Netshlix

Displays an RTP/JPEG stream on a Smalltv-pro (240x240 px LCD).

The roll-your-own minimal RTP/JPEG stack also works on Linux and is fully tested and fuzzed.

Build and deploy

This is an ESP-IDF 5 project.

source $IDF_PATH/export.sh
export ESPPORT=/dev/ttyACM0

# Configuration
cp sdkconfig.defaults.ci sdkconfig.defaults
# Now, change default config (e.g. WiFi credentials):
idf.py menuconfig
idf.py save-defconfig

# Build/flash (see below for Pinout info)
idf.py build flash

# Lint/format
./format.sh

# Flash and monitor
idf.py -p $ESPPORT build flash monitor
idf.py -p $ESPPORT monitor

# Send frames (`mtu` here means UDP payload size, not actual MTU).
gst-launch-1.0 filesrc location=components/rtpjpeg/BigBuckBunny_320x180.mp4 ! decodebin \
    ! videoconvert ! videoscale ! video/x-raw,width=240,height=240 \
    ! jpegenc \
    ! rtpjpegpay seqnum-offset=63000 mtu=1400 \
    ! udpsink host=10.0.0.134 port=1234

# With fps capped:
gst-launch-1.0 filesrc location=components/rtpjpeg/BigBuckBunny_320x180.mp4 ! decodebin \
    ! videorate ! "video/x-raw,framerate=10/1" ! videoconvert ! videoscale ! video/x-raw,width=240,height=240 \
    ! jpegenc \
    ! rtpjpegpay seqnum-offset=63000 mtu=1400 \
    ! udpsink host=10.0.0.134 port=1234

C Conventions

• Names: buf, sz, out
• Sizes: ptrdiff_t
• Objects: typedef struct X_t {} X_t, init_X(..., X_t *out), X_do(X_t *x, ...), X_destroy(X_t *x)

Notes

• There is no WiFi provisioning - the credentials are configured via KConfig (SMALLTV_WIFI_SSID, SMALLTV_WIFI_PASSWORD) and compiled in.
• After a timeout without frames arriving (FRAME_TIMEOUT_US), a test image will be shown on the screen.
• Next to the two jitterbuffer and the JPEG data buffer to decode from, we do not have enough RAM to keep a display framebuffer.
• Thus, there is a single pixel buffer which can hold only a fraction of the screen pixels.
• Both LVGL and the JPEG decoder use this same buffer, rendering one stripe at a time, which is then sent to the display.
• When frames are arriving, LVGL is deactivated by not calling lv_timer_handler().
• We are not using the esp_jpeg component (or ROM decoder) because its API does not allow to receive decoded data block by block.

Hardware

Picture: https://github.com/GeekMagicClock/smalltv-pro/blob/main/images/img-smalltv-pro.jpg

• ESP32-D0WD-V3 chip
• Xtensa® dual-core 32-bit LX6 CPU
• 448 KB of ROM
• 520 KB of SRAM
• 16 KB of RTCSRAM
• 8 MB of Flash memory (SPI)

PINs on header (verified with multimeter, WROOM module pin number in parens):

• 1 GND square
• 2 TX (35)
• 3 RX (34)
• 4 3V3
• 5 GPIO0 (25) - must be held low on reset
• 6 RST (3)

To let the programmer automatically reset the board: Connect pad 1 (GND) to pad 5 (GPIO0).