ALSA: request large enough buffers first (refs #10422)

With the current input clock and decoder buffering code, getting large
buffers is essential. So favor that over having short audio periods.
(Ideally the audio period should probably be an half or a third of the
PTS delay, rather than hard-coded to 40 ms, but that is a separate
issue).

(cherry picked from commit 4aeccbd7667c65bd278111a26c2aab088bc60a20)

modules/audio_output/alsa.c

@@ -495,15 +495,6 @@ static int Start (audio_output_t *aout, audio_sample_format_t *restrict fmt)
     }
     sys->rate = fmt->i_rate;
 
-#if 1 /* work-around for period-long latency outputs (e.g. PulseAudio): */
-    param = AOUT_MIN_PREPARE_TIME;
-    val = snd_pcm_hw_params_set_period_time_near (pcm, hw, &param, NULL);
-    if (val)
-    {
-        msg_Err (aout, "cannot set period: %s", snd_strerror (val));
-        goto error;
-    }
-#endif
     /* Set buffer size */
     param = AOUT_MAX_ADVANCE_TIME;
     val = snd_pcm_hw_params_set_buffer_time_near (pcm, hw, &param, NULL);
@@ -512,22 +503,14 @@ static int Start (audio_output_t *aout, audio_sample_format_t *restrict fmt)
         msg_Err (aout, "cannot set buffer duration: %s", snd_strerror (val));
         goto error;
     }
-#if 0
-    val = snd_pcm_hw_params_get_buffer_time (hw, &param, NULL);
-    if (val)
-    {
-        msg_Warn (aout, "cannot get buffer time: %s", snd_strerror(val));
-        param = AOUT_MIN_PREPARE_TIME;
-    }
-    else
-        param /= 2;
+
+    param = AOUT_MIN_PREPARE_TIME;
     val = snd_pcm_hw_params_set_period_time_near (pcm, hw, &param, NULL);
     if (val)
     {
         msg_Err (aout, "cannot set period: %s", snd_strerror (val));
         goto error;
     }
-#endif
 
     /* Commit hardware parameters */
     val = snd_pcm_hw_params (pcm, hw);