write a custom double to string formatting function to trim trailing 0s

shaka-project · Jul 21, 2023 · 4a642a1 · 4a642a1
1 parent 1dc1fa1
commit 4a642a1
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Showing 3 changed files with 22 additions and 3 deletions.
diff --git a/packager/mpd/base/mpd_utils.cc b/packager/mpd/base/mpd_utils.cc
@@ -188,13 +188,30 @@ std::string GetAdaptationSetKey(const MediaInfo& media_info,
   return key;
 }
 
+std::string FloatToXmlString(double number) {
+  // Keep up to microsecond accuracy but trim trailing 0s
+  std::string formatted = absl::StrFormat("%.6g", number);
+  size_t decimalPos = formatted.find('.');
+  if (decimalPos != std::string::npos) {
+    size_t lastNonZeroPos = formatted.find_last_not_of('0');
+    if (lastNonZeroPos >= decimalPos) {
+      formatted.erase(lastNonZeroPos + 1);
+    }
+    if (formatted.back() == '.') {
+      formatted.pop_back();
+    }
+  }
+
+  return formatted;
+}
+
 std::string SecondsToXmlDuration(double seconds) {
   // Chrome internally uses time accurate to microseconds, which is implemented
   // per MSE spec (https://www.w3.org/TR/media-source/).
   // We need a string formatter that has at least microseconds accuracy for a
-  // normal video (with duration up to 3 hours). Chrome's DoubleToString
+  // normal video (with duration up to 3 hours). FloatToXmlString
   // implementation meets the requirement.
-  return absl::StrFormat("PT%gS", seconds);
+  return absl::StrFormat("PT%sS", FloatToXmlString(seconds));
 }
 
 bool GetDurationAttribute(xmlNodePtr node, float* duration) {

diff --git a/packager/mpd/base/mpd_utils.h b/packager/mpd/base/mpd_utils.h
@@ -50,6 +50,8 @@ std::string GetBaseCodec(const MediaInfo& media_info);
 // Returns a key made from the characteristics that separate AdaptationSets.
 std::string GetAdaptationSetKey(const MediaInfo& media_info, bool ignore_codec);
 
+std::string FloatToXmlString(double number);
+
 std::string SecondsToXmlDuration(double seconds);
 
 // Tries to get "duration" attribute from |node|. On success |duration| is set.

diff --git a/packager/mpd/base/xml/xml_node.cc b/packager/mpd/base/xml/xml_node.cc
@@ -203,7 +203,7 @@ bool XmlNode::SetFloatingPointAttribute(const std::string& attribute_name,
                                         double number) {
   DCHECK(impl_->node);
   return xmlSetProp(impl_->node.get(), BAD_CAST attribute_name.c_str(),
-                    BAD_CAST(absl::StrFormat("%g", number).c_str())) != nullptr;
+                    BAD_CAST(FloatToXmlString(number).c_str())) != nullptr;
 }
 
 bool XmlNode::SetId(uint32_t id) {