2
* dv1394.h - 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>
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>
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.
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.
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.
29
/* This is the public user-space interface. Try not to break it. */
31
#define DV1394_API_VERSION 0x20011127
33
/* ********************
39
There are two methods of operating the DV1394 DV output device.
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
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.
54
To play a raw .DV file: cat foo.DV > /dev/dv1394
55
(cat will use write() internally)
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)
65
ioctl(fd, DV1394_INIT, &init);
68
read( <a raw DV file>, buf, DV1394_NTSC_FRAME_SIZE );
69
write( <the dv1394 FD>, buf, DV1394_NTSC_FRAME_SIZE );
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.
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).
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.
93
Example: here is what a four-frame ringbuffer might look like
94
during DV transmission:
97
frame 0 frame 1 frame 2 frame 3
99
*--------------------------------------*
100
| CLEAR | DV data | DV data | CLEAR |
101
*--------------------------------------*
104
transmission goes in this direction --->>>
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).
114
If you called DV1394_GET_STATUS at this instant, you would
115
receive the following values:
119
first_clear_frame = 3
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.
129
/* maximum number of frames in the ringbuffer */
130
#define DV1394_MAX_FRAMES 32
132
/* number of *full* isochronous packets per DV frame */
133
#define DV1394_NTSC_PACKETS_PER_FRAME 250
134
#define DV1394_PAL_PACKETS_PER_FRAME 300
136
/* size of one frame's worth of DV data, in bytes */
137
#define DV1394_NTSC_FRAME_SIZE (480 * DV1394_NTSC_PACKETS_PER_FRAME)
138
#define DV1394_PAL_FRAME_SIZE (480 * DV1394_PAL_PACKETS_PER_FRAME)
141
/* ioctl() commands */
144
/* I don't like using 0 as a valid ioctl() */
148
/* get the driver ready to transmit video.
149
pass a struct dv1394_init* as the parameter (see below),
150
or NULL to get default parameters */
154
/* stop transmitting video and free the ringbuffer */
158
/* submit N new frames to be transmitted, where
159
the index of the first new frame is first_clear_buffer,
160
and the index of the last new frame is
161
(first_clear_buffer + N) % n_frames */
162
DV1394_SUBMIT_FRAMES,
165
/* block until N buffers are clear (pass N as the parameter)
166
Because we re-transmit the last frame on underrun, there
167
will at most be n_frames - 1 clear frames at any time */
170
/* capture new frames that have been received, where
171
the index of the first new frame is first_clear_buffer,
172
and the index of the last new frame is
173
(first_clear_buffer + N) % n_frames */
174
DV1394_RECEIVE_FRAMES,
177
DV1394_START_RECEIVE,
180
/* pass a struct dv1394_status* as the parameter (see below) */
194
/* this is the argument to DV1394_INIT */
196
/* DV1394_API_VERSION */
197
unsigned int api_version;
199
/* isochronous transmission channel to use */
200
unsigned int channel;
202
/* number of frames in the ringbuffer. Must be at least 2
203
and at most DV1394_MAX_FRAMES. */
204
unsigned int n_frames;
206
/* send/receive PAL or NTSC video format */
207
enum pal_or_ntsc format;
209
/* the following are used only for transmission */
211
/* set these to zero unless you want a
212
non-default empty packet rate (see below) */
216
/* set this to zero unless you want a
217
non-default SYT cycle offset (default = 3 cycles) */
218
unsigned int syt_offset;
221
/* Q: What are cip_n and cip_d? */
224
A: DV video streams do not utilize 100% of the potential bandwidth offered
225
by IEEE 1394 (FireWire). To achieve the correct rate of data transmission,
226
DV devices must periodically insert empty packets into the 1394 data stream.
227
Typically there is one empty packet per 14-16 data-carrying packets.
229
Some DV devices will accept a wide range of empty packet rates, while others
230
require a precise rate. If the dv1394 driver produces empty packets at
231
a rate that your device does not accept, you may see ugly patterns on the
232
DV output, or even no output at all.
234
The default empty packet insertion rate seems to work for many people; if
235
your DV output is stable, you can simply ignore this discussion. However,
236
we have exposed the empty packet rate as a parameter to support devices that
237
do not work with the default rate.
239
The decision to insert an empty packet is made with a numerator/denominator
240
algorithm. Empty packets are produced at an average rate of CIP_N / CIP_D.
241
You can alter the empty packet rate by passing non-zero values for cip_n
242
and cip_d to the INIT ioctl.
248
struct dv1394_status {
249
/* this embedded init struct returns the current dv1394
251
struct dv1394_init init;
253
/* the ringbuffer frame that is currently being
254
displayed. (-1 if the device is not transmitting anything) */
257
/* index of the first buffer (ahead of active_frame) that
258
is ready to be filled with data */
259
unsigned int first_clear_frame;
261
/* how many buffers, including first_clear_buffer, are
262
ready to be filled with data */
263
unsigned int n_clear_frames;
265
/* how many times the DV output has underflowed
266
since the last call to DV1394_GET_STATUS */
267
unsigned int dropped_frames;
269
/* N.B. The dropped_frames counter is only a lower bound on the actual
270
number of dropped frames, with the special case that if dropped_frames
271
is zero, then it is guaranteed that NO frames have been dropped
272
since the last call to DV1394_GET_STATUS.
277
#endif /* _DV_1394_H */