Logging API for C scripts

[LordMZTE]

Expected behavior of the wanted feature

Similar to the mp.msg module for Lua scripts which allows sending log messages, we should implement a similar API that can be used by C scripts. I have checked client.h but could not find any function definitions that would allow this.

Alternative behavior of the wanted feature

Manually printing log messages to stderr. This not only looks out-of-line, but will also clobber term-osd.

Log File

No response

Sample Files

The API could perhaps look something like this:

typedef enum mpv_log_level {
    MPV_TRACE,
    MPV_DEBUG,
    MPV_VERBOSE,
    MPV_INFO,
    MPV_WARN,
    MPV_ERROR,
    MPV_FATAL
} mpv_log_level;

// Send a string log message
void mpv_msg_log(mpv_log_level level, const char *msg);

// Use format strings (this could also just be `mpv_msg_log`)
void mpv_msg_logf(mpv_log_level level, const char *fmt, ...);

// Perhaps also shorthands for log levels such as `mpv_msg_info`.

[sfan5]

Sounds useful 👍
Perhaps it should be a command instead? Then it's instantly applicable to Lua scripts and JSON IPC too.

[LordMZTE]

Interesting idea! This would cause a sort of API duplication for the higher-level scripting languages, though, as those already have mp.msg.log. Should we deprecate the mp.msg module, then?

[LordMZTE]

Another thought I forgot to mention: Since log messages are namespaced, should we add the ability to set this namespace to the API, or do we always use the client name as namespace?

[stax76]

I've requested this too in an older issue: #14551