Weihao Yuan

Team Management:

• The primary responsibility of the team is to optimize camera creation delay, video smoothness, quality and reliability.
• Chairing team meetings, tracking project progress, discussing technical designs and details, and overseeing code reviews within the team.
• Responsible for external communication on behalf of the team.
• Conducting interviews at the Shenzhen office and providing mentorship to newly hired employees.

Camera Creation Delay Optimization:

• MediaCodec management: Lease-based MediaCodec resource management; optimization of MediaCodec's thread model; preloading Recorder and Player; unified management of MediaCodec's lifecycle and resource reuse for the creation flow.
• Capture Intent Model: Analyzing user's data, building a predictive model for user's capture intention, predicting user's behavior for each capture session, and adjusting the video capture delay accordingly.
• Composite Capture Flow: Rewriting the entire creation flow of the application to support both finger up and finger down capture simultaneously.
• SurfaceView Management: Unified management of the SurfaceView lifecycle of the creation flow, and implementing resource reuse.

Video Smoothness Optimization:

• Double Camera Stream: Utilizing dual-stream technology for camera, separating video recording and video preview streams, transforming from serial to parallel rendering.
• Buffer Video Recording: Using techniques like FBO and ImageReader to implement video frame buffering between the camera data source and ViewFinder/Recorder, ensuring smoother camera preview and recording.
• Recorder Pre-encode: Pre-encoding the encoder of the recorder to reduce the stickiness in the initial frames of the video.
• Capture Animation Optimization: Optimizing the capture animation based on device performance and battery life, using OpenGL for rendering of the capture animation directly.

Video Quality Optimization:

• HEVC: Collaborated with the server team to drive the implementation of HEVC recording and HEVC transcoding.
• Video Quality Test Framework: Participating in the construction of the video quality testing framework.
• Adaptive Transcoding: Calculating video complexity and employing different bit rates for adaptive transcoding based on the complexity of the video.

Video Reliability Optimization:

• ExoExtractor: Integrating ExoExtractor into our video playback and transcoding process to address the Android 9 issues and improve overall performance and reliability of the streaming process.
• Recording Retry Strategy: Implementing a more flexible failure retry mechanism at the Media Level in the video recording and transcoding process.
• AV Sync: Identifying the cause of audio-video synchronization issues in video shooting and implementing PCM buffer solutions.

Capture Relative Functionalities:

• Mushroom: Participating in the rewrite of the Snapchat Android client, introducing technologies such as Dagger, Kotlin, and RxJava.
• Catalina: Implemented Snapchat's guest mode and collaborated with Google to enable a feature where double-tapping the back of a Pixel 7 series phone in the locked screen state would launch Snapchat in guest mode, allowing users to capture content in this mode.
• Hermosa: Participating in the development of Snapchat smart glasses, mainly responsible for implementing the capture module.
• Recovery: Restoring the capture content from the previous session if the user accidentally exits the application during the creation flow when reopening the application.

Micro Options (Startup Project):

• An app that provides over-the-counter derivative pricing, order placement, and news.
• Responsible for requirement gathering, technical design, development, and maintenance of the Android client for Micro Options for institutions such as Huatai, Xinhua, and Nanhua.
• Responsible for project scheduling and progress tracking for the mobile side (iOS and Android).
• Utilized technologies such as Retrofit, RxJava, JNI (for market data push), EventBus, and ButterKnife.

Mobile QQ:

• Analyzed user behavior data and optimized the strategy for pre-downloading images.
• Maintained and optimized basic components such as image preview, album, and image editing for Android QQ.
• Maintained the GIF shared object library (.so library) and participated in performance improvements.
• Developed with accessibility in mind to ensure the inclusive user experience.
• Participated in the development of short video features for Android QQ.