4 * Copyright (C) 2008 Adam Williams <broadcast at earthling dot net>
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation; either version 2 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
23 * dv1394.h - DV input/output over IEEE 1394 on OHCI chips
24 * Copyright (C)2001 Daniel Maas <dmaas@dcine.com>
25 * receive, proc_fs by Dan Dennedy <dan@dennedy.org>
28 * video1394.h - driver for OHCI 1394 boards
29 * Copyright (C)1999,2000 Sebastien Rougeaux <sebastien.rougeaux@anu.edu.au>
30 * Peter Schlaile <udbz@rz.uni-karlsruhe.de>
32 * This program is free software; you can redistribute it and/or modify
33 * it under the terms of the GNU General Public License as published by
34 * the Free Software Foundation; either version 2 of the License, or
35 * (at your option) any later version.
37 * This program is distributed in the hope that it will be useful,
38 * but WITHOUT ANY WARRANTY; without even the implied warranty of
39 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
40 * GNU General Public License for more details.
42 * You should have received a copy of the GNU General Public License
43 * along with this program; if not, write to the Free Software Foundation,
44 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
50 /* This is the public user-space interface. Try not to break it. */
52 #define DV1394_API_VERSION 0x20011127
54 /* ********************
60 There are two methods of operating the DV1394 DV output device.
64 The simplest is an interface based on write(): simply write
65 full DV frames of data to the device, and they will be transmitted
66 as quickly as possible. The FD may be set for non-blocking I/O,
67 in which case you can use select() or poll() to wait for output
70 To set the DV output parameters (e.g. whether you want NTSC or PAL
71 video), use the DV1394_INIT ioctl, passing in the parameters you
72 want in a struct dv1394_init.
75 To play a raw .DV file: cat foo.DV > /dev/dv1394
76 (cat will use write() internally)
79 static struct dv1394_init init = {
80 0x63, (broadcast channel)
81 4, (four-frame ringbuffer)
82 DV1394_NTSC, (send NTSC video)
83 0, 0 (default empty packet rate)
86 ioctl(fd, DV1394_INIT, &init);
89 read( <a raw DV file>, buf, DV1394_NTSC_FRAME_SIZE );
90 write( <the dv1394 FD>, buf, DV1394_NTSC_FRAME_SIZE );
95 For more control over buffering, and to avoid unnecessary copies
96 of the DV data, you can use the more sophisticated the mmap() interface.
97 First, call the DV1394_INIT ioctl to specify your parameters,
98 including the number of frames in the ringbuffer. Then, calling mmap()
99 on the dv1394 device will give you direct access to the ringbuffer
100 from which the DV card reads your frame data.
102 The ringbuffer is simply one large, contiguous region of memory
103 containing two or more frames of packed DV data. Each frame of DV data
104 is 120000 bytes (NTSC) or 144000 bytes (PAL).
106 Fill one or more frames in the ringbuffer, then use the DV1394_SUBMIT_FRAMES
107 ioctl to begin I/O. You can use either the DV1394_WAIT_FRAMES ioctl
108 or select()/poll() to wait until the frames are transmitted. Next, you'll
109 need to call the DV1394_GET_STATUS ioctl to determine which ringbuffer
110 frames are clear (ready to be filled with new DV data). Finally, use
111 DV1394_SUBMIT_FRAMES again to send the new data to the DV output.
114 Example: here is what a four-frame ringbuffer might look like
115 during DV transmission:
118 frame 0 frame 1 frame 2 frame 3
120 *--------------------------------------*
121 | CLEAR | DV data | DV data | CLEAR |
122 *--------------------------------------*
125 transmission goes in this direction --->>>
128 The DV hardware is currently transmitting the data in frame 1.
129 Once frame 1 is finished, it will automatically transmit frame 2.
130 (if frame 2 finishes before frame 3 is submitted, the device
131 will continue to transmit frame 2, and will increase the dropped_frames
132 counter each time it repeats the transmission).
135 If you called DV1394_GET_STATUS at this instant, you would
136 receive the following values:
140 first_clear_frame = 3
143 At this point, you should write new DV data into frame 3 and optionally
144 frame 0. Then call DV1394_SUBMIT_FRAMES to inform the device that
145 it may transmit the new frames.
