diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /drivers/ieee1394/dv1394.h |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'drivers/ieee1394/dv1394.h')
-rw-r--r-- | drivers/ieee1394/dv1394.h | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/drivers/ieee1394/dv1394.h b/drivers/ieee1394/dv1394.h new file mode 100644 index 000000000000..5807f5289810 --- /dev/null +++ b/drivers/ieee1394/dv1394.h | |||
@@ -0,0 +1,305 @@ | |||
1 | /* | ||
2 | * dv1394.h - DV input/output over IEEE 1394 on OHCI chips | ||
3 | * Copyright (C)2001 Daniel Maas <dmaas@dcine.com> | ||
4 | * receive 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 | /* This is the public user-space interface. Try not to break it. */ | ||
30 | |||
31 | #define DV1394_API_VERSION 0x20011127 | ||
32 | |||
33 | /* ******************** | ||
34 | ** ** | ||
35 | ** DV1394 API ** | ||
36 | ** ** | ||
37 | ******************** | ||
38 | |||
39 | There are two methods of operating the DV1394 DV output device. | ||
40 | |||
41 | 1) | ||
42 | |||
43 | The simplest is an interface based on write(): simply write | ||
44 | full DV frames of data to the device, and they will be transmitted | ||
45 | as quickly as possible. The FD may be set for non-blocking I/O, | ||
46 | in which case you can use select() or poll() to wait for output | ||
47 | buffer space. | ||
48 | |||
49 | To set the DV output parameters (e.g. whether you want NTSC or PAL | ||
50 | video), use the DV1394_INIT ioctl, passing in the parameters you | ||
51 | want in a struct dv1394_init. | ||
52 | |||
53 | Example 1: | ||
54 | To play a raw .DV file: cat foo.DV > /dev/dv1394 | ||
55 | (cat will use write() internally) | ||
56 | |||
57 | Example 2: | ||
58 | static struct dv1394_init init = { | ||
59 | 0x63, (broadcast channel) | ||
60 | 4, (four-frame ringbuffer) | ||
61 | DV1394_NTSC, (send NTSC video) | ||
62 | 0, 0 (default empty packet rate) | ||
63 | } | ||
64 | |||
65 | ioctl(fd, DV1394_INIT, &init); | ||
66 | |||
67 | while (1) { | ||
68 | read( <a raw DV file>, buf, DV1394_NTSC_FRAME_SIZE ); | ||
69 | write( <the dv1394 FD>, buf, DV1394_NTSC_FRAME_SIZE ); | ||
70 | } | ||
71 | |||
72 | 2) | ||
73 | |||
74 | For more control over buffering, and to avoid unnecessary copies | ||
75 | of the DV data, you can use the more sophisticated the mmap() interface. | ||
76 | First, call the DV1394_INIT ioctl to specify your parameters, | ||
77 | including the number of frames in the ringbuffer. Then, calling mmap() | ||
78 | on the dv1394 device will give you direct access to the ringbuffer | ||
79 | from which the DV card reads your frame data. | ||
80 | |||
81 | The ringbuffer is simply one large, contiguous region of memory | ||
82 | containing two or more frames of packed DV data. Each frame of DV data | ||
83 | is 120000 bytes (NTSC) or 144000 bytes (PAL). | ||
84 | |||
85 | Fill one or more frames in the ringbuffer, then use the DV1394_SUBMIT_FRAMES | ||
86 | ioctl to begin I/O. You can use either the DV1394_WAIT_FRAMES ioctl | ||
87 | or select()/poll() to wait until the frames are transmitted. Next, you'll | ||
88 | need to call the DV1394_GET_STATUS ioctl to determine which ringbuffer | ||
89 | frames are clear (ready to be filled with new DV data). Finally, use | ||
90 | DV1394_SUBMIT_FRAMES again to send the new data to the DV output. | ||
91 | |||
92 | |||
93 | Example: here is what a four-frame ringbuffer might look like | ||
94 | during DV transmission: | ||
95 | |||
96 | |||
97 | frame 0 frame 1 frame 2 frame 3 | ||
98 | |||
99 | *--------------------------------------* | ||
100 | | CLEAR | DV data | DV data | CLEAR | | ||
101 | *--------------------------------------* | ||
102 | <ACTIVE> | ||
103 | |||
104 | transmission goes in this direction --->>> | ||
105 | |||
106 | |||
107 | The DV hardware is currently transmitting the data in frame 1. | ||
108 | Once frame 1 is finished, it will automatically transmit frame 2. | ||
109 | (if frame 2 finishes before frame 3 is submitted, the device | ||
