我正在制作一个视频，使用this tutorial合并一个图像（只有一个帧）的电影文件和几秒钟的音频。
在iphone设备中，视频持续时间相当于音频持续时间，我在所有视频中看到了图像。
但是当我分享到Android设备（通过whatsapp）并且按下播放时，播放持续时间是来自图像持续时间（一帧）的电影。我做了一个测试，如果我从一个图像创建一个电影文件重复一百次（10fps，十秒），在Android设备中，playblack持续时间是十秒。
我认为Android设备只播放视频中最短的音轨，但如果我将视频的 addMutableTrackWithMediaType 中的时间范围修改为音频持续时间，则不会发生任何事情。
有什么建议吗？
感谢您的支持
我把所有代码放在这里：
-(void) writeImagesToMovieAtPath:(NSString *)path withSize:(CGSize) size {
NSMutableArray *m_PictArray = [NSMutableArray arrayWithCapacity:1];
[m_PictArray addObject:[UIImage imageNamed:@"prueba.jpg"]];
NSString *documentsDirectoryPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
NSArray *dirContents = [[NSFileManager defaultManager] contentsOfDirectoryAtPath:documentsDirectoryPath error:nil];
for (NSString *tString in dirContents) {
if ([tString isEqualToString:@"essai.mp4"])
{
[[NSFileManager defaultManager]removeItemAtPath:[NSString stringWithFormat:@"%@/%@",documentsDirectoryPath,tString] error:nil];
}
}
NSLog(@"Write Started");
NSError *error = nil;
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:
[NSURL fileURLWithPath:path] fileType:AVFileTypeMPEG4
error:&error];
NSParameterAssert(videoWriter);
NSDictionary *codecSettings = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:128000], AVVideoAverageBitRateKey,
[NSNumber numberWithInt:15],AVVideoMaxKeyFrameIntervalKey,
AVVideoProfileLevelH264Main30, AVVideoProfileLevelKey,
nil];
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
codecSettings,AVVideoCompressionPropertiesKey,
[NSNumber numberWithInt:size.width], AVVideoWidthKey,
[NSNumber numberWithInt:size.height], AVVideoHeightKey,
nil];
AVAssetWriterInput* videoWriterInput = [[AVAssetWriterInput
assetWriterInputWithMediaType:AVMediaTypeVideo
outputSettings:videoSettings] retain];
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
assetWriterInputPixelBufferAdaptorWithAssetWriterInput:videoWriterInput
sourcePixelBufferAttributes:nil];
NSParameterAssert(videoWriterInput);
NSParameterAssert([videoWriter canAddInput:videoWriterInput]);
videoWriterInput.expectsMediaDataInRealTime = YES;
[videoWriter addInput:videoWriterInput];
//Start a session:
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];
//Video encoding
CVPixelBufferRef buffer = NULL;
//convert uiimage to CGImage.
int frameCount = 0;
for(int i = 0; i<[m_PictArray count]; i++)
{
buffer = [self newPixelBufferFromCGImage:[[m_PictArray objectAtIndex:i] CGImage] andSize:size];
BOOL append_ok = NO;
int j = 0;
while (!append_ok && j < 30)
{
if (adaptor.assetWriterInput.readyForMoreMediaData)
{
printf("appending %d attemp %d\n", frameCount, j);
CMTime frameTime = CMTimeMake(frameCount,(int32_t) 10);
/*
Float64 seconds = 1;
int32_t preferredTimeScale = 10;
CMTime frameTime = CMTimeMakeWithSeconds(seconds, preferredTimeScale);
*/
append_ok = [adaptor appendPixelBuffer:buffer withPresentationTime:frameTime];
CVPixelBufferPoolRef bufferPool = adaptor.pixelBufferPool;
NSParameterAssert(bufferPool != NULL);
[NSThread sleepForTimeInterval:0.05];
}
else
{
printf("adaptor not ready %d, %d\n", frameCount, j);
[NSThread sleepForTimeInterval:0.1];
}
j++;
}
if (!append_ok) {
printf("error appending image %d times %d\n", frameCount, j);
}
frameCount++;
CVBufferRelease(buffer);
}
[videoWriterInput markAsFinished];
[videoWriter finishWriting];
[videoWriterInput release];
[videoWriter release];
[m_PictArray removeAllObjects];
NSLog(@"Write Ended");
[self saveVideoToAlbum:path];
}
-(void)CompileFilesToMakeMovie {
NSLog(@"CompileFilesToMakeMovie");
AVMutableComposition* mixComposition = [AVMutableComposition composition];
NSString *documentsDirectoryPath = [NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, NSUserDomainMask, YES) objectAtIndex:0];
//Audio file in AAC
NSString* audio_inputFileName = @"zApY4o8QY.m4a";
NSString* audio_inputFilePath = [NSString stringWithFormat:@"%@/%@",[[NSBundle mainBundle] resourcePath],audio_inputFileName];
NSURL* audio_inputFileUrl = [NSURL fileURLWithPath:audio_inputFilePath];
NSString* video_inputFileName = @"essai.mp4";
NSString* video_inputFilePath = [NSString stringWithFormat:@"%@/%@",documentsDirectoryPath,video_inputFileName];
