Reportedly FFmpeg fails to compile on Cygwin with vhook enabled, but FFserver
[libav.git] / libavformat / dv1394.h
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1/*
2 * dv1394.h - 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 program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License as published by
13 * the Free Software Foundation; either version 2 of the License, or
14 * (at your option) any later version.
15 *
16 * This program is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
19 * GNU General Public License for more details.
20 *
21 * You should have received a copy of the GNU General Public License
22 * along with this program; if not, write to the Free Software Foundation,
23 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
24 */
25
26#ifndef _DV_1394_H
27#define _DV_1394_H
28
1fbe1a61 29#define DV1394_DEFAULT_CHANNEL 63
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30#define DV1394_DEFAULT_CARD 0
31#define DV1394_RING_FRAMES 20
32
33#define DV1394_WIDTH 720
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34#define DV1394_NTSC_HEIGHT 480
35#define DV1394_PAL_HEIGHT 576
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36
37/* This is the public user-space interface. Try not to break it. */
38
39#define DV1394_API_VERSION 0x20011127
40
41/* ********************
42 ** **
43 ** DV1394 API **
44 ** **
45 ********************
46
47 There are two methods of operating the DV1394 DV output device.
48
49 1)
50
51 The simplest is an interface based on write(): simply write
52 full DV frames of data to the device, and they will be transmitted
53 as quickly as possible. The FD may be set for non-blocking I/O,
54 in which case you can use select() or poll() to wait for output
55 buffer space.
56
57 To set the DV output parameters (e.g. whether you want NTSC or PAL
58 video), use the DV1394_INIT ioctl, passing in the parameters you
59 want in a struct dv1394_init.
115329f1 60
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61 Example 1:
62 To play a raw .DV file: cat foo.DV > /dev/dv1394
63 (cat will use write() internally)
64
65 Example 2:
66 static struct dv1394_init init = {
67 0x63, (broadcast channel)
68 4, (four-frame ringbuffer)
69 DV1394_NTSC, (send NTSC video)
70 0, 0 (default empty packet rate)
71 }
72
73 ioctl(fd, DV1394_INIT, &init);
74
75 while(1) {
76 read( <a raw DV file>, buf, DV1394_NTSC_FRAME_SIZE );
77 write( <the dv1394 FD>, buf, DV1394_NTSC_FRAME_SIZE );
78 }
79
80 2)
81
82 For more control over buffering, and to avoid unnecessary copies
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83 of the DV data, you can use the more sophisticated the mmap() interface.
84 First, call the DV1394_INIT ioctl to specify your parameters,
85 including the number of frames in the ringbuffer. Then, calling mmap()
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86 on the dv1394 device will give you direct access to the ringbuffer
87 from which the DV card reads your frame data.
88
89 The ringbuffer is simply one large, contiguous region of memory
90 containing two or more frames of packed DV data. Each frame of DV data
91 is 120000 bytes (NTSC) or 144000 bytes (PAL).
92
93 Fill one or more frames in the ringbuffer, then use the DV1394_SUBMIT_FRAMES
94 ioctl to begin I/O. You can use either the DV1394_WAIT_FRAMES ioctl
95 or select()/poll() to wait until the frames are transmitted. Next, you'll
96 need to call the DV1394_GET_STATUS ioctl to determine which ringbuffer
97 frames are clear (ready to be filled with new DV data). Finally, use
98 DV1394_SUBMIT_FRAMES again to send the new data to the DV output.
99
100
101 Example: here is what a four-frame ringbuffer might look like
102 during DV transmission:
103
104
105 frame 0 frame 1 frame 2 frame 3
106
107 *--------------------------------------*
108 | CLEAR | DV data | DV data | CLEAR |
109 *--------------------------------------*
115329f1 110 <ACTIVE>
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111
112 transmission goes in this direction --->>>
113
114
115 The DV hardware is currently transmitting the data in frame 1.
116 Once frame 1 is finished, it will automatically transmit frame 2.
117 (if frame 2 finishes before frame 3 is submitted, the device
118 will continue to transmit frame 2, and will increase the dropped_frames
119 counter each time it repeats the transmission).
