dv patch by Max Krasnyansky (maxk at qualcomm dot com)
[libav.git] / libavformat / dv1394.h
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
29 #define DV1394_DEFAULT_CHANNEL 0x63
30 #define DV1394_DEFAULT_CARD 0
31 #define DV1394_RING_FRAMES 20
32
33 #define DV1394_WIDTH 720
34 #define DV1394_HEIGHT 480
35
36 /* This is the public user-space interface. Try not to break it. */
37
38 #define DV1394_API_VERSION 0x20011127
39
40 /* ********************
41 ** **
42 ** DV1394 API **
43 ** **
44 ********************
45
46 There are two methods of operating the DV1394 DV output device.
47
48 1)
49
50 The simplest is an interface based on write(): simply write
51 full DV frames of data to the device, and they will be transmitted
52 as quickly as possible. The FD may be set for non-blocking I/O,
53 in which case you can use select() or poll() to wait for output
54 buffer space.
55
56 To set the DV output parameters (e.g. whether you want NTSC or PAL
57 video), use the DV1394_INIT ioctl, passing in the parameters you
58 want in a struct dv1394_init.
59
60 Example 1:
61 To play a raw .DV file: cat foo.DV > /dev/dv1394
62 (cat will use write() internally)
63
64 Example 2:
65 static struct dv1394_init init = {
66 0x63, (broadcast channel)
67 4, (four-frame ringbuffer)
68 DV1394_NTSC, (send NTSC video)
69 0, 0 (default empty packet rate)
70 }
71
72 ioctl(fd, DV1394_INIT, &init);
73
74 while(1) {
75 read( <a raw DV file>, buf, DV1394_NTSC_FRAME_SIZE );
76 write( <the dv1394 FD>, buf, DV1394_NTSC_FRAME_SIZE );
77 }
78
79 2)
80
81 For more control over buffering, and to avoid unnecessary copies
82 of the DV data, you can use the more sophisticated the mmap() interface.
83 First, call the DV1394_INIT ioctl to specify your parameters,
84 including the number of frames in the ringbuffer. Then, calling mmap()
85 on the dv1394 device will give you direct access to the ringbuffer
86 from which the DV card reads your frame data.
87
88 The ringbuffer is simply one large, contiguous region of memory
89 containing two or more frames of packed DV data. Each frame of DV data
90 is 120000 bytes (NTSC) or 144000 bytes (PAL).
91
92 Fill one or more frames in the ringbuffer, then use the DV1394_SUBMIT_FRAMES
93 ioctl to begin I/O. You can use either the DV1394_WAIT_FRAMES ioctl
94 or select()/poll() to wait until the frames are transmitted. Next, you'll
95 need to call the DV1394_GET_STATUS ioctl to determine which ringbuffer
96 frames are clear (ready to be filled with new DV data). Finally, use
97 DV1394_SUBMIT_FRAMES again to send the new data to the DV output.
98
99
100 Example: here is what a four-frame ringbuffer might look like
101 during DV transmission:
102
103
104 frame 0 frame 1 frame 2 frame 3
105
106 *--------------------------------------*
107 | CLEAR | DV data | DV data | CLEAR |
108 *--------------------------------------*
109 <ACTIVE>
110
111 transmission goes in this direction --->>>
112
113
114 The DV hardware is currently transmitting the data in frame 1.
115 Once frame 1 is finished, it will automatically transmit frame 2.
116 (if frame 2 finishes before frame 3 is submitted, the device
117 will continue to transmit frame 2, and will increase the dropped_frames
118 counter each time it repeats the transmission).
119
120
121 If you called DV1394_GET_STATUS at this instant, you would
122 receive the following values:
123
124 n_frames = 4
125 active_frame = 1
126 first_clear_frame = 3
127 n_clear_frames = 2
128
129 At this point, you should write new DV data into frame 3 and optionally
130 frame 0. Then call DV1394_SUBMIT_FRAMES to inform the device that
131 it may transmit the new frames.
