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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 FFmpeg. | |
12 | * | |
13 | * FFmpeg 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 | * FFmpeg 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 FFmpeg; 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 | int i; | |
179 | for (i = 0; i < status.n_clear_frames; i++) { | |
180 | copy_DV_frame(); | |
181 | } | |
182 | } | |
183 | } | |
184 | } | |
185 | ||
186 | where copy_DV_frame() reads or writes on the dv1394 file descriptor | |
187 | (read/write mode) or copies data to/from the mmap ringbuffer and | |
188 | then calls ioctl(DV1394_SUBMIT_FRAMES) to notify dv1394 that new | |
189 | frames are available (mmap mode). | |
190 | ||
191 | reset_dv1394() is called in the event of a buffer | |
192 | underflow/overflow or a halt in the DV stream (e.g. due to a 1394 | |
193 | bus reset). To guarantee recovery from the error, this function | |
194 | should close the dv1394 file descriptor (and munmap() all | |
195 | ringbuffer mappings, if you are using them), then re-open the | |
196 | dv1394 device (and re-map the ringbuffer). | |
197 | ||
198 | */ | |
199 | ||
200 | ||
201 | /* maximum number of frames in the ringbuffer */ | |
202 | #define DV1394_MAX_FRAMES 32 | |
203 | ||
204 | /* number of *full* isochronous packets per DV frame */ | |
205 | #define DV1394_NTSC_PACKETS_PER_FRAME 250 | |
206 | #define DV1394_PAL_PACKETS_PER_FRAME 300 | |
207 | ||
208 | /* size of one frame's worth of DV data, in bytes */ | |
209 | #define DV1394_NTSC_FRAME_SIZE (480 * DV1394_NTSC_PACKETS_PER_FRAME) | |
210 | #define DV1394_PAL_FRAME_SIZE (480 * DV1394_PAL_PACKETS_PER_FRAME) | |
211 | ||
212 | ||
213 | /* ioctl() commands */ | |
214 | ||
215 | enum { | |
216 | /* I don't like using 0 as a valid ioctl() */ | |
217 | DV1394_INVALID = 0, | |
218 | ||
219 | ||
220 | /* get the driver ready to transmit video. | |
221 | pass a struct dv1394_init* as the parameter (see below), | |
222 | or NULL to get default parameters */ | |
223 | DV1394_INIT, | |
224 | ||
225 | ||
226 | /* stop transmitting video and free the ringbuffer */ | |
227 | DV1394_SHUTDOWN, | |
228 | ||
229 | ||
230 | /* submit N new frames to be transmitted, where | |
231 | the index of the first new frame is first_clear_buffer, | |
232 | and the index of the last new frame is | |
233 | (first_clear_buffer + N) % n_frames */ | |
234 | DV1394_SUBMIT_FRAMES, | |
235 | ||
236 | ||
237 | /* block until N buffers are clear (pass N as the parameter) | |
238 | Because we re-transmit the last frame on underrun, there | |
239 | will at most be n_frames - 1 clear frames at any time */ | |
240 | DV1394_WAIT_FRAMES, | |
241 | ||
242 | /* capture new frames that have been received, where | |
243 | the index of the first new frame is first_clear_buffer, | |
244 | and the index of the last new frame is | |
245 | (first_clear_buffer + N) % n_frames */ | |
246 | DV1394_RECEIVE_FRAMES, | |
247 | ||
248 | ||
249 | DV1394_START_RECEIVE, | |
250 | ||
251 | ||
252 | /* pass a struct dv1394_status* as the parameter (see below) */ | |
253 | DV1394_GET_STATUS, | |
254 | }; | |
255 | ||
256 | ||
257 | ||
258 | enum pal_or_ntsc { | |
259 | DV1394_NTSC = 0, | |
260 | DV1394_PAL | |
261 | }; | |
262 | ||
263 | ||
264 | ||
265 | ||
266 | /* this is the argument to DV1394_INIT */ | |
267 | struct dv1394_init { | |
268 | /* DV1394_API_VERSION */ | |
269 | unsigned int api_version; | |
270 | ||
271 | /* isochronous transmission channel to use */ | |
272 | unsigned int channel; | |
273 | ||
274 | /* number of frames in the ringbuffer. Must be at least 2 | |
