—To challenge real-time encoding of high-definition video sequences on heterogeneous desktop systems, a collaborative central processing units (CPU) + graphics processing unit (GPU) framework for interloop video encoding is proposed herein. The proposed framework considers the overall complexity of the collaborative interloop encoding as a unified optimization problem. Several functional blocks are integrated for simultaneous execution control, automatic data access management, performance characterization, and adaptive scheduling and load balancing. These blocks aim at fully exploiting the performance of heterogeneous devices, asymmetric bandwidth of communication links, and several levels of concurrency between computation and communication. To support a wide range of CPU and GPU architectures, a specific encoding library is developed with highly optimized algorithms for all interloop modules. The experimental results show that the proposed framework allows achieving a real-time...