My colleague and I are currently programming an iPhone-App (for iPhones having two cameras) using swift 4.1 for transmitting video and depth data over the network. But we ran into a problem:
We use 2 AvAssetWriter[1]to store Video and Depth (transformed into a Gray-Image) onto the phone. Therefore we use dataOutputSynchronizer[2]and write the video and depth frames with different AvAssetWriters, but one after the other in the same thread.
After some (seemingly random) time the following code
if avAssetWriterInput.isReadyForMoreMediaData {
let successful = avAssetWriterInput.append(sampleBuffer)
}
fails with the following avAssetWriter.errorlocalizedDescription:
**The operation could not be completed**
I suspect the one AvAssetWriter hasn’t finished writing the previous frame and therefore the other AvAssetWriter fails appending the next frame due to the occupied mp4 encoder.
Is there a way I can check if an AvAssetWriter has finished writing and released the encoder, so that another AvAssetWriter can use it? (Or another way to work around this problem)
[1] https://developer.apple.com/documentation/avfoundation/avassetwriter
