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• Nested c language function

  3 juillet 2017, par Saqrag

  #if AV_GCC_VERSION_AT_LEAST(4,3)
  
  #define av_alloc_size(...) __attribute__((alloc_size(__VA_ARGS__)))
  
  #else
  
  #define av_alloc_size(...)
  
  #endif
  
  
  
  /**
  
  * Allocate a memory block for an array with av_mallocz().
  
  *
  
  * The allocated memory will have size `size * nmemb` bytes.
  
  *
  
  * @param nmemb Number of elements
  
  * @param size  Size of the single element
  
  * @return Pointer to the allocated block, or `NULL` if the block cannot
  
  *         be allocated
  
  *
  
  * @see av_mallocz()
  
  * @see av_malloc_array()
  
  */
  
  
  
  av_alloc_size(1, 2) static inline void *av_mallocz_array(size_t nmemb, 
  
  size_t size)
  
  {
  
     if (!size || nmemb >= INT_MAX / size)
  
        return NULL;
  
     return av_mallocz(nmemb * size);
  
  }

  I am a c lang primer. I see this function when I read open source. but what kind of function is it ? I have never seen this kind of function before. av_alloc_size(1, 2) and *av_mallocz_array have any relationship ?

• Android libraries for ffmpeg + stagefright. language c++

  10 décembre 2017, par Serhii Skytyba

  I’v making cross-platform program in c++. In my program for Android platform i need video decoding hw acceleration. I have found out, that I need to look in libstagefright.cpp. which contains ffmpeg library. There I have found next includes :

  #include <binder></binder>ProcessState.h>
  
  #include <media></media>stagefright/MetaData.h>
  
  #include <media></media>stagefright/MediaBufferGroup.h>
  
  #include <media></media>stagefright/MediaDebug.h>
  
  #include <media></media>stagefright/MediaDefs.h>
  
  #include <media></media>stagefright/OMXClient.h>
  
  #include <media></media>stagefright/OMXCodec.h>
  
  #include <utils></utils>List.h>

  Also, I found out that the source code of these headers is here : https://android.googlesource.com . But I can’t understand in which way to build them. So, my question is : Where can i get these libraries or how can get the source code, that i need to build ? Also, I look for advice which way I can better use Android video decoding hw acceleration + ffmpeg.

• How to convert a video file into images in c language with libavcodec library ? [on hold]

  25 juillet 2018, par emb-pro

  I am very new to these ffmpeg and libavcodec, I want to produce the images from a video file. I have researched through the internet, I got the resources from dranger’s tutorials. When I was trying to compile that code, I was getting deprecated warnings. I got the updated code from github. Even though I am facing the same problem. Again I got the code from ffmpeg. But it is asking me to provide the correct codec when I am executing.

  I am compiling using the command

  gcc -o tutorial01 tutorial01.c -lavutil -lavformat -lavcodec -lz -lm

  I have installed new versions of ffmpeg, libavcodec, libavformats and libavutilities libraries. I am using ubuntu 16.

  I can update the question if you need any information. Thanks in advance.