FFMPEG研究: Android调试FFMPEG程序

为了方便在Android中调试基于FFMPEG的程序，需要对FFMPEG的log工具进行修改：

原来的av_log函数在log.h / log.c中声明和定义，如下

/**
 * Send the specified message to the log if the level is less than or equal
 * to the current av_log_level. By default, all logging messages are sent to
 * stderr. This behavior can be altered by setting a different logging callback
 * function.
 * @see av_log_set_callback
 *
 * @param avcl A pointer to an arbitrary struct of which the first field is a
 *        pointer to an AVClass struct or NULL if general log.
 * @param level The importance level of the message expressed using a @ref
 *        lavu_log_constants "Logging Constant".
 * @param fmt The format string (printf-compatible) that specifies how
 *        subsequent arguments are converted to output.
 */
void av_log(void *avcl, int level, const char *fmt, ...) av_printf_format(3, 4);

先把它定向到Android 系统log中，修改如下

#ifdef MTK_ANDROID_LOG

#define av_log(avcl, level, fmt, args...)  __android_log_print(ANDROID_LOG_INFO, "ALONG_FFMPEG", fmt, ##args)
//void av_log(void* avcl, int level, const char *fmt, ...);
#else

void av_log(void *avcl, int level, const char *fmt, ...) av_printf_format(3, 4);
#endif