Thank you. Can you point me to the right way to catch the exception without crashing? Thanks again.

The exception is Fatal Exception: NSInvalidArgumentException. It's worth noting these streams usually work fine. When I tested this for a while in the wild however, sometimes it will crash. Maybe the buffer is randomly malformed in someway.

Thank you. So this is how the Audio Frame is being allocated: private func audioPlayerShouldInputData(ioData: UnsafeMutableAudioBufferListPointer, numberOfFrames: UInt32) { var ioDataWriteOffset = 0 var numberOfSamples = Int(numberOfFrames) while numberOfSamples > 0 { if currentRender == nil { currentRender = renderSource?.getAudioOutputRender() } guard let currentRender = currentRender else { break } let residueLinesize = currentRender.numberOfSamples - currentRenderReadOffset guard residueLinesize > 0 else { self.currentRender = nil continue } let framesToCopy = min(numberOfSamples, residueLinesize) let bytesToCopy = framesToCopy * MemoryLayout<Float>.size let offset = currentRenderReadOffset * MemoryLayout<Float>.size for i in 0 ..< min(ioData.count, currentRender.dataWrap.data.count) { (ioData[i].mData! + ioDataWriteOffset).copyMemory(from: currentRender.dataWrap.data[i]! + offset, byteCount: bytesToCopy) } numberOfSamples -= framesToCopy ioDataWriteOffset += bytesToCopy currentRenderReadOffset += framesToCopy } let sizeCopied = (Int(numberOfFrames) - numberOfSamples) * MemoryLayout<Float>.size for i in 0 ..< ioData.count { let sizeLeft = Int(ioData[i].mDataByteSize) - sizeCopied if sizeLeft > 0 { memset(ioData[i].mData! + sizeCopied, 0, sizeLeft) } } } I've followed getAudioOutputRender and I believe the Audio Frame is first generated here: let result = avcodec_receive_frame(codecContext, coreFrame) if result == 0, let avframe = coreFrame { var frame = try swresample.transfer(avframe: filter?.filter(inputFrame: avframe) ?? avframe) frame.timebase = packet.assetTrack.timebase frame.duration = avframe.pointee.pkt_duration frame.size = Int64(avframe.pointee.pkt_size) if packet.assetTrack.mediaType == .audio { bestEffortTimestamp = max(bestEffortTimestamp, avframe.pointee.pts) frame.position = bestEffortTimestamp if frame.duration == 0 { frame.duration = Int64(avframe.pointee.nb_samples) * Int64(frame.timebase.den) / (Int64(avframe.pointee.sample_rate) * Int64(frame.timebase.num)) } bestEffortTimestamp += frame.duration } else { frame.position = avframe.pointee.best_effort_timestamp } delegate?.decodeResult(frame: frame)