Lines Matching refs:read
4 .. _func-read:
7 V4L2 read()
13 v4l2-read - Read from a V4L2 device
22 .. c:function:: ssize_t read( int fd, void *buf, size_t count )
34 Max number of bytes to read
39 :c:func:`read()` attempts to read up to ``count`` bytes from file
42 section, see ##. If ``count`` is zero, :c:func:`read()` returns zero
45 :c:func:`read()` call will provide at most one frame (two fields)
48 By default :c:func:`read()` blocks until data becomes available. When
54 :c:func:`read()` function must also support :c:func:`select()` and
57 Drivers can implement read functionality in different ways, using a
61 :c:func:`read()` never returns a "snapshot" of a buffer being filled.
63 application starts reading the buffer until the read is finished. Thus
68 The behavior of :c:func:`read()` when called during the active picture
72 previously, not read frame, and returns the frame being received at the
73 time of the :c:func:`read()` call as soon as it is complete.
76 :c:func:`read()` call. The frame being received at :c:func:`read()`
79 nominal frame rate. An example of this model is the video read mode of
80 the bttv driver, initiating a DMA to user memory when :c:func:`read()`
98 On success, the number of bytes read is returned. It is not an error if
101 :c:func:`read()` was interrupted by a signal. On error, -1 is
103 the next read will start at the beginning of a new frame. Possible error
115 The driver does not support multiple read streams and the device is
122 The call was interrupted by a signal before any data was read.
129 The :c:func:`read()` function is not supported by this driver, not