[Cast] Make additional Constraint fields optional

This patch makes the maxDelay and maxPixelsPerSecond fields optional.

Bug: 1154956
Change-Id: I0afc8b31a657a5a6224a74a7c168273fb86ac59b
Reviewed-on: https://chromium-review.googlesource.com/c/openscreen/+/2794863
Commit-Queue: Jordan Bayles <jophba@chromium.org>
Reviewed-by: Brandon Tolsch <btolsch@chromium.org>

7 files changed, 61 insertions, 33 deletions

diff --git a/cast/protocol/castv2/streaming_examples/answer.json b/cast/protocol/castv2/streaming_examples/answer.json
index 97a3e59a..73c45ea2 100644
--- a/cast/protocol/castv2/streaming_examples/answer.json
+++ b/cast/protocol/castv2/streaming_examples/answer.json
@@ -12,8 +12,7 @@
         "maxSampleRate": 96000,
         "maxChannels": 5,
         "minBitRate": 32000,
-        "maxBitRate": 320000,
-        "maxDelay": 4000
+        "maxBitRate": 320000
       },
       "video": {
         "maxPixelsPerSecond": 62208000,
diff --git a/cast/protocol/castv2/streaming_schema.json b/cast/protocol/castv2/streaming_schema.json
index 2c2fc59a..392d135c 100644
--- a/cast/protocol/castv2/streaming_schema.json
+++ b/cast/protocol/castv2/streaming_schema.json
@@ -110,7 +110,7 @@
         "maxBitRate": {"type": "integer", "minimum": 32000, "maximum": 320000},
         "maxDelay": {"$ref": "#/definitions/delay"}
       },
-      "required": ["maxSampleRate", "maxChannels", "maxBitRate", "maxDelay"]
+      "required": ["maxSampleRate", "maxChannels", "maxBitRate"]
     },
     "video_constraints": {
       "properties": {
@@ -122,10 +122,8 @@
         "maxDelay": {"$ref": "#/definitions/delay"}
       },
       "required": [
-        "maxPixelsPerSecond",
         "maxDimensions",
-        "maxBitRate",
-        "maxDelay"
+        "maxBitRate"
       ]
     },
     "constraints": {
diff --git a/cast/streaming/answer_messages.cc b/cast/streaming/answer_messages.cc
index ed308260..906e8901 100644
--- a/cast/streaming/answer_messages.cc
+++ b/cast/streaming/answer_messages.cc
@@ -210,10 +210,15 @@ bool AudioConstraints::ParseAndValidate(const Json::Value& root,
   if (!json::ParseAndValidateInt(root[kMaxSampleRate],
                                  &(out->max_sample_rate)) ||
       !json::ParseAndValidateInt(root[kMaxChannels], &(out->max_channels)) ||
-      !json::ParseAndValidateInt(root[kMaxBitRate], &(out->max_bit_rate)) ||
-      !json::ParseAndValidateMilliseconds(root[kMaxDelay], &(out->max_delay))) {
+      !json::ParseAndValidateInt(root[kMaxBitRate], &(out->max_bit_rate))) {
     return false;
   }
+
+  std::chrono::milliseconds max_delay;
+  if (json::ParseAndValidateMilliseconds(root[kMaxDelay], &max_delay)) {
+    out->max_delay = max_delay;
+  }
+
   if (!json::ParseAndValidateInt(root[kMinBitRate], &(out->min_bit_rate))) {
     out->min_bit_rate = kDefaultAudioMinBitRate;
   }
@@ -227,7 +232,9 @@ Json::Value AudioConstraints::ToJson() const {
   root[kMaxChannels] = max_channels;
   root[kMinBitRate] = min_bit_rate;
   root[kMaxBitRate] = max_bit_rate;
-  root[kMaxDelay] = Json::Value::Int64(max_delay.count());
+  if (max_delay.has_value()) {
+    root[kMaxDelay] = Json::Value::Int64(max_delay->count());
+  }
   return root;
 }
 
