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• fftools/ffmpeg_(filter|opt) : Use dedicated pointer for array elem access

  3 décembre 2021, par Andreas Rheinhardt

  fftools/ffmpeg_(filter|opt) : Use dedicated pointer for array elem access
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
  

  • [DH] fftools/ffmpeg_filter.c
  • [DH] fftools/ffmpeg_opt.c

• Improved dataerror (wave/spectrum) exception handling, should result in lowered CPU use if playback continues with access exceptions (eg. YouTube video going in another tab)

  26 novembre 2010, par Scott Schiller

  m src/SoundManager2_AS3.as Improved dataerror (wave/spectrum) exception handling, should result in lowered CPU use if playback continues with access exceptions (eg. YouTube video going in another tab)

• WinAPI multithreading access violation when writing in local variable

  26 février 2016, par JustPingo

  I’m making a multithreaded program using Visual C++, Win32 API (using _beginthread) that also uses FFmpeg (it is claimed to be thread-safe, and I’m using it only with one single thread anyway).

  Here is the part of my thread’s code that causes problems (everything is inside of the thread function) :

  Arena* arena = NULL;
  
  
  
  switch (task) {
  
      case TaskOne:
  
          arena = (Arena*) malloc(sizeof(Arena));
  
          for (uint i = 0; i < FIGHTSPERROUND; i++) {
  
              generateArena(arena, ARENAWALLSAMOUNT, ARENAWIDTH, ARENAHEIGHT, ARENAMAXENTITIES, 255);
  
              spawnPlayer(arena, playerOne, 3, 1, 0, 0, ARENAPLAYERLIFE);
  
              spawnPlayer(arena, playerTwo, 2, 2, ARENAWIDTH-1, ARENAHEIGHT-1, ARENAPLAYERLIFE);
  
  
  
              do {
  
                  tickArena(arena);
  
              } while ((result = getResult(arena)) == 0);
  
  
  
              switch (result) {
  
                  case 1: teamOneScore++; break;
  
                  case 2: teamTwoScore++; break;
  
                  default: break;
  
              }
  
  
  
              freeArena(arena);
  
              clearMemory(playerOne);
  
              clearMemory(playerTwo);
  
              clearBrain(playerOne);
  
              clearBrain(playerTwo);
  
          }
  
          threadTeamOneScore[threadID] = teamOneScore;
  
          threadTeamTwoScore[threadID] = teamTwoScore;
  
          break;
  
  
  
      default: break;
  
  }

  Here is how I generate my arena :

  void generateArena(Arena* arena, uint wallsAmount, uint xSize, uint ySize, uint maxEntities, uint maxTurns) {
  
      CasesTypes** map;
  
      map = (CasesTypes**) malloc(xSize * sizeof(CasesTypes*));
  
      memset(map, 0, xSize * sizeof(CasesTypes*));
  
      for (uint i = 0; i < xSize; i++) {
  
          map[i] = (CasesTypes*)malloc(ySize * sizeof(CasesTypes));
  
          memset(map[i], 0, ySize * sizeof(CasesTypes));
  
      }
  
  
  
      arena->map = map;
  
      arena->entities = (Entity*) malloc(maxEntities * sizeof(Entity));
  
      memset(arena->entities, 0, maxEntities * sizeof(Entity));
  
      arena->width = xSize;
  
      arena->height = ySize;
  
      arena->maxEntities = maxEntities;
  
      arena->maxTurns = maxTurns;
  
      arena->currentTurn = 0;
  
      arena->entitiesAmount = 0;
  
      for (uint i = 0; i < wallsAmount; i++)
  
          arena->map[random2(1, xSize-1)][random2(1, ySize-1)] = Wall;
  
  }

  This works as expected 4 times in 5.
  But sometimes, for some reason, arena = (Arena*) malloc(sizeof(Arena)); throws an access violation exception.

  For example, Visual Studio 2015’s debugger once said :
  Exception thrown at 0x77DBE389 (ntdll.dll) in MyProgram.exe: 0xC0000005: Access violation writing location 0x007C160F.

  When I used the debugger to find what ((void*) 0x007C160F) was, it always happened to be something similar to :

  avformat-57.dll!0x007c160f (load symbols for additional information)

  avformat is a part of FFmpeg. The address was different every times, but it always had something to do with FFmpeg.

  I can’t figure out what is causing the problem.
  If that can help, sometimes the arena also happens to get corrupted (some of its fields get extremely big while generating them with generateArena although it is never changed and only set once to an integer, this leads to a crash later).

  Thank you in advance !