esp-idf/examples/peripherals/usb/host/uvc/README.md

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| Supported Targets | ESP32-S2 | ESP32-S3 |
| ----------------- | -------- | -------- |
# USB Camera Example
## Overview
This example demonstrates how to:
- Capture video from a USB camera using the `libuvc` library.
- Stream the video over WiFi by hosting a TCP server.
The example enumerates connected camera, negotiates selected resolution together with `FPS` and starts capturing video.
`frame_callback` function is then invoked after receiving each frame. User can process received frame according to his needs.
Optionally, captured video can be visualized on computer with help of `player.py` script located in this example.
After setting `Enable streaming` menuconfig option, example will create TCP server upon start, and wait until `player.py` connects to server.
Once connection is established, example streams each received frame to computer for visualization.
**Notice** that `libuvc` selects highest possible `dwMaxPayloadTransferSize` by default, so example has to manually overwrite this value to 512 bytes (maximum transfer size supported by ESP32-S2/S3).
(See the README.md file in the upper level 'examples' directory for more information about examples.)
## How to Use Example
### Hardware Required
This example requires any ESP32-S2 or ESP32-S3 with external PSRAM and exposed USB connector attached to USB camera.
*ESP module without external PSRAM will fail to initialize*
### Configure the project
Following configuration is needed for streaming video:
Open the project configuration menu (`idf.py menuconfig`).
In the `Example Connection Configuration` menu:
* Set the Wi-Fi configuration.
* Set `WiFi SSID`.
* Set `WiFi Password`.
In the `Example Configuration` menu:
* Set the Example configuration
* `Enable streaming`
Optional: If you need, change the other options according to your requirements.
Additionally, `player.py` python script makes use of `opencv-python` and `numpy` packages,
not included in `idf-env` environment. Run following commands to install:
* `pip install opencv-python`
* `pip install numpy`
### Build and Flash
Build the project and flash it to the board, then run the monitor tool to view the serial output:
Run `idf.py set-target esp32s2` to set target chip.
Run `idf.py -p PORT flash monitor` to build, flash and monitor the project.
(To exit the serial monitor, type ``Ctrl-]``.)
See the Getting Started Guide for all the steps to configure and use the ESP-IDF to build projects.
## Known limitations
Having only Full Speed USB peripheral and hardware limited MPS (maximum packet size) to 512 bytes, ESP32-S2/S3 is capable of reading about 0.5 MB of data per second. When connected to Full Speed USB host, cameras normally provide resolution no larger than 640x480 pixels.
Following two supported formats are the most common (both encoded in MJPEG):
* 320x240 30 FPS
* 640x480 15 FPS
## Tested cameras
* Logitech C980
* CANYON CNE-CWC2
## Example Output
```
...
Waiting for device
Device found
DEVICE CONFIGURATION (0c45:6340/ S) ---
Status: idle
VideoControl:
bcdUVC: 0x0100
VideoStreaming(1):
bEndpointAddress: 129
Formats:
MJPEGFormat(1)
bits per pixel: 0
GUID: 4d4a5047000000000000000000000000 (MJPG)
default frame: 1
aspect ratio: 0x0
interlace flags: 00
copy protect: 00
FrameDescriptor(1)
capabilities: 00
size: 640x480
bit rate: 24576000-147456000
max frame size: 614400
default interval: 1/30
interval[0]: 1/30
interval[1]: 1/25
interval[2]: 1/20
interval[3]: 1/15
interval[4]: 1/10
interval[5]: 1/5
FrameDescriptor(2)
capabilities: 00
size: 352x288
bit rate: 8110080-48660480
max frame size: 202752
default interval: 1/30
interval[0]: 1/30
interval[1]: 1/25
interval[2]: 1/20
interval[3]: 1/15
interval[4]: 1/10
interval[5]: 1/5
FrameDescriptor(3)
capabilities: 00
size: 320x240
bit rate: 6144000-36864000
max frame size: 153600
default interval: 1/30
interval[0]: 1/30
interval[1]: 1/25
interval[2]: 1/20
interval[3]: 1/15
interval[4]: 1/10
interval[5]: 1/5
FrameDescriptor(4)
capabilities: 00
size: 176x144
bit rate: 2027520-12165120
max frame size: 50688
default interval: 1/30
interval[0]: 1/30
interval[1]: 1/25
interval[2]: 1/20
interval[3]: 1/15
interval[4]: 1/10
interval[5]: 1/5
FrameDescriptor(5)
capabilities: 00
size: 160x120
bit rate: 1536000-9216000
max frame size: 38400
default interval: 1/30
interval[0]: 1/30
interval[1]: 1/25
interval[2]: 1/20
interval[3]: 1/15
interval[4]: 1/10
interval[5]: 1/5
StillFrameDescriptor
bEndPointAddress: 00
wWidth(1) = 640
wHeight(1) = 480
wWidth(2) = 352
wHeight(2) = 288
wWidth(3) = 320
wHeight(3) = 240
wWidth(4) = 176
wHeight(4) = 144
wWidth(5) = 160
wHeight(5) = 120
END DEVICE CONFIGURATION
bmHint: 0001
bFormatIndex: 1
bFrameIndex: 3
dwFrameInterval: 333333
wKeyFrameRate: 0
wPFrameRate: 0
wCompQuality: 0
wCompWindowSize: 0
wDelay: 20905
dwMaxVideoFrameSize: 153600
dwMaxPayloadTransferSize: 512
bInterfaceNumber: 1
Streaming...
I (4801) example: fps: 35, bytes per second: 170480
I (5821) example: fps: 34, bytes per second: 172448
I (6841) example: fps: 34, bytes per second: 172448
I (7871) example: fps: 34, bytes per second: 172448
I (8891) example: fps: 34, bytes per second: 172448
I (9921) example: fps: 35, bytes per second: 177520
I (10941) example: fps: 34, bytes per second: 172448
I (11961) example: fps: 34, bytes per second: 172448
I (12991) example: fps: 34, bytes per second: 172448
I (14011) example: fps: 34, bytes per second: 172448
I (15041) example: fps: 34, bytes per second: 172448
I (16061) example: fps: 34, bytes per second: 172448
I (17081) example: fps: 34, bytes per second: 172448
Done streaming.
UVC exited
```