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• aacpsy : correct calculation of minath in psy_3gpp_init

  21 avril 2015, par Andreas Cadhalpun

  aacpsy : correct calculation of minath in psy_3gpp_init
  The minimum of the ath(x, ATH_ADD) function depends on ATH_ADD.
  
  This patch uses the first order approximation to determine it.
  For ATH_ADD = 4 this results in the value at 3407.06812 (-5.24241638)
  
  not the one at 3410 (-5.24237967).
  CC : libav-stabl@libav.org
  
  Signed-off-by : Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
  
  Signed-off-by : Anton Khirnov <anton@khirnov.net>
  

  • [DBH] libavcodec/aacpsy.c

• Converting From 4-bit RAW Audio to WAV (or another output format)

  10 février 2017, par Haravikk

  Okay, so I’ve got some .raw files from an old game (Zork Nemesis) and determined that they’re audio files, however I’m having trouble converting them into something meaningful.

  With a bit of trial and error in Audacity I’ve found that I can listen to a still noisy version of the audio using raw file input settings of 8-bit signed PCM in stereo with a sample rate of 22050hz. However, my suspicion is that the files may in fact be encoded in 4-bits with a sample rate of 44100hz, but I’m having trouble finding a tool that can handle this.

  What I’m looking for is either a tool that can handle 4-bit raw formats, or even a tool that can determine (or guess at) the format of a given .raw file, so I know for sure what I’m dealing with (as I’m just going by trial and error so far).

  I’ve tried sox, but I’m most likely doing something wrong as it complains of an unsupported size :

  sox -r 44100 -e signed -b 4 -c 2 in.raw out.wav

  I was also going to try ffmpeg, but I can’t find the appropriate format/codec to set.

  In case it gives any further clues ; I’ve tried various combinations of settings, increasing sample size while decreasing sample rate increases the (white-)noise, and even 8-bit is still noisy, which is why I’m thinking 4-bit. I’ve tried signed and unsigned, which strangely doesn’t seem to make much of a difference

• Accessing webcam mic from command line version of FFMPEG for android

  19 mai 2014, par user1545779

  I am currently testing audio and video streaming from a webcam using a command line version of FFMPEG on an android box. I am having a problem accessing the webcam mic

  Using Ubuntu as a reference, the correct command to determine the recording devices available is arecord -L . Unfortunately arecord -L does not work on the Android box

  The current command option alsa for accessing the webcam mic is ffmpeg -f alsa -alsa_device_name.. and the previous option of oss does not work either, ie ffmpeg -f -oss.. does not work either.

  The listed audio devices shown in /dev/snd shows the mic portion of the webcam as pcmC3D0c and controlC3. The reason I know this is because if I unplug the webcam these values vanish from the directory listing.

  Has anyone tried successfully to access the mic portion of a webcam using ffmpeg on an android box ?
  How do you formulate the correct format of the command to access the webcam mic.

  Please note that I am able to access the audio and video on my Ubuntu PC using ffmpeg hence i know that both devices work