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• ffmpeg Live Input MP4 Error [migrated]

  3 mars 2013, par Brianjs

  Currently I have a mic and a webcam connected to my computer. I am running ffmpeg on CentOS 6.3.

  When I try to record a video without audio by :

  ffmpeg -y -f video4linux2 -t 15 -s 640x480 -r 25 -i /dev/video0 /home/irdb/Desktop/out2.mp4

  it runs perfectly and I get a nice video. However when I try to run with audio included by :

  ffmpeg -y -f video4linux2 -t 15 -s 640x480 -r 25 -i /dev/video0 -f alsa -ar 22050 -ab 64k -ac 2 -i default /home/irdb/Desktop/out2.mp4

  It errors out and prints :

  [NULL @ 0x1e33fc0] Codec is experimental but experimental codecs are not enabled,      see -strict -2
  
  Output #0, mp4, to '/home/irdb/Desktop/out2.mp4':
  
  Stream #0:0: Video: h264, yuv420p, 640x480, q=-1--1, 90k tbn, 25 tbc
  
  Stream #0:1: Audio: none, 22050 Hz, 2 channels, flt, 128 kb/s
  
  Stream mapping:
  
  Stream #0:0 -> #0:0 (rawvideo -> libx264)
  
  Stream #1:0 -> #0:1 (pcm_s16le -> aac)
  
  Error while opening encoder for output stream #0:1 - maybe incorrect parameters such    as bit_rate, rate, width or height

  I assume this has to do with the first error as when I use something like mpg it works just fine. However I plan on streaming this live and want mp4 format as that is pretty much supported by all browsers (Firefox with flash fallback).

  Does anyone know how to get the audio to work without additional processing (as I want to stream live and not write to a file eventually).

• aaccoder : tweak PNS implementation further

  9 septembre 2015, par Rostislav Pehlivanov

  aaccoder : tweak PNS implementation further
  This commit changes a few things about the noise substitution
  
  logic :
  
   - Brings back the quantization factor (reduced to 3) during
  
     scalefactor index calculations.
  
   - Rejects any zeroed bands. They should be inaudiable and it’s
  
     a waste transmitting the scalefactor indices for these.
  
   - Uses swb_offsets instead of incrementing a ’start’ with every
  
     window group size.
  
   - Rejects all PNS during short windows.
  
  Overall improves quality. There was a plan to use the lfg system
  
  to create the random numbers instead of using whatever the decoder
  
  uses but for now this works fine. Entropy is far from important here.
  Signed-off-by : Rostislav Pehlivanov <atomnuker@gmail.com>
  

  • [DH] libavcodec/aaccoder.c
  • [DH] tests/fate/aac.mak

• How can I send a virtual camera to Genymotion or Android Studio Emulator in Ubuntu ?

  4 décembre 2020, par ykasur

  I created a virtual camera using v4l2loopback and ffmpeg. The command I use for ffmpeg is :
ffmpeg -re -l oop 1 -i vin.png -vf format=yuv420p -f v4l2 /dev/video2

  


  vin.png is the image I want to stream to the webcam and /dev/video2 is the virtual webcam I created with v4l2loopback.
The virtual webcam works and I can see it e.g. with onlinemicetest.com/webcam-test.
I'm using the Genymotion emulator with the newest Android API (I tried 7.0, 8.1 and 10.0) on Ubuntu 20.40.
Genymotion detects the virtual camera but only displays a dummy image :
Wrong dummy Image from Genymotion
I also tried (and would prefer to use) the android studio emulator. But I can only select Webcam0 in the configuration of the device camera and that points to the real integrated camera and not to my virtual webcam.

  


  I don't need to use ffmpeg, but I do need to use a tool that lets me control which image to stream from the command line.

  


  Is there a way to solve this ? Many thanks in advance !

  


  Update 17.11.2020 :
The Genymotion support answered me, that they plan to support virtual cameras in the future. They might be ready to add this in mid 2021.