mirror of
https://github.com/torvalds/linux.git
synced 2024-11-08 21:21:47 +00:00
1da177e4c3
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!
306 lines
10 KiB
C
306 lines
10 KiB
C
/*
|
|
* 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 */
|