Recherche avancée

Sur d’autres sites (6558)

• avformat/mxfdec : do not use sound essence descriptor quantization bits for bits_per_c...

  26 août 2018, par Marton Balint

  avformat/mxfdec : do not use sound essence descriptor quantization bits for bits_per_coded_sample
  It refers to the uncompressed quantization, therefore is not correct for AAC.
  Also change mxf_set_pts to work based on current edit unit if
  
  bits_per_coded_sample is not available.
  Fixes error messages in the sample of ticket #7366.
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] libavformat/mxfdec.c

• recording sound from webcam using ffmpeg

  1er août 2012, par user1545779

  Using ffmpeg arecord -L, I am able to identify my Logitech usb webcam as :

  hw:CARD=U0x46d0x821,DEV=0
  
      USB Device 0x46d:0x821, USB Audio
  
      Direct hardware device without any conversions
  
  plughw:CARD=U0x46d0x821,DEV=0
  
      USB Device 0x46d:0x821, USB Audio
  
      Hardware device with all software conversions

  when I go into /dev/snd/by-id, the webcam is described as :

  usb-046d_0821_6813BFD0-00 -> ../controlC1

  I know that the command to use a sound device in ffmpeg is

  ffmpeg -f alsa -i $ALSA_DEVICE_NAME..

  I have tried

  ffmpeg -f alsa -i "hw:CARD=U0x46d0x821,DEV=0"

  and

  ffmpeg -f alsa  -i "plughw:CARD=U0x46d0x821,DEV=0"

  and in both cases I receive the same error message :

  ALSA lib pcm.c:2208:(snd_pcm_open_noupdate) Unknown PCM hw=CARD=U0x46d0x821,DEV=0
  
  [alsa @ 0x9c96580] cannot open audio device hw=CARD=U0x46d0x821,DEV=0 (No such file or directory)
  
  hw:CARD=U0x46d0x821,DEV=0: Input/output error

  I have also tried :

  ffmpeg -f alsa -i "usb-046d_0821_6813BFD0-00"

  and

  ffmpeg -f alsa -i "usb-046d_0821_6813BFD0-00,DEV=0"

  and have still received error message

  Could you please help in formulating the correct format of the command

• Delay Issue in Screen Recording with Sound Using FFmpeg

  17 novembre 2023, par Vasilis B.

  I'm currently facing a puzzling issue with FFmpeg during screen recording sessions where I've noticed a small but noticeable delay when adding sound. I'm hoping to tap into the community's expertise to understand what might be causing this and how to resolve it.

  


  Here's the command I'm using :

  


  ffmpeg -f dshow -thread_queue_size 1024 -rtbufsize 100M -i "video=screen-capture-recorder:audio=virtual-audio-capturer" -f dshow -c:v h264_nvenc -g 30 -qp 10 -preset llhq -tune ull -pix_fmt yuv420p -vsync vfr -acodec libmp3lame -f rtsp "rtsp://rtsp-server:8554/stream"
This setup is intended to capture both video and audio for streaming purposes. However, I've noticed a small delay (output latency) in the audio when I add the sound component.

  


  


  q=9.0 size=N/A time=00:00:14.36 bitrate=N/A speed=0.998x

  


  


  Here are some specifics :

  


  The delay isn't present when recording video only.

  


  It's a consistent issue regardless of the streaming destination.

  


  The hardware and software environment hasn't shown similar issues with other applications.

  


  Could this delay be related to the way FFmpeg handles the audio and video synchronization, or might it be a hardware-related issue ?

  


  Are there specific FFmpeg flags or settings that could help mitigate this delay ?

  


  Has anyone else experienced similar issues and found workable solutions ?

  


  Any insights, suggestions, or shared experiences would be greatly appreciated. Thanks in advance for your help !

  


  P.S. : If additional details about my setup or configuration are needed, I'm happy to provide them.

  


  I've experimented with different -thread_queue_size and -rtbufsize values but haven't seen significant improvements.