mirrors
/
SDL
mirror of https://github.com/libsdl-org/SDL
1
0
Fork 0
Code Issues Packages Projects Releases Wiki Activity

camera: Added more accurate timestamps.

This commit is contained in:
Ryan C. Gordon 2023-12-16 16:00:15 -05:00
parent d3e6ef3cc6
commit f87d536229
3 changed files with 32 additions and 4 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

18
src/camera/SDL_camera.c
View File

@ -109,6 +109,9 @@ static void ClosePhysicalCameraDevice(SDL_CameraDevice *device)
device->filled_output_surfaces.next = NULL;
device->empty_output_surfaces.next = NULL;
device->app_held_output_surfaces.next = NULL;
device->base_timestamp = 0;
device->adjust_timestamp = 0;
}
// this must not be called while `device` is still in a device list, or while a device's camera thread is still running.
@ -535,7 +538,12 @@ SDL_bool SDL_CameraThreadIterate(SDL_CameraDevice *device)
SDL_Log("CAMERA: New frame available!");
#endif
if (device->empty_output_surfaces.next == NULL) {
if (device->drop_frames > 0) {
device->drop_frames--;
camera_driver.impl.ReleaseFrame(device, device->acquire_surface);
device->acquire_surface->pixels = NULL;
device->acquire_surface->pitch = 0;
} else if (device->empty_output_surfaces.next == NULL) {
// uhoh, no output frames available! Either the app is slow, or it forgot to release frames when done with them. Drop this new frame.
#if DEBUG_CAMERA
SDL_Log("CAMERA: No empty output surfaces! Dropping frame!");
@ -544,6 +552,12 @@ SDL_bool SDL_CameraThreadIterate(SDL_CameraDevice *device)
device->acquire_surface->pixels = NULL;
device->acquire_surface->pitch = 0;
} else {
if (!device->adjust_timestamp) {
device->adjust_timestamp = SDL_GetTicksNS();
device->base_timestamp = timestampNS;
}
timestampNS = (timestampNS - device->base_timestamp) + device->adjust_timestamp;
slist = device->empty_output_surfaces.next;
output_surface = slist->surface;
device->empty_output_surfaces.next = slist->next;
@ -828,6 +842,8 @@ SDL_Camera *SDL_OpenCameraDevice(SDL_CameraDeviceID instance_id, const SDL_Camer
device->output_surfaces[i].surface = surf;
}
device->drop_frames = 1;
// Start the camera thread if necessary
if (!camera_driver.impl.ProvidesOwnCallbackThread) {
char threadname[64];

11
src/camera/SDL_syscamera.h
View File

@ -25,7 +25,7 @@
#include "../SDL_hashtable.h"
#define DEBUG_CAMERA 1
#define DEBUG_CAMERA 0
// !!! FIXME: update these drivers!
@ -92,6 +92,15 @@ struct SDL_CameraDevice
// Driver-specific hardware data on how to open device (`hidden` is driver-specific data _when opened_).
void *handle;
// Dropping the first frame(s) after open seems to help timing on some platforms.
int drop_frames;
// Backend timestamp of first acquired frame, so we can keep these meaningful regardless of epoch.
Uint64 base_timestamp;
// SDL timestamp of first acquired frame, so we can roughly convert to SDL ticks.
Uint64 adjust_timestamp;
// Pixel data flows from the driver into these, then gets converted for the app if necessary.
SDL_Surface *acquire_surface;

7
src/camera/v4l2/SDL_camera_v4l2.c
View File

@ -67,7 +67,6 @@ struct SDL_PrivateCameraData
io_method io;
int nb_buffers;
struct buffer *buffers;
int first_start;
int driver_pitch;
};
@ -129,6 +128,7 @@ static int V4L2_AcquireFrame(SDL_CameraDevice *device, SDL_Surface *frame, Uint6
}
}
*timestampNS = SDL_GetTicksNS(); // oh well, close enough.
frame->pixels = device->hidden->buffers[0].start;
frame->pitch = device->hidden->driver_pitch;
break;
@ -161,6 +161,8 @@ static int V4L2_AcquireFrame(SDL_CameraDevice *device, SDL_Surface *frame, Uint6
frame->pitch = device->hidden->driver_pitch;
device->hidden->buffers[buf.index].available = 1;
*timestampNS = (((Uint64) buf.timestamp.tv_sec) * SDL_NS_PER_SECOND) + SDL_US_TO_NS(buf.timestamp.tv_usec);
#if DEBUG_CAMERA
SDL_Log("CAMERA: debug mmap: image %d/%d data[0]=%p", buf.index, device->hidden->nb_buffers, (void*)frame->pixels);
#endif
@ -202,6 +204,8 @@ static int V4L2_AcquireFrame(SDL_CameraDevice *device, SDL_Surface *frame, Uint6
frame->pitch = device->hidden->driver_pitch;
device->hidden->buffers[i].available = 1;
*timestampNS = (((Uint64) buf.timestamp.tv_sec) * SDL_NS_PER_SECOND) + SDL_US_TO_NS(buf.timestamp.tv_usec);
#if DEBUG_CAMERA
SDL_Log("CAMERA: debug userptr: image %d/%d data[0]=%p", buf.index, device->hidden->nb_buffers, (void*)frame->pixels);
#endif
@ -212,7 +216,6 @@ static int V4L2_AcquireFrame(SDL_CameraDevice *device, SDL_Surface *frame, Uint6
break;
}
*timestampNS = SDL_GetTicksNS(); // !!! FIXME: can we get this info more accurately from v4l2?
return 1;
}