spa: bump channels to 128 again

Remove the SPA_AUDIO_MAX_POSITION define and use the
SPA_AUDIO_MAX_CHANNELS again.

Make a compile time define to override the default max channels of 64.

Make sure we compile the SPA library with the default 64 channels. If
you use the SPA library on a spa_audio_info you will get 64 channel
support, like before. If you want more channels, you will need to make
a padded structure or redefine the MAX_CHANNELS before you use the
spa_audio_info structures. You can use the padded structure with the
new functions that take the structure size.

With the extra checks in the parsing code, we avoid making a
valid spa_audio_info with too many channels that don't fit in the
structure. This means that code that receives a spa_audio_info can
assume there is enough padding for all the channels.

meson.build

@@ -115,6 +115,7 @@ cc_flags = common_flags + [
   '-Werror=old-style-definition',
   '-Werror=missing-parameter-type',
   '-Werror=strict-prototypes',
+  '-DSPA_AUDIO_MAX_CHANNELS=128u',
 ]
 add_project_arguments(cc.get_supported_arguments(cc_flags), language: 'c')
 

spa/include/spa/param/audio/dsd.h

@@ -45,7 +45,7 @@ struct spa_audio_info_dsd {
 	int32_t interleave;				/*< interleave bytes */
 	uint32_t rate;					/*< sample rate (in bytes per second) */
 	uint32_t channels;				/*< channels */
-	uint32_t position[SPA_AUDIO_MAX_POSITION];	/*< channel position from enum spa_audio_channel */
+	uint32_t position[SPA_AUDIO_MAX_CHANNELS];	/*< channel position from enum spa_audio_channel */
 };
 
 #define SPA_AUDIO_INFO_DSD_INIT(...)		((struct spa_audio_info_dsd) { __VA_ARGS__ })

spa/include/spa/param/audio/layout.h

@@ -20,7 +20,7 @@ extern "C" {
 
 struct spa_audio_layout_info {
 	uint32_t n_channels;
-	uint32_t position[SPA_AUDIO_MAX_POSITION];
+	uint32_t position[SPA_AUDIO_MAX_CHANNELS];
 };
 
 #define SPA_AUDIO_LAYOUT_Mono		1, { SPA_AUDIO_CHANNEL_MONO, }

spa/include/spa/param/audio/raw-json.h

@@ -51,7 +51,7 @@ SPA_API_AUDIO_RAW_JSON int
 spa_audio_parse_position(const char *str, size_t len,
 		uint32_t *position, uint32_t *n_channels)
 {
-	return spa_audio_parse_position_n(str, len, position, SPA_AUDIO_MAX_POSITION, n_channels);
+	return spa_audio_parse_position_n(str, len, position, SPA_AUDIO_MAX_CHANNELS, n_channels);
 }
 
 SPA_API_AUDIO_RAW_JSON int

spa/include/spa/param/audio/raw.h

@@ -18,14 +18,10 @@ extern "C" {
  * \{
  */
 
-/* This is the max number of position info, changing this will change the
+/* This is the max number of channels, changing this will change the
- * ABI */
+ * size of some helper structures. This value should be at least 64 */
-#define SPA_AUDIO_MAX_POSITION	64u
-
-/* The suggested number of max channels, can be a compile time constant and
- * does not affect ABI or API */
 #ifndef SPA_AUDIO_MAX_CHANNELS
-#define SPA_AUDIO_MAX_CHANNELS	128u
+#define SPA_AUDIO_MAX_CHANNELS	64u
 #endif
 
 enum spa_audio_format {
@@ -279,16 +275,18 @@ enum spa_audio_volume_ramp_scale {
 #define SPA_AUDIO_FLAG_NONE		(0)		/*< no valid flag */
 #define SPA_AUDIO_FLAG_UNPOSITIONED	(1 << 0)	/*< the position array explicitly
 							 *  contains unpositioned channels. */
-/** Audio information description */
+/** Audio information description. You can assume when you receive this structure
+ * that there is enought padding to accomodate all channel positions in case the
+ * channel count is more than SPA_AUDIO_MAX_CHANNELS. */
 struct spa_audio_info_raw {
 	enum spa_audio_format format;		/*< format, one of enum spa_audio_format */
 	uint32_t flags;				/*< extra flags */
 	uint32_t rate;				/*< sample rate */
-	uint32_t channels;			/*< number of channels. This can be more than SPA_AUDIO_MAX_POSITION
+	uint32_t channels;			/*< number of channels. This can be more than SPA_AUDIO_MAX_CHANNELS
 						 *  and you may assume there is enough padding for the extra
 						 *  channel positions. */
-	uint32_t position[SPA_AUDIO_MAX_POSITION];	/*< channel position from enum spa_audio_channel */
+	uint32_t position[SPA_AUDIO_MAX_CHANNELS];	/*< channel position from enum spa_audio_channel */
-	/* more channels can be added here */
+	/* padding follows here when channels > SPA_AUDIO_MAX_CHANNELS */
 };
 
 #define SPA_AUDIO_INFO_RAW_INIT(...)		((struct spa_audio_info_raw) { __VA_ARGS__ })

spa/lib/lib.c

@@ -1,4 +1,6 @@
 
+#undef SPA_AUDIO_MAX_CHANNELS
+
 #define SPA_API_IMPL	SPA_EXPORT
 #include <spa/utils/defs.h>
 #include <spa/buffer/alloc.h>
@@ -165,9 +167,3 @@
 #include <spa/utils/string.h>
 #include <spa/utils/type.h>
 #include <spa/utils/type-info.h>
-
-
-
-
-
-