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authorLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-17 00:20:36 +0200
committerLinus Torvalds <torvalds@ppc970.osdl.org>2005-04-17 00:20:36 +0200
commit1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch)
tree0bba044c4ce775e45a88a51686b5d9f90697ea9d /drivers/ieee1394/dv1394.h
downloadlinux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz
linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.zip
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!
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diff --git a/drivers/ieee1394/dv1394.h b/drivers/ieee1394/dv1394.h
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+/*
+ * dv1394.h - DV input/output over IEEE 1394 on OHCI chips
+ * Copyright (C)2001 Daniel Maas <dmaas@dcine.com>
+ * receive 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 program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
+ */
+
+#ifndef _DV_1394_H
+#define _DV_1394_H
+
+/* 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 {
+ for (int 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 availble (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 */
+#include "ieee1394-ioctl.h"
+
+
+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 /* _DV_1394_H */