Streaming region-of-interest JPEG decoder for ESP32 based on tjpgd. Stream JPEG data in from any source, stream decoded pixel rows out to your callback — without loading the full image into RAM, without a seekable source, without a full-frame output buffer. Stream in from a file, a flash blob, an HTTP response body, a UART byte stream, a FreeRTOS queue, a TCP socket, or a DMA ring buffer. If you can hand bytes to a callback, you can decode a JPEG.