usbvision.c

这是一个Linux下的USB摄像头捕捉程序

	if ((usbvision->curFrameNum < 0)
	    || (usbvision->curFrameNum >= USBVISION_NUMFRAMES)) {
		printk(KERN_ERR "%s: usbvision->curFrameNum=%d.\n", proc,
		       usbvision->curFrameNum);
		return;
	}

	/* Grab the current frame */
	frame = &usbvision->frame[usbvision->curFrameNum];

	/* Optionally start at the beginning */
	if (fullframe) {
		frame->curline = 0;
		frame->scanlength = 0;
	}

	/* Form every scan line */
	for (; frame->curline < frame->frmheight; frame->curline++) {
		int i;

		f = frame->data + (usbvision->curwidth * 3 * frame->curline);
		for (i = 0; i < usbvision->curwidth; i++) {
			unsigned char cb = 0x80;
			unsigned char cg = 0;
			unsigned char cr = 0;

			if (pmode == 1) {
				if (frame->curline % 32 == 0)
					cb = 0, cg = cr = 0xFF;
				else if (i % 32 == 0) {
					if (frame->curline % 32 == 1)
						num_cell++;
					cb = 0, cg = cr = 0xFF;
				} else {
					cb =
					    ((num_cell * 7) +
					     num_pass) & 0xFF;
					cg =
					    ((num_cell * 5) +
					     num_pass * 2) & 0xFF;
					cr =
					    ((num_cell * 3) +
					     num_pass * 3) & 0xFF;
				}
			} else {
				/* Just the blue screen */
			}

			*f++ = cb;
			*f++ = cg;
			*f++ = cr;
			scan_length += 3;
		}
	}

	frame->grabstate = FrameState_Done;
	frame->scanlength += scan_length;
	++num_pass;

	/* We do this unconditionally, regardless of FLAGS_OSD_STATS */
	usbvision_osd_stats(usbvision, frame);
}

/*
 * Here comes the data parsing stuff that is run as interrupt
 */

/*
 * usbvision_find_header()
 *
 * Locate one of supported header markers in the scratch buffer.
 */
static enum ParseState usbvision_find_header(struct usb_usbvision *usbvision)
{
	struct usbvision_frame *frame;
	int foundHeader = 0;

	if (usbvision->overlay) {
		frame = &usbvision->overlay_frame;
	}
	else {
		frame = &usbvision->frame[usbvision->curFrameNum];
	}

	while (scratch_get_header(usbvision, &frame->isocHeader) == USBVISION_HEADER_LENGTH) {
		// found header in scratch
		PDEBUG(DBG_HEADER, "found header: 0x%02x%02x %d %d %d %d %#x 0x%02x %u %u",
				frame->isocHeader.magic_2,
				frame->isocHeader.magic_1,
				frame->isocHeader.headerLength,
				frame->isocHeader.frameNum,
				frame->isocHeader.framePhase,
				frame->isocHeader.frameLatency,
				frame->isocHeader.dataFormat,
				frame->isocHeader.formatParam,
				frame->isocHeader.frameWidth,
				frame->isocHeader.frameHeight);

		if (usbvision->requestIntra) {
			if (frame->isocHeader.formatParam & 0x80) {
				foundHeader = 1;
				usbvision->lastIsocFrameNum = -1; // do not check for lost frames this time
				usbvision_unrequest_intra(usbvision);
				break;
			}
		}
		else {
			foundHeader = 1;
			break;
		}
	}

	if (foundHeader) {
		frame->frmwidth = frame->isocHeader.frameWidth * usbvision->stretch_width;
		frame->frmheight = frame->isocHeader.frameHeight * usbvision->stretch_height;
		frame->v4l_linesize = (frame->frmwidth * usbvision_v4l_format[frame->v4l_format].depth)>> 3;
		usbvision->curFrame = frame;
	}
	else { // no header found
		PDEBUG(DBG_HEADER, "skipping scratch data, no header");
		scratch_reset(usbvision);
		return ParseState_EndParse;
	}

