Add resolution alignment properties to RTCVideoEncoder protocol.

With this change, RTCVideoEncoder can specify:
- requested_resolution_alignment,
- apply_alignment_to_all_simulcast_layers
in the same way scaling_settings is specified.

Change-Id: I3de79a2eabaae581d6a9f2ef3e39496b9545a4f5

Bug: webrtc:12829
Change-Id: I3de79a2eabaae581d6a9f2ef3e39496b9545a4f5
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/220933
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Reviewed-by: Åsa Persson <asapersson@webrtc.org>
Reviewed-by: Abby Yeh <abbyyeh@webrtc.org>
Commit-Queue: Peter Hanspers <peterhanspers@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#34196}

sdk/objc/api/video_codec/RTCWrappedNativeVideoEncoder.mm

@@ -69,4 +69,14 @@
   return nil;
 }
 
+- (NSInteger)resolutionAlignment {
+  RTC_NOTREACHED();
+  return 1;
+}
+
+- (BOOL)applyAlignmentToAllSimulcastLayers {
+  RTC_NOTREACHED();
+  return NO;
+}
+
 @end

sdk/objc/base/RTCVideoEncoder.h

@@ -43,6 +43,13 @@ RTC_OBJC_EXPORT
  *  disables quality scaling. */
 - (nullable RTC_OBJC_TYPE(RTCVideoEncoderQpThresholds) *)scalingSettings;
 
+/** Resolutions should be aligned to this value. */
+@property(nonatomic, readonly) NSInteger resolutionAlignment;
+
+/** If enabled, resolution alignment is applied to all simulcast layers simultaneously so that when
+    scaled, all resolutions comply with 'resolutionAlignment'. */
+@property(nonatomic, readonly) BOOL applyAlignmentToAllSimulcastLayers;
+
 @end
 
 NS_ASSUME_NONNULL_END

sdk/objc/components/video_codec/RTCVideoEncoderH264.mm

@@ -529,6 +529,14 @@ NSUInteger GetMaxSampleRate(const webrtc::H264ProfileLevelId &profile_level_id)
   return WEBRTC_VIDEO_CODEC_OK;
 }
 
+- (NSInteger)resolutionAlignment {
+  return 1;
+}
+
+- (BOOL)applyAlignmentToAllSimulcastLayers {
+  return NO;
+}
+
 #pragma mark - Private
 
 - (NSInteger)releaseEncoder {

sdk/objc/native/src/objc_video_encoder_factory.mm

@@ -95,6 +95,8 @@ class ObjCVideoEncoder : public VideoEncoder {
     info.scaling_settings = qp_thresholds ? ScalingSettings(qp_thresholds.low, qp_thresholds.high) :
                                             ScalingSettings::kOff;
 
+    info.requested_resolution_alignment = encoder_.resolutionAlignment > 0 ?: 1;
+    info.apply_alignment_to_all_simulcast_layers = encoder_.applyAlignmentToAllSimulcastLayers;
     info.is_hardware_accelerated = true;
     info.has_internal_source = false;
     return info;