X-Git-Url: https://git.stderr.nl/gitweb?a=blobdiff_plain;f=libchimara%2Fschannel.c;h=617adc19eb90b46736ecf817468beadf7db6c80b;hb=6bf471dcb4c7d0c36b67bed84097a88b26629258;hp=f4c7bd63a43bdc7f62b1d3826e170f5f07fa4ab5;hpb=1b895ec59efa2ff68e7ca57a4d7ada77f46162ce;p=projects%2Fchimara%2Fchimara.git
diff --git a/libchimara/schannel.c b/libchimara/schannel.c
index f4c7bd6..617adc1 100644
--- a/libchimara/schannel.c
+++ b/libchimara/schannel.c
@@ -172,6 +172,23 @@ finally:
* Remember that it is possible that the library will be unable to create a new
* channel, in which case glk_schannel_create() will return %NULL.
*
+ * When you create a channel using glk_schannel_create(), it has full volume,
+ * represented by the value 0x10000. Half volume would be 0x8000, three-quarters
+ * volume would be 0xC000, and so on. A volume of zero represents silence.
+ *
+ * You can overdrive the volume of a channel by setting a volume greater than
+ * 0x10000. However, this is not recommended; the library may be unable to
+ * increase the volume past full, or the sound may become distorted. You should
+ * always create sound resources with the maximum volume you will need, and then
+ * reduce the volume when appropriate using the channel-volume calls.
+ *
+ *
+ * Mathematically, these volume changes should be taken as linear
+ * multiplication of a waveform represented as linear samples. As I
+ * understand it, linear PCM encodes the sound pressure, and therefore a
+ * volume of 0x8000 should represent a 6 dB drop.
+ *
+ *
* Returns: A new sound channel, or %NULL.
*/
schanid_t
@@ -185,11 +202,14 @@ glk_schannel_create(glui32 rock)
* @rock: The rock value to give the new sound channel.
* @volume: Integer representing the volume; 0x10000 is 100%.
*
- * [DRAFT SPEC]
- *
* The glk_schannel_create_ext() call lets you create a channel with the volume
* already set at a given level.
*
+ * Not all libraries support glk_schannel_create_ext(). You should test the
+ * %gestalt_Sound2 selector before you rely on it; see Testing for Sound
+ * Capabilities.
+ *
* Returns: A new sound channel, or %NULL.
*/
schanid_t
@@ -402,9 +422,14 @@ glk_schannel_play(schanid_t chan, glui32 snd)
* sound is playing, there will be no notification event.
*
* Not all libraries support sound notification. You should test the
- * %gestalt_SoundNotify selector before you rely on it; see Testing for Sound
* Capabilities.
+ *
+ * Note that you can play a sound on a channel whose volume is zero. This has
+ * no audible result, unless you later change the volume; but it produces
+ * notifications as usual. You can also play a sound on a paused channel; the
+ * sound is paused immediately, and does not progress.
*
* Returns: 1 on success, 0 on failure.
*/
@@ -482,8 +507,6 @@ glk_schannel_play_ext(schanid_t chan, glui32 snd, glui32 repeats, glui32 notify)
* @sndarray: Array of sound resource numbers.
* @soundcount: Length of @sndarray, must be equal to @chanarray.
* @notify: If nonzero, request a notification when each sound finishes.
- *
- * [DRAFT SPEC]
*
* This works the same as glk_schannel_play_ext(), except that you can specify
* more than one sound. The channel references and sound resource numbers are
@@ -496,6 +519,11 @@ glk_schannel_play_ext(schanid_t chan, glui32 snd, glui32 repeats, glui32 notify)
* a number from 0 to @soundcount.)
*
*
+ * If the @notify argument is nonzero, you will get a separate sound
+ * notification event as each sound finishes. They will all have the same
+ * @val2 value.
+ *
+ *
* Note that you have to supply @chancount and @soundcount as separate
* arguments, even though they are required to be the same. This is an awkward
* consequence of the way array arguments are dispatched in Glulx.
@@ -610,9 +638,7 @@ glk_schannel_stop(schanid_t chan)
/**
* glk_schannel_pause:
* @chan: Channel to pause.
- *
- * [DRAFT SPEC]
- *
+ *
* Pause any sound playing in the channel. This does not generate any
* notification events. If the channel is already paused, this does nothing.
*
@@ -649,11 +675,16 @@ glk_schannel_pause(schanid_t chan)
/**
* glk_schannel_unpause:
* @chan: Channel to unpause.
- *
- * [DRAFT SPEC]
*
* Unpause the channel. Any paused sounds begin playing where they left off. If
* the channel is not already paused, this does nothing.
+ *
+ *
+ * This means, for example, that you can pause a channel that is currently
+ * not playing any sounds. If you then add a sound to the channel, it will
+ * not start playing; it will be paused at its beginning. If you later
+ * unpaise the channel, the sound will commence.
