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• mips : put "disable mipsfpu" in a better place for loongson

  3 décembre 2015, par Vicente Olivert Riera

  mips : put "disable mipsfpu" in a better place for loongson
  Let’s disable the ISAs first, and then the core capabilities, as we do
  
  for the rest of the cores. This way the code is better organized.
  Signed-off-by : Vicente Olivert Riera <Vincent.Riera@imgtec.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] configure

• using ffmpeg to create a wavefile image from opus

  29 décembre 2015, par edwardsmarkf

  I have been trying to use ffmpeg to create a wavefile image from an opus file. so far i have found three different methods but cannot seem to determine which one is the best.

  The end result is hopefully to have a sound-wave that is only approx. 55px in height. The image will become part of a css background-image.

  Adapted from Generating a waveform using ffmpeg :

  ffmpeg -i file.opus -filter_complex
  "showwavespic,colorbalance=bs=0.5:gm=0.3:bh=-0.5,drawbox=x=(iw-w)/2:y=(ih-h)/2:w=iw:h=1:color=black@0.5"
  file.png

  which produces this image :
  

  Next, I found this one (and my favorite because of the simplicity) :

  ffmpeg -i test.opus -lavfi showwavespic=split_channels=1:s=1024x800 test.png

  And here is what that one looks like :

  

  Finally, this one from FFmpeg Wiki : Waveform, but it seems less efficient using a second utility (gnuplot) rather than just ffmpeg :

  ffmpeg -i file.opus -ac 1 -filter:a
  aresample=4000 -map 0:a -c:a pcm_s16le -f data - | \
  gnuplot -e "set
  terminal png size 525,050 ;set output
  ’file.png’ ;unset key ;unset tics ;unset border ; set
  lmargin 0 ;set rmargin 0 ;set tmargin 0 ;set bmargin 0 ; plot ’

  

  Option two is my favorite, but i dont like the margins on the top and bottom of the waveforms.

  Option three (using gnuplot) makes the best ’shaped’ image for our needs, since the initial spike in sound seems to make the rest almost too small to use (lines tend to almost disappear) when the image is sized at only 50 pixels high.

  Any suggestions how might best approach this ? I really understand very little about any of the options I see, except of course for the size. Note too i have 10’s of thousands to process, so naturally i want to make a wise choice at the very beginning.

• aacenc_tns : tune and reduce artifacts

  6 décembre 2015, par Rostislav Pehlivanov

  aacenc_tns : tune and reduce artifacts
  There are a couple of major changes here :
  1. Start using TNS coefficient compression.
  
  2. Start using 3 bits per coefficient maximum for short windows.
  
  The bits we save from these 2 changes seem to make a nice impact on the
  
  rest of the file/windows.
  3. Remove special case gain checking for short windows.
  
  4. Modify the coefficient loop to support up to 3 windows.
  
  The additional restrictions on TNS were something that was no in the
  
  specifications and furthermore restricting TNS to only low energy short
  
  windows was done to compensate for bugs elsewhere in the code.
  Overall, the improvements here reduce crackling artifacts heard in very
  
  noisy tracks.
  Signed-off-by : Rostislav Pehlivanov <atomnuker@gmail.com>
  

  • [DH] libavcodec/aacenc_tns.c