From bbd22ca8bb0f8aa030830136ae92fbfb9edd5585 Mon Sep 17 00:00:00 2001
From: Single <libobjc@gmail.com>
Date: Mon, 4 Nov 2019 12:38:00 +0800
Subject: [PATCH] SGVideoDecoder: Add outputFromKeyFrame.

---
 .../Classes/Core/SGDecoder/SGVideoDecoder.h   |  5 +++
 .../Classes/Core/SGDecoder/SGVideoDecoder.m   | 32 +++++++++++++++++++
 2 files changed, 37 insertions(+)

diff --git a/SGPlayer/Classes/Core/SGDecoder/SGVideoDecoder.h b/SGPlayer/Classes/Core/SGDecoder/SGVideoDecoder.h
index 82a01f21..1b068927 100644
--- a/SGPlayer/Classes/Core/SGDecoder/SGVideoDecoder.h
+++ b/SGPlayer/Classes/Core/SGDecoder/SGVideoDecoder.h
@@ -10,4 +10,9 @@
 
 @interface SGVideoDecoder : NSObject <SGDecodable>
 
+/**
+ *
+ */
+@property (nonatomic) BOOL outputFromKeyFrame;
+
 @end
diff --git a/SGPlayer/Classes/Core/SGDecoder/SGVideoDecoder.m b/SGPlayer/Classes/Core/SGDecoder/SGVideoDecoder.m
index 3c6c21e8..3bea5c1c 100644
--- a/SGPlayer/Classes/Core/SGDecoder/SGVideoDecoder.m
+++ b/SGPlayer/Classes/Core/SGDecoder/SGVideoDecoder.m
@@ -16,6 +16,7 @@ @interface SGVideoDecoder ()
 
 {
     struct {
+        BOOL needsKeyFrame;
         BOOL needsAlignment;
         NSUInteger outputCount;
     } _flags;
@@ -31,6 +32,14 @@ @implementation SGVideoDecoder
 
 @synthesize options = _options;
 
+- (instancetype)init
+{
+    if (self = [super init]) {
+        self->_outputFromKeyFrame = YES;
+    }
+    return self;
+}
+
 - (void)dealloc
 {
     [self destroy];
@@ -50,6 +59,7 @@ - (void)setup
 - (void)destroy
 {
     self->_flags.outputCount = 0;
+    self->_flags.needsKeyFrame = YES;
     self->_flags.needsAlignment = YES;
     [self->_codecContext close];
     self->_codecContext = nil;
@@ -62,6 +72,7 @@ - (void)destroy
 - (void)flush
 {
     self->_flags.outputCount = 0;
+    self->_flags.needsKeyFrame = YES;
     self->_flags.needsAlignment = YES;
     [self->_codecContext flush];
     [self->_lastFrame unlock];
@@ -123,6 +134,7 @@ - (void)flush
     SGCodecDescriptor *cd = self->_codecDescriptor;
     NSArray *objs = [self->_codecContext decode:packet];
     objs = [self processFrames:objs done:!packet];
+    objs = [self clipKeyFrames:objs];
     objs = [self clipFrames:objs timeRange:cd.timeRange];
     return objs;
 }
@@ -138,6 +150,26 @@ - (void)flush
     return ret;
 }
 
+- (NSArray<__kindof SGFrame *> *)clipKeyFrames:(NSArray<__kindof SGFrame *> *)frames
+{
+    if (self->_outputFromKeyFrame == NO ||
+        self->_flags.needsKeyFrame == NO) {
+        return frames;
+    }
+    NSMutableArray *ret = [NSMutableArray array];
+    for (SGFrame *obj in frames) {
+        if (self->_flags.needsKeyFrame == NO) {
+            [ret addObject:obj];
+        } else if (obj.core->key_frame) {
+            [ret addObject:obj];
+            self->_flags.needsKeyFrame = NO;
+        } else {
+            [obj unlock];
+        }
+    }
+    return ret;
+}
+
 - (NSArray<__kindof SGFrame *> *)clipFrames:(NSArray<__kindof SGFrame *> *)frames timeRange:(CMTimeRange)timeRange
 {
     if (frames.count <= 0) {