1 files changed, 68 insertions, 5 deletions

diff --git a/channels/iax2/format_compatibility.c b/channels/iax2/format_compatibility.c
index 8085c2c26..be7852c8f 100644
--- a/channels/iax2/format_compatibility.c
+++ b/channels/iax2/format_compatibility.c
@@ -38,6 +38,7 @@ ASTERISK_FILE_VERSION(__FILE__, "$Revision$")
 #include "asterisk/format_compatibility.h"
 #include "asterisk/format_cache.h"
 #include "asterisk/format_cap.h"
+#include "asterisk/utils.h"
 
 #include "include/format_compatibility.h"
 
@@ -59,13 +60,75 @@ uint64_t iax2_format_compatibility_cap2bitfield(const struct ast_format_cap *cap
 
 int iax2_format_compatibility_bitfield2cap(uint64_t bitfield, struct ast_format_cap *cap)
 {
-	int x;
+	int bit;
+
+	for (bit = 0; bit < 64; ++bit) {
+		uint64_t mask = (1ULL << bit);
+
+		if (mask & bitfield) {
+			struct ast_format *format;
+
+			format = ast_format_compatibility_bitfield2format(mask);
+			if (format && ast_format_cap_append(cap, format, 0)) {
+				return -1;
+			}
+		}
+	}
 
-	for (x = 0; x < 64; x++) {
-		uint64_t tmp = (1ULL << x);
+	return 0;
+}
+
+uint64_t iax2_format_compatibility_best(uint64_t formats)
+{
+	/*
+	 * This just our opinion, expressed in code.  We are
+	 * asked to choose the best codec to use, given no
+	 * information.
+	 */
+	static const uint64_t best[] = {
+		/*! Okay, ulaw is used by all telephony equipment, so start with it */
+		AST_FORMAT_ULAW,
+		/*! Unless of course, you're a silly European, so then prefer ALAW */
+		AST_FORMAT_ALAW,
+		AST_FORMAT_G719,
+		AST_FORMAT_SIREN14,
+		AST_FORMAT_SIREN7,
+		AST_FORMAT_TESTLAW,
+		/*! G.722 is better then all below, but not as common as the above... so give ulaw and alaw priority */
+		AST_FORMAT_G722,
+		/*! Okay, well, signed linear is easy to translate into other stuff */
+		AST_FORMAT_SLIN16,
+		AST_FORMAT_SLIN,
+		/*! G.726 is standard ADPCM, in RFC3551 packing order */
+		AST_FORMAT_G726,
+		/*! G.726 is standard ADPCM, in AAL2 packing order */
+		AST_FORMAT_G726_AAL2,
+		/*! ADPCM has great sound quality and is still pretty easy to translate */
+		AST_FORMAT_ADPCM,
+		/*! Okay, we're down to vocoders now, so pick GSM because it's small and easier to
+		    translate and sounds pretty good */
+		AST_FORMAT_GSM,
+		/*! iLBC is not too bad */
+		AST_FORMAT_ILBC,
+		/*! Speex is free, but computationally more expensive than GSM */
+		AST_FORMAT_SPEEX16,
+		AST_FORMAT_SPEEX,
+		/*! Opus */
+		AST_FORMAT_OPUS,
+		/*! Ick, LPC10 sounds terrible, but at least we have code for it, if you're tacky enough
+		    to use it */
+		AST_FORMAT_LPC10,
+		/*! G.729a is faster than 723 and slightly less expensive */
+		AST_FORMAT_G729,
+		/*! Down to G.723.1 which is proprietary but at least designed for voice */
+		AST_FORMAT_G723,
+	};
+	int idx;
 
-		if ((tmp & bitfield) && ast_format_cap_append(cap, ast_format_compatibility_bitfield2format(tmp), 0)) {
-			return -1;
+	/* Find the first preferred codec in the format given */
+	for (idx = 0; idx < ARRAY_LEN(best); ++idx) {
+		if (formats & best[idx]) {
+			return best[idx];
 		}
 	}