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/*
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 * dv1394.h - DV input/output over IEEE 1394 on OHCI chips
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 *   Copyright (C)2001 Daniel Maas <dmaas@dcine.com>
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 *     receive, proc_fs by Dan Dennedy <dan@dennedy.org>
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 *
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 * based on:
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 *   video1394.h - driver for OHCI 1394 boards
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 *   Copyright (C)1999,2000 Sebastien Rougeaux <sebastien.rougeaux@anu.edu.au>
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 *                          Peter Schlaile <udbz@rz.uni-karlsruhe.de>
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 *
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 * This program is free software; you can redistribute it and/or modify
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 * it under the terms of the GNU General Public License as published by
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 * the Free Software Foundation; either version 2 of the License, or
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 * (at your option) any later version.
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 *
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 * This program is distributed in the hope that it will be useful,
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 * but WITHOUT ANY WARRANTY; without even the implied warranty of
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 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
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 * GNU General Public License for more details.
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 *
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 * You should have received a copy of the GNU General Public License
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 * along with this program; if not, write to the Free Software Foundation,
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 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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 */
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#ifndef _DV_1394_H
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#define _DV_1394_H
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#define DV1394_DEFAULT_CHANNEL 63
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#define DV1394_DEFAULT_CARD    0
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#define DV1394_RING_FRAMES     20
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#define DV1394_WIDTH  720
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#define DV1394_NTSC_HEIGHT 480
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#define DV1394_PAL_HEIGHT 576
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/* This is the public user-space interface. Try not to break it. */
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#define DV1394_API_VERSION 0x20011127
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/* ********************
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   **                **
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   **   DV1394 API   **
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   **                **
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   ********************
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   There are two methods of operating the DV1394 DV output device.
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   1)
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   The simplest is an interface based on write(): simply write
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   full DV frames of data to the device, and they will be transmitted
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   as quickly as possible. The FD may be set for non-blocking I/O,
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   in which case you can use select() or poll() to wait for output
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   buffer space.
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   To set the DV output parameters (e.g. whether you want NTSC or PAL
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   video), use the DV1394_INIT ioctl, passing in the parameters you
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   want in a struct dv1394_init.
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   Example 1:
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         To play a raw .DV file:   cat foo.DV > /dev/dv1394
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         (cat will use write() internally)
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   Example 2:
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           static struct dv1394_init init = {
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              0x63,        (broadcast channel)
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              4,           (four-frame ringbuffer)
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              DV1394_NTSC, (send NTSC video)
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              0, 0         (default empty packet rate)
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           }
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           ioctl(fd, DV1394_INIT, &init);
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           while(1) {
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                  read( <a raw DV file>, buf, DV1394_NTSC_FRAME_SIZE );
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                  write( <the dv1394 FD>, buf, DV1394_NTSC_FRAME_SIZE );
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           }
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   2)
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   For more control over buffering, and to avoid unnecessary copies
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   of the DV data, you can use the more sophisticated the mmap() interface. 
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   First, call the DV1394_INIT ioctl to specify your parameters, 
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   including the number of frames in the ringbuffer. Then, calling mmap() 
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   on the dv1394 device will give you direct access to the ringbuffer
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   from which the DV card reads your frame data.
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   The ringbuffer is simply one large, contiguous region of memory
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   containing two or more frames of packed DV data. Each frame of DV data
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   is 120000 bytes (NTSC) or 144000 bytes (PAL).
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   Fill one or more frames in the ringbuffer, then use the DV1394_SUBMIT_FRAMES
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   ioctl to begin I/O. You can use either the DV1394_WAIT_FRAMES ioctl
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   or select()/poll() to wait until the frames are transmitted. Next, you'll
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   need to call the DV1394_GET_STATUS ioctl to determine which ringbuffer
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   frames are clear (ready to be filled with new DV data). Finally, use
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   DV1394_SUBMIT_FRAMES again to send the new data to the DV output.
