aout: dec: don't require a valid time_get cb

Refs #27023

include/vlc_aout.h

@@ -181,7 +181,7 @@ struct audio_output
       */
 
     int (*time_get)(audio_output_t *, vlc_tick_t *delay);
-    /**< Estimates playback buffer latency (mandatory, cannot be NULL).
+    /**< Estimates playback buffer latency (can be NULL).
       *
       * This callback computes an estimation of the delay until the current
       * tail of the audio output buffer would be rendered. This is essential
@@ -189,10 +189,9 @@ struct audio_output
       * clock and the media upstream clock (if any).
       *
       * If the audio output clock is exactly synchronized with the system
-      * monotonic clock (i.e. vlc_tick_now()), then aout_TimeGetDefault() can
-      * implement this callback. In that case, drain must be implemented (since
-      * the default implementation uses the delay to wait for the end of the
-      * stream).
+      * monotonic clock (i.e. vlc_tick_now()), then this callback is not
+      * mandatory.  In that case, drain must be implemented (since the default
+      * implementation uses the delay to wait for the end of the stream).
       *
       * This callback is called before the first play() in order to get the
       * initial delay (the hw latency). Most modules won't be able to know this

src/audio_output/dec.c

@@ -101,6 +101,8 @@ static inline struct vlc_tracer *aout_stream_tracer(vlc_aout_stream *stream)
 
 static int aout_TimeGet(audio_output_t *aout, vlc_tick_t *delay)
 {
+    if (aout->time_get == NULL)
+        return -1;
     return aout->time_get(aout, delay);
 }
 

src/audio_output/output.c

@@ -772,7 +772,7 @@ int aout_OutputNew(audio_output_t *aout, vlc_aout_stream *stream,
                       "failing back to linear format");
         return -1;
     }
-    assert(aout->flush && aout->play && aout->time_get && aout->pause);
+    assert(aout->flush && aout->play && aout->pause);
 
     /* Autoselect the headphones mode if available and if the user didn't
      * request any mode */