275 | and at most DV1394_MAX_FRAMES. */ | |
276 | unsigned int n_frames; | |
277 | ||
278 | /* send/receive PAL or NTSC video format */ | |
279 | enum pal_or_ntsc format; | |
280 | ||
281 | /* the following are used only for transmission */ | |
282 | ||
283 | /* set these to zero unless you want a | |
284 | non-default empty packet rate (see below) */ | |
285 | unsigned long cip_n; | |
286 | unsigned long cip_d; | |
287 | ||
288 | /* set this to zero unless you want a | |
289 | non-default SYT cycle offset (default = 3 cycles) */ | |
290 | unsigned int syt_offset; | |
291 | }; | |
292 | ||
293 | /* NOTE: you may only allocate the DV frame ringbuffer once each time | |
294 | you open the dv1394 device. DV1394_INIT will fail if you call it a | |
295 | second time with different 'n_frames' or 'format' arguments (which | |
296 | would imply a different size for the ringbuffer). If you need a | |
297 | different buffer size, simply close and re-open the device, then | |
298 | initialize it with your new settings. */ | |
299 | ||
300 | /* Q: What are cip_n and cip_d? */ | |
301 | ||
302 | /* | |
303 | A: DV video streams do not utilize 100% of the potential bandwidth offered | |
304 | by IEEE 1394 (FireWire). To achieve the correct rate of data transmission, | |
305 | DV devices must periodically insert empty packets into the 1394 data stream. | |
306 | Typically there is one empty packet per 14-16 data-carrying packets. | |
307 | ||
308 | Some DV devices will accept a wide range of empty packet rates, while others | |
309 | require a precise rate. If the dv1394 driver produces empty packets at | |
310 | a rate that your device does not accept, you may see ugly patterns on the | |
311 | DV output, or even no output at all. | |
312 | ||
313 | The default empty packet insertion rate seems to work for many people; if | |
314 | your DV output is stable, you can simply ignore this discussion. However, | |
315 | we have exposed the empty packet rate as a parameter to support devices that | |
316 | do not work with the default rate. | |
317 | ||
318 | The decision to insert an empty packet is made with a numerator/denominator | |
319 | algorithm. Empty packets are produced at an average rate of CIP_N / CIP_D. | |
320 | You can alter the empty packet rate by passing non-zero values for cip_n | |
321 | and cip_d to the INIT ioctl. | |
322 | ||
323 | */ | |
324 | ||
325 | ||
326 | ||
327 | struct dv1394_status { | |
328 | /* this embedded init struct returns the current dv1394 | |
329 | parameters in use */ | |
330 | struct dv1394_init init; | |
331 | ||
332 | /* the ringbuffer frame that is currently being | |
333 | displayed. (-1 if the device is not transmitting anything) */ | |
334 | int active_frame; | |
335 | ||
336 | /* index of the first buffer (ahead of active_frame) that | |
337 | is ready to be filled with data */ | |
338 | unsigned int first_clear_frame; | |
339 | ||
340 | /* how many buffers, including first_clear_buffer, are | |
341 | ready to be filled with data */ | |
342 | unsigned int n_clear_frames; | |
343 | ||
344 | /* how many times the DV stream has underflowed, overflowed, | |
345 | or otherwise encountered an error, since the previous call | |
346 | to DV1394_GET_STATUS */ | |
347 | unsigned int dropped_frames; | |
348 | ||
349 | /* N.B. The dropped_frames counter is only a lower bound on the actual | |
350 | number of dropped frames, with the special case that if dropped_frames | |
351 | is zero, then it is guaranteed that NO frames have been dropped | |
352 | since the last call to DV1394_GET_STATUS. | |
353 | */ | |
354 | }; | |
355 | ||
356 | ||
357 | #endif /* AVDEVICE_DV1394_H */ |