Music&Video

Convert MP4 to MP3 files

• general options

ffmpeg -v 5 -y -i input.mp4 -acodec libmp3lame -ac 2 -ab 192k output.mp3

• general from scipt *

ffmpeg -v 5 -y -i input.mp4 -acodec libmp3lame -ac 2 -ab 192k output.mp3 < /dev/null

3 steps to find out and test a microphone on linux with alsa

1) find out cards and inputs

shell> cat /proc/asound/cards
 0 [Intel          ]: HDA-Intel - HDA Intel
                      HDA Intel at 0xff950000 irq 22
 1 [HVR900         ]: USB-Audio - WinTV HVR-900
                      WinTV HVR-900 at usb-0000:00:1a.7-3, high speed
 2 [Webcam         ]: USB-Audio - Philips SPC 1000NC Webcam
                      Philips CE Philips SPC 1000NC Webcam at
usb-0000:00:1a.7-5.4, high speed

=> I'm going to use the Webcam built in mic => card # 2

2) find out the input

shell> cat /proc/asound/devices
  0: [ 0]   : control
  1:        : sequencer
  6: [ 0- 2]: hardware dependent
  7: [ 0- 3]: hardware dependent
 16: [ 0- 0]: digital audio playback
 17: [ 0- 1]: digital audio playback
 19: [ 0- 3]: digital audio playback
 24: [ 0- 0]: digital audio capture
 32: [ 1]   : control
 33:        : timer
 56: [ 1- 0]: digital audio capture
 64: [ 2]   : control
 88: [ 2- 0]: digital audio capture

=> my input is the capture on the second card

 88: [ 2- 0]: digital audio capture

3) so no we can test the mic

shell> arecord -c1 -Dplughw:2,0 -f cd -vv /dev/null