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| DVB Video APIThe DVB video device controls the MPEG2 video decoder of the DVB hardware. It can be accessed through /dev/ost/audio. The include file video.h describes the data types and lists all i/o calls. A complete explanation of all calls can be found below: Video API IO control calls
int open(const char *deviceName, int flags); FUNCTION This system call opens a named video device (e.g. /dev/ost/video) for subsequent use. When an open() call has succeeded, the device will be ready for use. The significance of blocking or non-blocking mode is described in the documentation for functions where there is a difference. It does not affect the semantics of the open() call itself. A device opened in blocking mode can later be put into non- blocking mode (and vice versa) using the F_SETFL command of the fcntl system call. This is a standard system call, documented in the Linux manual page for fcntl. Only one user can open the Video Device in O_RDWR mode. All other attemts to open the device in this mode will fail, and an errorcode will be returned. If the Video Device is opened in O_RDONLY mode, the only ioctl call that can be used is VIDEO_GET_STATUS. All other call will return an error code. PARAMETERS const char *deviceName Name of specific video device. In the current implementation, /dev/ost/video is the only one available. int flags A bit-wise OR of the following flags: O_RDONLY read-only access O_RDWR read/write access O_NONBLOCK open in non-blocking mode (blocking mode is the default) RETURNS ENODEV Device driver not loaded/available. EINTERNAL Internal error, possibly in the communication with the DVB subsystem. EBUSY Device or resource busy. EINVAL Invalid argument.
int close(int fd); DESCRIPTION This system call closes a previously opened video device PARAMETERS int fd File descriptor returned by a previous call to open(). RETURNS EBADF fd is not a valid open file descriptor
size_t write(int fd, const void *buf, size_t count); DESCRIPTION This system call is only provided if VIDEO_SOURCE_MEMORY is selected in the ioctl call VIDEO_SELECT_SOURCE. The data provided shall be in PES format. If O_NONBLOCK is not specified the function will block until buffer space is available. The amount of data to be transferred is implied by count. PARAMETERS int fd File descriptor returned by a previous call to open(). void *buf Pointer to the buffer containing the PES data. size_t count Size of buf. RETURNS EPERM Mode VIDEO_SOURCE_MEMORY not selected. ENOMEM Attempted to write more data than the internal buffer can hold. EBADF fd is not a valid open file descriptor
int ioctl(int fd, int request = VIDEO_STOP, boolean mode); FUNCTION This ioctl call asks the Video Device to stop playing the current stream. Depending on the input parameter, the screen can be blanked out or displaying the last decoded frame. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_STOP for this command. Boolean mode Indicates how the screen shall be handled. TRUE: Blank screen when stop. FALSE: Show last decoded frame. RETURNS EBADF fd is not a valid open file descriptor EINTERNAL Internal error, possibly in the communication with the DVB subsystem.
int ioctl(int fd, int request = VIDEO_PLAY); FUNCTION This ioctl call asks the Video Device to start playing a video stream from the selected source. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_PLAY for this command. RETURNS EBADF fd is not a valid open file descriptor EINTERNAL Internal error, possibly in the communication with the DVB subsystem.
int ioctl(int fd, int request = VIDEO_FREEZE); FUNCTION This ioctl call suspends the live video stream being played. Decoding and playing are frozen. It is then possible to restart the decoding and playing process of the video stream using VIDEO_CONTINUE command. If VIDEO_SOURCE_MEMORY is selected in the ioctl call VIDEO_SELECT_SOURCE, the DVB-subsystem will not decode any more data until the ioctl call VIDEO_FREEZE or VIDEO_PLAY is performed. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_FREEZE for this command. RETURNS EBADF fd is not a valid open file descriptor. EINTERNAL Internal error, possibly in the communication with the DVB subsystem.
int ioctl(int fd, int request = VIDEO_CONTINUE); FUNCTION This ioctl call restarts decoding and playing processes of the video stream which was played before a call to VIDEO_FREEZE was made. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_CONTINUE for this command. RETURNS EBADF fd is not a valid open file descriptor. EINTERNAL Internal error, possibly in the communication with the DVB subsystem.