NSURL* video_inputFileUrl = [NSURL fileURLWithPath:video_inputFilePath];
NSString* outputFileName = @"outputFile.mov";
NSString* outputFilePath = [NSString stringWithFormat:@"%@/%@",documentsDirectoryPath,outputFileName];
NSURL* outputFileUrl = [NSURL fileURLWithPath:outputFilePath];
if ([[NSFileManager defaultManager] fileExistsAtPath:outputFilePath])
[[NSFileManager defaultManager] removeItemAtPath:outputFilePath error:nil];
CMTime nextClipStartTime = kCMTimeZero;
AVURLAsset* videoAsset = [[AVURLAsset alloc]initWithURL:video_inputFileUrl options:nil];
AVURLAsset* audioAsset = [[AVURLAsset alloc]initWithURL:audio_inputFileUrl options:nil];
//CMTimeRange video_timeRange = CMTimeRangeMake(kCMTimeZero,videoAsset.duration);
CMTimeRange video_timeRange = CMTimeRangeMake(kCMTimeZero,videoAsset.duration);
AVMutableCompositionTrack *a_compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[a_compositionVideoTrack insertTimeRange:video_timeRange ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:nextClipStartTime error:nil];
CMTimeRange audio_timeRange = CMTimeRangeMake(kCMTimeZero, audioAsset.duration);
AVMutableCompositionTrack *b_compositionAudioTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeAudio preferredTrackID:kCMPersistentTrackID_Invalid];
[b_compositionAudioTrack insertTimeRange:audio_timeRange ofTrack:[[audioAsset tracksWithMediaType:AVMediaTypeAudio] objectAtIndex:0] atTime:nextClipStartTime error:nil];
AVAssetExportSession* _assetExport = [[AVAssetExportSession alloc] initWithAsset:mixComposition presetName:AVAssetExportPresetLowQuality];
_assetExport.shouldOptimizeForNetworkUse = YES;
_assetExport.outputFileType = @"com.apple.quicktime-movie";
_assetExport.outputURL = outputFileUrl;
_assetExport.timeRange = CMTimeRangeMake(kCMTimeZero, audioAsset.duration);
[_assetExport exportAsynchronouslyWithCompletionHandler:
^(void ) {
[self saveVideoToAlbum:outputFilePath];
}
];
NSLog(@"CompileFilesToMakeMovie Finish");
}
- (void) saveVideoToAlbum:(NSString*)path {
NSLog(@"saveVideoToAlbum");
if(UIVideoAtPathIsCompatibleWithSavedPhotosAlbum(path)){
UISaveVideoAtPathToSavedPhotosAlbum (path, self, @selector(video:didFinishSavingWithError: contextInfo:), nil);
}
}
-(void) video:(NSString *)videoPath didFinishSavingWithError:(NSError *)error contextInfo:(void *)contextInfo {
if(error)
NSLog(@"Exportado con error: %@", error);
else
NSLog(@"Exportado OK");
}
- (CVPixelBufferRef) newPixelBufferFromCGImage: (CGImageRef)image andSize:(CGSize)frameSize {
CGAffineTransform frameTransform = CGAffineTransformMake(0, 0, 0, 0, 0, 0);
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey,
nil];
CVPixelBufferRef pxbuffer = NULL;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, frameSize.width,
frameSize.height, kCVPixelFormatType_32ARGB, (CFDictionaryRef) options,
&pxbuffer);
NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);
CVPixelBufferLockBaseAddress(pxbuffer, 0);
void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
NSParameterAssert(pxdata != NULL);
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pxdata, frameSize.width,
frameSize.height, 8, 4*frameSize.width, rgbColorSpace,
kCGImageAlphaNoneSkipFirst);
NSParameterAssert(context);
//CGContextConcatCTM(context, frameTransform);
CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image),
CGImageGetHeight(image)), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return (CVPixelBufferRef)pxbuffer;
}
答案 0 :(得分：0)
刚修好！
我创建的电影文件重复X次图像，然后在合成过程中我缩放到audioAsset.duration的大小
CMTimeRange video_timeRange = CMTimeRangeMake(kCMTimeZero,videoAsset.duration);
AVMutableCompositionTrack *a_compositionVideoTrack = [mixComposition addMutableTrackWithMediaType:AVMediaTypeVideo preferredTrackID:kCMPersistentTrackID_Invalid];
[a_compositionVideoTrack insertTimeRange:video_timeRange ofTrack:[[videoAsset tracksWithMediaType:AVMediaTypeVideo] objectAtIndex:0] atTime:kCMTimeZero error:nil];
[a_compositionVideoTrack scaleTimeRange:video_timeRange toDuration:audioAsset.duration];
你需要重复一次图像以允许跟踪缩放，但如果电影只有2帧，在Android中只播放8秒，所以我制作了一个重复10次图像的视频，让我超出限制在whatsapp的视频分享中的45个secons
答案 1 :(得分：0)
在CompileFilesToMakeMovie方法中，在需要的地方使用video_timeRange而不是audio_timeRange ...