V4L和V4L2的区别

mijianbin2008

以下是v4l2-common.c（内核版本:2.6.20）中的部分内容：
#ifdef CONFIG_VIDEO_V4L1_COMPAT
static const char *v4l1_ioctls[] = {
[_IOC_NR(VIDIOCGCAP)] = "VIDIOCGCAP",
[_IOC_NR(VIDIOCGCHAN)] = "VIDIOCGCHAN",
[_IOC_NR(VIDIOCSCHAN)] = "VIDIOCSCHAN",
[_IOC_NR(VIDIOCGTUNER)] = "VIDIOCGTUNER",
[_IOC_NR(VIDIOCSTUNER)] = "VIDIOCSTUNER",
[_IOC_NR(VIDIOCGPICT)] = "VIDIOCGPICT",
[_IOC_NR(VIDIOCSPICT)] = "VIDIOCSPICT",
[_IOC_NR(VIDIOCCAPTURE)] = "VIDIOCCAPTURE",
[_IOC_NR(VIDIOCGWIN)] = "VIDIOCGWIN",
[_IOC_NR(VIDIOCSWIN)] = "VIDIOCSWIN",
[_IOC_NR(VIDIOCGFBUF)] = "VIDIOCGFBUF",
[_IOC_NR(VIDIOCSFBUF)] = "VIDIOCSFBUF",
[_IOC_NR(VIDIOCKEY)] = "VIDIOCKEY",
[_IOC_NR(VIDIOCGFREQ)] = "VIDIOCGFREQ",
[_IOC_NR(VIDIOCSFREQ)] = "VIDIOCSFREQ",
[_IOC_NR(VIDIOCGAUDIO)] = "VIDIOCGAUDIO",
[_IOC_NR(VIDIOCSAUDIO)] = "VIDIOCSAUDIO",
[_IOC_NR(VIDIOCSYNC)] = "VIDIOCSYNC",
[_IOC_NR(VIDIOCMCAPTURE)] = "VIDIOCMCAPTURE",
[_IOC_NR(VIDIOCGMBUF)] = "VIDIOCGMBUF",
[_IOC_NR(VIDIOCGUNIT)] = "VIDIOCGUNIT",
[_IOC_NR(VIDIOCGCAPTURE)] = "VIDIOCGCAPTURE",
[_IOC_NR(VIDIOCSCAPTURE)] = "VIDIOCSCAPTURE",
[_IOC_NR(VIDIOCSPLAYMODE)] = "VIDIOCSPLAYMODE",
[_IOC_NR(VIDIOCSWRITEMODE)] = "VIDIOCSWRITEMODE",
[_IOC_NR(VIDIOCGPLAYINFO)] = "VIDIOCGPLAYINFO",
[_IOC_NR(VIDIOCSMICROCODE)] = "VIDIOCSMICROCODE",
[_IOC_NR(VIDIOCGVBIFMT)] = "VIDIOCGVBIFMT",
[_IOC_NR(VIDIOCSVBIFMT)] = "VIDIOCSVBIFMT"
};
#define V4L1_IOCTLS ARRAY_SIZE(v4l1_ioctls)
#endif
static const char *v4l2_ioctls[] = {
[_IOC_NR(VIDIOC_QUERYCAP)] = "VIDIOC_QUERYCAP",
[_IOC_NR(VIDIOC_RESERVED)] = "VIDIOC_RESERVED",
[_IOC_NR(VIDIOC_ENUM_FMT)] = "VIDIOC_ENUM_FMT",
[_IOC_NR(VIDIOC_G_FMT)] = "VIDIOC_G_FMT",
[_IOC_NR(VIDIOC_S_FMT)] = "VIDIOC_S_FMT",
[_IOC_NR(VIDIOC_G_MPEGCOMP)] = "VIDIOC_G_MPEGCOMP",
[_IOC_NR(VIDIOC_S_MPEGCOMP)] = "VIDIOC_S_MPEGCOMP",
[_IOC_NR(VIDIOC_REQBUFS)] = "VIDIOC_REQBUFS",
[_IOC_NR(VIDIOC_QUERYBUF)] = "VIDIOC_QUERYBUF",
[_IOC_NR(VIDIOC_G_FBUF)] = "VIDIOC_G_FBUF",
[_IOC_NR(VIDIOC_S_FBUF)] = "VIDIOC_S_FBUF",
[_IOC_NR(VIDIOC_OVERLAY)] = "VIDIOC_OVERLAY",
[_IOC_NR(VIDIOC_QBUF)] = "VIDIOC_QBUF",
[_IOC_NR(VIDIOC_DQBUF)] = "VIDIOC_DQBUF",
[_IOC_NR(VIDIOC_STREAMON)] = "VIDIOC_STREAMON",
[_IOC_NR(VIDIOC_STREAMOFF)] = "VIDIOC_STREAMOFF",
[_IOC_NR(VIDIOC_G_PARM)] = "VIDIOC_G_PARM",
[_IOC_NR(VIDIOC_S_PARM)] = "VIDIOC_S_PARM",
[_IOC_NR(VIDIOC_G_STD)] = "VIDIOC_G_STD",
[_IOC_NR(VIDIOC_S_STD)] = "VIDIOC_S_STD",
[_IOC_NR(VIDIOC_ENUMSTD)] = "VIDIOC_ENUMSTD",
[_IOC_NR(VIDIOC_ENUMINPUT)] = "VIDIOC_ENUMINPUT",
[_IOC_NR(VIDIOC_G_CTRL)] = "VIDIOC_G_CTRL",
[_IOC_NR(VIDIOC_S_CTRL)] = "VIDIOC_S_CTRL",
[_IOC_NR(VIDIOC_G_TUNER)] = "VIDIOC_G_TUNER",
[_IOC_NR(VIDIOC_S_TUNER)] = "VIDIOC_S_TUNER",
