GLInject to Python (numpy)

glinject.py

import ctypes
import glob
import mmap
import operator
import os.path
import time

import numpy
import matplotlib.pyplot as plt

GLINJECT_RING_BUFFER_SIZE = 4

GLINJECT_IDENTIFIER = 0x8af7a476

GLINJECT_FLAG_CAPTURE_ENABLED = 0x0001
GLINJECT_FLAG_RECORD_CURSOR   = 0x0002
GLINJECT_FLAG_LIMIT_FPS       = 0x0004

class GLInjectHeader(ctypes.Structure):
	_pack_ = 1
	_fields_ = [
		("identifier", ctypes.c_uint32),
		("ring_buffer_read_pos", ctypes.c_uint32),
		("ring_buffer_write_pos", ctypes.c_uint32),
		("current_width", ctypes.c_uint32),
		("current_height", ctypes.c_uint32),
		("frame_counter", ctypes.c_uint32),
		("capture_flags", ctypes.c_uint32),
		("capture_target_fps", ctypes.c_uint32),
	]

class GLInjectFrameInfo(ctypes.Structure):
	_pack_ = 1
	_fields_ = [
		("timestamp", ctypes.c_int64),
		("width", ctypes.c_uint32),
		("height", ctypes.c_uint32),
		("stride", ctypes.c_int32),
	]

class GLInjectMain(ctypes.Structure):
	_pack_ = 1
	_fields_ = [
		("header", GLInjectHeader),
		("frameinfo", GLInjectFrameInfo * GLINJECT_RING_BUFFER_SIZE),
	]

def makepagesize(x):
	return (x + mmap.PAGESIZE - 1) // mmap.PAGESIZE * mmap.PAGESIZE

def releasemem(x):
	for mv in x._objects.values():
		if isinstance(mv, memoryview):
			mv.release()

def showimage(img):
	plt.figure("Image", figsize=(img.shape[1] / 80, img.shape[0] / 80), dpi=80)
	plt.clf()
	plt.figimage(img)
	plt.show()

channel_dir = "/dev/shm/ssr-channel-maarten"

streamlist = [os.path.basename(filename).split("-") for filename in glob.glob(os.path.join(channel_dir, "video-*"))]
if len(streamlist) == 0:
	print("Could not find any streams!")
streamlist.sort(key=operator.itemgetter(1))
selected_stream = streamlist[-1]

fp_video = open(os.path.join(channel_dir, "-".join(selected_stream)), "r+b")
fp_videoframes = [open(os.path.join(channel_dir, "-".join(["videoframe%d" % (i)] + selected_stream[1:])), "r+b") for i in range(GLINJECT_RING_BUFFER_SIZE)]

try:
	
	mmap_video = mmap.mmap(fp_video.fileno(), makepagesize(ctypes.sizeof(GLInjectMain)))
	struct_video = GLInjectMain.from_buffer(mmap_video)
	
	print("Clearing old frames", struct_video.header.ring_buffer_read_pos, struct_video.header.ring_buffer_write_pos)
	struct_video.header.ring_buffer_read_pos = struct_video.header.ring_buffer_write_pos
	
	print("Starting capture")
	struct_video.header.capture_flags = GLINJECT_FLAG_CAPTURE_ENABLED | GLINJECT_FLAG_LIMIT_FPS
	
	print("Waiting for frame ... ", end="")
	while struct_video.header.ring_buffer_read_pos == struct_video.header.ring_buffer_write_pos:
		time.sleep(0.01)
	print("got frame %d" % (struct_video.header.ring_buffer_read_pos))
	framenum = struct_video.header.ring_buffer_read_pos % GLINJECT_RING_BUFFER_SIZE
	
	print("Reading frame %d ... " % (framenum), end="")
	(timestamp, width, height, stride) = (struct_video.frameinfo[framenum].timestamp, struct_video.frameinfo[framenum].width, struct_video.frameinfo[framenum].height, struct_video.frameinfo[framenum].stride)
	required_size = abs(stride) * height
	mmap_videoframe = mmap.mmap(fp_videoframes[framenum].fileno(), makepagesize(abs(stride) * height))
	rawimage = numpy.frombuffer(mmap_videoframe, dtype=numpy.uint8, count=abs(stride) * height).reshape((height, abs(stride)))
	rawimage = rawimage[:, :width*4] if stride > 0 else rawimage[::-1, :width*4]
	image = rawimage.reshape((height, width, 4))[:, :, 2::-1].copy()
	mmap_videoframe.close()
	struct_video.header.ring_buffer_read_pos = (struct_video.header.ring_buffer_read_pos + 1) % (GLINJECT_RING_BUFFER_SIZE * 2)
	print(" done")
	
	print("Stopping capture")
	struct_video.header.capture_flags = 0
	
	print("Cleaning up ...", end="")
	releasemem(struct_video)
	mmap_video.close()
	print(" done")
	
finally:
	fp_video.close()
	for fp in fp_videoframes:
		fp.close()

showimage(image)