120
115329f1 121
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122 If you called DV1394_GET_STATUS at this instant, you would
123 receive the following values:
115329f1 124
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125 n_frames = 4
126 active_frame = 1
127 first_clear_frame = 3
128 n_clear_frames = 2
129
130 At this point, you should write new DV data into frame 3 and optionally
131 frame 0. Then call DV1394_SUBMIT_FRAMES to inform the device that
132 it may transmit the new frames.
133
134 ERROR HANDLING
135
136 An error (buffer underflow/overflow or a break in the DV stream due
137 to a 1394 bus reset) can be detected by checking the dropped_frames
138 field of struct dv1394_status (obtained through the
139 DV1394_GET_STATUS ioctl).
140
141 The best way to recover from such an error is to re-initialize
142 dv1394, either by using the DV1394_INIT ioctl call, or closing the
143 file descriptor and opening it again. (note that you must unmap all
144 ringbuffer mappings when closing the file descriptor, or else
145 dv1394 will still be considered 'in use').
146
147 MAIN LOOP
148
149 For maximum efficiency and robustness against bus errors, you are
150 advised to model the main loop of your application after the
151 following pseudo-code example:
152
153 (checks of system call return values omitted for brevity; always
154 check return values in your code!)
115329f1 155
8aa3ee32 156 while( frames left ) {
115329f1 157
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158 struct pollfd *pfd = ...;
159
160 pfd->fd = dv1394_fd;
161 pfd->revents = 0;
162 pfd->events = POLLOUT | POLLIN; (OUT for transmit, IN for receive)
163
164 (add other sources of I/O here)
115329f1 165
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166 poll(pfd, 1, -1); (or select(); add a timeout if you want)
167
168 if(pfd->revents) {
169 struct dv1394_status status;
115329f1 170
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171 ioctl(dv1394_fd, DV1394_GET_STATUS, &status);
172
173 if(status.dropped_frames > 0) {
174 reset_dv1394();
175 } else {
176 for(int i = 0; i < status.n_clear_frames; i++) {
177 copy_DV_frame();
178 }
179 }
180 }
181 }
182
183 where copy_DV_frame() reads or writes on the dv1394 file descriptor
184 (read/write mode) or copies data to/from the mmap ringbuffer and
185 then calls ioctl(DV1394_SUBMIT_FRAMES) to notify dv1394 that new
186 frames are availble (mmap mode).
187
188 reset_dv1394() is called in the event of a buffer
189 underflow/overflow or a halt in the DV stream (e.g. due to a 1394
190 bus reset). To guarantee recovery from the error, this function
191 should close the dv1394 file descriptor (and munmap() all
192 ringbuffer mappings, if you are using them), then re-open the
193 dv1394 device (and re-map the ringbuffer).
115329f1 194
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195*/
196
197
198/* maximum number of frames in the ringbuffer */
199#define DV1394_MAX_FRAMES 32
200
201/* number of *full* isochronous packets per DV frame */
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202#define DV1394_NTSC_PACKETS_PER_FRAME 250
203#define DV1394_PAL_PACKETS_PER_FRAME 300
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204
205/* size of one frame's worth of DV data, in bytes */
206#define DV1394_NTSC_FRAME_SIZE (480 * DV1394_NTSC_PACKETS_PER_FRAME)
1fbe1a61 207#define DV1394_PAL_FRAME_SIZE (480 * DV1394_PAL_PACKETS_PER_FRAME)
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208
209
210/* ioctl() commands */
211
212enum {
213 /* I don't like using 0 as a valid ioctl() */
214 DV1394_INVALID = 0,
215
216
217 /* get the driver ready to transmit video.
