the ffmpeg output directly into audacity but I can't seem to work out how to do it.

  


  Yes - I know that using the GUI of Audacity I can just 'open' the mp4 directly into audacity but I would like to use a CLI command

  


  Thank you for your help ( and have a peaceful and joyful Christmas !)

  


• ffmpeg recording audio / video sync issues [closed]

  1er novembre 2022, par sling jones

  I'm using ffmpeg to record NTSC analog video on Linux Fedora 36 using a Blackmagic Intensity Pro 4K for video and a Scarlett 2i2 for audio. I'm using a TBC to avoid dropped frames and to ensure a constant S-Video Y/C framerate on the analog end.

  


  The problem I'm running into is that on playback the audio will start out relatively in sync with the video at the beginning of the captured file but will eventually run ahead of the video eventually becoming many seconds off.

  


  Nothing I do seems to change this or change the degree to which it happens. The audio and video stay in sync throughout the entire video as I'm monitoring the source so I don't understand how they can diverge so much once encoded into a digital file ?

  


  Here is the command I am using :

  


  ffmpeg -hwaccel cuda -fflags +igndts -format_code ntsc -f decklink -raw_format auto -vsync passthrough -rtbufsize 1500M -thread_queue_size 512 -i 'Intensity Pro 4K' -f pulse -rtbufsize 500M -thread_queue_size 512 -i 'Scarlett 2i2 Camera Analog Stereo' -c copy -map 0:1 -map 1:0 "/tmp/ffmpeg-raw/file-raw.avi"


  


  here's the ffprobe output from one of my files :

  


  Input #0, avi, from 'test2-raw.avi':
  Metadata:
    software        : Lavf59.33.100
  Duration: 00:11:42.87, start: 0.000000, bitrate: 169341 kb/s
  Stream #0:0: Video: rawvideo (UYVY / 0x59565955), uyvy422, 720x486, 167801 kb/s, 59.94 fps, 59.94 tbr, 59.94 tbn
  Stream #0:1: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 48000 Hz, 2 channels, s16, 1536 kb/s



  


  As you can see in my code snippet, I've been throwing things at the wall for a bit. I've tried different rtbufsizes, adding -copyts, and going through the different -vsync options. I've tried it with and without hardware acceleration ( I do have a NVIDIA card), +igdts did get rid of a warning but did not help with the sync, as did changing the thread queue sizes.

  


  OBS can do this, why can't I ?

  


• Recording a Surface using MediaCodec

  3 février 2014, par RuntimeException

  So, In my application, I am able to show effects(like blur filter, gaussian) to video that comes from Camera using GPUImage library.

  Basically, I (library) will take the input from the Camera, get's the raw byte data, converts it into RGBA format from YUV format, then applies effects to this image and displays on the Surface of GLSurfaceView using OpenGL. finally, to the user, it looks like a video with effects applied.

  Now I want to record the frames of Surface as a video using MediaCodec API.

  but this discussion says that we can not pass a predefined Surface to the MediaCodec.

  I have seen some samples at bigflake where he is creating Surface using MediaCodec.createInputSurface() but for me, Surface comes from the GLSurfaceView.

  So, how can I record a frames of a Surface as a video ?

  I will record the audio parallelly, merge that video and audio using FFMPEG and present to the user as a Video with effects applied.