/*      $OpenBSD: videotest.c,v 1.6 2021/10/24 21:24:20 deraadt Exp $ */

/*
 * Copyright (c) 2010 Marcus Glocker <mglocker@openbsd.org>
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

/*
 * Regression test program for the video(4) interface.
 *
 * TODO:
 * - Add test for VIDIOC_ENUM_FRAMEINTERVALS ioctl.
 * - Add test for VIDIOC_ENUMINPUT ioctl.
 * - Add test for VIDIOC_S_INPUT ioctl.
 * - Add test for VIDIOC_TRY_FMT ioctl.
 * - Add test for VIDIOC_QUERYCTRL ioctl.
 * - Add test for VIDIOC_G_CTRL ioctl.
 * - Add test for VIDIOC_S_CTRL ioctl.
 */

#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/mman.h>
#include <sys/videoio.h>

#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <poll.h>
#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

/*
 * Defines.
 */
#define DEV_CHECK_NR            128
#define DEV_PATH                "/dev/"

/*
 * Some devices need a hell of time to initialize and stop (e.g. the
 * Logitech Pro 9000).  If we don't give them that time, they will stall
 * at some point in the open / close cycle and will require a cold reset
 * (detach / attach) to operate again.
 */
#define WAIT_INIT               5               /* seconds */
#define WAIT_STOP               15              /* seconds */

#define POLL_NO                 0
#define POLL_YES                1
#define POLL_TIMEOUT            2000            /* milliseconds */

#define ACCESS_READ             0
#define ACCESS_MMAP             1

#define MMAP_QUEUE_NR           4

/*
 * Prototypes.
 */
int      test_ioctl_querycap(int);
int      test_ioctl_g_fmt(int);
int      test_ioctl_enum_fmt(int);
int      test_ioctl_enum_fsizes(int, uint32_t, int);
int      test_capture(char *, char *, int, int);
int      test_capture_read(int, char *, int, int);
int      test_capture_mmap(int, char *, int, int);
void     jpeg_insert_dht(uint8_t *, int, uint8_t *, int *);
char    *print_pixelformat(uint32_t, int);

/*
 * Structures.
 */
struct frame_buffer {
        uint8_t         *buf;
        int              len;
};

struct sizes {
        uint32_t        width;
        uint32_t        height;
};

/*
 * Global variables.
 */
struct fmt_sizes {
        uint32_t        pixelformat;
        struct sizes    s[32];
} dev_fmts[8];

/*
 * Main program.
 */
int
main(void)
{
        int     i, fd, r;
        char    dev_name[32], dev_full[32];

        for (i = 0; i < DEV_CHECK_NR; i++) {
                /* assemble device name and path */
                snprintf(dev_name, sizeof(dev_name), "video%d", i);
                snprintf(dev_full, sizeof(dev_full), "%s%s",
                    DEV_PATH, dev_name);

                /* open video device */
                fd = open(dev_full, O_RDWR);
                if (fd == -1) {
                        warn("%s", dev_full);
                        break;
                }

                /* run some ioctl tests */
                r = test_ioctl_querycap(fd);
                if (r == -1)
                        err(1, "ioctl_querycap");

                r = test_ioctl_g_fmt(fd);
                if (r == -1)
                        err(1, "ioctl_g_fmt");

                r = test_ioctl_enum_fmt(fd);
                if (r == -1)
                        err(1, "ioctl_enum_fmt");

                /* close video device */
                close(fd);

                /* run frame capture tests */
                r = test_capture(dev_name, dev_full, ACCESS_READ, POLL_NO);
                if (r == -1)
                        err(1, "test_capture");

                r = test_capture(dev_name, dev_full, ACCESS_READ, POLL_YES);
                if (r == -1)
                        err(1, "test_capture");

                r = test_capture(dev_name, dev_full, ACCESS_MMAP, POLL_NO);
                if (r == -1)
                        err(1, "test_capture");

                r = test_capture(dev_name, dev_full, ACCESS_MMAP, POLL_YES);
                if (r == -1)
                        err(1, "test_capture");
        }

        return (0);
}

int
test_ioctl_querycap(int fd)
{
        int                     r;
        struct v4l2_capability  caps;

