2020-4-10 GPU update: improved transcoding and GPU support for rmvb and other formats

This update focuses on GPU transcoding. Previously, GPU transcoding used GPU to decode videos into graphics memory, then GPU processing added watermarks and scrolling text. Formats such as rmvb unsupported by gpu decoding were incompatible. We added compatibility for rmvb and other formats: RMVB uses CPU decoding followed by GPU encoding, retaining high efficiency with much broader compatibility.

Updates

• One: Improved transcoding logic and watermark handling for portrait and widescreen, on both CPU and GPU.
• Two: GPU transcoding supports RMVB and other formats through CPU decoding followed by GPU encoding.