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   Example: here is what a four-frame ringbuffer might look like
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            during DV transmission:
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         frame 0   frame 1   frame 2   frame 3
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        *--------------------------------------*
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        | CLEAR   | DV data | DV data | CLEAR  |
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        *--------------------------------------*
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                   <ACTIVE> 
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        transmission goes in this direction --->>>
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   The DV hardware is currently transmitting the data in frame 1.
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   Once frame 1 is finished, it will automatically transmit frame 2.
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   (if frame 2 finishes before frame 3 is submitted, the device
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   will continue to transmit frame 2, and will increase the dropped_frames
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   counter each time it repeats the transmission).
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   If you called DV1394_GET_STATUS at this instant, you would
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   receive the following values:
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                  n_frames          = 4
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                  active_frame      = 1
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                  first_clear_frame = 3
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                  n_clear_frames    = 2
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   At this point, you should write new DV data into frame 3 and optionally
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   frame 0. Then call DV1394_SUBMIT_FRAMES to inform the device that
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   it may transmit the new frames.
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   ERROR HANDLING
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   An error (buffer underflow/overflow or a break in the DV stream due
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   to a 1394 bus reset) can be detected by checking the dropped_frames
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   field of struct dv1394_status (obtained through the
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   DV1394_GET_STATUS ioctl).
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   The best way to recover from such an error is to re-initialize
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   dv1394, either by using the DV1394_INIT ioctl call, or closing the
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   file descriptor and opening it again. (note that you must unmap all
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   ringbuffer mappings when closing the file descriptor, or else
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   dv1394 will still be considered 'in use').
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   MAIN LOOP
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   For maximum efficiency and robustness against bus errors, you are
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   advised to model the main loop of your application after the
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   following pseudo-code example:
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   (checks of system call return values omitted for brevity; always
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   check return values in your code!)
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   while( frames left ) {
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    struct pollfd *pfd = ...;
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    pfd->fd = dv1394_fd;
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    pfd->revents = 0;
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    pfd->events = POLLOUT | POLLIN; (OUT for transmit, IN for receive)
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    (add other sources of I/O here)
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    poll(pfd, 1, -1); (or select(); add a timeout if you want)
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    if(pfd->revents) {
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         struct dv1394_status status;
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         ioctl(dv1394_fd, DV1394_GET_STATUS, &status);
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         if(status.dropped_frames > 0) {
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              reset_dv1394();
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         } else {
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              for(int i = 0; i < status.n_clear_frames; i++) {
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                  copy_DV_frame();
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              }
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         }
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    }
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   }
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   where copy_DV_frame() reads or writes on the dv1394 file descriptor
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   (read/write mode) or copies data to/from the mmap ringbuffer and
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   then calls ioctl(DV1394_SUBMIT_FRAMES) to notify dv1394 that new
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   frames are availble (mmap mode).
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   reset_dv1394() is called in the event of a buffer
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   underflow/overflow or a halt in the DV stream (e.g. due to a 1394
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   bus reset). To guarantee recovery from the error, this function
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   should close the dv1394 file descriptor (and munmap() all
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   ringbuffer mappings, if you are using them), then re-open the
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   dv1394 device (and re-map the ringbuffer).
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*/
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/* maximum number of frames in the ringbuffer */
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#define DV1394_MAX_FRAMES 32
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/* number of *full* isochronous packets per DV frame */
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#define DV1394_NTSC_PACKETS_PER_FRAME 250
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#define DV1394_PAL_PACKETS_PER_FRAME  300
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/* size of one frame's worth of DV data, in bytes */
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#define DV1394_NTSC_FRAME_SIZE (480 * DV1394_NTSC_PACKETS_PER_FRAME)
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#define DV1394_PAL_FRAME_SIZE  (480 * DV1394_PAL_PACKETS_PER_FRAME)
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/* ioctl() commands */
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enum {
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        /* I don't like using 0 as a valid ioctl() */
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        DV1394_INVALID = 0,
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        /* get the driver ready to transmit video.
