| /* |
| * DV input/output over IEEE 1394 on OHCI chips |
| * Copyright (C)2001 Daniel Maas <dmaas@dcine.com> |
| * receive, proc_fs by Dan Dennedy <dan@dennedy.org> |
| * |
| * based on: |
| * video1394.h - driver for OHCI 1394 boards |
| * Copyright (C)1999,2000 Sebastien Rougeaux <sebastien.rougeaux@anu.edu.au> |
| * Peter Schlaile <udbz@rz.uni-karlsruhe.de> |
| * |
| * This file is part of FFmpeg. |
| * |
| * FFmpeg is free software; you can redistribute it and/or |
| * modify it under the terms of the GNU Lesser General Public |
| * License as published by the Free Software Foundation; either |
| * version 2.1 of the License, or (at your option) any later version. |
| * |
| * FFmpeg is distributed in the hope that it will be useful, |
| * but WITHOUT ANY WARRANTY; without even the implied warranty of |
| * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| * Lesser General Public License for more details. |
| * |
| * You should have received a copy of the GNU Lesser General Public |
| * License along with FFmpeg; if not, write to the Free Software |
| * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| |
| #ifndef AVDEVICE_DV1394_H |
| #define AVDEVICE_DV1394_H |
| |
| #define DV1394_DEFAULT_CHANNEL 63 |
| #define DV1394_DEFAULT_CARD 0 |
| #define DV1394_RING_FRAMES 20 |
| |
| #define DV1394_WIDTH 720 |
| #define DV1394_NTSC_HEIGHT 480 |
| #define DV1394_PAL_HEIGHT 576 |
| |
| /* This is the public user-space interface. Try not to break it. */ |
| |
| #define DV1394_API_VERSION 0x20011127 |
| |
| /* ******************** |
| ** ** |
| ** DV1394 API ** |
| ** ** |
| ******************** |
| |
| There are two methods of operating the DV1394 DV output device. |
| |
| 1) |
| |
| The simplest is an interface based on write(): simply write |
| full DV frames of data to the device, and they will be transmitted |
| as quickly as possible. The FD may be set for non-blocking I/O, |
| in which case you can use select() or poll() to wait for output |
| buffer space. |
| |
| To set the DV output parameters (e.g. whether you want NTSC or PAL |
| video), use the DV1394_INIT ioctl, passing in the parameters you |
| want in a struct dv1394_init. |
| |
| Example 1: |
| To play a raw .DV file: cat foo.DV > /dev/dv1394 |
| (cat will use write() internally) |
| |
| Example 2: |
| static struct dv1394_init init = { |
| 0x63, (broadcast channel) |
| 4, (four-frame ringbuffer) |
| DV1394_NTSC, (send NTSC video) |
| 0, 0 (default empty packet rate) |
| } |
| |
| ioctl(fd, DV1394_INIT, &init); |
| |
| while(1) { |
| read( <a raw DV file>, buf, DV1394_NTSC_FRAME_SIZE ); |
| write( <the dv1394 FD>, buf, DV1394_NTSC_FRAME_SIZE ); |
| } |
| |
| 2) |
| |
| For more control over buffering, and to avoid unnecessary copies |
| of the DV data, you can use the more sophisticated the mmap() interface. |
| First, call the DV1394_INIT ioctl to specify your parameters, |
| including the number of frames in the ringbuffer. Then, calling mmap() |
| on the dv1394 device will give you direct access to the ringbuffer |
| from which the DV card reads your frame data. |
| |
| The ringbuffer is simply one large, contiguous region of memory |
| containing two or more frames of packed DV data. Each frame of DV data |
| is 120000 bytes (NTSC) or 144000 bytes (PAL). |
| |
| Fill one or more frames in the ringbuffer, then use the DV1394_SUBMIT_FRAMES |
| ioctl to begin I/O. You can use either the DV1394_WAIT_FRAMES ioctl |
| or select()/poll() to wait until the frames are transmitted. Next, you'll |
| need to call the DV1394_GET_STATUS ioctl to determine which ringbuffer |
| frames are clear (ready to be filled with new DV data). Finally, use |
| DV1394_SUBMIT_FRAMES again to send the new data to the DV output. |
| |
| |
| Example: here is what a four-frame ringbuffer might look like |
| during DV transmission: |
| |
| |
| frame 0 frame 1 frame 2 frame 3 |
| |
| *--------------------------------------* |
| | CLEAR | DV data | DV data | CLEAR | |
| *--------------------------------------* |
| <ACTIVE> |
| |
| transmission goes in this direction --->>> |
| |
| |
| The DV hardware is currently transmitting the data in frame 1. |
| Once frame 1 is finished, it will automatically transmit frame 2. |
| (if frame 2 finishes before frame 3 is submitted, the device |
| will continue to transmit frame 2, and will increase the dropped_frames |
| counter each time it repeats the transmission). |
| |
| |
| If you called DV1394_GET_STATUS at this instant, you would |
| receive the following values: |
| |
| n_frames = 4 |
| active_frame = 1 |
| first_clear_frame = 3 |
| n_clear_frames = 2 |
| |
| At this point, you should write new DV data into frame 3 and optionally |
| frame 0. Then call DV1394_SUBMIT_FRAMES to inform the device that |
| it may transmit the new frames. |
| |
| ERROR HANDLING |
| |
| An error (buffer underflow/overflow or a break in the DV stream due |
| to a 1394 bus reset) can be detected by checking the dropped_frames |
| field of struct dv1394_status (obtained through the |
| DV1394_GET_STATUS ioctl). |
| |
| The best way to recover from such an error is to re-initialize |
| dv1394, either by using the DV1394_INIT ioctl call, or closing the |
| file descriptor and opening it again. (note that you must unmap all |
| ringbuffer mappings when closing the file descriptor, or else |
| dv1394 will still be considered 'in use'). |
| |
| MAIN LOOP |
| |
| For maximum efficiency and robustness against bus errors, you are |
| advised to model the main loop of your application after the |
| following pseudo-code example: |
| |
| (checks of system call return values omitted for brevity; always |
| check return values in your code!) |
| |
| while( frames left ) { |
| |
| struct pollfd *pfd = ...; |
| |
| pfd->fd = dv1394_fd; |
| pfd->revents = 0; |
| pfd->events = POLLOUT | POLLIN; (OUT for transmit, IN for receive) |
| |
| (add other sources of I/O here) |
| |
| poll(pfd, 1, -1); (or select(); add a timeout if you want) |
| |
| if(pfd->revents) { |
| struct dv1394_status status; |
| |
| ioctl(dv1394_fd, DV1394_GET_STATUS, &status); |
| |
| if(status.dropped_frames > 0) { |
| reset_dv1394(); |
| } else { |
| int i; |
| for (i = 0; i < status.n_clear_frames; i++) { |
| copy_DV_frame(); |
| } |
| } |
| } |
| } |
| |
| where copy_DV_frame() reads or writes on the dv1394 file descriptor |
| (read/write mode) or copies data to/from the mmap ringbuffer and |
| then calls ioctl(DV1394_SUBMIT_FRAMES) to notify dv1394 that new |
| frames are available (mmap mode). |
| |
| reset_dv1394() is called in the event of a buffer |
| underflow/overflow or a halt in the DV stream (e.g. due to a 1394 |
| bus reset). To guarantee recovery from the error, this function |
| should close the dv1394 file descriptor (and munmap() all |
| ringbuffer mappings, if you are using them), then re-open the |
| dv1394 device (and re-map the ringbuffer). |
| |
| */ |
| |
| |
| /* maximum number of frames in the ringbuffer */ |
| #define DV1394_MAX_FRAMES 32 |
| |
| /* number of *full* isochronous packets per DV frame */ |
| #define DV1394_NTSC_PACKETS_PER_FRAME 250 |
| #define DV1394_PAL_PACKETS_PER_FRAME 300 |
| |
| /* size of one frame's worth of DV data, in bytes */ |
| #define DV1394_NTSC_FRAME_SIZE (480 * DV1394_NTSC_PACKETS_PER_FRAME) |
| #define DV1394_PAL_FRAME_SIZE (480 * DV1394_PAL_PACKETS_PER_FRAME) |
| |
| |
| /* ioctl() commands */ |
| |
| enum { |
| /* I don't like using 0 as a valid ioctl() */ |
| DV1394_INVALID = 0, |
| |
| |
| /* get the driver ready to transmit video. |
| pass a struct dv1394_init* as the parameter (see below), |
| or NULL to get default parameters */ |
| DV1394_INIT, |
| |
| |
| /* stop transmitting video and free the ringbuffer */ |
| DV1394_SHUTDOWN, |
| |
| |
| /* submit N new frames to be transmitted, where |
| the index of the first new frame is first_clear_buffer, |
| and the index of the last new frame is |
| (first_clear_buffer + N) % n_frames */ |
| DV1394_SUBMIT_FRAMES, |
| |
| |
| /* block until N buffers are clear (pass N as the parameter) |
| Because we re-transmit the last frame on underrun, there |
| will at most be n_frames - 1 clear frames at any time */ |
| DV1394_WAIT_FRAMES, |
| |
| /* capture new frames that have been received, where |
| the index of the first new frame is first_clear_buffer, |
| and the index of the last new frame is |
| (first_clear_buffer + N) % n_frames */ |
| DV1394_RECEIVE_FRAMES, |
| |
| |
| DV1394_START_RECEIVE, |
| |
| |
| /* pass a struct dv1394_status* as the parameter (see below) */ |
| DV1394_GET_STATUS, |
| }; |
| |
| |
| |
| enum pal_or_ntsc { |
| DV1394_NTSC = 0, |
| DV1394_PAL |
| }; |
| |
| |
| |
| |
| /* this is the argument to DV1394_INIT */ |
| struct dv1394_init { |
| /* DV1394_API_VERSION */ |
| unsigned int api_version; |
| |
| /* isochronous transmission channel to use */ |
| unsigned int channel; |
| |
| /* number of frames in the ringbuffer. Must be at least 2 |
| and at most DV1394_MAX_FRAMES. */ |
| unsigned int n_frames; |
| |
| /* send/receive PAL or NTSC video format */ |
| enum pal_or_ntsc format; |
| |
| /* the following are used only for transmission */ |
| |
| /* set these to zero unless you want a |
| non-default empty packet rate (see below) */ |
| unsigned long cip_n; |
| unsigned long cip_d; |
| |
| /* set this to zero unless you want a |
| non-default SYT cycle offset (default = 3 cycles) */ |
| unsigned int syt_offset; |
| }; |
| |
| /* NOTE: you may only allocate the DV frame ringbuffer once each time |
| you open the dv1394 device. DV1394_INIT will fail if you call it a |
| second time with different 'n_frames' or 'format' arguments (which |
| would imply a different size for the ringbuffer). If you need a |
| different buffer size, simply close and re-open the device, then |
| initialize it with your new settings. */ |
| |
| /* Q: What are cip_n and cip_d? */ |
| |
| /* |
| A: DV video streams do not utilize 100% of the potential bandwidth offered |
| by IEEE 1394 (FireWire). To achieve the correct rate of data transmission, |
| DV devices must periodically insert empty packets into the 1394 data stream. |
| Typically there is one empty packet per 14-16 data-carrying packets. |
| |
| Some DV devices will accept a wide range of empty packet rates, while others |
| require a precise rate. If the dv1394 driver produces empty packets at |
| a rate that your device does not accept, you may see ugly patterns on the |
| DV output, or even no output at all. |
| |
| The default empty packet insertion rate seems to work for many people; if |
| your DV output is stable, you can simply ignore this discussion. However, |
| we have exposed the empty packet rate as a parameter to support devices that |
| do not work with the default rate. |
| |
| The decision to insert an empty packet is made with a numerator/denominator |
| algorithm. Empty packets are produced at an average rate of CIP_N / CIP_D. |
| You can alter the empty packet rate by passing non-zero values for cip_n |
| and cip_d to the INIT ioctl. |
| |
| */ |
| |
| |
| |
| struct dv1394_status { |
| /* this embedded init struct returns the current dv1394 |
| parameters in use */ |
| struct dv1394_init init; |
| |
| /* the ringbuffer frame that is currently being |
| displayed. (-1 if the device is not transmitting anything) */ |
| int active_frame; |
| |
| /* index of the first buffer (ahead of active_frame) that |
| is ready to be filled with data */ |
| unsigned int first_clear_frame; |
| |
| /* how many buffers, including first_clear_buffer, are |
| ready to be filled with data */ |
| unsigned int n_clear_frames; |
| |
| /* how many times the DV stream has underflowed, overflowed, |
| or otherwise encountered an error, since the previous call |
| to DV1394_GET_STATUS */ |
| unsigned int dropped_frames; |
| |
| /* N.B. The dropped_frames counter is only a lower bound on the actual |
| number of dropped frames, with the special case that if dropped_frames |
| is zero, then it is guaranteed that NO frames have been dropped |
| since the last call to DV1394_GET_STATUS. |
| */ |
| }; |
| |
| |
| #endif /* AVDEVICE_DV1394_H */ |