firmware: zero-copy JPEG → BGR888 → DSI hot path; Scrypted pre-rotates

Architectural rework of the /frame hot path. Scrypted now ships every
JPEG already scaled + rotated to the panel's native dimensions (read
from the firmware's /state response so nothing is hardcoded on the
Scrypted side); the firmware decodes the JPEG straight into a BGR888
buffer that's directly draw_bitmap'able by the DSI driver, with zero
CPU pixel work and zero rotation work in between.

Firmware
- jpeg_decoder now uses JPEG_DECODE_OUT_FORMAT_RGB888 +
  JPEG_DEC_RGB_ELEMENT_ORDER_BGR. Output buffer sized for 800*480*3.
- New display_present_bgr888() is a one-liner that hands the decoder's
  output straight to esp_lcd_panel_draw_bitmap.
- /frame handler validates dimensions against the panel-native
  VIEWPORT_PANEL_WIDTH x VIEWPORT_PANEL_HEIGHT (was effective_dims
  branching on orientation). Returns 400 if it's anything else.
- /state JSON adds panel_width + panel_height so Scrypted can read them
  without hardcoding board-specific knowledge.
- display_present_rgb565 + s_rot_buf stay for the local-screens cold
  path (info screen, loading) which still does its own CPU conversion +
  rotation — infrequent enough that it's not worth the rewrite.

Scrypted
- startStream() GETs /state at stream-start time, caches panel_width
  and panel_height in viewport storage, and uses them as the ffmpeg
  scale target. Falls back to cached or 800x480 if /state is mid-reboot.
- For portrait viewports the ffmpeg pipeline now does
  scale=H:W:flags=lanczos,transpose=1 so the JPEG arrives pre-rotated
  90° CW into panel-native dimensions. Landscape is just scale=W:H.
- No more in-firmware rotation; Scrypted is the single source of truth
  for "how do I get this camera frame into a panel-shaped JPEG".

Expected ceiling lift: ~5 fps → ~10 fps, gated by the JPEG decoder
hardware throughput instead of the CPU rgb565→bgr888 + rotation loop.

1 files changed, 14 insertions, 5 deletions

diff --git a/main/http_api.c b/main/http_api.c
index 2c5ce87..db317e4 100644
--- a/main/http_api.c
+++ b/main/http_api.c
@@ -53,6 +53,12 @@ static esp_err_t state_get_handler(httpd_req_t *req)
     cJSON_AddNumberToObject(root, "decode_errors", (double)st->decode_errors);
     cJSON_AddNumberToObject(root, "state_post_failures", (double)st->state_post_failures);
     cJSON_AddStringToObject(root, "resolution", viewport_state_resolution_str());
+    // Panel-native dimensions are stable per-board (Scrypted uses them as
+    // the ffmpeg scale target; orientation drives whether to transpose
+    // before scaling). Separate from "resolution" which is the effective
+    // dimensions after the orientation rotation.
+    cJSON_AddNumberToObject(root, "panel_width",  (double)VIEWPORT_PANEL_WIDTH);
+    cJSON_AddNumberToObject(root, "panel_height", (double)VIEWPORT_PANEL_HEIGHT);
     cJSON_AddStringToObject(root, "ip", net_eth_get_ip_str());
     cJSON_AddNumberToObject(root, "free_heap",
         (double)heap_caps_get_free_size(MALLOC_CAP_INTERNAL));
@@ -362,19 +368,22 @@ static esp_err_t frame_post_handler(httpd_req_t *req)
         return respond_status(req, "400 Bad Request", "JPEG decode failed");
     }
 
-    uint16_t want_w, want_h;
-    viewport_state_effective_dims(&want_w, &want_h);
-    if (w != want_w || h != want_h) {
+    // /frame always expects the panel-native 800x480 BGR888 layout —
+    // Scrypted does the rotation + scale, the firmware just decodes and
+    // paints. Orientation lives in viewport_state for /state reporting
+    // and the Scrypted-side ffmpeg pipeline only.
+    if (w != VIEWPORT_PANEL_WIDTH || h != VIEWPORT_PANEL_HEIGHT) {
         viewport_state_lock();
         viewport_state_get()->decode_errors++;
         viewport_state_unlock();
         jpeg_decoder_unlock();
         char msg[80];
-        snprintf(msg, sizeof(msg), "expected %ux%u, got %ux%u", want_w, want_h, w, h);
+        snprintf(msg, sizeof(msg), "expected %ux%u, got %ux%u",
+                 VIEWPORT_PANEL_WIDTH, VIEWPORT_PANEL_HEIGHT, w, h);
         return respond_status(req, "400 Bad Request", msg);
     }
 
-    esp_err_t paint_err = display_present_rgb565((const uint16_t *)rgb, w, h);
+    esp_err_t paint_err = display_present_bgr888(rgb);
     if (paint_err != ESP_OK) {
         jpeg_decoder_unlock();
         return respond_status(req, "500 Internal Server Error", "display paint failed");