	// found header
	if (frame->isocHeader.dataFormat==ISOC_MODE_COMPRESS) {
		//check isocHeader.frameNum for lost frames
		if (usbvision->lastIsocFrameNum >= 0) {
			if (((usbvision->lastIsocFrameNum + 1) % 32) != frame->isocHeader.frameNum) {
				// unexpected frame drop: need to request new intra frame
				PDEBUG(DBG_HEADER, "Lost frame before %d on USB", frame->isocHeader.frameNum);
				usbvision_request_intra(usbvision);
				return ParseState_NextFrame;
			}
		}
		usbvision->lastIsocFrameNum = frame->isocHeader.frameNum;
	}
	usbvision->header_count++;
	frame->scanstate = ScanState_Lines;
	frame->curline = 0;

	if (flags & FLAGS_FORCE_TESTPATTERN) {
		usbvision_testpattern(usbvision, 1, 1);
		return ParseState_NextFrame;
	}
	return ParseState_Continue;
}

static enum ParseState usbvision_parse_lines_422(struct usb_usbvision *usbvision,
					   long *pcopylen)
{
	volatile struct usbvision_frame *frame;
	unsigned char *f;
	int len;
	int i;
	unsigned char yuyv[4]={180, 128, 10, 128}; // YUV components
	unsigned char rv, gv, bv;	// RGB components
	int clipmask_index, bytes_per_pixel;
	int overlay = usbvision->overlay;
	int stretch_bytes, clipmask_add;

	if (overlay) {
		frame  = &usbvision->overlay_frame;
		if (usbvision->overlay_base == NULL) {
			//video_buffer is not set yet
			return ParseState_NextFrame;
		}
		f = usbvision->overlay_win + frame->curline *
			usbvision->vid_buf.bytesperline;
	}
	else {
		frame  = &usbvision->frame[usbvision->curFrameNum];
		f = frame->data + (frame->v4l_linesize * frame->curline);
	}

	/* Make sure there's enough data for the entire line */
	len = (frame->isocHeader.frameWidth * 2)+5;
	if (scratch_len(usbvision) < len) {
		PDEBUG(DBG_PARSE, "out of data in line %d, need %u.\n", frame->curline, len);
		return ParseState_Out;
	}

	if ((frame->curline + 1) >= frame->frmheight) {
		return ParseState_NextFrame;
	}

	bytes_per_pixel = usbvision_v4l_format[frame->v4l_format].bytes_per_pixel;
	stretch_bytes = (usbvision->stretch_width - 1) * bytes_per_pixel;
	clipmask_index = frame->curline * MAX_FRAME_WIDTH;
	clipmask_add = usbvision->stretch_width;

	for (i = 0; i < frame->frmwidth; i+=(2 * usbvision->stretch_width)) {

		scratch_get(usbvision, &yuyv[0], 4);

		if((overlay) && (clipped_pixel(clipmask_index))) {
			f += bytes_per_pixel;
		}
		else if (frame->v4l_format == VIDEO_PALETTE_YUV422) {
			*f++ = yuyv[0]; // Y
			*f++ = yuyv[3]; // U
		}
		else {

			YUV_TO_RGB_BY_THE_BOOK(yuyv[0], yuyv[1], yuyv[3], rv, gv, bv);
			switch (frame->v4l_format) {
				case VIDEO_PALETTE_RGB565:
					*f++ = (0x1F & (bv >> 3)) | (0xE0 & (gv << 3));
					*f++ = (0x07 & (gv >> 5)) | (0xF8 &  rv);
					break;
				case VIDEO_PALETTE_RGB24:
					*f++ = bv;
					*f++ = gv;
					*f++ = rv;
					break;
				case VIDEO_PALETTE_RGB32:
					*f++ = bv;
					*f++ = gv;
					*f++ = rv;
					f++;
					break;
				case VIDEO_PALETTE_RGB555:
					*f++ = (0x1F & (bv >> 3)) | (0xE0 & (gv << 2));
					*f++ = (0x03 & (gv >> 6)) | (0x7C & (rv >> 1));
					break;
			}
		}
		clipmask_index += clipmask_add;
		f += stretch_bytes;

		if((overlay) && (clipped_pixel(clipmask_index))) {
			f += bytes_per_pixel;
		}
		else if (frame->v4l_format == VIDEO_PALETTE_YUV422) {
			*f++ = yuyv[2]; // Y
			*f++ = yuyv[1]; // V
		}
		else {