110 | will continue to transmit frame 2, and will increase the dropped_frames | ||
111 | counter each time it repeats the transmission). | ||
112 | |||
113 | |||
114 | If you called DV1394_GET_STATUS at this instant, you would | ||
115 | receive the following values: | ||
116 | |||
117 | n_frames = 4 | ||
118 | active_frame = 1 | ||
119 | first_clear_frame = 3 | ||
120 | n_clear_frames = 2 | ||
121 | |||
122 | At this point, you should write new DV data into frame 3 and optionally | ||
123 | frame 0. Then call DV1394_SUBMIT_FRAMES to inform the device that | ||
124 | it may transmit the new frames. | ||
125 | |||
126 | ERROR HANDLING | ||
127 | |||
128 | An error (buffer underflow/overflow or a break in the DV stream due | ||
129 | to a 1394 bus reset) can be detected by checking the dropped_frames | ||
130 | field of struct dv1394_status (obtained through the | ||
131 | DV1394_GET_STATUS ioctl). | ||
132 | |||
133 | The best way to recover from such an error is to re-initialize | ||
134 | dv1394, either by using the DV1394_INIT ioctl call, or closing the | ||
135 | file descriptor and opening it again. (note that you must unmap all | ||
136 | ringbuffer mappings when closing the file descriptor, or else | ||
137 | dv1394 will still be considered 'in use'). | ||
138 | |||
139 | MAIN LOOP | ||
140 | |||
141 | For maximum efficiency and robustness against bus errors, you are | ||
142 | advised to model the main loop of your application after the | ||
143 | following pseudo-code example: | ||
144 | |||
145 | (checks of system call return values omitted for brevity; always | ||
146 | check return values in your code!) | ||
147 | |||
148 | while ( frames left ) { | ||
149 | |||
150 | struct pollfd *pfd = ...; | ||
151 | |||
152 | pfd->fd = dv1394_fd; | ||
153 | pfd->revents = 0; | ||
154 | pfd->events = POLLOUT | POLLIN; (OUT for transmit, IN for receive) | ||
155 | |||
156 | (add other sources of I/O here) | ||
157 | |||
158 | poll(pfd, 1, -1); (or select(); add a timeout if you want) | ||
159 | |||
160 | if (pfd->revents) { | ||
161 | struct dv1394_status status; | ||
162 | |||
163 | ioctl(dv1394_fd, DV1394_GET_STATUS, &status); | ||
164 | |||
165 | if (status.dropped_frames > 0) { | ||
166 | reset_dv1394(); | ||
167 | } else { | ||
168 | for (int i = 0; i < status.n_clear_frames; i++) { | ||
169 | copy_DV_frame(); | ||
170 | } | ||
171 | } | ||
172 | } | ||
173 | } | ||
174 | |||
175 | where copy_DV_frame() reads or writes on the dv1394 file descriptor | ||
176 | (read/write mode) or copies data to/from the mmap ringbuffer and | ||
177 | then calls ioctl(DV1394_SUBMIT_FRAMES) to notify dv1394 that new | ||
178 | frames are availble (mmap mode). | ||
179 | |||
180 | reset_dv1394() is called in the event of a buffer | ||
181 | underflow/overflow or a halt in the DV stream (e.g. due to a 1394 | ||
182 | bus reset). To guarantee recovery from the error, this function | ||
183 | should close the dv1394 file descriptor (and munmap() all | ||
184 | ringbuffer mappings, if you are using them), then re-open the | ||
185 | dv1394 device (and re-map the ringbuffer). | ||
186 | |||
187 | */ | ||
188 | |||
189 | |||
190 | /* maximum number of frames in the ringbuffer */ | ||
191 | #define DV1394_MAX_FRAMES 32 | ||
192 | |||
193 | /* number of *full* isochronous packets per DV frame */ | ||
194 | #define DV1394_NTSC_PACKETS_PER_FRAME 250 | ||
195 | #define DV1394_PAL_PACKETS_PER_FRAME 300 | ||
196 | |||
197 | /* size of one frame's worth of DV data, in bytes */ | ||
198 | #define DV1394_NTSC_FRAME_SIZE (480 * DV1394_NTSC_PACKETS_PER_FRAME) | ||
199 | #define DV1394_PAL_FRAME_SIZE (480 * DV1394_PAL_PACKETS_PER_FRAME) | ||
200 | |||
201 | |||
202 | /* ioctl() commands */ | ||
203 | #include "ieee1394-ioctl.h" | ||
204 | |||
205 | |||
206 | enum pal_or_ntsc { | ||
207 | DV1394_NTSC = 0, | ||
208 | DV1394_PAL | ||
209 | }; | ||
210 | |||
211 | |||
212 | |||
213 | |||
214 | /* this is the argument to DV1394_INIT */ | ||
215 | struct dv1394_init { | ||
