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• Can I run a program from Command Prompt on only a numbered subset of files ?

  28 août 2020, par Andrew Shibata

  I have an experiment with 2 groups : English speakers and Mandarin-English bilinguals. I have a batch file that works for converting audio files (using ffmpeg) for the English monolingual group. The Mandarin speaker group also has a few additional trials where they record some more sentences in Mandarin and I'd like to either run ffmpeg separately on just those trials or move that subset to a different folder after the fact.

  


  The file formats are [subject ID]-[trial #]-vowels_record.ogg. The English trials are trial #s 6-35 and the Mandarin trials are trial #s 36-50.

  


  The following code WORKS for my English only dataset :

  


  for %%a in ("*vowels_record.ogg") do ffmpeg -i "%%a" "vowel_wavs\%%~na.wav

  


  This is my attempt at figuring out how to get just the relevant files into relevant folders :

  


  for %%a in ("*{6..35}-vowels_record.ogg") do ffmpeg -i "%%a" "vowel_wavs\%%~na.wav"
for %%a in ("*{36..50}-vowels_record.ogg") do ffmpeg -i "%%a" "mandarin_wavs\%%~na.wav"


  


  I have some regex experience, but not as much with making .bat files and I'm unsure what the right way is to target the range of files I'm looking for.

  


• Enhance text image in x264 encoding

  24 août 2016, par useprxf

  I’m making use of x264 for remote desktop streaming. The goal is to achieve both low bitrate and high video quality within the computation budget. The current parameter set I used almost achieve this goal, but it fails in handling images with many texts (e.g. browsing websites scene). The text in image is blurred and affects the user experience.

  I think it’s the quantization in x264 that causes this. The quantization after DCT transform will eliminate high frequency sinals which mainly correspond to texts in image.

  So, my question is how to improve the text quality in x264 encoding ?

  My idea : when the bitrate stays at a low level for a period of time,

  1. set crf to be 0 (lossless) ;
  2. encode current frame as an IDR frame and then send it ;
  3. recover the crf.

  Also, a flag should be used to prevent resending when bitrate keeps low for a long time. I haven’t try this method since I don’t know how to mark a frame as an IDR frame manully and then encode it.

• avdevice/decklink : fix MSVC build issues

  6 mai 2017, par Aaron Levinson

  avdevice/decklink : fix MSVC build issues
  Purpose : Made minor changes to get the decklink avdevice code to build
  
  using Visual C++.
  Notes : Made changes to configure per Hendrik Leppkes's review of first
  
  and second versions of patch.  Also made slight alterations per Marton
  
  Balint's reviews.
  Comments :
  — configure : Added if enabled decklink section and setting
  
     decklink_indev_extralibs and decklink_outdev_extralibs here for
  
     both mingw and Windows.  Also eliminated the setting of these
  
     variables in the mingw section earlier in the file.
  — libavdevice/decklink_common.cpp : Switched the order of the include
  
     of libavformat/internal.h to workaround build issues with Visual
  
     C++.  See comment in file for more details.
  — libavdevice/decklink_dec.cpp :
  
  a) Rearranged the include of libavformat/internal.h (for reasons as
  
     described above).
  
  b) Made slight alteration to an argument for call to av_rescale_q() to
  
     workaround a compiler error with Visual C++.  This appears to only
  
     be an issue when building C++ files with Visual C++.  See comment
  
     in code for more details.
  — libavdevice/decklink_enc.cpp : Rearranged the include of
  
     libavformat/internal.h (for reasons as described above).
  Signed-off-by : Aaron Levinson <alevinsn@aracnet.com>
  
  Signed-off-by : Marton Balint <cus@passwd.hu>
  

  • [DH] configure
  • [DH] libavdevice/decklink_common.cpp
  • [DH] libavdevice/decklink_dec.cpp
  • [DH] libavdevice/decklink_enc.cpp