Efficient PCIe transmission for Multi-Channel video using dynamic splicing and conditional prefetching

PCI Express (PCIe) interface has been extensively used in high-speed digital systems for multimedia communication. With the migration of the video processing algorithms from host to embedded hardware, multi-channel video capturing systems will produce not only different channels of raw video data but also different types of auxiliary data, such as analyzed data and compressed stream. In order to display multi-channel video in real-time and explore the auxiliary data, conventional transmission strategies are no longer applicable, due to the fact that heterogeneous data will cause frequent interactions and lead to the waste of PCIe bandwidth. In this paper, an efficient PCIe transmission method for multi-channel video is presented. Firstly, for the transmission of multi-type video data, a dynamic splicing mechanism is proposed to combine the video analyzed data and the compressed stream with the raw video to avoid the individual transmission of the auxiliary data. Secondly, as the spliced data are from different channels, a conditional prefetching mechanism is employed to determine whether there exists any entire video frame in other channel buffers, so that multi-channel video data can be transmitted possibly at one time. Finally, in the host-side driver, direct kernel buffer access technique is used to improve the application I/O request packet (IRP) performance. And to ensure the transmission efficiency of the conditional prefetching, DMA circular queue buffer and timer self-feedback monitor techniques are designed to avoid the possible visit bursts and abnormal interruptions. Experimental results demonstrate that compared with the conventional methods, the proposed method reduces the interrupt interactions by 60%, increases the transmission channel number by 94%, and also increases the application IRP number by 54%. The peak transmission speed of PCIe is up to 155 MB/s, which can meet 7 channels 704 × 576 YUV raw video and its auxiliary data transmission requirements using one 1-lane PCIe endpoint.