如何使用的Qt4 libav codeC？

编程入门行业动态更新时间:2024-10-22 20:41:52

本文介绍了如何使用的Qt4 libav codeC？的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！问题描述

我如何使用libav codeC在Qt4的访问单个视频帧？

How do I use libavcodec in Qt4 to access individual video frames?

验证该视频流可以通过libav $ C $立方厘米德$ C $光盘通过编译这个例子，我搬到源$ C $ C到我的C ++程序。现在 av_open_input_file（）突然无法打开我的视频文件。（返回错误code：-2）

After verifying that the video stream can be decoded by libavcodec by compiling this example, I moved the source code to my C++ program. Now av_open_input_file() is suddenly unable to open my video file (returning an errorcode: -2).

调用看起来像这样现在：

The call looks like this right now:

... // Register all formats and codecs avcodec_register_all(); // Open video file QString videoFileName("/absolute/path/to/video.avi"); // from somewhere else in the application const char* fileName = videoFileName.toStdString().c_str(); int err = 0; if((err = av_open_input_file(&pFormatCtx, fileName, NULL, 0, NULL)) != 0) { doErrorHandling(err, fileName); // err = -2 }

当我在看为const char *文件名在调试器中它看起来是正确的。我在做一些基本的错误在混合C和C ++ code（我刚刚从倾倒的例子中，code到一个类的构造函数第一次尝试）？

When I look at const char* fileName inside the debugger it looks correct. Am I making some basic mistake in mixing C and C++ code (for a first attempt I just dumped the code from the example into the constructor of a class)?

注意：为了获取应用程序编译包括我这样的标题：

Note: In order to get the application to compile I include the headers like this:

extern "C" { #define __STDC_CONSTANT_MACROS // for UINT64_C #include <libavcodec/avcodec.h> #include <libavformat/avformat.h> #include <libswscale/swscale.h> }

我也试图硬code的路径，视频文件到应用程序中没有任何成功：

I have also tried to hard code the path to the video file into the application without any success:

av_open_input_file(&pFormatCtx, "/home/bjoernz/video.avi", NULL, 0, NULL);

我是能够编译和执行使用的例子（AV codec_sample.0.5.0.c） G ++ 。

推荐答案

那么，这是尴尬的：

当我转移从这个例子给C ++应用程序我犯了一个愚蠢的错误，当我链接错误，这对我的源$ C $ C，它 av_register_all（）; 不可用......我它重命名为 AV codec_register_all（），一会儿后，我固定链接问题，忘了...

When I transfered the source code from the example to the c++ application I made a stupid mistake when I got linker errors, that told me that av_register_all(); was unavailable... and I renamed it to avcodec_register_all(), a little while later I fixed the linker problem and forgot about it...