132
133 ERROR HANDLING
134
135 An error (buffer underflow/overflow or a break in the DV stream due
136 to a 1394 bus reset) can be detected by checking the dropped_frames
137 field of struct dv1394_status (obtained through the
138 DV1394_GET_STATUS ioctl).
139
140 The best way to recover from such an error is to re-initialize
141 dv1394, either by using the DV1394_INIT ioctl call, or closing the
142 file descriptor and opening it again. (note that you must unmap all
143 ringbuffer mappings when closing the file descriptor, or else
144 dv1394 will still be considered 'in use').
145
146 MAIN LOOP
147
148 For maximum efficiency and robustness against bus errors, you are
149 advised to model the main loop of your application after the
150 following pseudo-code example:
151
152 (checks of system call return values omitted for brevity; always
153 check return values in your code!)
154
155 while( frames left ) {
156
157 struct pollfd *pfd = ...;
158
159 pfd->fd = dv1394_fd;
160 pfd->revents = 0;
161 pfd->events = POLLOUT | POLLIN; (OUT for transmit, IN for receive)
162
163 (add other sources of I/O here)
164
165 poll(pfd, 1, -1); (or select(); add a timeout if you want)
166
167 if(pfd->revents) {
168 struct dv1394_status status;
169
170 ioctl(dv1394_fd, DV1394_GET_STATUS, &status);
171
172 if(status.dropped_frames > 0) {
173 reset_dv1394();
174 } else {
175 for(int i = 0; i < status.n_clear_frames; i++) {
176 copy_DV_frame();
177 }
178 }
179 }
180 }
181
182 where copy_DV_frame() reads or writes on the dv1394 file descriptor
183 (read/write mode) or copies data to/from the mmap ringbuffer and
184 then calls ioctl(DV1394_SUBMIT_FRAMES) to notify dv1394 that new
185 frames are availble (mmap mode).
186
187 reset_dv1394() is called in the event of a buffer
188 underflow/overflow or a halt in the DV stream (e.g. due to a 1394
189 bus reset). To guarantee recovery from the error, this function
190 should close the dv1394 file descriptor (and munmap() all
191 ringbuffer mappings, if you are using them), then re-open the
192 dv1394 device (and re-map the ringbuffer).
193
194 */
195
196
197 /* maximum number of frames in the ringbuffer */
198 #define DV1394_MAX_FRAMES 32
199
200 /* number of *full* isochronous packets per DV frame */
201 #define DV1394_NTSC_PACKETS_PER_FRAME 250
202 #define DV1394_PAL_PACKETS_PER_FRAME 300
203
204 /* size of one frame's worth of DV data, in bytes */
205 #define DV1394_NTSC_FRAME_SIZE (480 * DV1394_NTSC_PACKETS_PER_FRAME)
206 #define DV1394_PAL_FRAME_SIZE (480 * DV1394_PAL_PACKETS_PER_FRAME)
207
208
209 /* ioctl() commands */
210
211 enum {
212 /* I don't like using 0 as a valid ioctl() */
213 DV1394_INVALID = 0,
214
215
216 /* get the driver ready to transmit video.
