I try to read a video frame-by-frame from iPhone photo album.
After image processing, I will save them as a new video.
I’m running my code without any error, but there is no new video in the album.
Here is my code.
// Video writer init
- (BOOL)setupAssetWriterForURL:(CMFormatDescriptionRef)formatDescription
{
float bitsPerPixel;
CMVideoDimensions dimensions = CMVideoFormatDescriptionGetDimensions(formatDescription);
int numPixels = dimensions.width * dimensions.height;
int bitsPerSecond;
if ( numPixels < (640 * 480) )
bitsPerPixel = 4.05;
else
bitsPerPixel = 11.4;
bitsPerSecond = numPixels * bitsPerPixel;
NSDictionary *videoCompressionSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInteger:dimensions.width], AVVideoWidthKey,
[NSNumber numberWithInteger:dimensions.height], AVVideoHeightKey,
[NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInteger:bitsPerSecond], AVVideoAverageBitRateKey,
[NSNumber numberWithInteger:30], AVVideoMaxKeyFrameIntervalKey,
nil], AVVideoCompressionPropertiesKey,
nil];
if ([assetWriter canApplyOutputSettings:videoCompressionSettings forMediaType:AVMediaTypeVideo]) {
assetWriterVideoIn = [[AVAssetWriterInput alloc] initWithMediaType:AVMediaTypeVideo outputSettings:videoCompressionSettings];
assetWriterVideoIn.expectsMediaDataInRealTime = YES;
assetWriterVideoIn.transform = [self transformFromCurrentVideoOrientationToOrientation:self.referenceOrientation];
if ([assetWriter canAddInput:assetWriterVideoIn])
[assetWriter addInput:assetWriterVideoIn];
else {
NSLog(@"Couldn't add asset writer video input.");
return NO;
}
}
else {
NSLog(@"Couldn't apply video output settings.");
return NO;
}
return YES;
}
Read video
- (void)readMovie:(NSURL *)url
{
AVURLAsset * asset = [AVURLAsset URLAssetWithURL:url options:nil];
[asset loadValuesAsynchronouslyForKeys:[NSArray arrayWithObject:@"tracks"] completionHandler:
^{
dispatch_async(dispatch_get_main_queue(),
^{
AVAssetTrack * videoTrack = nil;
NSArray * tracks = [asset tracksWithMediaType:AVMediaTypeVideo];
if ([tracks count] == 1)
{
videoTrack = [tracks objectAtIndex:0];
NSError * error = nil;
// _movieReader is a member variable
AVAssetReader *movieReader = [[AVAssetReader alloc] initWithAsset:asset error:&error];
if (error)
NSLog(@"_movieReader fail!\n");
NSString* key = (NSString*)kCVPixelBufferPixelFormatTypeKey;
NSNumber* value = [NSNumber numberWithUnsignedInt:kCVPixelFormatType_32BGRA];
NSDictionary* videoSettings =
[NSDictionary dictionaryWithObject:value forKey:key];
[movieReader addOutput:[AVAssetReaderTrackOutput
assetReaderTrackOutputWithTrack:videoTrack
outputSettings:videoSettings]];
[movieReader startReading];
while ([movieReader status] == AVAssetReaderStatusReading)
{
AVAssetReaderTrackOutput * output = [movieReader.outputs objectAtIndex:0];
CMSampleBufferRef sampleBuffer = [output copyNextSampleBuffer];
if (sampleBuffer)
{
if ( !assetWriter ) {
outputURL = [NSURL fileURLWithPath:[NSString stringWithFormat:@"%@/%llu.mov", NSTemporaryDirectory(), mach_absolute_time()]];
NSError *error = nil;
assetWriter = [[AVAssetWriter alloc] initWithURL:outputURL fileType:(NSString *)kUTTypeQuickTimeMovie error:&error];
if (error)
[self showError:error];
if (assetWriter) {
CMFormatDescriptionRef formatDescription = CMSampleBufferGetFormatDescription(sampleBuffer);
[self setupAssetWriterForURL:formatDescription];
}
}
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
CVPixelBufferLockBaseAddress(imageBuffer,0);
int bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
int bufferWidth = CVPixelBufferGetWidth(imageBuffer);
int bufferHeight = CVPixelBufferGetHeight(imageBuffer);
unsigned char *pixel = (unsigned char *)CVPixelBufferGetBaseAddress(imageBuffer);
for( int row = 0; row < bufferHeight; row++ ) {
for( int column = 0; column < bufferWidth; column++ ) {
pixel[0] = (pixel[0]+pixel[1]+pixel[2])/3;
pixel[1] = (pixel[0]+pixel[1]+pixel[2])/3;
pixel[2] = (pixel[0]+pixel[1]+pixel[2])/3;
pixel += 4;
}
}
CVPixelBufferUnlockBaseAddress(imageBuffer,0);
if ( assetWriter ) {
[self writeSampleBuffer:sampleBuffer ofType:AVMediaTypeVideo];
}
CFRelease(sampleBuffer);
}
}
if (assetWriter) {
[assetWriterVideoIn markAsFinished];
assetWriter = nil;
[assetWriter finishWriting];
assetWriterVideoIn = nil;
assetWriter = nil;
[self saveMovieToCameraRoll];
}
else {
[self showError:[assetWriter error]];
}
}
});
}];
}
- (void) writeSampleBuffer:(CMSampleBufferRef)sampleBuffer ofType:(NSString *)mediaType
{
if ( assetWriter.status == AVAssetWriterStatusUnknown ) {
if ([assetWriter startWriting]) {
[assetWriter startSessionAtSourceTime:CMSampleBufferGetPresentationTimeStamp(sampleBuffer)];
}
else {
[self showError:[assetWriter error]];
}
}
if ( assetWriter.status == AVAssetWriterStatusWriting ) {
if (mediaType == AVMediaTypeVideo) {
if (assetWriterVideoIn.readyForMoreMediaData) {
if (![assetWriterVideoIn appendSampleBuffer:sampleBuffer]) {
[self showError:[assetWriter error]];
}
}
}
}
}
- (void)saveMovieToCameraRoll
{
ALAssetsLibrary *library = [[ALAssetsLibrary alloc] init];
[library writeVideoAtPathToSavedPhotosAlbum:outputURL
completionBlock:^(NSURL *assetURL, NSError *error) {
if (error){
[self showError:error];
NSLog(@"save fail");
}
else
{
[self removeFile:outputURL];
NSLog(@"!!!");
}
});
}];
}
- (void)removeFile:(NSURL *)fileURL
{
NSFileManager *fileManager = [NSFileManager defaultManager];
NSString *filePath = [fileURL path];
if ([fileManager fileExistsAtPath:filePath]) {
NSError *error;
BOOL success = [fileManager removeItemAtPath:filePath error:&error];
if (!success)
[self showError:error];
}
}
Any suggestions?
And Here is an answer for Creating Movie from images.
Hope You will get Some Help from there.