Add started event directly after process is started.

docs/api.md

@@ -37,6 +37,15 @@ This event is emitted just before `FFmpeg` is executed.
 |-------------|-------------|-----------------------------------------|
 | `arguments` | `list[str]` | A list of arguments to execute `FFmpeg` |
 
+### `started`
+This event is emitted just after `FFmpeg` is executed.
+
+**Parameters:**
+
+|    Name     |     Type    |               Description               |
+|-------------|-------------|-----------------------------------------|
+| `process` | `Popen` | The process object created right after starting `FFmpeg` |
+
 
 ### `stderr`
 This event is emitted when a line is output to the standard error by `FFmpeg`.

docs/examples/monitoring-status.md

@@ -28,6 +28,11 @@ In **python-ffmpeg**, the processing status of ffmpeg can be monitored through e
         def on_start(arguments: list[str]):
             print("arguments:", arguments)
 
+        @ffmpeg.on("started")
+        def on_started(process: subprocess.Popen):
+            print("process id: {process.pid}")
+            os.setpriority(os.PRIO_PROCESS, process.pid, 10)
+
         @ffmpeg.on("stderr")
         def on_stderr(line):
             print("stderr:", line)
@@ -80,6 +85,11 @@ In **python-ffmpeg**, the processing status of ffmpeg can be monitored through e
         def on_start(arguments: list[str]):
             print("arguments:", arguments)
 
+        @ffmpeg.on("started")
+        def on_started(process: subprocess.Popen):
+            print("process id: {process.pid}")
+            os.setpriority(os.PRIO_PROCESS, process.pid, 10)
+
         @ffmpeg.on("stderr")
         def on_stderr(line):
             print("stderr:", line)

ffmpeg/ffmpeg.py

@@ -177,6 +177,8 @@ def execute(self, stream: Optional[Union[bytes, IO[bytes]]] = None, timeout: Opt
             stderr=subprocess.PIPE,
         )
 
+        self.emit("started", self._process)
+
         with concurrent.futures.ThreadPoolExecutor(max_workers=4) as executor:
             self._executed = True
             futures = [