150 /* maximum number of frames in the ringbuffer */
151 #define DV1394_MAX_FRAMES 32
153 /* number of *full* isochronous packets per DV frame */
154 #define DV1394_NTSC_PACKETS_PER_FRAME 250
155 #define DV1394_PAL_PACKETS_PER_FRAME 300
157 /* size of one frame's worth of DV data, in bytes */
158 #define DV1394_NTSC_FRAME_SIZE (480 * DV1394_NTSC_PACKETS_PER_FRAME)
159 #define DV1394_PAL_FRAME_SIZE (480 * DV1394_PAL_PACKETS_PER_FRAME)
162 /* ioctl() commands */
165 /* I don't like using 0 as a valid ioctl() */
169 /* get the driver ready to transmit video.
170 pass a struct dv1394_init* as the parameter (see below),
171 or NULL to get default parameters */
175 /* stop transmitting video and free the ringbuffer */
179 /* submit N new frames to be transmitted, where
180 the index of the first new frame is first_clear_buffer,
181 and the index of the last new frame is
182 (first_clear_buffer + N) % n_frames */
183 DV1394_SUBMIT_FRAMES,
186 /* block until N buffers are clear (pass N as the parameter)
187 Because we re-transmit the last frame on underrun, there
188 will at most be n_frames - 1 clear frames at any time */
191 /* capture new frames that have been received, where
192 the index of the first new frame is first_clear_buffer,
193 and the index of the last new frame is
194 (first_clear_buffer + N) % n_frames */
195 DV1394_RECEIVE_FRAMES,
198 DV1394_START_RECEIVE,
201 /* pass a struct dv1394_status* as the parameter (see below) */
215 /* this is the argument to DV1394_INIT */
217 /* DV1394_API_VERSION */
218 unsigned int api_version;
220 /* isochronous transmission channel to use */
221 unsigned int channel;
223 /* number of frames in the ringbuffer. Must be at least 2
224 and at most DV1394_MAX_FRAMES. */
225 unsigned int n_frames;
227 /* send/receive PAL or NTSC video format */
228 enum pal_or_ntsc format;
230 /* the following are used only for transmission */
232 /* set these to zero unless you want a
233 non-default empty packet rate (see below) */
237 /* set this to zero unless you want a
238 non-default SYT cycle offset (default = 3 cycles) */
239 unsigned int syt_offset;
242 /* Q: What are cip_n and cip_d? */
245 A: DV video streams do not utilize 100% of the potential bandwidth offered
246 by IEEE 1394 (FireWire). To achieve the correct rate of data transmission,
247 DV devices must periodically insert empty packets into the 1394 data stream.
248 Typically there is one empty packet per 14-16 data-carrying packets.
250 Some DV devices will accept a wide range of empty packet rates, while others
251 require a precise rate. If the dv1394 driver produces empty packets at
252 a rate that your device does not accept, you may see ugly patterns on the
253 DV output, or even no output at all.
255 The default empty packet insertion rate seems to work for many people; if
256 your DV output is stable, you can simply ignore this discussion. However,
257 we have exposed the empty packet rate as a parameter to support devices that
258 do not work with the default rate.
260 The decision to insert an empty packet is made with a numerator/denominator
261 algorithm. Empty packets are produced at an average rate of CIP_N / CIP_D.
262 You can alter the empty packet rate by passing non-zero values for cip_n
263 and cip_d to the INIT ioctl.
269 struct dv1394_status {
270 /* this embedded init struct returns the current dv1394
272 struct dv1394_init init;
274 /* the ringbuffer frame that is currently being
275 displayed. (-1 if the device is not transmitting anything) */
278 /* index of the first buffer (ahead of active_frame) that
279 is ready to be filled with data */
280 unsigned int first_clear_frame;
282 /* how many buffers, including first_clear_buffer, are
283 ready to be filled with data */
284 unsigned int n_clear_frames;
286 /* how many times the DV output has underflowed
287 since the last call to DV1394_GET_STATUS */
288 unsigned int dropped_frames;
290 /* N.B. The dropped_frames counter is only a lower bound on the actual
291 number of dropped frames, with the special case that if dropped_frames
292 is zero, then it is guaranteed that NO frames have been dropped
293 since the last call to DV1394_GET_STATUS.
298 #endif /* _DV_1394_H */