摄像头预设

// _1080P
capture: deviceId="cameraCapMain", position=FRONT, facingMode=USER, width=1920, height=1080, maxFps=30
publish(main): desc="camera_big"(TRACK_MAIN), codec=H264, maxBitrate=2000*1024, width=1920, height=1080, maxFps=25
publish(sub):  desc="camera_small"(TRACK_SUB), codec=H264, maxBitrate=128*1024, width=320, height=180, maxFps=25

// _720P
capture: deviceId="cameraCapMain", position=FRONT, facingMode=USER, width=1280, height=720, maxFps=30
publish(main): desc="camera_big"(TRACK_MAIN), codec=H264, maxBitrate=900*1024, width=1280, height=720, maxFps=25
publish(sub):  desc="camera_small"(TRACK_SUB), codec=H264, maxBitrate=128*1024, width=320, height=180, maxFps=25

// _480P
capture: deviceId="cameraCapMain", position=FRONT, facingMode=USER, width=640, height=480, maxFps=30
publish(main): desc="camera_big"(TRACK_MAIN), codec=H264, maxBitrate=512*1024, width=640, height=480, maxFps=25
publish(sub):  desc="camera_small"(TRACK_SUB), codec=H264, maxBitrate=128*1024, width=320, height=180, maxFps=25

// _180P
capture: deviceId="cameraCapMain", position=FRONT, facingMode=USER, width=320, height=180, maxFps=30
publish(main): desc="camera_big"(TRACK_MAIN), codec=H264, maxBitrate=128*1024, width=320, height=180, maxFps=25
publish(sub):  desc="camera_small"(TRACK_SUB), codec=H264, maxBitrate=128*1024, width=320, height=180, maxFps=25