217 pass a struct dv1394_init* as the parameter (see below),
218 or NULL to get default parameters */
219 DV1394_INIT,
220
221
222 /* stop transmitting video and free the ringbuffer */
223 DV1394_SHUTDOWN,
224
225
226 /* submit N new frames to be transmitted, where
227 the index of the first new frame is first_clear_buffer,
228 and the index of the last new frame is
229 (first_clear_buffer + N) % n_frames */
230 DV1394_SUBMIT_FRAMES,
231
232
233 /* block until N buffers are clear (pass N as the parameter)
234 Because we re-transmit the last frame on underrun, there
235 will at most be n_frames - 1 clear frames at any time */
236 DV1394_WAIT_FRAMES,
237
238 /* capture new frames that have been received, where
239 the index of the first new frame is first_clear_buffer,
240 and the index of the last new frame is
241 (first_clear_buffer + N) % n_frames */
242 DV1394_RECEIVE_FRAMES,
243
244
245 DV1394_START_RECEIVE,
246
247
248 /* pass a struct dv1394_status* as the parameter (see below) */
249 DV1394_GET_STATUS,
250 };
251
252
253
254 enum pal_or_ntsc {
255 DV1394_NTSC = 0,
256 DV1394_PAL
257 };
258
259
260
261
262 /* this is the argument to DV1394_INIT */
263 struct dv1394_init {
264 /* DV1394_API_VERSION */
265 unsigned int api_version;
266
267 /* isochronous transmission channel to use */
268 unsigned int channel;
269
270 /* number of frames in the ringbuffer. Must be at least 2
271 and at most DV1394_MAX_FRAMES. */
272 unsigned int n_frames;
273
274 /* send/receive PAL or NTSC video format */
275 enum pal_or_ntsc format;
276
277 /* the following are used only for transmission */
278
279 /* set these to zero unless you want a
280 non-default empty packet rate (see below) */
281 unsigned long cip_n;
282 unsigned long cip_d;
283
284 /* set this to zero unless you want a
285 non-default SYT cycle offset (default = 3 cycles) */
286 unsigned int syt_offset;
287 };
288
289 /* NOTE: you may only allocate the DV frame ringbuffer once each time
290 you open the dv1394 device. DV1394_INIT will fail if you call it a
291 second time with different 'n_frames' or 'format' arguments (which
292 would imply a different size for the ringbuffer). If you need a
293 different buffer size, simply close and re-open the device, then
294 initialize it with your new settings. */
295
296 /* Q: What are cip_n and cip_d? */
297
298 /*
299 A: DV video streams do not utilize 100% of the potential bandwidth offered
300 by IEEE 1394 (FireWire). To achieve the correct rate of data transmission,
301 DV devices must periodically insert empty packets into the 1394 data stream.
302 Typically there is one empty packet per 14-16 data-carrying packets.
303
304 Some DV devices will accept a wide range of empty packet rates, while others
305 require a precise rate. If the dv1394 driver produces empty packets at
306 a rate that your device does not accept, you may see ugly patterns on the
307 DV output, or even no output at all.
308
309 The default empty packet insertion rate seems to work for many people; if
310 your DV output is stable, you can simply ignore this discussion. However,
311 we have exposed the empty packet rate as a parameter to support devices that
312 do not work with the default rate.
313
314 The decision to insert an empty packet is made with a numerator/denominator
315 algorithm. Empty packets are produced at an average rate of CIP_N / CIP_D.
316 You can alter the empty packet rate by passing non-zero values for cip_n
317 and cip_d to the INIT ioctl.
318
319 */
320
321
322
323 struct dv1394_status {
324 /* this embedded init struct returns the current dv1394
325 parameters in use */
326 struct dv1394_init init;
327
328 /* the ringbuffer frame that is currently being
329 displayed. (-1 if the device is not transmitting anything) */
330 int active_frame;
331
332 /* index of the first buffer (ahead of active_frame) that
333 is ready to be filled with data */
334 unsigned int first_clear_frame;
335
336 /* how many buffers, including first_clear_buffer, are
337 ready to be filled with data */
338 unsigned int n_clear_frames;
339
340 /* how many times the DV stream has underflowed, overflowed,
341 or otherwise encountered an error, since the previous call
342 to DV1394_GET_STATUS */
343 unsigned int dropped_frames;
344
345 /* N.B. The dropped_frames counter is only a lower bound on the actual
346 number of dropped frames, with the special case that if dropped_frames
347 is zero, then it is guaranteed that NO frames have been dropped
348 since the last call to DV1394_GET_STATUS.
349 */
350 };
351
352
353 #endif /* _DV_1394_H */