mirror of https://github.com/libsdl-org/SDL
camera: Added more accurate timestamps.
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@ -109,6 +109,9 @@ static void ClosePhysicalCameraDevice(SDL_CameraDevice *device)
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device->filled_output_surfaces.next = NULL;
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device->empty_output_surfaces.next = NULL;
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device->app_held_output_surfaces.next = NULL;
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device->base_timestamp = 0;
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device->adjust_timestamp = 0;
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}
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// this must not be called while `device` is still in a device list, or while a device's camera thread is still running.
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@ -535,7 +538,12 @@ SDL_bool SDL_CameraThreadIterate(SDL_CameraDevice *device)
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SDL_Log("CAMERA: New frame available!");
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#endif
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if (device->empty_output_surfaces.next == NULL) {
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if (device->drop_frames > 0) {
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device->drop_frames--;
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camera_driver.impl.ReleaseFrame(device, device->acquire_surface);
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device->acquire_surface->pixels = NULL;
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device->acquire_surface->pitch = 0;
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} else if (device->empty_output_surfaces.next == NULL) {
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// uhoh, no output frames available! Either the app is slow, or it forgot to release frames when done with them. Drop this new frame.
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#if DEBUG_CAMERA
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SDL_Log("CAMERA: No empty output surfaces! Dropping frame!");
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@ -544,6 +552,12 @@ SDL_bool SDL_CameraThreadIterate(SDL_CameraDevice *device)
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device->acquire_surface->pixels = NULL;
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device->acquire_surface->pitch = 0;
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} else {
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if (!device->adjust_timestamp) {
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device->adjust_timestamp = SDL_GetTicksNS();
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device->base_timestamp = timestampNS;
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}
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timestampNS = (timestampNS - device->base_timestamp) + device->adjust_timestamp;
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slist = device->empty_output_surfaces.next;
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output_surface = slist->surface;
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device->empty_output_surfaces.next = slist->next;
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@ -828,6 +842,8 @@ SDL_Camera *SDL_OpenCameraDevice(SDL_CameraDeviceID instance_id, const SDL_Camer
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device->output_surfaces[i].surface = surf;
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}
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device->drop_frames = 1;
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// Start the camera thread if necessary
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if (!camera_driver.impl.ProvidesOwnCallbackThread) {
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char threadname[64];
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@ -25,7 +25,7 @@
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#include "../SDL_hashtable.h"
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#define DEBUG_CAMERA 1
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#define DEBUG_CAMERA 0
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// !!! FIXME: update these drivers!
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@ -92,6 +92,15 @@ struct SDL_CameraDevice
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// Driver-specific hardware data on how to open device (`hidden` is driver-specific data _when opened_).
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void *handle;
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// Dropping the first frame(s) after open seems to help timing on some platforms.
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int drop_frames;
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// Backend timestamp of first acquired frame, so we can keep these meaningful regardless of epoch.
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Uint64 base_timestamp;
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// SDL timestamp of first acquired frame, so we can roughly convert to SDL ticks.
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Uint64 adjust_timestamp;
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// Pixel data flows from the driver into these, then gets converted for the app if necessary.
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SDL_Surface *acquire_surface;
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@ -67,7 +67,6 @@ struct SDL_PrivateCameraData
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io_method io;
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int nb_buffers;
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struct buffer *buffers;
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int first_start;
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int driver_pitch;
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};
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@ -129,6 +128,7 @@ static int V4L2_AcquireFrame(SDL_CameraDevice *device, SDL_Surface *frame, Uint6
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}
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}
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*timestampNS = SDL_GetTicksNS(); // oh well, close enough.
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frame->pixels = device->hidden->buffers[0].start;
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frame->pitch = device->hidden->driver_pitch;
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break;
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@ -161,6 +161,8 @@ static int V4L2_AcquireFrame(SDL_CameraDevice *device, SDL_Surface *frame, Uint6
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frame->pitch = device->hidden->driver_pitch;
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device->hidden->buffers[buf.index].available = 1;
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*timestampNS = (((Uint64) buf.timestamp.tv_sec) * SDL_NS_PER_SECOND) + SDL_US_TO_NS(buf.timestamp.tv_usec);
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#if DEBUG_CAMERA
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SDL_Log("CAMERA: debug mmap: image %d/%d data[0]=%p", buf.index, device->hidden->nb_buffers, (void*)frame->pixels);
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#endif
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@ -202,6 +204,8 @@ static int V4L2_AcquireFrame(SDL_CameraDevice *device, SDL_Surface *frame, Uint6
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frame->pitch = device->hidden->driver_pitch;
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device->hidden->buffers[i].available = 1;
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*timestampNS = (((Uint64) buf.timestamp.tv_sec) * SDL_NS_PER_SECOND) + SDL_US_TO_NS(buf.timestamp.tv_usec);
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#if DEBUG_CAMERA
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SDL_Log("CAMERA: debug userptr: image %d/%d data[0]=%p", buf.index, device->hidden->nb_buffers, (void*)frame->pixels);
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#endif
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@ -212,7 +216,6 @@ static int V4L2_AcquireFrame(SDL_CameraDevice *device, SDL_Surface *frame, Uint6
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break;
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}
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*timestampNS = SDL_GetTicksNS(); // !!! FIXME: can we get this info more accurately from v4l2?
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return 1;
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}
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