How to use CVPixelBufferPool in conjunction with AVAssetWriterInputPixelBufferAdaptor in iPhone? - iphone

Question

I have successfully created video from images using the following code
-(void)writeImageAsMovie:(NSArray *)array toPath:(NSString*)path size:(CGSize)size duration:(int)duration
{
NSError *error = nil;
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:
[NSURL fileURLWithPath:path] fileType:AVFileTypeQuickTimeMovie
error:&error];
NSParameterAssert(videoWriter);
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:
AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:size.width], AVVideoWidthKey,
[NSNumber numberWithInt:size.height], AVVideoHeightKey,
nil];
AVAssetWriterInput* writerInput = [[AVAssetWriterInput
assetWriterInputWithMediaType:AVMediaTypeVideo
outputSettings:videoSettings] retain];
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor
assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
sourcePixelBufferAttributes:nil];
NSParameterAssert(writerInput);
NSParameterAssert([videoWriter canAddInput:writerInput]);
[videoWriter addInput:writerInput];
//Start a session:
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];
CVPixelBufferRef buffer = NULL;
buffer = [self pixelBufferFromCGImage:[[array objectAtIndex:0] CGImage]];
[adaptor appendPixelBuffer:buffer withPresentationTime:kCMTimeZero];
//Write samples:
for (int i = 0;i<[array count]; i++)
{
if([writerInput isReadyForMoreMediaData])
{
NSLog(#"inside for loop %d",i);
CMTime frameTime = CMTimeMake(1, 20);
CMTime lastTime=CMTimeMake(i, 20); //i is from 0 to 24 of the loop above
CMTime presentTime=CMTimeAdd(lastTime, frameTime);
buffer = [self pixelBufferFromCGImage:[[array objectAtIndex:i] CGImage]];
[adaptor appendPixelBuffer:buffer withPresentationTime:presentTime];
}
else
{
NSLog(#"error");
i--;
}
}
NSLog(#"outside for loop");
//Finish the session:
[writerInput markAsFinished];
[videoWriter finishWriting];
}
Here I have used CVPixelBufferRef. Instead of this, I want to use the CVPixelBufferPoolRef in conjunction with AVAssetWriterInputPixelBufferAdaptor.
Can anybody provide an example which I can debug and use?

Answer 1

You are passing nil 'sourcePixelBufferAttributes', because of which the pixel buffer pool will not get created:
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput sourcePixelBufferAttributes:nil];
Instead pass some attributes, for example:
NSDictionary *bufferAttributes = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:kCVPixelFormatType_32ARGB], kCVPixelBufferPixelFormatTypeKey, nil];
Then you can use the pool to create the pixel buffers, like:
CVPixelBufferPoolCreatePixelBuffer (NULL, adaptor.pixelBufferPool, &pixelBuffer);

Answer 2

#Atulkumar V. Jain : great! good luck ^^
#Brian : you are right thanks, I correct it and I am getting it work now here is the working code (if someone else need it :-) )
CVPixelBufferRef buffer = NULL;
buffer = [self pixelBufferFromCGImage:[[imagesArray objectAtIndex:0] CGImage]];
CVPixelBufferPoolCreatePixelBuffer (NULL, adaptor_.pixelBufferPool, &buffer);
[adaptor_ appendPixelBuffer:buffer withPresentationTime:kCMTimeZero];
__block UInt64 convertedByteCount = 0;
dispatch_queue_t mediaInputQueue = dispatch_queue_create("mediaInputQueue", NULL);
static int i = 1;
int frameNumber = [imagesArray count];
[writerInput requestMediaDataWhenReadyOnQueue:mediaInputQueue usingBlock:^{
while (1){
if (i == frameNumber) {
break;
}
if ([writerInput isReadyForMoreMediaData]) {
CVPixelBufferRef sampleBuffer = [self pixelBufferFromCGImage:[[imagesArray objectAtIndex:i] CGImage]];
NSLog(#"inside for loop %d",i);
CMTime frameTime = CMTimeMake(1, 20);
CMTime lastTime=CMTimeMake(i, 20); //i is from 0 to 19 of the loop above
CMTime presentTime=CMTimeAdd(lastTime, frameTime);
if (sampleBuffer) {
[adaptor_ appendPixelBuffer:sampleBuffer withPresentationTime:presentTime];
i++;
CFRelease(sampleBuffer);
} else {
break;
}
}
}
NSLog (#"done");
[writerInput markAsFinished];
[videoWriter finishWriting];
CVPixelBufferPoolRelease(adaptor_.pixelBufferPool);
[videoWriter release];
[writerInput release];
[imagesArray removeAllObjects];
}];

Answer 3

Instead of using "for" use this code :
dispatch_queue_t mediaInputQueue = dispatch_queue_create("mediaInputQueue", NULL);
[writerInput requestMediaDataWhenReadyOnQueue:mediaInputQueue usingBlock:^{
CVPixelBufferRef buffer = NULL;
buffer = [self pixelBufferFromCGImage:[[array objectAtIndex:0] CGImage]];
CVPixelBufferPoolCreatePixelBuffer (NULL, adaptor.pixelBufferPool, &buffer);
[adaptor appendPixelBuffer:buffer withPresentationTime:kCMTimeZero];
int i = 1;
while (writerInput.readyForMoreMediaData) {
NSLog(#"inside for loop %d",i);
CMTime frameTime = CMTimeMake(1, 20);
CMTime lastTime=CMTimeMake(i, 20); //i is from 0 to 19 of the loop above
CMTime presentTime=CMTimeAdd(lastTime, frameTime);
if (i >= [array count]) {
buffer = NULL;
}else {
buffer = [self pixelBufferFromCGImage:[[array objectAtIndex:i] CGImage]];
}
//CVBufferRetain(buffer);
if (buffer) {
// append buffer
[adaptor appendPixelBuffer:buffer withPresentationTime:presentTime];
i++;
} else {
// done!
//Finish the session:
[writerInput markAsFinished];
[videoWriter finishWriting];
CVPixelBufferPoolRelease(adaptor.pixelBufferPool);
[videoWriter release];
[writerInput release];
NSLog (#"Done");
[imageArray removeAllObjects];
break;
}
}
}];