        printf("[ Calling VIDIOC_QUERYCAP ioctl ]\n\n");

        memset(&caps, 0, sizeof(struct v4l2_capability));
        r = ioctl(fd, VIDIOC_QUERYCAP, &caps);
        if (r == -1)
                return (-1);

        printf("Driver       : %s\n", caps.driver);
        printf("Card         : %s\n", caps.card);
        printf("Bus Info     : %s\n", caps.bus_info);
        printf("Version      : %d\n", caps.version);
        printf("Capabilities : ");
        if (caps.capabilities & V4L2_CAP_VIDEO_CAPTURE)
                printf("CAPTURE ");
        if (caps.capabilities & V4L2_CAP_STREAMING)
                printf("STREAMING ");
        if (caps.capabilities & V4L2_CAP_READWRITE)
                printf("READWRITE ");
        printf("\n");

        printf("\n");

        return (0);
}

int
test_ioctl_g_fmt(int fd)
{
        int                     r;
        struct v4l2_format      fmt;

        printf("[ Calling VIDIOC_G_FMT ioctl ]\n\n");

        memset(&fmt, 0, sizeof(struct v4l2_format));
        fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        r = ioctl(fd, VIDIOC_G_FMT, &fmt);
        if (r == -1)
                return (r);

        printf("Current format         : %s\n",
            print_pixelformat(fmt.fmt.pix.pixelformat, 0));
        printf("Current width          : %u pixels\n", fmt.fmt.pix.width);
        printf("Current height         : %u pixels\n", fmt.fmt.pix.height);
        printf("Current max. framesize : %u bytes\n", fmt.fmt.pix.sizeimage);

        printf("\n");

        return (0);
}

int
test_ioctl_enum_fmt(int fd)
{
        int                     r;
        struct v4l2_fmtdesc     fmtdesc;

        printf("[ Calling VIDIOC_ENUM_FMT|VIDIOC_ENUM_FRAMESIZES ioctl ]\n\n");

        memset(&fmtdesc, 0, sizeof(struct v4l2_fmtdesc));
        fmtdesc.index = 0;
        fmtdesc.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        while ((r = ioctl(fd, VIDIOC_ENUM_FMT, &fmtdesc)) == 0) {
                printf("Pixelformat '%s' ", fmtdesc.description);

                (void)test_ioctl_enum_fsizes(fd, fmtdesc.pixelformat,
                    fmtdesc.index);

                fmtdesc.index++;
        }
        if (errno != EINVAL)
                return (-1);

        return (0);
}

int
test_ioctl_enum_fsizes(int fd, uint32_t pixelformat, int index)
{
        int                     r;
        struct v4l2_frmsizeenum fsizes;

        printf("supports following sizes:\n");

        memset(&fsizes, 0, sizeof(struct v4l2_frmsizeenum));
        fsizes.index = 0;
        fsizes.pixel_format = pixelformat;
        while ((r = ioctl(fd, VIDIOC_ENUM_FRAMESIZES, &fsizes)) == 0) {
                if (fsizes.type == V4L2_FRMSIZE_TYPE_DISCRETE) {
                        printf("discrete width = %u, height = %u\n",
                            fsizes.discrete.width,
                            fsizes.discrete.height);

                        /* save format and sizes for later use */
                        dev_fmts[index].pixelformat = pixelformat;
                        dev_fmts[index].s[fsizes.index].width =
                            fsizes.discrete.width;
                        dev_fmts[index].s[fsizes.index].height =
                            fsizes.discrete.height;
                }

                fsizes.index++;
        }
        if (errno != EINVAL)
                return (-1);

        printf("\n");

        return (0);
}

int
test_capture(char *dev_name, char *dev_full, int access, int use_poll)
{
        ssize_t                  n1, n2;
        int                      fd1, fd2;
        int                      i, j, r;
        int                      buf_size, img_size, img_len;
        char                     filename[64];
        uint8_t                 *buf, *img;
        uint32_t                 last_pixelformat;
        struct v4l2_format       fmt;

        fd1 = last_pixelformat = n1 = 0;
        img = buf = NULL;

        printf("[ Testing %s access type %s]\n\n",
            access == ACCESS_READ ? "READ" : "MMAP",
            use_poll ? "with poll " : "");

        for (i = 0; i < 8; i++) {
                /* did we reach end of formats? */
                if (dev_fmts[i].pixelformat == 0)
                        return (0);