@@ -262,16 +269,25 @@ Json::Value Dimensions::ToJson() const {
 // static
 bool VideoConstraints::ParseAndValidate(const Json::Value& root,
                                         VideoConstraints* out) {
-  if (!json::ParseAndValidateDouble(root[kMaxPixelsPerSecond],
-                                    &(out->max_pixels_per_second)) ||
-      !Dimensions::ParseAndValidate(root[kMaxDimensions],
+  if (!Dimensions::ParseAndValidate(root[kMaxDimensions],
                                     &(out->max_dimensions)) ||
       !json::ParseAndValidateInt(root[kMaxBitRate], &(out->max_bit_rate)) ||
-      !json::ParseAndValidateMilliseconds(root[kMaxDelay], &(out->max_delay)) ||
       !ParseOptional<Dimensions>(root[kMinDimensions],
                                  &(out->min_dimensions))) {
     return false;
   }
+
+  std::chrono::milliseconds max_delay;
+  if (json::ParseAndValidateMilliseconds(root[kMaxDelay], &max_delay)) {
+    out->max_delay = max_delay;
+  }
+
+  double max_pixels_per_second;
+  if (json::ParseAndValidateDouble(root[kMaxPixelsPerSecond],
+                                   &max_pixels_per_second)) {
+    out->max_pixels_per_second = max_pixels_per_second;
+  }
+
   if (!json::ParseAndValidateInt(root[kMinBitRate], &(out->min_bit_rate))) {
     out->min_bit_rate = kDefaultVideoMinBitRate;
   }
@@ -280,7 +296,8 @@ bool VideoConstraints::ParseAndValidate(const Json::Value& root,
 
 bool VideoConstraints::IsValid() const {
   return max_pixels_per_second > 0 && min_bit_rate > 0 &&
-         max_bit_rate > min_bit_rate && max_delay.count() > 0 &&
+         max_bit_rate > min_bit_rate &&
+         (!max_delay.has_value() || max_delay->count() > 0) &&
          max_dimensions.IsValid() &&
          (!min_dimensions.has_value() || min_dimensions->IsValid()) &&
          max_dimensions.frame_rate.numerator > 0;
@@ -289,14 +306,20 @@ bool VideoConstraints::IsValid() const {
 Json::Value VideoConstraints::ToJson() const {
   OSP_DCHECK(IsValid());
   Json::Value root;
-  root[kMaxPixelsPerSecond] = max_pixels_per_second;
-  if (min_dimensions.has_value()) {
-    root[kMinDimensions] = min_dimensions->ToJson();
-  }
   root[kMaxDimensions] = max_dimensions.ToJson();
   root[kMinBitRate] = min_bit_rate;
   root[kMaxBitRate] = max_bit_rate;
-  root[kMaxDelay] = Json::Value::Int64(max_delay.count());
+  if (max_pixels_per_second.has_value()) {
+    root[kMaxPixelsPerSecond] = max_pixels_per_second.value();
+  }
+
+  if (min_dimensions.has_value()) {
+    root[kMinDimensions] = min_dimensions->ToJson();
+  }
+
+  if (max_delay.has_value()) {
+    root[kMaxDelay] = Json::Value::Int64(max_delay->count());
+  }
   return root;
 }
 
@@ -346,9 +369,11 @@ bool DisplayDescription::IsValid() const {
   if (aspect_ratio.has_value() && !aspect_ratio->IsValid()) {
     return false;
   }
+
   if (dimensions.has_value() && !dimensions->IsValid()) {
     return false;
   }
+
   // Sender behavior is undefined if the aspect ratio is fixed but no
   // dimensions or aspect ratio are provided.
   if (aspect_ratio_constraint.has_value() &&
diff --git a/cast/streaming/answer_messages.h b/cast/streaming/answer_messages.h
index 4298913b..1f62706a 100644
--- a/cast/streaming/answer_messages.h
+++ b/cast/streaming/answer_messages.h
@@ -41,10 +41,9 @@ struct AudioConstraints {
 
   int max_sample_rate = 0;
   int max_channels = 0;
-  // Technically optional, sender will assume 32kbps if omitted.
-  int min_bit_rate = 0;
+  int min_bit_rate = 0;  // optional
   int max_bit_rate = 0;
-  std::chrono::milliseconds max_delay = {};
+  absl::optional<std::chrono::milliseconds> max_delay = {};
 };
 
 struct Dimensions {
@@ -62,13 +61,12 @@ struct VideoConstraints {
   Json::Value ToJson() const;
   bool IsValid() const;
 
