Implement H264 codec in Objective-C classes.

webrtc/sdk/objc/Framework/Classes/VideoToolbox/RTCVideoCodecH264.mm

+/*
+ *  Copyright 2017 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#import "WebRTC/RTCVideoCodecH264.h"
+
+#import <VideoToolbox/VideoToolbox.h>
+#include <vector>
+
+#import "RTCVideoCodec+Private.h"
+#import "WebRTC/RTCVideoCodec.h"
+#import "WebRTC/RTCVideoFrame.h"
+#import "WebRTC/RTCVideoFrameBuffer.h"
+
+#include "webrtc/rtc_base/timeutils.h"
+#include "webrtc/sdk/objc/Framework/Classes/Video/objc_frame_buffer.h"
+#include "webrtc/system_wrappers/include/field_trial.h"
+
+const char kHighProfileExperiment[] = "WebRTC-H264HighProfile";
+static NSString *kLevel31ConstrainedHigh = @"640c1f";
+static NSString *kLevel31ConstrainedBaseline = @"42e01f";
+
+bool IsHighProfileEnabled() {
+  return webrtc::field_trial::IsEnabled(kHighProfileExperiment);
+}
+
+// H264 specific settings.
+@implementation RTCCodecSpecificInfoH264
+
+@synthesize packetizationMode = _packetizationMode;
+
+- (webrtc::CodecSpecificInfo)toCpp {
+  webrtc::CodecSpecificInfo codecSpecificInfo;
+  codecSpecificInfo.codecType = webrtc::kVideoCodecH264;
+  codecSpecificInfo.codec_name = "H264";
+  codecSpecificInfo.codecSpecific.H264.packetization_mode =
+      (webrtc::H264PacketizationMode)_packetizationMode;
+
+  return codecSpecificInfo;
+}
+
+@end
+
+// Encoder factory.
+@implementation RTCVideoEncoderFactoryH264
+
+- (NSArray<RTCVideoCodecInfo *> *)supportedCodecs {
+  NSMutableArray<RTCVideoCodecInfo *> *codecs = [NSMutableArray array];
+  NSString *codecName = [NSString stringWithUTF8String:cricket::kH264CodecName];
+
+  if (IsHighProfileEnabled()) {
+    NSDictionary<NSString *, NSString *> *constrainedHighParams = @{
+      @"profile-level-id" : kLevel31ConstrainedHigh,
+      @"level-asymmetry-allowed" : @"1",
+      @"packetization-mode" : @"1",
+      // VideoToolbox does not have a constant for Constrained High.
+      @"videotoolbox-profile" : (__bridge NSString *)kVTProfileLevel_H264_High_3_1,
+    };
+    RTCVideoCodecInfo *constrainedHighInfo =
+        [[RTCVideoCodecInfo alloc] initWithPayload:0
+                                              name:codecName
+                                        parameters:constrainedHighParams];
+    [codecs addObject:constrainedHighInfo];
+  }
+
+  NSDictionary<NSString *, NSString *> *constrainedBaselineParams = @{
+    @"profile-level-id" : kLevel31ConstrainedBaseline,
+    @"level-asymmetry-allowed" : @"1",
+    @"packetization-mode" : @"1",
+    // VideoToolbox does not have a constant for Constrained Baseline.
+    @"videotoolbox-profile" : (__bridge NSString *)kVTProfileLevel_H264_Baseline_3_1,
+  };
+  RTCVideoCodecInfo *constrainedBaselineInfo =
+      [[RTCVideoCodecInfo alloc] initWithPayload:0
+                                            name:codecName
+                                      parameters:constrainedBaselineParams];
+  [codecs addObject:constrainedBaselineInfo];
+
+  return [codecs copy];
+}
+
+- (id<RTCVideoEncoder>)createEncoder:(RTCVideoCodecInfo *)info {
+  return [[RTCVideoEncoderH264 alloc] initWithCodecInfo:info];
+}
+
+@end
+
+// Decoder factory.
+@implementation RTCVideoDecoderFactoryH264
+
+- (id<RTCVideoDecoder>)createDecoder:(RTCVideoCodecInfo *)info {
+  return [[RTCVideoDecoderH264 alloc] init];
+}
+
+- (NSArray<RTCVideoCodecInfo *> *)supportedCodecs {
+  NSString *codecName = [NSString stringWithUTF8String:cricket::kH264CodecName];
+  return @[ [[RTCVideoCodecInfo alloc] initWithPayload:0 name:codecName parameters:@{}] ];
+}
+
+@end