                /* some devices have duplicate format descriptors */
                if (last_pixelformat == dev_fmts[i].pixelformat)
                        continue;
                else
                        last_pixelformat = dev_fmts[i].pixelformat;

                for (j = 0; j < 32; j++) {
                        /* did we reach end of sizes? */
                        if (dev_fmts[i].s[j].width == 0) {
                                free(buf);
                                buf = NULL;
                                free(img);
                                img = NULL;
                                break;
                        }

                        /* open device */
                        fd1 = open(dev_full, O_RDWR);
                        if (fd1 == -1)
                                err(1, "open");
                        sleep(WAIT_INIT);       /* let device initialize */

                        /* set format */
                        printf("Set format to %s-%ux%u ... ",
                            print_pixelformat(dev_fmts[i].pixelformat, 0),
                            dev_fmts[i].s[j].width,
                            dev_fmts[i].s[j].height);

                        memset(&fmt, 0, sizeof(struct v4l2_format));
                        fmt.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                        fmt.fmt.pix.width = dev_fmts[i].s[j].width;
                        fmt.fmt.pix.height = dev_fmts[i].s[j].height;
                        fmt.fmt.pix.pixelformat = dev_fmts[i].pixelformat;
                        fmt.fmt.pix.field = V4L2_FIELD_ANY;
                        r = ioctl(fd1, VIDIOC_S_FMT, &fmt);
                        if (r == -1)
                                goto error;

                        printf("results in %u bytes max. framesize.\n",
                            fmt.fmt.pix.sizeimage);

                        /* allocate frame and image buffer */
                        free(buf);
                        buf = NULL;
                        free(img);
                        img = NULL;

                        buf_size = fmt.fmt.pix.sizeimage;
                        buf = calloc(1, buf_size);
                        if (buf == NULL)
                                goto error;

                        img_size = fmt.fmt.pix.sizeimage + 1024;
                        img = calloc(1, img_size);
                        if (img == NULL)
                                goto error;

                        /* get frame */
                        if (access == ACCESS_READ)
                                n1 = test_capture_read(fd1, buf, buf_size,
                                    use_poll);
                        else
                                n1 = test_capture_mmap(fd1, buf, buf_size,
                                    use_poll);
                        if (n1 == -1)
                                goto error;

                        /*
                         * Convert frame to JPEG image.
                         *
                         * TODO:
                         * For now just MJPEG convertion is supported.
                         */
                        snprintf(filename, sizeof(filename),
                            "%s_img_%s_%ux%u%s%s",
                            dev_name,
                            print_pixelformat(dev_fmts[i].pixelformat, 1),
                            fmt.fmt.pix.width,
                            fmt.fmt.pix.height,
                            access == ACCESS_READ ? "_read" : "_mmap",
                            use_poll ? "_poll" : "");

                        switch (dev_fmts[i].pixelformat) {
                        case V4L2_PIX_FMT_MJPEG:
                                printf("Converting MJPEG to JPEG.\n");

                                /* insert dynamic huffmann table to mjpeg */
                                jpeg_insert_dht(buf, n1, img, &img_len);

                                strlcat(filename, ".jpg", sizeof(filename));
                                break;
                        case V4L2_PIX_FMT_YUYV:
                                printf("Convertion for YUYV not supported!\n");

                                img_len = n1;
                                memcpy(img, buf, img_len);

                                strlcat(filename, ".raw", sizeof(filename));
                                break;
                        default:
                                break;
                        }

                        /* write image file */
                        fd2 = open(filename, O_RDWR|O_CREAT|O_TRUNC, 0644);
                        if (fd2 == -1)
                                goto error;
                        n2 = write(fd2, img, img_len);
                        if (n2 == -1)
                                goto error;
                        printf("Saving image to '%s'.\n\n", filename);
                        close(fd2);

