7.20.4. Description
To query the attributes of a video standard, especially a custom (driver
defined) one, applications initialize the index
field of struct
v4l2_standard
and call the ioctl VIDIOC_ENUMSTD
ioctl with a pointer to this structure. Drivers fill the rest of the
structure or return an EINVAL
error code when the index is out of
bounds. To enumerate all standards applications shall begin at index
zero, incrementing by one until the driver returns EINVAL
. Drivers may
enumerate a different set of standards after switching the video input
or output.
-
v4l2_standard
struct v4l2_standard
__u32 |
index |
Number of the video standard, set by the application. |
v4l2_std_id |
id |
The bits in this field identify the standard as one of the common
standards listed in typedef v4l2_std_id, or if bits 32 to 63 are
set as custom standards. Multiple bits can be set if the hardware
does not distinguish between these standards, however separate
indices do not indicate the opposite. The id must be unique.
No other enumerated struct v4l2_standard structure,
for this input or output anyway, can contain the same set of bits. |
__u8 |
name [24] |
Name of the standard, a NUL-terminated ASCII string, for example:
“PAL-B/G”, “NTSC Japan”. This information is intended for the
user. |
struct v4l2_fract |
frameperiod |
The frame period (not field period) is numerator / denominator.
For example M/NTSC has a frame period of 1001 / 30000 seconds. |
__u32 |
framelines |
Total lines per frame including blanking, e. g. 625 for B/PAL. |
__u32 |
reserved [4] |
Reserved for future extensions. Drivers must set the array to
zero. |
-
v4l2_fract
struct v4l2_fract
__u32 |
numerator |
|
__u32 |
denominator |
|
typedef v4l2_std_id
__u64 |
v4l2_std_id |
This type is a set, each bit representing another video standard
as listed below and in Video Standards (based on itu470). The 32 most
significant bits are reserved for custom (driver defined) video
standards. |
#define V4L2_STD_PAL_B ((v4l2_std_id)0x00000001)
#define V4L2_STD_PAL_B1 ((v4l2_std_id)0x00000002)
#define V4L2_STD_PAL_G ((v4l2_std_id)0x00000004)
#define V4L2_STD_PAL_H ((v4l2_std_id)0x00000008)
#define V4L2_STD_PAL_I ((v4l2_std_id)0x00000010)
#define V4L2_STD_PAL_D ((v4l2_std_id)0x00000020)
#define V4L2_STD_PAL_D1 ((v4l2_std_id)0x00000040)
#define V4L2_STD_PAL_K ((v4l2_std_id)0x00000080)
#define V4L2_STD_PAL_M ((v4l2_std_id)0x00000100)
#define V4L2_STD_PAL_N ((v4l2_std_id)0x00000200)
#define V4L2_STD_PAL_Nc ((v4l2_std_id)0x00000400)
#define V4L2_STD_PAL_60 ((v4l2_std_id)0x00000800)
V4L2_STD_PAL_60
is a hybrid standard with 525 lines, 60 Hz refresh
rate, and PAL color modulation with a 4.43 MHz color subcarrier. Some
PAL video recorders can play back NTSC tapes in this mode for display on
a 50/60 Hz agnostic PAL TV.
#define V4L2_STD_NTSC_M ((v4l2_std_id)0x00001000)
#define V4L2_STD_NTSC_M_JP ((v4l2_std_id)0x00002000)
#define V4L2_STD_NTSC_443 ((v4l2_std_id)0x00004000)
V4L2_STD_NTSC_443
is a hybrid standard with 525 lines, 60 Hz refresh
rate, and NTSC color modulation with a 4.43 MHz color subcarrier.
#define V4L2_STD_NTSC_M_KR ((v4l2_std_id)0x00008000)
#define V4L2_STD_SECAM_B ((v4l2_std_id)0x00010000)
#define V4L2_STD_SECAM_D ((v4l2_std_id)0x00020000)
#define V4L2_STD_SECAM_G ((v4l2_std_id)0x00040000)
#define V4L2_STD_SECAM_H ((v4l2_std_id)0x00080000)
#define V4L2_STD_SECAM_K ((v4l2_std_id)0x00100000)
#define V4L2_STD_SECAM_K1 ((v4l2_std_id)0x00200000)
#define V4L2_STD_SECAM_L ((v4l2_std_id)0x00400000)
#define V4L2_STD_SECAM_LC ((v4l2_std_id)0x00800000)
/* ATSC/HDTV */
#define V4L2_STD_ATSC_8_VSB ((v4l2_std_id)0x01000000)
#define V4L2_STD_ATSC_16_VSB ((v4l2_std_id)0x02000000)
V4L2_STD_ATSC_8_VSB
and V4L2_STD_ATSC_16_VSB
are U.S.
terrestrial digital TV standards. Presently the V4L2 API does not
support digital TV. See also the Linux DVB API at
https://linuxtv.org.
#define V4L2_STD_PAL_BG (V4L2_STD_PAL_B |
V4L2_STD_PAL_B1 |
V4L2_STD_PAL_G)
#define V4L2_STD_B (V4L2_STD_PAL_B |
V4L2_STD_PAL_B1 |
V4L2_STD_SECAM_B)
#define V4L2_STD_GH (V4L2_STD_PAL_G |
V4L2_STD_PAL_H |
V4L2_STD_SECAM_G |
V4L2_STD_SECAM_H)
#define V4L2_STD_PAL_DK (V4L2_STD_PAL_D |
V4L2_STD_PAL_D1 |
V4L2_STD_PAL_K)
#define V4L2_STD_PAL (V4L2_STD_PAL_BG |
V4L2_STD_PAL_DK |
V4L2_STD_PAL_H |
V4L2_STD_PAL_I)
#define V4L2_STD_NTSC (V4L2_STD_NTSC_M |
V4L2_STD_NTSC_M_JP |
V4L2_STD_NTSC_M_KR)
#define V4L2_STD_MN (V4L2_STD_PAL_M |
V4L2_STD_PAL_N |
V4L2_STD_PAL_Nc |
V4L2_STD_NTSC)
#define V4L2_STD_SECAM_DK (V4L2_STD_SECAM_D |
V4L2_STD_SECAM_K |
V4L2_STD_SECAM_K1)
#define V4L2_STD_DK (V4L2_STD_PAL_DK |
V4L2_STD_SECAM_DK)
#define V4L2_STD_SECAM (V4L2_STD_SECAM_B |
V4L2_STD_SECAM_G |
V4L2_STD_SECAM_H |
V4L2_STD_SECAM_DK |
V4L2_STD_SECAM_L |
V4L2_STD_SECAM_LC)
#define V4L2_STD_525_60 (V4L2_STD_PAL_M |
V4L2_STD_PAL_60 |
V4L2_STD_NTSC |
V4L2_STD_NTSC_443)
#define V4L2_STD_625_50 (V4L2_STD_PAL |
V4L2_STD_PAL_N |
V4L2_STD_PAL_Nc |
V4L2_STD_SECAM)
#define V4L2_STD_UNKNOWN 0
#define V4L2_STD_ALL (V4L2_STD_525_60 |
V4L2_STD_625_50)
Video Standards (based on ITU BT.470)
Characteristics |
M/NTSC |
M/PAL |
N/PAL |
B, B1, G/PAL |
D, D1, K/PAL |
H/PAL |
I/PAL |
B, G/SECAM |
D, K/SECAM |
K1/SECAM |
L/SECAM |
Frame lines |
525 |
625 |
Frame period (s) |
1001/30000 |
1/25 |
Chrominance sub-carrier frequency (Hz) |
3579545 ± 10 |
3579611.49 ± 10 |
4433618.75 ± 5
(3582056.25 ± 5)
|
4433618.75 ± 5 |
4433618.75 ± 1 |
fOR = 4406250 ± 2000,
fOB = 4250000 ± 2000
|
Nominal radio-frequency channel bandwidth (MHz) |
6 |
6 |
6 |
B: 7; B1, G: 8 |
8 |
8 |
8 |
8 |
8 |
8 |
8 |
Sound carrier relative to vision carrier (MHz) |
4.5 |
4.5 |
4.5 |
5.5 ± 0.001 |
6.5 ± 0.001 |
5.5 |
5.9996 ± 0.0005 |
5.5 ± 0.001 |
6.5 ± 0.001 |
6.5 |
6.5 |