1/*
2 * DV input/output over IEEE 1394 on OHCI chips
3 *   Copyright (C)2001 Daniel Maas <dmaas@dcine.com>
4 *     receive, proc_fs by Dan Dennedy <dan@dennedy.org>
5 *
6 * based on:
7 *   video1394.h - driver for OHCI 1394 boards
8 *   Copyright (C)1999,2000 Sebastien Rougeaux <sebastien.rougeaux@anu.edu.au>
9 *                          Peter Schlaile <udbz@rz.uni-karlsruhe.de>
10 *
11 * This file is part of Libav.
12 *
13 * Libav is free software; you can redistribute it and/or
14 * modify it under the terms of the GNU Lesser General Public
15 * License as published by the Free Software Foundation; either
16 * version 2.1 of the License, or (at your option) any later version.
17 *
18 * Libav is distributed in the hope that it will be useful,
19 * but WITHOUT ANY WARRANTY; without even the implied warranty of
20 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
21 * Lesser General Public License for more details.
22 *
23 * You should have received a copy of the GNU Lesser General Public
24 * License along with Libav; if not, write to the Free Software
25 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
26 */
27
28#ifndef AVDEVICE_DV1394_H
29#define AVDEVICE_DV1394_H
30
31#define DV1394_DEFAULT_CHANNEL 63
32#define DV1394_DEFAULT_CARD    0
33#define DV1394_RING_FRAMES     20
34
35#define DV1394_WIDTH  720
36#define DV1394_NTSC_HEIGHT 480
37#define DV1394_PAL_HEIGHT 576
38
39/* This is the public user-space interface. Try not to break it. */
40
41#define DV1394_API_VERSION 0x20011127
42
43/* ********************
44   **                **
45   **   DV1394 API   **
46   **                **
47   ********************
48
49   There are two methods of operating the DV1394 DV output device.
50
51   1)
52
53   The simplest is an interface based on write(): simply write
54   full DV frames of data to the device, and they will be transmitted
55   as quickly as possible. The FD may be set for non-blocking I/O,
56   in which case you can use select() or poll() to wait for output
57   buffer space.
58
59   To set the DV output parameters (e.g. whether you want NTSC or PAL
60   video), use the DV1394_INIT ioctl, passing in the parameters you
61   want in a struct dv1394_init.
62
63   Example 1:
64         To play a raw .DV file:   cat foo.DV > /dev/dv1394
65         (cat will use write() internally)
66
67   Example 2:
68           static struct dv1394_init init = {
69              0x63,        (broadcast channel)
70              4,           (four-frame ringbuffer)
71              DV1394_NTSC, (send NTSC video)
72              0, 0         (default empty packet rate)
73           }
74
75           ioctl(fd, DV1394_INIT, &init);
76
77           while(1) {
78                  read( <a raw DV file>, buf, DV1394_NTSC_FRAME_SIZE );
79                  write( <the dv1394 FD>, buf, DV1394_NTSC_FRAME_SIZE );
80           }
81
82   2)
83
84   For more control over buffering, and to avoid unnecessary copies
85   of the DV data, you can use the more sophisticated the mmap() interface.
86   First, call the DV1394_INIT ioctl to specify your parameters,
87   including the number of frames in the ringbuffer. Then, calling mmap()
88   on the dv1394 device will give you direct access to the ringbuffer
89   from which the DV card reads your frame data.
90
91   The ringbuffer is simply one large, contiguous region of memory
92   containing two or more frames of packed DV data. Each frame of DV data
93   is 120000 bytes (NTSC) or 144000 bytes (PAL).
94
95   Fill one or more frames in the ringbuffer, then use the DV1394_SUBMIT_FRAMES
96   ioctl to begin I/O. You can use either the DV1394_WAIT_FRAMES ioctl
97   or select()/poll() to wait until the frames are transmitted. Next, you'll
98   need to call the DV1394_GET_STATUS ioctl to determine which ringbuffer
99   frames are clear (ready to be filled with new DV data). Finally, use
100   DV1394_SUBMIT_FRAMES again to send the new data to the DV output.
101
102
103   Example: here is what a four-frame ringbuffer might look like
104            during DV transmission:
105
106
107         frame 0   frame 1   frame 2   frame 3
108
109        *--------------------------------------*
110        | CLEAR   | DV data | DV data | CLEAR  |
111        *--------------------------------------*
112                   <ACTIVE>
113
114        transmission goes in this direction --->>>
115
116
117   The DV hardware is currently transmitting the data in frame 1.
118   Once frame 1 is finished, it will automatically transmit frame 2.
119   (if frame 2 finishes before frame 3 is submitted, the device
120   will continue to transmit frame 2, and will increase the dropped_frames
121   counter each time it repeats the transmission).