                        /* shutdown device */
                        close(fd1);
                        sleep(WAIT_STOP);       /* let device stop */
                }
        }
error:
        free(buf);
        buf = NULL;
        free(img);
        img = NULL;
        close(fd1);

        printf("\n");

        return (-1);
}

int
test_capture_read(int fd, char *buf, int buf_size, int use_poll)
{
        ssize_t         n1;
        int             i, r;
        struct pollfd   pfds[1];

        n1 = 0;

        /*
         * Read frame data.
         *
         * Some devices need a while until they start
         * sending a sane image.  Therefore skip the
         * first few frames.
         */
        printf("Reading frame data ... ");

        for (i = 0; i < 3; i++) {
                if (use_poll) {
                        pfds[0].fd = fd;
                        pfds[0].events = POLLIN;

                        r = poll(pfds, 1, POLL_TIMEOUT);
                        if (r == -1)
                                return (-1);
                        if (r == 0) {
                                printf("poll timeout (%d seconds)!\n",
                                    POLL_TIMEOUT / 1000);
                                continue;
                        }
                }

                n1 = read(fd, buf, buf_size);
                if (n1 == -1)
                        return (-1);
        }
        printf("%ld bytes read.\n", n1);

        return (n1);
}

int
test_capture_mmap(int fd, char *buf, int buf_size, int use_poll)
{
        int                              i, r, type;
        struct v4l2_requestbuffers       reqbufs;
        struct v4l2_buffer               buffer;
        struct frame_buffer              fbuffer[MMAP_QUEUE_NR];
        struct pollfd                    pfds[1];

        /* request buffers */
        memset(&reqbufs, 0, sizeof(struct v4l2_requestbuffers));
        reqbufs.count = MMAP_QUEUE_NR;
        reqbufs.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        reqbufs.memory = V4L2_MEMORY_MMAP;
        r = ioctl(fd, VIDIOC_REQBUFS, &reqbufs);
        if (r == -1)
                return (-1);

        /* map the buffers */
        for (i = 0; i < MMAP_QUEUE_NR; i++) {
                memset(&buffer, 0, sizeof(struct v4l2_buffer));
                buffer.index = i;
                buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                buffer.memory = V4L2_MEMORY_MMAP;
                r = ioctl(fd, VIDIOC_QUERYBUF, &buffer);
                if (r == -1)
                        return (-1);

                fbuffer[i].buf =
                    mmap(0, buffer.length, PROT_READ, MAP_SHARED, fd,
                        buffer.m.offset);
                if (fbuffer[i].buf == MAP_FAILED)
                        return (-1);
                fbuffer[i].len = buffer.length;
        }

        /* queue the buffers */
        for (i = 0; i < MMAP_QUEUE_NR; i++) {
                memset(&buffer, 0, sizeof(struct v4l2_buffer));
                buffer.index = i;
                buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                buffer.memory = V4L2_MEMORY_MMAP;
                r = ioctl(fd, VIDIOC_QBUF, &buffer);
                if (r == -1)
                        return (-1);
        }

        /* turn on stream */
        type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        r = ioctl(fd, VIDIOC_STREAMON, &type);
        if (r == -1)
                return (-1);

        /* dequeue buffers */
        printf("Dequeue frame data ... ");

        for (i = 0; i < MMAP_QUEUE_NR; i++) {
                if (use_poll) {
                        pfds[0].fd = fd;
                        pfds[0].events = POLLIN;

                        r = poll(pfds, 1, POLL_TIMEOUT);
                        if (r == -1)
                                return (-1);
                        if (r == 0) {
                                printf("poll timeout (%d seconds)!\n",
                                    POLL_TIMEOUT / 1000);
                                return (-1);
                        }
                }

                memset(&buffer, 0, sizeof(struct v4l2_buffer));
                buffer.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
                buffer.memory = V4L2_MEMORY_MMAP;
                r = ioctl(fd, VIDIOC_DQBUF, &buffer);
                if (r == -1)
                        return (-1);
        }
        printf("%d bytes dequeued.\n", buffer.bytesused);
        memcpy(buf, fbuffer[buffer.index].buf, buffer.bytesused);

        /* turn off stream */
        type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
        r = ioctl(fd, VIDIOC_STREAMOFF, &type);
        if (r == -1)
                return (-1);