+ *
*/
void
glk_schannel_unpause(schanid_t chan)
@@ -680,39 +711,25 @@ glk_schannel_unpause(schanid_t chan)
}
}
-static double
-volume_glk_to_gstreamer(glui32 volume_glk)
-{
- return CLAMP(((double)volume_glk / 0x10000), 0.0, 10.0);
-}
-
-static void
-channel_set_volume_immediately(schanid_t chan, double volume, glui32 notify)
-{
- g_object_set(chan->filter, "volume", volume, NULL);
-
- if(notify != 0)
- event_throw(chan->glk, evtype_VolumeNotify, NULL, 0, notify);
-}
-
/**
* glk_schannel_set_volume:
* @chan: Channel to set the volume of.
* @vol: Integer representing the volume; 0x10000 is 100%.
*
- * Sets the volume in the channel. When you create a channel, it has full
- * volume, represented by the value 0x10000. Half volume would be 0x8000,
- * three-quarters volume would be 0xC000, and so on. A volume of zero represents
- * silence, although the sound is still considered to be playing.
+ * Sets the volume in the channel, from 0 (silence) to 0x10000 (full volume).
+ * Again, you can overdrive the volume by setting a value greater than 0x10000,
+ * but this is not recommended.
+ *
+ * The glk_schannel_set_volume() function does not include duration and notify
+ * values. Both are assumed to be zero: immediate change, no notification.
*
- * You can call this function between sounds, or while a sound is playing. The
- * effect is immediate.
+ * You can call this function between sounds, or while a sound is playing.
+ * However, a zero-duration change while a sound is playing may produce
+ * unpleasant clicks.
*
- * You can overdrive the volume of a channel by setting a volume greater than
- * 0x10000. However, this is not recommended; the library may be unable to
- * increase the volume past full, or the sound may become distorted. You should
- * always create sound resources with the maximum volume you will need, and then
- * call glk_schannel_set_volume() to reduce the volume when appropriate.
+ * At most one volume change can be occurring on a sound channel at any time.
+ * If you call this function while a previous volume change is in progress, the
+ * previous change is interrupted.
*
* Not all libraries support this function. You should test the
* %gestalt_SoundVolume selector before you rely on it; see volume_notify)
event_throw(chan->glk, evtype_VolumeNotify, NULL, 0, chan->volume_notify);
+ chan->volume_timer_id = 0;
return FALSE;
}
@@ -765,6 +784,7 @@ volume_change_timeout(schanid_t chan)
return TRUE;
}
+#endif /* GSTREAMER_SOUND */
/**
* glk_schannel_set_volume_ext:
@@ -772,9 +792,7 @@ volume_change_timeout(schanid_t chan)
* @vol: Integer representing the volume; 0x10000 is 100%.
* @duration: Length of volume change in milliseconds, or 0 for immediate.
* @notify: If nonzero, requests a notification when the volume change finishes.
- *
- * [DRAFT SPEC]
- *
+ *
* Sets the volume in the channel, from 0 (silence) to 0x10000 (full volume).
* Again, you can overdrive the volume by setting a value greater than 0x10000,
* but this is not recommended.
@@ -787,18 +805,15 @@ volume_change_timeout(schanid_t chan)
* event with type #evtype_VolumeNotify. The window will be %NULL, @val1 will be
* zero, and @val2 will be the nonzero value you passed as @notify.
*
- * The glk_schannel_set_volume() does not include @duration and @notify values.
- * Both are assumed to be zero: immediate change, no notification.
- *
- * You can call these functions between sounds, or while a sound is playing.
+ * You can call this function between sounds, or while a sound is playing.
* However, a zero-duration change while a sound is playing may produce
* unpleasant clicks.
*
* At most one volume change can be occurring on a sound channel at any time. If
- * you call one of these functions while a previous volume change is in
- * progress, the previous change is interrupted. The beginning point of the new
- * volume change should be wherever the previous volume change was interrupted
- * (rather than the previous change's beginning or ending point).
+ * you call this function while a previous volume change is in progress, the
+ * previous change is interrupted. The beginning point of the new volume change
+ * should be wherever the previous volume change was interrupted (rather than
+ * the previous change's beginning or ending point).
*
* Not all libraries support these functions. You should test the appropriate
* gestalt selectors before you rely on them; see "Testing for Sound
@@ -809,12 +824,20 @@ glk_schannel_set_volume_ext(schanid_t chan, glui32 vol, glui32 duration, glui32
{
VALID_SCHANNEL(chan, return);
/* Silently ignore out-of-range volume values */
-
+
#ifdef GSTREAMER_SOUND
+ /* Interrupt a previous volume change */
+ if(chan->volume_timer_id > 0)
+ g_source_remove(chan->volume_timer_id);
+
double target_volume = volume_glk_to_gstreamer(vol);
if(duration == 0) {
- channel_set_volume_immediately(chan, target_volume, notify);
+ g_object_set(chan->filter, "volume", target_volume, NULL);
+
+ if(notify != 0)
+ event_throw(chan->glk, evtype_VolumeNotify, NULL, 0, notify);
+
return;
}
@@ -828,7 +851,7 @@ glk_schannel_set_volume_ext(schanid_t chan, glui32 vol, glui32 duration, glui32
chan->volume_notify = notify;
/* Set up a timer for the volume */
- g_timeout_add(VOLUME_TIMER_RESOLUTION, (GSourceFunc)volume_change_timeout, chan);
+ chan->volume_timer_id = g_timeout_add(VOLUME_TIMER_RESOLUTION, (GSourceFunc)volume_change_timeout, chan);
#endif
}