122
123
124   If you called DV1394_GET_STATUS at this instant, you would
125   receive the following values:
126
127                  n_frames          = 4
128                  active_frame      = 1
129                  first_clear_frame = 3
130                  n_clear_frames    = 2
131
132   At this point, you should write new DV data into frame 3 and optionally
133   frame 0. Then call DV1394_SUBMIT_FRAMES to inform the device that
134   it may transmit the new frames.
135
136   ERROR HANDLING
137
138   An error (buffer underflow/overflow or a break in the DV stream due
139   to a 1394 bus reset) can be detected by checking the dropped_frames
140   field of struct dv1394_status (obtained through the
141   DV1394_GET_STATUS ioctl).
142
143   The best way to recover from such an error is to re-initialize
144   dv1394, either by using the DV1394_INIT ioctl call, or closing the
145   file descriptor and opening it again. (note that you must unmap all
146   ringbuffer mappings when closing the file descriptor, or else
147   dv1394 will still be considered 'in use').
148
149   MAIN LOOP
150
151   For maximum efficiency and robustness against bus errors, you are
152   advised to model the main loop of your application after the
153   following pseudo-code example:
154
155   (checks of system call return values omitted for brevity; always
156   check return values in your code!)
157
158   while( frames left ) {
159
160    struct pollfd *pfd = ...;
161
162    pfd->fd = dv1394_fd;
163    pfd->revents = 0;
164    pfd->events = POLLOUT | POLLIN; (OUT for transmit, IN for receive)
165
166    (add other sources of I/O here)
167
168    poll(pfd, 1, -1); (or select(); add a timeout if you want)
169
170    if(pfd->revents) {
171         struct dv1394_status status;
172
173         ioctl(dv1394_fd, DV1394_GET_STATUS, &status);
174
175         if(status.dropped_frames > 0) {
176              reset_dv1394();
177         } else {
178              for(int i = 0; i < status.n_clear_frames; i++) {
179                  copy_DV_frame();
180              }
181         }
182    }
183   }
184
185   where copy_DV_frame() reads or writes on the dv1394 file descriptor
186   (read/write mode) or copies data to/from the mmap ringbuffer and
187   then calls ioctl(DV1394_SUBMIT_FRAMES) to notify dv1394 that new
188   frames are availble (mmap mode).
189
190   reset_dv1394() is called in the event of a buffer
191   underflow/overflow or a halt in the DV stream (e.g. due to a 1394
192   bus reset). To guarantee recovery from the error, this function
193   should close the dv1394 file descriptor (and munmap() all
194   ringbuffer mappings, if you are using them), then re-open the
195   dv1394 device (and re-map the ringbuffer).
196
197*/
198
199
200/* maximum number of frames in the ringbuffer */
201#define DV1394_MAX_FRAMES 32
202
203/* number of *full* isochronous packets per DV frame */
204#define DV1394_NTSC_PACKETS_PER_FRAME 250
205#define DV1394_PAL_PACKETS_PER_FRAME  300
206
207/* size of one frame's worth of DV data, in bytes */
208#define DV1394_NTSC_FRAME_SIZE (480 * DV1394_NTSC_PACKETS_PER_FRAME)
209#define DV1394_PAL_FRAME_SIZE  (480 * DV1394_PAL_PACKETS_PER_FRAME)
210
211
212/* ioctl() commands */
213
214enum {
215        /* I don't like using 0 as a valid ioctl() */
216        DV1394_INVALID = 0,
217
218
219        /* get the driver ready to transmit video.
