blob: b76d633ef698bd75529706a30b62fd5b6a57620c
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 */ |
358 |