Qcarcam Api 🎁 Must See

For embedded software engineers, systems architects, and ADAS developers, understanding the Qcarcam API is no longer optional—it is a prerequisite for building reliable, low-latency camera pipelines on Snapdragon Ride, SA8155P, SA8295P, and other Qualcomm Automotive Development Platforms (QADP).

In the rapidly evolving landscape of automotive technology, the camera has become the most critical sensor for Advanced Driver Assistance Systems (ADAS), surround-view parking, and autonomous driving. At the heart of many high-performance automotive System-on-Chips (SoCs) from Qualcomm lies a specialized software interface known as the Qcarcam API . qcarcam api

typedef void (*qcarcam_frame_ready_cb)(uint32_t session_id, qcarcam_buffer_t *buf); typedef void (*qcarcam_error_cb)(uint32_t session_id, qcarcam_error_t error); qcarcam_register_callback(session_id, QCARCAM_CB_FRAME_READY, my_frame_handler); Let’s walk through a minimal implementation for capturing YUV frames from a single automotive camera (e.g., a 2MP front camera on SA8155P). Step 1: Initialize the API qcarcam_init_params_t init_param = .debug_mask = QCARCAM_DBG_INFO, .num_sessions = 1 ; qcarcam_init(&init_param); Step 2: Configure the Hardware (Sensor + CSI) qcarcam_hw_cfg_t hw_cfg = .csi_lane_id = 0, .csi_lane_assign = 0x4321, .csi_data_type = QCARCAM_CSI_DT_RAW10, .sensor_id = SONY_IMX390_ID ; qcarcam_set_hw_config(session_id, &hw_cfg); Step 3: Set Stream Parameters qcarcam_stream_cfg_t stream_cfg = .width = 1920, .height = 1080, .pixel_format = QCARCAM_PIX_FMT_NV12, // Popular YUV 4:2:0 .framerate_min = 30, .framerate_max = 30, .num_buffers = 4 // Double buffering for smooth flow ; qcarcam_configure_stream(session_id, QCARCAM_STREAM_MAIN, &stream_cfg); Step 4: Allocate ION Buffers and Start Streaming qcarcam_req_buf(session_id, 4); qcarcam_start_session(session_id); // Main loop: block on frame_ready callback while (running) qcarcam_buffer_t *buf; qcarcam_dqbuf(session_id, &buf); // wait for frame process_frame(buf->vaddr, buf->size, buf->timestamp); qcarcam_qbuf(session_id, buf); // return buffer to driver // Enqueue for filling int32_t qcarcam_dqbuf(session_id

Always set num_buffers >= 3 to prevent pipeline stalls on automotive ISP pipelines. 5. Multi-Camera Synchronization: The Killer Feature Where the Qcarcam API truly shines is multi-camera synchronization. For surround-view or stereo vision, frame timestamps across cameras must match within microseconds. Hardware Sync via GPIO or Frame Sync Signal The API provides a qcarcam_set_sync_config() function that ties capture start times across sessions: typedef void (*qcarcam_frame_ready_cb)(uint32_t session_id

| SoC | Max Cameras | Max Resolution | Special Notes | | :--- | :--- | :--- | :--- | | | 5 | 8MP @ 30fps | Limited to 4 CSI lanes total | | SA8155P | 7 | 20MP aggregate | Supports 4K @ 60fps | | SA8195P | 5 | 8K @ 30fps | Dual ISP, virtual channel support | | SA8295P | 11 | 20MP per camera | Real-time warping, 3D surround view acceleration |

// 4. Buffer Queuing (Zero-copy pipeline) int32_t qcarcam_req_buf(session_id, uint32_t num_buffers); int32_t qcarcam_qbuf(session_id, qcarcam_buffer_t *buf); // Enqueue for filling int32_t qcarcam_dqbuf(session_id, qcarcam_buffer_t **buf); // Dequeue filled buffer The API uses callbacks for event notification: