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