			YUV_TO_RGB_BY_THE_BOOK(yuyv[2], yuyv[1], yuyv[3], rv, gv, bv);
			switch (frame->v4l_format) {
				case VIDEO_PALETTE_RGB565:
					*f++ = (0x1F & (bv >> 3)) | (0xE0 & (gv << 3));
					*f++ = (0x07 & (gv >> 5)) | (0xF8 &  rv);
					break;
				case VIDEO_PALETTE_RGB24:
					*f++ = bv;
					*f++ = gv;
					*f++ = rv;
					break;
				case VIDEO_PALETTE_RGB32:
					*f++ = bv;
					*f++ = gv;
					*f++ = rv;
					f++;
					break;
				case VIDEO_PALETTE_RGB555:
					*f++ = (0x1F & (bv >> 3)) | (0xE0 & (gv << 2));
					*f++ = (0x03 & (gv >> 6)) | (0x7C & (rv >> 1));
					break;
			}
		}
		clipmask_index += clipmask_add;
		f += stretch_bytes;
	}

	frame->curline += usbvision->stretch_height;
	*pcopylen += frame->v4l_linesize * usbvision->stretch_height;

	if (frame->curline >= frame->frmheight) {
		return ParseState_NextFrame;
	}
	else {
		return ParseState_Continue;
	}
}


static int usbvision_decompress(struct usb_usbvision *usbvision,unsigned char *Compressed,
								unsigned char *Decompressed, int *StartPos,
								int *BlockTypeStartPos, int Len)
{
	int RestPixel, Idx, MaxPos, Pos, ExtraPos, BlockLen, BlockTypePos, BlockTypeLen;
	unsigned char BlockByte, BlockCode, BlockType, BlockTypeByte, Integrator;

	Integrator = 0;
	Pos = *StartPos;
	BlockTypePos = *BlockTypeStartPos;
	MaxPos = 396; //Pos + Len;
	ExtraPos = Pos;
	BlockLen = 0;
	BlockByte = 0;
	BlockCode = 0;
	BlockType = 0;
	BlockTypeByte = 0;
	BlockTypeLen = 0;
	RestPixel = Len;

	for (Idx = 0; Idx < Len; Idx++) {

		if (BlockLen == 0) {
			if (BlockTypeLen==0) {
				BlockTypeByte = Compressed[BlockTypePos];
				BlockTypePos++;
				BlockTypeLen = 4;
			}
			BlockType = (BlockTypeByte & 0xC0) >> 6;

			//statistic:
			usbvision->ComprBlockTypes[BlockType]++;

			Pos = ExtraPos;
			if (BlockType == 0) {
				if(RestPixel >= 24) {
					Idx += 23;
					RestPixel -= 24;
					Integrator = Decompressed[Idx];
				} else {
					Idx += RestPixel - 1;
					RestPixel = 0;
				}
			} else {
				BlockCode = Compressed[Pos];
				Pos++;
				if (RestPixel >= 24) {
					BlockLen  = 24;
				} else {
					BlockLen = RestPixel;
				}
				RestPixel -= BlockLen;
				ExtraPos = Pos + (BlockLen / 4);
			}
			BlockTypeByte <<= 2;
			BlockTypeLen -= 1;
		}
		if (BlockLen > 0) {
			if ((BlockLen%4) == 0) {
				BlockByte = Compressed[Pos];
				Pos++;
			}
			if (BlockType == 1) { //inter Block
				Integrator = Decompressed[Idx];
			}
			switch (BlockByte & 0xC0) {
				case 0x03<<6:
					Integrator += Compressed[ExtraPos];
					ExtraPos++;
					break;
				case 0x02<<6:
					Integrator += BlockCode;
					break;
				case 0x00:
					Integrator -= BlockCode;
					break;
			}
			Decompressed[Idx] = Integrator;
			BlockByte <<= 2;
			BlockLen -= 1;
		}
	}
	*StartPos = ExtraPos;
	*BlockTypeStartPos = BlockTypePos;
	return Idx;
}


/*
 * usbvision_parse_compress()
 *
 * Parse compressed frame from the scratch buffer, put
 * decoded RGB value into the current frame buffer and add the written
 * number of bytes (RGB) to the *pcopylen.
 *
 */
static enum ParseState usbvision_parse_compress(struct usb_usbvision *usbvision,
					   long *pcopylen)
{
#define USBVISION_STRIP_MAGIC		0x5A
#define USBVISION_STRIP_LEN_MAX		400
#define USBVISION_STRIP_HEADER_LEN	3

	struct usbvision_frame *frame;
	unsigned char *f,*u = NULL ,*v = NULL;
	unsigned char StripData[USBVISION_STRIP_LEN_MAX];
	unsigned char StripHeader[USBVISION_STRIP_HEADER_LEN];
	int Idx, IdxEnd, StripLen, StripPtr, StartBlockPos, BlockPos, BlockTypePos;
	in