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 Libav. 12 * 13 * Libav 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 * Libav 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 Libav; 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 for(int i = 0; i < status.n_clear_frames; i++) { 179 copy_DV_frame(); 180 } 181 } 182 } 183 } 184 185 where copy_DV_frame() reads or writes on the dv1394 file descriptor 186 (read/write mode) or copies data to/from the mmap ringbuffer and 187 then calls ioctl(DV1394_SUBMIT_FRAMES) to notify dv1394 that new 188 frames are availble (mmap mode). 189 190 reset_dv1394() is called in the event of a buffer 191 underflow/overflow or a halt in the DV stream (e.g. due to a 1394 192 bus reset). To guarantee recovery from the error, this function 193 should close the dv1394 file descriptor (and munmap() all 194 ringbuffer mappings, if you are using them), then re-open the 195 dv1394 device (and re-map the ringbuffer). 196 197*/ 198 199 200/* maximum number of frames in the ringbuffer */ 201#define DV1394_MAX_FRAMES 32 202 203/* number of *full* isochronous packets per DV frame */ 204#define DV1394_NTSC_PACKETS_PER_FRAME 250 205#define DV1394_PAL_PACKETS_PER_FRAME 300 206 207/* size of one frame's worth of DV data, in bytes */ 208#define DV1394_NTSC_FRAME_SIZE (480 * DV1394_NTSC_PACKETS_PER_FRAME) 209#define DV1394_PAL_FRAME_SIZE (480 * DV1394_PAL_PACKETS_PER_FRAME) 210 211 212/* ioctl() commands */ 213 214enum { 215 /* I don't like using 0 as a valid ioctl() */ 216 DV1394_INVALID = 0, 217 218 219 /* get the driver ready to transmit video. 220 pass a struct dv1394_init* as the parameter (see below), 221 or NULL to get default parameters */ 222 DV1394_INIT, 223 224 225 /* stop transmitting video and free the ringbuffer */ 226 DV1394_SHUTDOWN, 227 228 229 /* submit N new frames to be transmitted, where 230 the index of the first new frame is first_clear_buffer, 231 and the index of the last new frame is 232 (first_clear_buffer + N) % n_frames */ 233 DV1394_SUBMIT_FRAMES, 234 235 236 /* block until N buffers are clear (pass N as the parameter) 237 Because we re-transmit the last frame on underrun, there 238 will at most be n_frames - 1 clear frames at any time */ 239 DV1394_WAIT_FRAMES, 240 241 /* capture new frames that have been received, where 242 the index of the first new frame is first_clear_buffer, 243 and the index of the last new frame is 244 (first_clear_buffer + N) % n_frames */ 245 DV1394_RECEIVE_FRAMES, 246 247 248 DV1394_START_RECEIVE, 249 250 251 /* pass a struct dv1394_status* as the parameter (see below) */ 252 DV1394_GET_STATUS, 253}; 254 255 256 257enum pal_or_ntsc { 258 DV1394_NTSC = 0, 259 DV1394_PAL 260}; 261 262 263 264 265/* this is the argument to DV1394_INIT */ 266struct dv1394_init { 267 /* DV1394_API_VERSION */ 268 unsigned int api_version; 269 270 /* isochronous transmission channel to use */ 271 unsigned int channel; 272 273 /* number of frames in the ringbuffer. Must be at least 2 274 and at most DV1394_MAX_FRAMES. */ 275 unsigned int n_frames; 276 277 /* send/receive PAL or NTSC video format */ 278 enum pal_or_ntsc format; 279 280 /* the following are used only for transmission */ 281 282 /* set these to zero unless you want a 283 non-default empty packet rate (see below) */ 284 unsigned long cip_n; 285 unsigned long cip_d; 286 287 /* set this to zero unless you want a 288 non-default SYT cycle offset (default = 3 cycles) */ 289 unsigned int syt_offset; 290}; 291 292/* NOTE: you may only allocate the DV frame ringbuffer once each time 293 you open the dv1394 device. DV1394_INIT will fail if you call it a 294 second time with different 'n_frames' or 'format' arguments (which 295 would imply a different size for the ringbuffer). If you need a 296 different buffer size, simply close and re-open the device, then 297 initialize it with your new settings. */ 298 299/* Q: What are cip_n and cip_d? */ 300 301/* 302 A: DV video streams do not utilize 100% of the potential bandwidth offered 303 by IEEE 1394 (FireWire). To achieve the correct rate of data transmission, 304 DV devices must periodically insert empty packets into the 1394 data stream. 305 Typically there is one empty packet per 14-16 data-carrying packets. 306 307 Some DV devices will accept a wide range of empty packet rates, while others 308 require a precise rate. If the dv1394 driver produces empty packets at 309 a rate that your device does not accept, you may see ugly patterns on the 310 DV output, or even no output at all. 311 312 The default empty packet insertion rate seems to work for many people; if 313 your DV output is stable, you can simply ignore this discussion. However, 314 we have exposed the empty packet rate as a parameter to support devices that 315 do not work with the default rate. 316 317 The decision to insert an empty packet is made with a numerator/denominator 318 algorithm. Empty packets are produced at an average rate of CIP_N / CIP_D. 319 You can alter the empty packet rate by passing non-zero values for cip_n 320 and cip_d to the INIT ioctl. 321 322 */ 323 324 325 326struct dv1394_status { 327 /* this embedded init struct returns the current dv1394 328 parameters in use */ 329 struct dv1394_init init; 330 331 /* the ringbuffer frame that is currently being 332 displayed. (-1 if the device is not transmitting anything) */ 333 int active_frame; 334 335 /* index of the first buffer (ahead of active_frame) that 336 is ready to be filled with data */ 337 unsigned int first_clear_frame; 338 339 /* how many buffers, including first_clear_buffer, are 340 ready to be filled with data */ 341 unsigned int n_clear_frames; 342 343 /* how many times the DV stream has underflowed, overflowed, 344 or otherwise encountered an error, since the previous call 345 to DV1394_GET_STATUS */ 346 unsigned int dropped_frames; 347 348 /* N.B. The dropped_frames counter is only a lower bound on the actual 349 number of dropped frames, with the special case that if dropped_frames 350 is zero, then it is guaranteed that NO frames have been dropped 351 since the last call to DV1394_GET_STATUS. 352 */ 353}; 354 355 356#endif /* AVDEVICE_DV1394_H */ 357