AudioFormat: split the printf() calls in ToString()

src/AudioFormat.cxx

@@ -44,16 +44,21 @@ AudioFormat::ApplyMask(AudioFormat mask) noexcept
 StringBuffer<24>
 ToString(const AudioFormat af) noexcept
 {
+	StringBuffer<24> buffer;
+	char *p = buffer.data();
+
 	if (af.format == SampleFormat::DSD && af.sample_rate > 0 &&
 	    af.sample_rate % 44100 == 0) {
 		/* use shortcuts such as "dsd64" which implies the
 		   sample rate */
-		return StringFormat<24>("dsd%u:%u",
-					af.sample_rate * 8 / 44100,
-					af.channels);
+		p += sprintf(p, "dsd%u:", af.sample_rate * 8 / 44100);
+	} else {
+		p += sprintf(p, "%u:%s:",
+			     af.sample_rate,
+			     sample_format_to_string(af.format));
 	}
 
-	return StringFormat<24>("%u:%s:%u",
-				af.sample_rate, sample_format_to_string(af.format),
-				af.channels);
+	p += sprintf(p, "%u", af.channels);
+
+	return buffer;
 }