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           pass a struct dv1394_init* as the parameter (see below),
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           or NULL to get default parameters */
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        DV1394_INIT,
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        /* stop transmitting video and free the ringbuffer */
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        DV1394_SHUTDOWN,
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        /* submit N new frames to be transmitted, where
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           the index of the first new frame is first_clear_buffer,
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           and the index of the last new frame is
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           (first_clear_buffer + N) % n_frames */
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        DV1394_SUBMIT_FRAMES,
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        /* block until N buffers are clear (pass N as the parameter)
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           Because we re-transmit the last frame on underrun, there
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           will at most be n_frames - 1 clear frames at any time */
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        DV1394_WAIT_FRAMES,
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        /* capture new frames that have been received, where
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           the index of the first new frame is first_clear_buffer,
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           and the index of the last new frame is
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           (first_clear_buffer + N) % n_frames */
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        DV1394_RECEIVE_FRAMES,
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        DV1394_START_RECEIVE,
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        /* pass a struct dv1394_status* as the parameter (see below) */
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        DV1394_GET_STATUS,
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};
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enum pal_or_ntsc {
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        DV1394_NTSC = 0,
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        DV1394_PAL
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};
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/* this is the argument to DV1394_INIT */
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struct dv1394_init {
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        /* DV1394_API_VERSION */
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        unsigned int api_version;
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        /* isochronous transmission channel to use */
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        unsigned int channel;
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        /* number of frames in the ringbuffer. Must be at least 2
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           and at most DV1394_MAX_FRAMES. */
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        unsigned int n_frames;
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        /* send/receive PAL or NTSC video format */
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        enum pal_or_ntsc format;
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        /* the following are used only for transmission */
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        /* set these to zero unless you want a
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           non-default empty packet rate (see below) */
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        unsigned long cip_n;
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        unsigned long cip_d;
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        /* set this to zero unless you want a
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           non-default SYT cycle offset (default = 3 cycles) */
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        unsigned int syt_offset;
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};
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/* NOTE: you may only allocate the DV frame ringbuffer once each time
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   you open the dv1394 device. DV1394_INIT will fail if you call it a
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   second time with different 'n_frames' or 'format' arguments (which
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   would imply a different size for the ringbuffer). If you need a
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   different buffer size, simply close and re-open the device, then
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   initialize it with your new settings. */
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/* Q: What are cip_n and cip_d? */
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/*
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  A: DV video streams do not utilize 100% of the potential bandwidth offered
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  by IEEE 1394 (FireWire). To achieve the correct rate of data transmission,
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  DV devices must periodically insert empty packets into the 1394 data stream.
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  Typically there is one empty packet per 14-16 data-carrying packets.
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  Some DV devices will accept a wide range of empty packet rates, while others
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  require a precise rate. If the dv1394 driver produces empty packets at
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  a rate that your device does not accept, you may see ugly patterns on the
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  DV output, or even no output at all.
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  The default empty packet insertion rate seems to work for many people; if
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  your DV output is stable, you can simply ignore this discussion. However,
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  we have exposed the empty packet rate as a parameter to support devices that
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  do not work with the default rate. 
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  The decision to insert an empty packet is made with a numerator/denominator
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  algorithm. Empty packets are produced at an average rate of CIP_N / CIP_D.
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  You can alter the empty packet rate by passing non-zero values for cip_n
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  and cip_d to the INIT ioctl.
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 */
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struct dv1394_status {
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        /* this embedded init struct returns the current dv1394
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           parameters in use */
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        struct dv1394_init init;
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        /* the ringbuffer frame that is currently being
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           displayed. (-1 if the device is not transmitting anything) */
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        int active_frame;
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        /* index of the first buffer (ahead of active_frame) that
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           is ready to be filled with data */
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        unsigned int first_clear_frame;
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        /* how many buffers, including first_clear_buffer, are
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           ready to be filled with data */
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        unsigned int n_clear_frames;
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        /* how many times the DV stream has underflowed, overflowed,
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           or otherwise encountered an error, since the previous call
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           to DV1394_GET_STATUS */
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        unsigned int dropped_frames;
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        /* N.B. The dropped_frames counter is only a lower bound on the actual
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           number of dropped frames, with the special case that if dropped_frames
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           is zero, then it is guaranteed that NO frames have been dropped
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           since the last call to DV1394_GET_STATUS.
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        */
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};
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#endif /* _DV_1394_H */