220           pass a struct dv1394_init* as the parameter (see below),
221           or NULL to get default parameters */
222        DV1394_INIT,
223
224
225        /* stop transmitting video and free the ringbuffer */
226        DV1394_SHUTDOWN,
227
228
229        /* submit N new frames to be transmitted, where
230           the index of the first new frame is first_clear_buffer,
231           and the index of the last new frame is
232           (first_clear_buffer + N) % n_frames */
233        DV1394_SUBMIT_FRAMES,
234
235
236        /* block until N buffers are clear (pass N as the parameter)
237           Because we re-transmit the last frame on underrun, there
238           will at most be n_frames - 1 clear frames at any time */
239        DV1394_WAIT_FRAMES,
240
241        /* capture new frames that have been received, where
242           the index of the first new frame is first_clear_buffer,
243           and the index of the last new frame is
244           (first_clear_buffer + N) % n_frames */
245        DV1394_RECEIVE_FRAMES,
246
247
248        DV1394_START_RECEIVE,
249
250
251        /* pass a struct dv1394_status* as the parameter (see below) */
252        DV1394_GET_STATUS,
253};
254
255
256
257enum pal_or_ntsc {
258        DV1394_NTSC = 0,
259        DV1394_PAL
260};
261
262
263
264
265/* this is the argument to DV1394_INIT */
266struct dv1394_init {
267        /* DV1394_API_VERSION */
268        unsigned int api_version;
269
270        /* isochronous transmission channel to use */
271        unsigned int channel;
272
273        /* number of frames in the ringbuffer. Must be at least 2
274           and at most DV1394_MAX_FRAMES. */
275        unsigned int n_frames;
276
277        /* send/receive PAL or NTSC video format */
278        enum pal_or_ntsc format;
279
280        /* the following are used only for transmission */
281
282        /* set these to zero unless you want a
283           non-default empty packet rate (see below) */
284        unsigned long cip_n;
285        unsigned long cip_d;
286
287        /* set this to zero unless you want a
288           non-default SYT cycle offset (default = 3 cycles) */
289        unsigned int syt_offset;
290};
291
292/* NOTE: you may only allocate the DV frame ringbuffer once each time
293   you open the dv1394 device. DV1394_INIT will fail if you call it a
294   second time with different 'n_frames' or 'format' arguments (which
295   would imply a different size for the ringbuffer). If you need a
296   different buffer size, simply close and re-open the device, then
297   initialize it with your new settings. */
298
299/* Q: What are cip_n and cip_d? */
300
301/*
302  A: DV video streams do not utilize 100% of the potential bandwidth offered
303  by IEEE 1394 (FireWire). To achieve the correct rate of data transmission,
304  DV devices must periodically insert empty packets into the 1394 data stream.
305  Typically there is one empty packet per 14-16 data-carrying packets.
306
307  Some DV devices will accept a wide range of empty packet rates, while others
308  require a precise rate. If the dv1394 driver produces empty packets at
309  a rate that your device does not accept, you may see ugly patterns on the
310  DV output, or even no output at all.
311
312  The default empty packet insertion rate seems to work for many people; if
313  your DV output is stable, you can simply ignore this discussion. However,
314  we have exposed the empty packet rate as a parameter to support devices that
315  do not work with the default rate.
316
317  The decision to insert an empty packet is made with a numerator/denominator
318  algorithm. Empty packets are produced at an average rate of CIP_N / CIP_D.
319  You can alter the empty packet rate by passing non-zero values for cip_n
320  and cip_d to the INIT ioctl.
321
322 */
323
324
325
326struct dv1394_status {
327        /* this embedded init struct returns the current dv1394
328           parameters in use */
329        struct dv1394_init init;
330
331        /* the ringbuffer frame that is currently being
332           displayed. (-1 if the device is not transmitting anything) */
333        int active_frame;
334
335        /* index of the first buffer (ahead of active_frame) that
336           is ready to be filled with data */
337        unsigned int first_clear_frame;
338
339        /* how many buffers, including first_clear_buffer, are
340           ready to be filled with data */
341        unsigned int n_clear_frames;
342
343        /* how many times the DV stream has underflowed, overflowed,
344           or otherwise encountered an error, since the previous call
345           to DV1394_GET_STATUS */
346        unsigned int dropped_frames;
347
348        /* N.B. The dropped_frames counter is only a lower bound on the actual
349           number of dropped frames, with the special case that if dropped_frames
350           is zero, then it is guaranteed that NO frames have been dropped
351           since the last call to DV1394_GET_STATUS.
352        */
353};
354
355
356#endif /* AVDEVICE_DV1394_H */
357