Improve CTS calculation.

shogo4405 · Feb 9, 2025 · 453ce29 · 453ce29
1 parent f2ab619
commit 453ce29
Show file tree

Hide file tree

Showing 4 changed files with 18 additions and 14 deletions.
diff --git a/HaishinKit/Sources/RTMP/RTMPFoundation.swift b/HaishinKit/Sources/RTMP/RTMPFoundation.swift
@@ -243,3 +243,13 @@ enum RTMPVideoCodec: UInt8 {
         }
     }
 }
+
+
+extension CMSampleBuffer {
+    func getCompositionTime(_ offset: TimeInterval) -> Int32 {
+        guard decodeTimeStamp.isValid else {
+            return 0
+        }
+        return max(0, Int32(((presentationTimeStamp - decodeTimeStamp).seconds + offset) * 1000))
+    }
+}
diff --git a/HaishinKit/Sources/RTMP/RTMPMessage.swift b/HaishinKit/Sources/RTMP/RTMPMessage.swift
@@ -461,6 +461,8 @@ struct RTMPAudioMessage: RTMPMessage {
  7.1.5. Video Message (9)
  */
 struct RTMPVideoMessage: RTMPMessage {
+    static let ctsOffset = 0.066
+
     // MARK: RTMPMessage
     let type: RTMPMessageType = .video
     let streamId: UInt32
@@ -526,20 +528,22 @@ struct RTMPVideoMessage: RTMPMessage {
         }
     }
 
-    init?(streamId: UInt32, timestamp: UInt32, compositionTime: Int32, sampleBuffer: CMSampleBuffer?) {
+    init?(streamId: UInt32, timestamp: UInt32, sampleBuffer: CMSampleBuffer?) {
         guard let sampleBuffer, let data = try? sampleBuffer.dataBuffer?.dataBytes() else {
             return nil
         }
         self.streamId = streamId
         self.timestamp = timestamp
         let keyframe = !sampleBuffer.isNotSync
         switch sampleBuffer.formatDescription?.mediaSubType {
-        case .h264?:
+        case .h264:
+            let compositionTime = sampleBuffer.getCompositionTime(Self.ctsOffset)
             var buffer = Data([((keyframe ? RTMPFrameType.key.rawValue : RTMPFrameType.inter.rawValue) << 4) | RTMPVideoCodec.avc.rawValue, RTMPAVCPacketType.nal.rawValue])
             buffer.append(contentsOf: compositionTime.bigEndian.data[1..<4])
             buffer.append(data)
             payload = buffer
-        case .hevc?:
+        case .hevc:
+            let compositionTime = sampleBuffer.getCompositionTime(Self.ctsOffset)
             var buffer = Data([0b10000000 | ((keyframe ? RTMPFrameType.key.rawValue : RTMPFrameType.inter.rawValue) << 4) | RTMPVideoPacketType.codedFrames.rawValue, 0x68, 0x76, 0x63, 0x31])
             buffer.append(contentsOf: compositionTime.bigEndian.data[1..<4])
             buffer.append(data)

diff --git a/HaishinKit/Sources/RTMP/RTMPStream.swift b/HaishinKit/Sources/RTMP/RTMPStream.swift
@@ -735,11 +735,10 @@ extension RTMPStream: HKStream {
             if sampleBuffer.formatDescription?.isCompressed == true {
                 do {
                     let decodeTimeStamp = sampleBuffer.decodeTimeStamp.isValid ? sampleBuffer.decodeTimeStamp : sampleBuffer.presentationTimeStamp
-                    let compositionTime = videoTimestamp.getCompositionTime(sampleBuffer)
                     let timedelta = try videoTimestamp.update(decodeTimeStamp)
                     frameCount += 1
                     videoFormat = sampleBuffer.formatDescription
-                    guard let message = RTMPVideoMessage(streamId: id, timestamp: timedelta, compositionTime: compositionTime, sampleBuffer: sampleBuffer) else {
+                    guard let message = RTMPVideoMessage(streamId: id, timestamp: timedelta, sampleBuffer: sampleBuffer) else {
                         return
                     }
                     doOutput(.one, chunkStreamId: .video, message: message)

diff --git a/HaishinKit/Sources/RTMP/RTMPTimestamp.swift b/HaishinKit/Sources/RTMP/RTMPTimestamp.swift
@@ -7,7 +7,6 @@ protocol RTMPTimeConvertible {
 }
 
 private let kRTMPTimestamp_defaultTimeInterval: TimeInterval = 0
-private let kRTMPTimestamp_compositiionTimeOffset = CMTime(value: 3, timescale: 30)
 
 struct RTMPTimestamp<T: RTMPTimeConvertible> {
     enum Error: Swift.Error {
@@ -56,14 +55,6 @@ struct RTMPTimestamp<T: RTMPTimeConvertible> {
         updatedAt = kRTMPTimestamp_defaultTimeInterval
         timedeltaFraction = kRTMPTimestamp_defaultTimeInterval
     }
-
-    func getCompositionTime(_ sampleBuffer: CMSampleBuffer) -> Int32 {
-        guard sampleBuffer.decodeTimeStamp.isValid, sampleBuffer.decodeTimeStamp != sampleBuffer.presentationTimeStamp else {
-            return 0
-        }
-        let compositionTime = (sampleBuffer.presentationTimeStamp + kRTMPTimestamp_compositiionTimeOffset).seconds - updatedAt
-        return Int32(compositionTime * 1000)
-    }
 }
 
 extension AVAudioTime: RTMPTimeConvertible {