-  double max_pixels_per_second = {};
+  absl::optional<double> max_pixels_per_second = {};
   absl::optional<Dimensions> min_dimensions = {};
   Dimensions max_dimensions = {};
-  // Technically optional, sender will assume 300kbps if omitted.
-  int min_bit_rate = 0;
+  int min_bit_rate = 0;  // optional
   int max_bit_rate = 0;
-  std::chrono::milliseconds max_delay = {};
+  absl::optional<std::chrono::milliseconds> max_delay = {};
 };
 
 struct Constraints {
diff --git a/cast/streaming/capture_recommendations.cc b/cast/streaming/capture_recommendations.cc
index 94ac47de..b30b5dc1 100644
--- a/cast/streaming/capture_recommendations.cc
+++ b/cast/streaming/capture_recommendations.cc
@@ -83,7 +83,9 @@ void ApplyConstraints(const Constraints& constraints,
                       Recommendations* recommendations) {
   // Audio has no fields in the display description, so we can safely
   // ignore the current recommendations when setting values here.
-  recommendations->audio.max_delay = constraints.audio.max_delay;
+  if (constraints.audio.max_delay.has_value()) {
+    recommendations->audio.max_delay = constraints.audio.max_delay.value();
+  }
   recommendations->audio.max_channels = constraints.audio.max_channels;
   recommendations->audio.max_sample_rate = constraints.audio.max_sample_rate;
 
@@ -93,9 +95,15 @@ void ApplyConstraints(const Constraints& constraints,
 
   // With video, we take the intersection of values of the constraints and
   // the display description.
-  recommendations->video.max_delay = constraints.video.max_delay;
-  recommendations->video.max_pixels_per_second =
-      constraints.video.max_pixels_per_second;
+  if (constraints.video.max_delay.has_value()) {
+    recommendations->video.max_delay = constraints.video.max_delay.value();
+  }
+
+  if (constraints.video.max_pixels_per_second.has_value()) {
+    recommendations->video.max_pixels_per_second =
+        constraints.video.max_pixels_per_second.value();
+  }
+
   recommendations->video.bit_rate_limits =
       BitRateLimits{std::max(constraints.video.min_bit_rate,
                              recommendations->video.bit_rate_limits.minimum),
diff --git a/cast/streaming/capture_recommendations.h b/cast/streaming/capture_recommendations.h
index 94855c7c..ccb2475b 100644
--- a/cast/streaming/capture_recommendations.h
+++ b/cast/streaming/capture_recommendations.h
@@ -29,7 +29,7 @@ namespace capture_recommendations {
 
 // Default maximum delay for both audio and video. Used if the sender fails
 // to provide any constraints.
-constexpr std::chrono::milliseconds kDefaultMaxDelayMs(4000);
+constexpr std::chrono::milliseconds kDefaultMaxDelayMs(400);
 
 // Bit rate limits, used for both audio and video streams.
 struct BitRateLimits {
diff --git a/cast/streaming/capture_recommendations_unittest.cc b/cast/streaming/capture_recommendations_unittest.cc
index 8e9765af..4f76b9d9 100644
--- a/cast/streaming/capture_recommendations_unittest.cc
+++ b/cast/streaming/capture_recommendations_unittest.cc
@@ -16,9 +16,9 @@ namespace capture_recommendations {
 namespace {
 
 constexpr Recommendations kDefaultRecommendations{
-    Audio{BitRateLimits{32000, 256000}, milliseconds(4000), 2, 48000, 16000},
+    Audio{BitRateLimits{32000, 256000}, milliseconds(400), 2, 48000, 16000},
     Video{BitRateLimits{300000, 1920 * 1080 * 30}, Resolution{320, 240, 30},
-          Resolution{1920, 1080, 30}, false, milliseconds(4000),
+          Resolution{1920, 1080, 30}, false, milliseconds(400),
           1920 * 1080 * 30 / 8}};
 
 constexpr DisplayDescription kEmptyDescription{};