Changing AVCaptureDeviceInput leads to AVAssetWriterStatusFailed - ios

Question

I am trying to change the Camera View Front and Back.it is working well.if video is recorded without flipping with Pause/Record Option it is working fine.But if we Flip Camera View once then, further recording video is not saving which leads to AVAssetWriterStatusFailed-The operation could not be completed. Can anybody help me to find where i have gone wrong ? Below is my code.
Camera.m
- (void)flipCamera{
NSArray * inputs = _session.inputs;
for ( AVCaptureDeviceInput * INPUT in inputs ) {
AVCaptureDevice * Device = INPUT.device ;
if ( [ Device hasMediaType : AVMediaTypeVideo ] ) {
AVCaptureDevicePosition position = Device . position ; AVCaptureDevice * newCamera = nil ; AVCaptureDeviceInput * newInput = nil ;
if ( position == AVCaptureDevicePositionFront )
newCamera = [ self cameraWithPosition : AVCaptureDevicePositionBack ] ;
else
newCamera = [ self cameraWithPosition : AVCaptureDevicePositionFront ] ; newInput = [ AVCaptureDeviceInput deviceInputWithDevice : newCamera error : nil ] ;
// beginConfiguration ensures that pending changes are not applied immediately
[ _session beginConfiguration ] ;
[ _session removeInput : INPUT ] ;
[ _session addInput : newInput ] ;
// Changes take effect once the outermost commitConfiguration is invoked.
[ _session commitConfiguration ] ;
break ;
}
}
for ( AVCaptureDeviceInput * INPUT in inputs ) {
AVCaptureDevice * Device = INPUT.device ;
if ( [ Device hasMediaType : AVMediaTypeAudio ] ) {
// audio input from default mic
AVCaptureDevice* mic = [AVCaptureDevice defaultDeviceWithMediaType:AVMediaTypeAudio];
AVCaptureDeviceInput* newInput = [AVCaptureDeviceInput deviceInputWithDevice:mic error:nil];
// [_session addInput:micinput];
// beginConfiguration ensures that pending changes are not applied immediately
[ _session beginConfiguration ] ;
[ _session removeInput : INPUT ] ;
[ _session addInput : newInput ] ;
// Changes take effect once the outermost commitConfiguration is invoked.
[ _session commitConfiguration ] ;
break ;
}
}
}
- ( AVCaptureDevice * ) cameraWithPosition : ( AVCaptureDevicePosition ) position
{
NSArray * Devices = [ AVCaptureDevice devicesWithMediaType : AVMediaTypeVideo ] ;
for ( AVCaptureDevice * Device in Devices )
if ( Device . position == position )
return Device ;
return nil ;
}
- (void) captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection
{
BOOL bVideo = YES;
#synchronized(self)
{
if (!self.isCapturing || self.isPaused)
{
return;
}
if (connection != _videoConnection)
{
bVideo = NO;
}
if ((_encoder == nil) && !bVideo)
{
CMFormatDescriptionRef fmt = CMSampleBufferGetFormatDescription(sampleBuffer);
[self setAudioFormat:fmt];
NSString* filename = [NSString stringWithFormat:#"capture%d.mp4", _currentFile];
NSString* path = [NSTemporaryDirectory() stringByAppendingPathComponent:filename];
_encoder = [VideoEncoder encoderForPath:path Height:_cy width:_cx channels:_channels samples:_samplerate];
}
if (_discont)
{
if (bVideo)
{
return;
}
_discont = NO;
// calc adjustment
CMTime pts = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
CMTime last = bVideo ? _lastVideo : _lastAudio;
if (last.flags & kCMTimeFlags_Valid)
{
if (_timeOffset.flags & kCMTimeFlags_Valid)
{
pts = CMTimeSubtract(pts, _timeOffset);
}
CMTime offset = CMTimeSubtract(pts, last);
NSLog(#"Setting offset from %s", bVideo?"video": "audio");
NSLog(#"Adding %f to %f (pts %f)", ((double)offset.value)/offset.timescale, ((double)_timeOffset.value)/_timeOffset.timescale, ((double)pts.value/pts.timescale));
// this stops us having to set a scale for _timeOffset before we see the first video time
if (_timeOffset.value == 0)
{
_timeOffset = offset;
}
else
{
_timeOffset = CMTimeAdd(_timeOffset, offset);
}
}
_lastVideo.flags = 0;
_lastAudio.flags = 0;
}
// retain so that we can release either this or modified one
CFRetain(sampleBuffer);
if (_timeOffset.value > 0)
{
CFRelease(sampleBuffer);
sampleBuffer = [self adjustTime:sampleBuffer by:_timeOffset];
}
// record most recent time so we know the length of the pause
CMTime pts = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
CMTime dur = CMSampleBufferGetDuration(sampleBuffer);
if (dur.value > 0)
{
pts = CMTimeAdd(pts, dur);
}
if (bVideo)
{
_lastVideo = pts;
}
else
{
_lastAudio = pts;
}
}
// pass frame to encoder
[_encoder encodeFrame:sampleBuffer isVideo:bVideo];
CFRelease(sampleBuffer);
}
Encoder.m
- (BOOL) encodeFrame:(CMSampleBufferRef) sampleBuffer isVideo:(BOOL)bVideo
{
if (CMSampleBufferDataIsReady(sampleBuffer))
{
if (_writer.status == AVAssetWriterStatusUnknown)
{
CMTime startTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
[_writer startWriting];
[_writer startSessionAtSourceTime:startTime];
}
if (_writer.status == AVAssetWriterStatusFailed)
{ // If Camera View is Flipped then Loop Enters inside this condition - writer error The operation could not be completed
NSLog(#"writer error %#", _writer.error.localizedDescription);
return NO;
}
if (bVideo)
{
if (_videoInput.readyForMoreMediaData == YES)
{
[_videoInput appendSampleBuffer:sampleBuffer];
return YES;
}
}
else
{
if (_audioInput.readyForMoreMediaData)
{
[_audioInput appendSampleBuffer:sampleBuffer];
return YES;
}
}
}
return NO;
}
Thanks in Advance.

Answer 1

The problem is this line:
if (connection != _videoConnection)
{
bVideo = NO;
}
When you change the camera a new videoConnection is created, I don't know where either how. But if you change this line like below it works:
//if (connection != _videoConnection)
if ([connection.output connectionWithMediaType:AVMediaTypeVideo] == nil)
{
bVideo = NO;
}