The example enumerates a connected USB camera, negotiates a selected resolution along with an associated `FPS`, then starts capturing video. The `frame_callback` function is then invoked after receiving each frame. Users can process the received frames according to their needs.
Optionally, the captured video can be visualized on a PC with help of the `player.py` script provided in this example. After setting the `Example Configuration->Enable streaming` option in menuconfig, the example will create a TCP server upon startup, and waits until `player.py` connects to the server. Once a connection is established, the example streams each received frame to the PC for visualization. The network connection can be configured in menuconfig via `Example Connection Configuration`.
**Notice** that `libuvc` selects highest possible `dwMaxPayloadTransferSize` by default. As a result, this example will manually overwrite this value to 512 bytes (the maximum packet size supported by ESP32-S2/S3).
Running this example on an **ESP module without external PSRAM will fail on initialization**. Please select your PSRAM configuration in menuconfig `Component config->ESP PSRAM`. If you manually disable PSRAM, the required framebuffers might not fit into DRAM (especially on ESP32-S2).
Additionally, the `player.py` python script makes use of the `opencv-python` and `numpy` packages which are not included in the `idf-env` environment by default. Run following command to install those packages:
When the protocol mode set to Custom, the example tries to negotiate the protocol using user provided values for the following parameters: Attempts, Width, Height, FPS, and Frame Coding format. After all attempts result in an error, the example displays the error message and suggests to try another USB UVC device.
Having only a Full Speed USB peripheral and hardware limited MPS (maximum packet size) to 512 bytes, the ESP32-S2/S3 is capable of reading data at approximately 0.5 MB/s. When connected to Full Speed USB host, cameras normally provide resolution no larger than 640x480 pixels. The following two formats are the most commonly supported at Full Speed (both encoded in MJPEG):
