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• fast encoding video codec ?

  10 mai 2016, par Andy T

  can anybody compare popular video codecs by encoding speed ? I understand that usually better compression requires more processing time, but it’s also possible that some codecs still provide comparably good compression with fast encoding. any comparison links ?

  thanks for your help

  [EDIT] : codecs can be compared by used algorithms, regardless of its particular implementation, hardware used or video source, something like big O for mathematical algorithms

• fast encoding video codec ?

  4 août 2023, par Andriy Tylychko

  can anybody compare popular video codecs by encoding speed ? I understand that usually better compression requires more processing time, but it's also possible that some codecs still provide comparably good compression with fast encoding. any comparison links ?

  



  thanks for your help

  



  [EDIT] : codecs can be compared by used algorithms, regardless of its particular implementation, hardware used or video source, something like big O for mathematical algorithms

  


• Compile error when using ffmpeg

  30 janvier 2016, par polin

  I’ve found a strange problem during the compile of an example of ffmpeg in Qt Mac.

  I have installed the ffmpeg library and I have tested the examples of this with cc and gcc compiler on the terminal, and I don’t have any problem in the case of compile and run.

  But when I call the library (ffmpeg are C library) in Qt for compile the same code of the example, the g++ compiler give me many error.

  I have used this structure in the main.cpp code :

  #include "mainwindow.h"
  
  #include "ui_mainwindow.h"
  
  #include <qfiledialog>
  
  
  
  extern "C" {
  
  #include <libavutil></libavutil>imgutils.h>
  
  #include <libavutil></libavutil>samplefmt.h>
  
  #include <libavutil></libavutil>timestamp.h>
  
  #include <libavformat></libavformat>avformat.h>
  
  }
  
  
  
  #include <qdebug>
  
  </qdebug></qfiledialog>

  and the Compile Output gives me :

  In file included from ../audvid/main.cpp:7:
  
  /opt/local/include/libavutil/timestamp.h: In function 'char*
  
  av_ts_make_string(char*, int64_t)':
  
  /opt/local/include/libavutil/timestamp.h:48: warning: comparison
  
  between signed and unsigned integer expressions
  
  /opt/local/include/libavutil/timestamp.h:49: error: expected `)'
  
  before 'PRId64' /opt/local/include/libavutil/timestamp.h:49: warning:
  
  spurious trailing '%' in format
  
  /opt/local/include/libavutil/timestamp.h:49: warning: too many
  
  arguments for format /opt/local/include/libavutil/timestamp.h: At
  
  global scope: /opt/local/include/libavutil/timestamp.h:68: error:
  
  'AVRational' has not been declared
  
  /opt/local/include/libavutil/timestamp.h: In function 'char*
  
  av_ts_make_time_string(char*, int64_t, int*)':
  
  /opt/local/include/libavutil/timestamp.h:70: warning: comparison
  
  between signed and unsigned integer expressions
  
  /opt/local/include/libavutil/timestamp.h:71: error: 'av_q2d' was not
  
  declared in this scope ../audvid/main.cpp: In function 'int
  
  decode_packet(int*, int)': ../audvid/main.cpp:50: error: cannot
  
  convert 'AVRational*' to 'int*' for argument '3' to 'char*
  
  av_ts_make_time_string(char*, int64_t, int*)' ../audvid/main.cpp:73:
  
  error: cannot convert 'AVRational*' to 'int*' for argument '3' to
  
  'char* av_ts_make_time_string(char*, int64_t, int*)'
  
  ../audvid/main.cpp:75: error: 'struct AVFrame' has no member named
  
  'channels' ../audvid/main.cpp:84: error: 'struct AVFrame' has no
  
  member named 'channels' ../audvid/main.cpp:90: error: 'struct AVFrame'
  
  has no member named 'channels' ../audvid/main.cpp: In function 'int
  
  open_codec_context(int*, AVFormatContext*, AVMediaType)':
  
  ../audvid/main.cpp:112: error: 'av_get_media_type_string' was not
  
  declared in this scope ../audvid/main.cpp:123: error:
  
  'av_get_media_type_string' was not declared in this scope
  
  ../audvid/main.cpp:129: error: 'av_get_media_type_string' was not
  
  declared in this scope ../audvid/main.cpp: In function 'int
  
  get_format_from_sample_fmt(const char**, AVSampleFormat)':
  
  ../audvid/main.cpp:152: warning: comparison between signed and
  
  unsigned integer expressions ../audvid/main.cpp: In function 'int
  
  main(int, char**)': ../audvid/main.cpp:239: error: invalid conversion
  
  from 'void*' to 'uint8_t**' make: *** [main.o] Error 1 make: Leaving
  
  directory
  
  `/Users/polin/Desktop/audvid/audvid-build-    Qt_4_8_0_qt_everywhere_opensource_src_4_8_0_tp-Release'
  
  10:44:37: The process "/usr/bin/make" exited with code 2. Error while
  
  building/deploying project audvid (target: Qt 4.8.0
  
  (qt-everywhere-opensource-src-4.8.0-tp)) When executing step 'Make'

  I don’t understand if I make a mistake in the code or if I must change the Qt compiler ? (and I don’t know how can do this)