Reland of Injectable Obj-C video codecs

webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h

Index: webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h
diff --git a/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h b/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h
new file mode 100644
index 0000000000000000000000000000000000000000..f093049faf8309a808732f729f7564bc4168a15f
--- /dev/null
+++ b/webrtc/sdk/objc/Framework/Headers/WebRTC/RTCVideoCodec.h
@@ -0,0 +1,137 @@
+/*
+ *  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 <Foundation/Foundation.h>
+
+#import <WebRTC/RTCMacros.h>
+
+@class RTCVideoFrame;
+
+NS_ASSUME_NONNULL_BEGIN
+
+/** Represents an encoded frame's type. */
+typedef NS_ENUM(NSUInteger, RTCFrameType) {
+  EmptyFrame,

[Chuck, 2017/07/14 14:57:30]

Enum values should be prefixed with enum name: RTCFrameTypeEmptyFrame,
RTCFrameTypeVideoFrameKey,...

+  VideoFrameKey,
+  VideoFrameDelta,
+};
+
+/** Represents an encoded frame. Corresponds to webrtc::EncodedImage. */
+RTC_EXPORT
+@interface RTCEncodedImage : NSObject
+
+@property(nonatomic, retain) NSData *buffer;

[Chuck, 2017/07/14 14:57:31]

Use strong instead of retain for consistency throughout.

+@property(nonatomic, assign) int encodedWidth;
+@property(nonatomic, assign) int encodedHeight;
+@property(nonatomic, assign) uint32_t timeStamp;
+@property(nonatomic, assign) long captureTimeMs;
+@property(nonatomic, assign) long ntpTimeMs;
+@property(nonatomic, assign) BOOL isTimingFrame;
+@property(nonatomic, assign) long encodeStartMs;
+@property(nonatomic, assign) long encodeFinishMs;
+@property(nonatomic, assign) RTCFrameType frameType;
+@property(nonatomic, assign) int rotation;
+@property(nonatomic, assign) BOOL completeFrame;
+@property(nonatomic, retain) NSNumber *qp;
+
+@end
+
+/** Information for header. Corresponds to webrtc::RTPFragmentationHeader. */
+RTC_EXPORT
+@interface RTCRtpFragmentationHeader : NSObject
+
+@property(nonatomic, retain) NSArray<NSNumber *> *fragmentationOffset;
+@property(nonatomic, retain) NSArray<NSNumber *> *fragmentationLength;
+@property(nonatomic, retain) NSArray<NSNumber *> *fragmentationTimeDiff;
+@property(nonatomic, retain) NSArray<NSNumber *> *fragmentationPlType;
+
+@end
+
+/** Implement this protocol to pass codec specific info from the encoder.
+ *  Corresponds to webrtc::CodecSpecificInfo.
+ */
+RTC_EXPORT
+@protocol RTCCodecSpecificInfo <NSObject>
+
+@end
+
+/** Callback block for encoder. */
+typedef void (^RTCVideoEncoderCallback)(RTCEncodedImage *frame,
+                                        id<RTCCodecSpecificInfo> info,
+                                        RTCRtpFragmentationHeader *header);
+
+/** Callback block for decoder. */
+typedef void (^RTCVideoDecoderCallback)(RTCVideoFrame *frame);
+
+/** Settings for encoder. Corresponds to webrtc::VideoCodec. */
+RTC_EXPORT
+@interface RTCVideoEncoderSettings : NSObject
+
+@property(nonatomic, retain) NSString *name;
+
+@property(nonatomic, assign) unsigned short width;
+@property(nonatomic, assign) unsigned short height;
+
+@property(nonatomic, assign) unsigned int startBitrate;  // kilobits/sec.
+@property(nonatomic, assign) unsigned int maxBitrate;
+@property(nonatomic, assign) unsigned int minBitrate;
+@property(nonatomic, assign) unsigned int targetBitrate;
+
+@property(nonatomic, assign) uint32_t maxFramerate;
+
+@property(nonatomic, assign) unsigned int qpMax;
+
+@end
+
+/** Holds information to identify a codec. Corresponds to cricket::VideoCodec. */
+RTC_EXPORT
+@interface RTCVideoCodecInfo : NSObject
+
+- (instancetype)initWithPayload:(int)payload
+                           name:(NSString *)name
+                     parameters:(NSDictionary<NSString *, NSString *> *)parameters;
+
+@property(nonatomic, readonly) int payload;
+@property(nonatomic, readonly) NSString *name;
+@property(nonatomic, readonly) NSDictionary<NSString *, NSString *> *parameters;
+
+@end
+
+/** Protocol for encoder implementations. */
+RTC_EXPORT
+@protocol RTCVideoEncoder <NSObject>
+
+- (instancetype)initWithCodecInfo:(RTCVideoCodecInfo *)codecInfo;

[Chuck, 2017/07/14 14:57:30]

init methods in a protocol seems very weird, why is this necessary? 

+- (void)setCallback:(RTCVideoEncoderCallback)callback;
+- (int)initEncodeWithSettings:(RTCVideoEncoderSettings *)settings numberOfCores:(int)numberOfCores;

[Chuck, 2017/07/14 14:57:30]

init methods should return instancetype

[Chuck, 2017/07/14 14:57:30]

Do these need to be int? Prefer NSInteger

+- (int)releaseEncode;
+- (int)encode:(RTCVideoFrame *)frame
+    codecSpecificInfo:(id<RTCCodecSpecificInfo>)info
+           frameTypes:(NSArray<NSNumber *> *)frameTypes;
+- (BOOL)setBitrate:(uint32_t)bitrateKbit framerate:(uint32_t)framerate;
+
+@end
+
+/** Protocol for decoder implementations. */
+RTC_EXPORT
+@protocol RTCVideoDecoder <NSObject>
+
+- (void)setCallback:(RTCVideoDecoderCallback)callback;
+- (int)initDecodeWithSettings:(RTCVideoEncoderSettings *)settings numberOfCores:(int)numberOfCores;
+- (int)releaseDecode;
+- (int)decode:(RTCEncodedImage *)encodedImage
+          missingFrames:(BOOL)missingFrames
+    fragmentationHeader:(RTCRtpFragmentationHeader *)fragmentationHeader
+      codecSpecificInfo:(__nullable id<RTCCodecSpecificInfo>)info
+           renderTimeMs:(int64_t)renderTimeMs;
+
+@end
+
+NS_ASSUME_NONNULL_END