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• ffmpeg - multiple output with thumbnails

  9 décembre 2016, par Thomas

  I would like ffmpeg to do the following :

  • read an input mp4 (-i movie.mp4)
  • skip the first 5 seconds (-ss 5)
  • find scene changes and display the frame numbers (-vf "select=gt(scene\, 0.4, showinfo))
  • output #1 - a gif file (output.gif)
  • output #2 - a contact sheet with all the thumbnails (-vf "select scale=320 :-1, tile=12x200" thumbnails.png)

  This will generate the thumbnails :

  ffmpeg -hide_banner -i d:/Test/movie01.mp4 -ss 5 -vf "select=gt(scene\,0.4), showinfo, scale=320:-1, tile=12x200" -vsync 0 thumbnails%03d.png

  this will generate the gif :

  ffmpeg -hide_banner -i d:/Test/movie01.mp4 -ss 5 -vf "select='not(mod(n,60))',setpts='N/(30*TB)', scale=320:-1" -vsync 0 output.gif

  I would like to do both at once with 2 more features :

  • set fps and resolution for the gif ; I would like the gif to represent the whole movie in X seconds, at Y fps (I know the duration of the input movie so I can calculate how often a frame needs to be captured)

  • set the width only for the thumbnail picture (tile=12 for example) and let ffmpeg determine the appropriate height

  I have tried to compose a command line from what I read on this page : https://trac.ffmpeg.org/wiki/Creating%20multiple%20outputs, using the split / map commands but I couldn’t get it to work

• Mapping streams by language in FFmpeg

  8 décembre 2016, par ffmpeg123

  I have lots of files with multiple audio and subtitle languages, however the track numbers aren’t consistent (the English audio stream isn’t always the first) so using a command such as :

  ffmpeg -i "input.mkv" -map 0 -map -0:a:1 -c:v copy -c:a copy "output.mkv"

  doesn’t yield expected results. After searching around I discovered it was possible to map streams based on language with this command :

  ffmpeg -i "input.mkv" -map 0 -map -0:m:language:eng -c:v copy -c:a copy "output.mkv"

  However -map -0:m:language:eng will remove all tracks with the English language flag. To keep the subtitle tracks you can use -map 0:s this is a good solution however, I want to know if it’s possible to only map audio streams based on language.

• arm : vp9 : Add NEON itxfm routines

  14 novembre 2016, par Martin Storsjö

  arm : vp9 : Add NEON itxfm routines
  This work is sponsored by, and copyright, Google.
  For the transforms up to 8x8, we can fit all the data (including
  
  temporaries) in registers and just do a straightforward transform
  
  of all the data. For 16x16, we do a transform of 4x16 pixels in
  
  4 slices, using a temporary buffer. For 32x32, we transform 4x32
  
  pixels at a time, in two steps of 4x16 pixels each.
  Examples of relative speedup compared to the C version, from checkasm :
  
                           Cortex       A7     A8     A9    A53
  
  vp9_inv_adst_adst_4x4_add_neon :     3.39   5.83   4.17   4.01
  
  vp9_inv_adst_adst_8x8_add_neon :     3.79   4.86   4.23   3.98
  
  vp9_inv_adst_adst_16x16_add_neon :   3.33   4.36   4.11   4.16
  
  vp9_inv_dct_dct_4x4_add_neon :       4.06   6.16   4.59   4.46
  
  vp9_inv_dct_dct_8x8_add_neon :       4.61   6.01   4.98   4.86
  
  vp9_inv_dct_dct_16x16_add_neon :     3.35   3.44   3.36   3.79
  
  vp9_inv_dct_dct_32x32_add_neon :     3.89   3.50   3.79   4.42
  
  vp9_inv_wht_wht_4x4_add_neon :       3.22   5.13   3.53   3.77
  Thus, the speedup vs C code is around 3-6x.
  This is mostly marginally faster than the corresponding routines
  
  in libvpx on most cores, tested with their 32x32 idct (compared to
  
  vpx_idct32x32_1024_add_neon). These numbers are slightly in libvpx’s
  
  favour since their version doesn’t clear the input buffer like ours
  
  do (although the effect of that on the total runtime probably is
  
  negligible.)
                             Cortex       A7       A8       A9      A53
  
  vp9_inv_dct_dct_32x32_add_neon :    18436.8  16874.1  14235.1  11988.9
  
  libvpx vpx_idct32x32_1024_add_neon 20789.0  13344.3  15049.9  13030.5
  Only on the Cortex A8, the libvpx function is faster. On the other cores,
  
  ours is slightly faster even though ours has got source block clearing
  
  integrated.
  This is an adapted cherry-pick from libav commits
  
  a67ae67083151f2f9595a1f2d17b601da19b939e and
  
  52d196fb30fb6628921b5f1b31e7bd11eb7e1d9a.
  Signed-off-by : Ronald S. Bultje <rsbultje@gmail.com>
  

  • [DH] libavcodec/arm/Makefile
  • [DH] libavcodec/arm/vp9dsp_init_arm.c
  • [DH] libavcodec/arm/vp9itxfm_neon.S