218 pass a struct dv1394_init* as the parameter (see below),
219 or NULL to get default parameters */
220 DV1394_INIT,
221
222
223 /* stop transmitting video and free the ringbuffer */
224 DV1394_SHUTDOWN,
225
226
227 /* submit N new frames to be transmitted, where
228 the index of the first new frame is first_clear_buffer,
229 and the index of the last new frame is
230 (first_clear_buffer + N) % n_frames */
231 DV1394_SUBMIT_FRAMES,
232
233
234 /* block until N buffers are clear (pass N as the parameter)
235 Because we re-transmit the last frame on underrun, there
236 will at most be n_frames - 1 clear frames at any time */
237 DV1394_WAIT_FRAMES,
238
239 /* capture new frames that have been received, where
240 the index of the first new frame is first_clear_buffer,
241 and the index of the last new frame is
242 (first_clear_buffer + N) % n_frames */
243 DV1394_RECEIVE_FRAMES,
244
245
246 DV1394_START_RECEIVE,
247
248
249 /* pass a struct dv1394_status* as the parameter (see below) */
250 DV1394_GET_STATUS,
251};
252
253
254
255enum pal_or_ntsc {
256 DV1394_NTSC = 0,
257 DV1394_PAL
258};
259
260
261
262
263/* this is the argument to DV1394_INIT */
264struct dv1394_init {
265 /* DV1394_API_VERSION */
266 unsigned int api_version;
115329f1 267
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268 /* isochronous transmission channel to use */
269 unsigned int channel;
270
271 /* number of frames in the ringbuffer. Must be at least 2
272 and at most DV1394_MAX_FRAMES. */
273 unsigned int n_frames;
274
275 /* send/receive PAL or NTSC video format */
276 enum pal_or_ntsc format;
277
278 /* the following are used only for transmission */
115329f1 279
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280 /* set these to zero unless you want a
281 non-default empty packet rate (see below) */
282 unsigned long cip_n;
283 unsigned long cip_d;
284
285 /* set this to zero unless you want a
286 non-default SYT cycle offset (default = 3 cycles) */
287 unsigned int syt_offset;
288};
289
290/* NOTE: you may only allocate the DV frame ringbuffer once each time
291 you open the dv1394 device. DV1394_INIT will fail if you call it a
292 second time with different 'n_frames' or 'format' arguments (which
293 would imply a different size for the ringbuffer). If you need a
294 different buffer size, simply close and re-open the device, then
295 initialize it with your new settings. */
115329f1 296
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297/* Q: What are cip_n and cip_d? */
298
299/*
300 A: DV video streams do not utilize 100% of the potential bandwidth offered
301 by IEEE 1394 (FireWire). To achieve the correct rate of data transmission,
302 DV devices must periodically insert empty packets into the 1394 data stream.
303 Typically there is one empty packet per 14-16 data-carrying packets.
304
305 Some DV devices will accept a wide range of empty packet rates, while others
306 require a precise rate. If the dv1394 driver produces empty packets at
307 a rate that your device does not accept, you may see ugly patterns on the
308 DV output, or even no output at all.
309
310 The default empty packet insertion rate seems to work for many people; if
311 your DV output is stable, you can simply ignore this discussion. However,
312 we have exposed the empty packet rate as a parameter to support devices that
115329f1 313 do not work with the default rate.
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314
315 The decision to insert an empty packet is made with a numerator/denominator
316 algorithm. Empty packets are produced at an average rate of CIP_N / CIP_D.
317 You can alter the empty packet rate by passing non-zero values for cip_n
318 and cip_d to the INIT ioctl.
115329f1 319
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320 */
321
322
323
324struct dv1394_status {
325 /* this embedded init struct returns the current dv1394
326 parameters in use */
327 struct dv1394_init init;
328
329 /* the ringbuffer frame that is currently being
330 displayed. (-1 if the device is not transmitting anything) */
331 int active_frame;
332
333 /* index of the first buffer (ahead of active_frame) that
334 is ready to be filled with data */
335 unsigned int first_clear_frame;
336
337 /* how many buffers, including first_clear_buffer, are
338 ready to be filled with data */
339 unsigned int n_clear_frames;
340
341 /* how many times the DV stream has underflowed, overflowed,
342 or otherwise encountered an error, since the previous call
343 to DV1394_GET_STATUS */
344 unsigned int dropped_frames;
345
346 /* N.B. The dropped_frames counter is only a lower bound on the actual
347 number of dropped frames, with the special case that if dropped_frames
348 is zero, then it is guaranteed that NO frames have been dropped
349 since the last call to DV1394_GET_STATUS.
350 */
351};
352
353
354#endif /* _DV_1394_H */