int ioctl(int fd, int request = VIDEO_SELECT_SOURCE, videoStreamSource_t source); FUNCTION This ioctl call informs the video device which source shall be used for the input data. The possible sources are demux or memory. If internal is selected, the data is feed to the Video Device through the write command. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_SELECT_SOURCE for this command. videoStreamSource_t source Indicates which source shall be used for the Video stream. RETURNS EBADF fd is not a valid open file descriptor. EINTERNAL Internal error, possibly in the communication with the DVB subsystem.
int ioctl(int fd, int request = VIDEO_SET_BLANK, boolean mode); DESCRIPTION This ioctl call asks the Video Device to blank out the picture. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_SET_BLANK for this command. boolean mode TRUE: Blank screen when stop. FALSE: Show last decoded frame. RETURNS EBADF fd is not a valid open file descriptor. EINTERNAL Internal error EINVAL Illegal input parameter.
int ioctl(int fd, int request = VIDEO_GET_STATUS, struct videoStatus *status); DESCRIPTION This ioctl call asks the Video Device to return the current status of the device. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_GET_STATUS for this command. struct videoStatus Returns the current status of the Video Device. *status RETURNS EBADF fd is not a valid open file descriptor. EINTERNAL Internal error EFAULT status points to invalid address
int ioctl(int fd, int request = VIDEO_GET_EVENT, struct videoEvent *ev); DESCRIPTION This ioctl call returns an event of type videoEvent if available. If an event is not available, the behavior depends on whether the device is in blocking or non-blocking mode. In the latter case, the call fails immediately with errno set to EWOULDBLOCK. In the former case, the call blocks until an event becomes available. The standard Linux poll() and/or select() system calls can be used with the device file descriptor to watch for new events. For select(), the file descriptor should be included in the exceptfds argument, and for poll(), POLLPRI should be specified as the wake-up condition. Read-only permissions are sufficient for this ioctl call. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_GET_EVENT for this command. struct videoEvent *ev Points to the location where the event, if any, is to be stored. RETURNS EBADF fd is not a valid open file descriptor EFAULT ev points to invalid address EWOULDBLOCK There is no event pending, and the device is in non-blocking mode. EBUFFEROVERFLOW Overflow in event queue - one or more events were lost.
int ioctl(int fd, int request = VIDEO_SET_DISPLAY_FORMAT, videoDisplayFormat_t format); DESCRIPTION This ioctl call asks the Video Device to select the video format to be applied by the MPEG chip on the video. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_SET_DISPLAY_FORMAT for this command. videoDisplayFormat_t Selects the video format to be used. format RETURNS EBADF fd is not a valid open file descriptor. EINTERNAL Internal error EINVAL Illegal parameter format.
int ioctl(int fd, int request = VIDEO_STILLPICTURE, struct videoDisplayStillPicture *sp); DESCRIPTION This ioctl call asks the Video Device to display a still picture (I-frame). The input data shall contain an I-frame. If the pointer is NULL, then the current displayed still picture is blanked. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_STILLPICTURE for this command. struct videoDisplayStillPicture *sp Pointer to a location where an I-frame and size is stored. RETURNS EBADF fd is not a valid open file descriptor. EINTERNAL Internal error EFAULT sp points to an invalid iframe.
int ioctl(int fd, int request = VIDEO_FAST_FORWARD, int nFrames); DESCRIPTION This ioctl call asks the Video Device to skip decoding of N number of I-frames. This call can only be used if VIDEO_SOURCE_INTRENAL is selected. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_FAST_FORWARD for this command. int nFrames The number of frames to skip. RETURNS EBADF fd is not a valid open file descriptor. EINTERNAL Internal error EPERM Mode VIDEO_SOURCE_MEMORY not selected. EINVAL Illegal parameter format.
int ioctl(int fd, int request = VIDEO_SLOWMOTION, int nFrames); DESCRIPTION This ioctl call asks the Video Device to repeat decoding frames N number of times. This call can only be used if VIDEO_SOURCE_MEMORY is selected. PARAMETERS int fd File descriptor returned by a previous call to open(). int request Equals VIDEO_SLOWMOTION for this command. int nFrames The number of frames to skip. RETURNS EBADF fd is not a valid open file descriptor. EINTERNAL Internal error EPERM Mode VIDEO_SOURCE_MEMORY not selected. EINVAL Illegal parameter format. |