        /* unmap buffers */
        for (i = 0; i < MMAP_QUEUE_NR; i++) {
                r = munmap(fbuffer[i].buf, fbuffer[i].len);
                if (r == -1)
                        return (-1);
        }

        return (buffer.bytesused);
}

void
jpeg_insert_dht(uint8_t *src, int src_len, uint8_t *dst, int *dst_len)
{
        int      i;
        uint8_t *p;

        static unsigned char dht[] = {
            0xff, 0xc4, 0x01, 0xa2, 0x00, 0x00, 0x01, 0x05, 0x01, 0x01,
            0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x00, 0x00, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08,
            0x09, 0x0a, 0x0b, 0x10, 0x00, 0x02, 0x01, 0x03, 0x03, 0x02,
            0x04, 0x03, 0x05, 0x05, 0x04, 0x04, 0x00, 0x00, 0x01, 0x7d,
            0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12, 0x21, 0x31,
            0x41, 0x06, 0x13, 0x51, 0x61, 0x07, 0x22, 0x71, 0x14, 0x32,
            0x81, 0x91, 0xa1, 0x08, 0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52,
            0xd1, 0xf0, 0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
            0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28, 0x29, 0x2a,
            0x34, 0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x43, 0x44, 0x45,
            0x46, 0x47, 0x48, 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57,
            0x58, 0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
            0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x83,
            0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x92, 0x93, 0x94,
            0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
            0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
            0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
            0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8,
            0xd9, 0xda, 0xe1, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8,
            0xe9, 0xea, 0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
            0xf9, 0xfa, 0x01, 0x00, 0x03, 0x01, 0x01, 0x01, 0x01, 0x01,
            0x01, 0x01, 0x01, 0x01, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
            0x01, 0x02, 0x03, 0x04, 0x05, 0x06, 0x07, 0x08, 0x09, 0x0a,
            0x0b, 0x11, 0x00, 0x02, 0x01, 0x02, 0x04, 0x04, 0x03, 0x04,
            0x07, 0x05, 0x04, 0x04, 0x00, 0x01, 0x02, 0x77, 0x00, 0x01,
            0x02, 0x03, 0x11, 0x04, 0x05, 0x21, 0x31, 0x06, 0x12, 0x41,
            0x51, 0x07, 0x61, 0x71, 0x13, 0x22, 0x32, 0x81, 0x08, 0x14,
            0x42, 0x91, 0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
            0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34, 0xe1, 0x25,
            0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26, 0x27, 0x28, 0x29, 0x2a,
            0x35, 0x36, 0x37, 0x38, 0x39, 0x3a, 0x43, 0x44, 0x45, 0x46,
            0x47, 0x48, 0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
            0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69, 0x6a,
            0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79, 0x7a, 0x82, 0x83,
            0x84, 0x85, 0x86, 0x87, 0x88, 0x89, 0x8a, 0x92, 0x93, 0x94,
            0x95, 0x96, 0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
            0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
            0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5, 0xc6, 0xc7,
            0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8,
            0xd9, 0xda, 0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
            0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8, 0xf9, 0xfa
        };

        p = src;
        for (i = 0; i < src_len; i++, p++) {
                if (*p != 0xff)
                        continue;

                p++;
                if (*p == 0xda)
                        break;
                else
                        i++;
        }

        memcpy(dst, src, i);
        dst += i;
        memcpy(dst, dht, sizeof(dht));
        dst += sizeof(dht);
        src += i;
        memcpy(dst, src, src_len - i);

        *dst_len = src_len + sizeof(dht);
}

char *
print_pixelformat(uint32_t pixelformat, int lowercase)
{
        static char     pformat[8];

        memset(pformat, 0, sizeof(pformat));

        switch (pixelformat) {
        case V4L2_PIX_FMT_MJPEG:
                if (lowercase)
                        memcpy(pformat, "mjpeg", 5);
                else
                        memcpy(pformat, "MJPEG", 5);
                break;
        case V4L2_PIX_FMT_YUYV:
                if (lowercase)
                        memcpy(pformat, "yuyv", 4);
                else
                        memcpy(pformat, "YUYV", 4);
                break;
        default:
                memcpy(pformat, "unknown", 7);
                break;
        }

        return (pformat);
}