Answer 4

I got it all working!
Here is the sample code link: git#github.com:RudyAramayo/AVAssetWriterInputPixelBufferAdaptorSample.git
Here is the code you need:
- (void) testCompressionSession
{
CGSize size = CGSizeMake(480, 320);
NSString *betaCompressionDirectory = [NSHomeDirectory() stringByAppendingPathComponent:#"Documents/Movie.m4v"];
NSError *error = nil;
unlink([betaCompressionDirectory UTF8String]);
//----initialize compression engine
AVAssetWriter *videoWriter = [[AVAssetWriter alloc] initWithURL:[NSURL fileURLWithPath:betaCompressionDirectory]
fileType:AVFileTypeQuickTimeMovie
error:&error];
NSParameterAssert(videoWriter);
if(error)
NSLog(#"error = %#", [error localizedDescription]);
NSDictionary *videoSettings = [NSDictionary dictionaryWithObjectsAndKeys:AVVideoCodecH264, AVVideoCodecKey,
[NSNumber numberWithInt:size.width], AVVideoWidthKey,
[NSNumber numberWithInt:size.height], AVVideoHeightKey, nil];
AVAssetWriterInput *writerInput = [AVAssetWriterInput assetWriterInputWithMediaType:AVMediaTypeVideo outputSettings:videoSettings];
NSDictionary *sourcePixelBufferAttributesDictionary = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithInt:kCVPixelFormatType_32ARGB], kCVPixelBufferPixelFormatTypeKey, nil];
AVAssetWriterInputPixelBufferAdaptor *adaptor = [AVAssetWriterInputPixelBufferAdaptor assetWriterInputPixelBufferAdaptorWithAssetWriterInput:writerInput
sourcePixelBufferAttributes:sourcePixelBufferAttributesDictionary];
NSParameterAssert(writerInput);
NSParameterAssert([videoWriter canAddInput:writerInput]);
if ([videoWriter canAddInput:writerInput])
NSLog(#"I can add this input");
else
NSLog(#"i can't add this input");
[videoWriter addInput:writerInput];
[videoWriter startWriting];
[videoWriter startSessionAtSourceTime:kCMTimeZero];
//---
// insert demo debugging code to write the same image repeated as a movie
CGImageRef theImage = [[UIImage imageNamed:#"Lotus.png"] CGImage];
dispatch_queue_t dispatchQueue = dispatch_queue_create("mediaInputQueue", NULL);
int __block frame = 0;
[writerInput requestMediaDataWhenReadyOnQueue:dispatchQueue usingBlock:^{
while ([writerInput isReadyForMoreMediaData])
{
if(++frame >= 120)
{
[writerInput markAsFinished];
[videoWriter finishWriting];
[videoWriter release];
break;
}
CVPixelBufferRef buffer = (CVPixelBufferRef)[self pixelBufferFromCGImage:theImage size:size];
if (buffer)
{
if(![adaptor appendPixelBuffer:buffer withPresentationTime:CMTimeMake(frame, 20)])
NSLog(#"FAIL");
else
NSLog(#"Success:%d", frame);
CFRelease(buffer);
}
}
}];
NSLog(#"outside for loop");
}
- (CVPixelBufferRef )pixelBufferFromCGImage:(CGImageRef)image size:(CGSize)size
{
NSDictionary *options = [NSDictionary dictionaryWithObjectsAndKeys:
[NSNumber numberWithBool:YES], kCVPixelBufferCGImageCompatibilityKey,
[NSNumber numberWithBool:YES], kCVPixelBufferCGBitmapContextCompatibilityKey, nil];
CVPixelBufferRef pxbuffer = NULL;
CVReturn status = CVPixelBufferCreate(kCFAllocatorDefault, size.width, size.height, kCVPixelFormatType_32ARGB, (CFDictionaryRef) options, &pxbuffer);
// CVReturn status = CVPixelBufferPoolCreatePixelBuffer(NULL, adaptor.pixelBufferPool, &pxbuffer);
NSParameterAssert(status == kCVReturnSuccess && pxbuffer != NULL);
CVPixelBufferLockBaseAddress(pxbuffer, 0);
void *pxdata = CVPixelBufferGetBaseAddress(pxbuffer);
NSParameterAssert(pxdata != NULL);
CGColorSpaceRef rgbColorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pxdata, size.width, size.height, 8, 4*size.width, rgbColorSpace, kCGImageAlphaPremultipliedFirst);
NSParameterAssert(context);
CGContextDrawImage(context, CGRectMake(0, 0, CGImageGetWidth(image), CGImageGetHeight(image)), image);
CGColorSpaceRelease(rgbColorSpace);
CGContextRelease(context);
CVPixelBufferUnlockBaseAddress(pxbuffer, 0);
return pxbuffer;
}