216 | /* DV1394_API_VERSION */ | ||
217 | unsigned int api_version; | ||
218 | |||
219 | /* isochronous transmission channel to use */ | ||
220 | unsigned int channel; | ||
221 | |||
222 | /* number of frames in the ringbuffer. Must be at least 2 | ||
223 | and at most DV1394_MAX_FRAMES. */ | ||
224 | unsigned int n_frames; | ||
225 | |||
226 | /* send/receive PAL or NTSC video format */ | ||
227 | enum pal_or_ntsc format; | ||
228 | |||
229 | /* the following are used only for transmission */ | ||
230 | |||
231 | /* set these to zero unless you want a | ||
232 | non-default empty packet rate (see below) */ | ||
233 | unsigned long cip_n; | ||
234 | unsigned long cip_d; | ||
235 | |||
236 | /* set this to zero unless you want a | ||
237 | non-default SYT cycle offset (default = 3 cycles) */ | ||
238 | unsigned int syt_offset; | ||
239 | }; | ||
240 | |||
241 | /* NOTE: you may only allocate the DV frame ringbuffer once each time | ||
242 | you open the dv1394 device. DV1394_INIT will fail if you call it a | ||
243 | second time with different 'n_frames' or 'format' arguments (which | ||
244 | would imply a different size for the ringbuffer). If you need a | ||
245 | different buffer size, simply close and re-open the device, then | ||
246 | initialize it with your new settings. */ | ||
247 | |||
248 | /* Q: What are cip_n and cip_d? */ | ||
249 | |||
250 | /* | ||
251 | A: DV video streams do not utilize 100% of the potential bandwidth offered | ||
252 | by IEEE 1394 (FireWire). To achieve the correct rate of data transmission, | ||
253 | DV devices must periodically insert empty packets into the 1394 data stream. | ||
254 | Typically there is one empty packet per 14-16 data-carrying packets. | ||
255 | |||
256 | Some DV devices will accept a wide range of empty packet rates, while others | ||
257 | require a precise rate. If the dv1394 driver produces empty packets at | ||
258 | a rate that your device does not accept, you may see ugly patterns on the | ||
259 | DV output, or even no output at all. | ||
260 | |||
261 | The default empty packet insertion rate seems to work for many people; if | ||
262 | your DV output is stable, you can simply ignore this discussion. However, | ||
263 | we have exposed the empty packet rate as a parameter to support devices that | ||
264 | do not work with the default rate. | ||
265 | |||
266 | The decision to insert an empty packet is made with a numerator/denominator | ||
267 | algorithm. Empty packets are produced at an average rate of CIP_N / CIP_D. | ||
268 | You can alter the empty packet rate by passing non-zero values for cip_n | ||
269 | and cip_d to the INIT ioctl. | ||
270 | |||
271 | */ | ||
272 | |||
273 | |||
274 | |||
275 | struct dv1394_status { | ||
276 | /* this embedded init struct returns the current dv1394 | ||
277 | parameters in use */ | ||
278 | struct dv1394_init init; | ||
279 | |||
280 | /* the ringbuffer frame that is currently being | ||
281 | displayed. (-1 if the device is not transmitting anything) */ | ||
282 | int active_frame; | ||
283 | |||
284 | /* index of the first buffer (ahead of active_frame) that | ||
285 | is ready to be filled with data */ | ||
286 | unsigned int first_clear_frame; | ||
287 | |||
288 | /* how many buffers, including first_clear_buffer, are | ||
289 | ready to be filled with data */ | ||
290 | unsigned int n_clear_frames; | ||
291 | |||
292 | /* how many times the DV stream has underflowed, overflowed, | ||
293 | or otherwise encountered an error, since the previous call | ||
294 | to DV1394_GET_STATUS */ | ||
295 | unsigned int dropped_frames; | ||
296 | |||
297 | /* N.B. The dropped_frames counter is only a lower bound on the actual | ||
298 | number of dropped frames, with the special case that if dropped_frames | ||
299 | is zero, then it is guaranteed that NO frames have been dropped | ||
300 | since the last call to DV1394_GET_STATUS. | ||
301 | */ | ||
302 | }; | ||
303 | |||
304 | |||
305 | #endif /* _DV_1394_H */ | ||