Simple log messages with priorities and categories. A message's SDL_LogPriority signifies how important the message is. A message's SDL_LogCategory signifies from what domain it belongs to. Every category has a minimum priority specified: when a message belongs to that category, it will only be sent out if it has that minimum priority or higher.
SDL's own logs are sent below the default priority threshold, so they are quiet by default.
You can change the log verbosity programmatically using SDL_SetLogPriority() or with SDL_SetHint(SDL_HINT_LOGGING, ...), or with the "SDL_LOGGING" environment variable. This variable is a comma separated set of category=level tokens that define the default logging levels for SDL applications.
The category can be a numeric category, one of "app", "error", "assert", "system", "audio", "video", "render", "input", "test", or * for any unspecified category.
The level can be a numeric level, one of "verbose", "debug", "info", "warn", "error", "critical", or "quiet" to disable that category.
You can omit the category if you want to set the logging level for all categories.
If this hint isn't set, the default log levels are equivalent to:
app=info,assert=warn,test=verbose,*=error
Here's where the messages go on different platforms: