iOS AVWritter Key 从中心裁剪视频偏移

Question

我正在使用 AVCapture 来录制视频。我需要裁剪视频。我能够通过设置

AVVideoWidthKey : [NSNumber numberWithInteger:outputSize.width],
AVVideoHeightKey : [NSNumber numberWithInteger:outputSize.height],

但是，我需要用偏移裁剪，我不想从中心裁剪，因为它默认工作。

我在 AVFoundation 的 AVVideoSettings.h 中读到我可以使用 AVVideoCleanApertureVerticalOffsetKey

The value for this key is an NSDictionary containing AVVideoCleanAperture*Key keys. AVVideoCleanApertureWidthKey and AVVideoCleanApertureHeightKey define a clean rectangle which is centered on the video frame. To offset this rectangle from center, use AVVideoCleanApertureHorizontalOffsetKey and AVVideoCleanApertureVerticalOffsetKey. A positive value for AVVideoCleanApertureHorizontalOffsetKey moves the clean aperture region to the right, and a positive value for AVVideoCleanApertureVerticalOffsetKey moves the clean aperture region down.

我正在尝试以下操作，但我只在没有偏移的情况下在中心进行裁剪。

NSDictionary *videoCleanApertureSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                            [NSNumber numberWithInteger:outputSize.width], AVVideoCleanApertureWidthKey,
                                            [NSNumber numberWithInteger:outputSize.height], AVVideoCleanApertureHeightKey,
                                            [NSNumber numberWithInteger:0], AVVideoCleanApertureHorizontalOffsetKey,
                                            [NSNumber numberWithInteger:-200], AVVideoCleanApertureVerticalOffsetKey,
                                            nil];

NSMutableDictionary *compressionSettings = [NSMutableDictionary dictionaryWithObject:[NSNumber numberWithUnsignedLong:bitrate] forKey:AVVideoAverageBitRateKey];

[compressionSettings setObject:videoCleanApertureSettings forKey:AVVideoCleanApertureKey];

if (self.shouldKeepOnlyKeyFrames) {
    [compressionSettings setObject:@1 forKey:AVVideoMaxKeyFrameIntervalKey];
}

if (self.profileLevel) {
    [compressionSettings setObject:self.profileLevel forKey:AVVideoProfileLevelKey];
}
[compressionSettings setObject:@NO forKey:AVVideoAllowFrameReorderingKey];
[compressionSettings setObject:@30 forKey:AVVideoExpectedSourceFrameRateKey];



return @{
         AVVideoCodecKey : self.codec,
         AVVideoScalingModeKey : self.scalingMode,
         AVVideoWidthKey : [NSNumber numberWithInteger:outputSize.width],
         AVVideoHeightKey : [NSNumber numberWithInteger:outputSize.height],
         AVVideoCompressionPropertiesKey : compressionSettings
         };

Answer 1

您缺少信息。您的参数应该更像这样。

NSDictionary *videoCleanApertureSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                       [NSNumber numberWithInt:320], AVVideoCleanApertureWidthKey,
                                       [NSNumber numberWithInt:480], AVVideoCleanApertureHeightKey,
                                       [NSNumber numberWithInt:10], AVVideoCleanApertureHorizontalOffsetKey,
                                       [NSNumber numberWithInt:10], AVVideoCleanApertureVerticalOffsetKey,
                                        nil];


NSDictionary *videoAspectRatioSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                                         [NSNumber numberWithInt:3], AVVideoPixelAspectRatioHorizontalSpacingKey,
                                         [NSNumber numberWithInt:3],AVVideoPixelAspectRatioVerticalSpacingKey,
                                                nil];



NSDictionary *codecSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                           [NSNumber numberWithInt:960000], AVVideoAverageBitRateKey,
                           [NSNumber numberWithInt:1],AVVideoMaxKeyFrameIntervalKey,
                           videoCleanApertureSettings, AVVideoCleanApertureKey,
                           //videoAspectRatioSettings, AVVideoPixelAspectRatioKey,
                           //AVVideoProfileLevelH264Main30, AVVideoProfileLevelKey,
                           nil];





NSString *targetDevice = [[UIDevice currentDevice] model];

NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
                           AVVideoCodecH264, AVVideoCodecKey,
                           codecSettings,AVVideoCompressionPropertiesKey,
                           [NSNumber numberWithInt:320], AVVideoWidthKey,
                           [NSNumber numberWithInt:480], AVVideoHeightKey,
                           nil];