OpenCores
URL https://opencores.org/ocsvn/test_project/test_project/trunk

Subversion Repositories test_project

[/] [test_project/] [trunk/] [linux_sd_driver/] [drivers/] [ieee1394/] [dv1394.h] - Blame information for rev 65

Go to most recent revision | Details | Compare with Previous | View Log

Line No. Rev Author Line
1 62 marcus.erl
/*
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 */

powered by: WebSVN 2.1.0

© copyright 1999-2025 OpenCores.org, equivalent to Oliscience, all rights reserved. OpenCores®, registered trademark.