[_IOC_NR(VIDIOC_G_AUDIO)] = "VIDIOC_G_AUDIO",
[_IOC_NR(VIDIOC_S_AUDIO)] = "VIDIOC_S_AUDIO",
[_IOC_NR(VIDIOC_QUERYCTRL)] = "VIDIOC_QUERYCTRL",
[_IOC_NR(VIDIOC_QUERYMENU)] = "VIDIOC_QUERYMENU",
[_IOC_NR(VIDIOC_G_INPUT)] = "VIDIOC_G_INPUT",
[_IOC_NR(VIDIOC_S_INPUT)] = "VIDIOC_S_INPUT",
[_IOC_NR(VIDIOC_G_OUTPUT)] = "VIDIOC_G_OUTPUT",
[_IOC_NR(VIDIOC_S_OUTPUT)] = "VIDIOC_S_OUTPUT",
[_IOC_NR(VIDIOC_ENUMOUTPUT)] = "VIDIOC_ENUMOUTPUT",
[_IOC_NR(VIDIOC_G_AUDOUT)] = "VIDIOC_G_AUDOUT",
[_IOC_NR(VIDIOC_S_AUDOUT)] = "VIDIOC_S_AUDOUT",
[_IOC_NR(VIDIOC_G_MODULATOR)] = "VIDIOC_G_MODULATOR",
[_IOC_NR(VIDIOC_S_MODULATOR)] = "VIDIOC_S_MODULATOR",
[_IOC_NR(VIDIOC_G_FREQUENCY)] = "VIDIOC_G_FREQUENCY",
[_IOC_NR(VIDIOC_S_FREQUENCY)] = "VIDIOC_S_FREQUENCY",
[_IOC_NR(VIDIOC_CROPCAP)] = "VIDIOC_CROPCAP",
[_IOC_NR(VIDIOC_G_CROP)] = "VIDIOC_G_CROP",
[_IOC_NR(VIDIOC_S_CROP)] = "VIDIOC_S_CROP",
[_IOC_NR(VIDIOC_G_JPEGCOMP)] = "VIDIOC_G_JPEGCOMP",
[_IOC_NR(VIDIOC_S_JPEGCOMP)] = "VIDIOC_S_JPEGCOMP",
[_IOC_NR(VIDIOC_QUERYSTD)] = "VIDIOC_QUERYSTD",
[_IOC_NR(VIDIOC_TRY_FMT)] = "VIDIOC_TRY_FMT",
[_IOC_NR(VIDIOC_ENUMAUDIO)] = "VIDIOC_ENUMAUDIO",
[_IOC_NR(VIDIOC_ENUMAUDOUT)] = "VIDIOC_ENUMAUDOUT",
[_IOC_NR(VIDIOC_G_PRIORITY)] = "VIDIOC_G_PRIORITY",
[_IOC_NR(VIDIOC_S_PRIORITY)] = "VIDIOC_S_PRIORITY",
#if 1
[_IOC_NR(VIDIOC_G_SLICED_VBI_CAP)] = "VIDIOC_G_SLICED_VBI_CAP",
#endif
[_IOC_NR(VIDIOC_LOG_STATUS)] = "VIDIOC_LOG_STATUS",
[_IOC_NR(VIDIOC_G_EXT_CTRLS)] = "VIDIOC_G_EXT_CTRLS",
[_IOC_NR(VIDIOC_S_EXT_CTRLS)] = "VIDIOC_S_EXT_CTRLS",
[_IOC_NR(VIDIOC_TRY_EXT_CTRLS)] = "VIDIOC_TRY_EXT_CTRLS"
};
#define V4L2_IOCTLS ARRAY_SIZE(v4l2_ioctls)
static const char *v4l2_int_ioctls[] = {
#ifdef CONFIG_VIDEO_V4L1_COMPAT
[_IOC_NR(DECODER_GET_CAPABILITIES)] = "DECODER_GET_CAPABILITIES",
[_IOC_NR(DECODER_GET_STATUS)] = "DECODER_GET_STATUS",
[_IOC_NR(DECODER_SET_NORM)] = "DECODER_SET_NORM",
[_IOC_NR(DECODER_SET_INPUT)] = "DECODER_SET_INPUT",
[_IOC_NR(DECODER_SET_OUTPUT)] = "DECODER_SET_OUTPUT",
[_IOC_NR(DECODER_ENABLE_OUTPUT)] = "DECODER_ENABLE_OUTPUT",
[_IOC_NR(DECODER_SET_PICTURE)] = "DECODER_SET_PICTURE",
[_IOC_NR(DECODER_SET_GPIO)] = "DECODER_SET_GPIO",
[_IOC_NR(DECODER_INIT)] = "DECODER_INIT",
[_IOC_NR(DECODER_SET_VBI_BYPASS)] = "DECODER_SET_VBI_BYPASS",
[_IOC_NR(DECODER_DUMP)] = "DECODER_DUMP",
#endif
[_IOC_NR(AUDC_SET_RADIO)] = "AUDC_SET_RADIO",
[_IOC_NR(TUNER_SET_TYPE_ADDR)] = "TUNER_SET_TYPE_ADDR",
[_IOC_NR(TUNER_SET_STANDBY)] = "TUNER_SET_STANDBY",
[_IOC_NR(TDA9887_SET_CONFIG)] = "TDA9887_SET_CONFIG",
[_IOC_NR(VIDIOC_INT_S_TUNER_MODE)] = "VIDIOC_INT_S_TUNER_MODE",
[_IOC_NR(VIDIOC_INT_S_REGISTER)] = "VIDIOC_INT_S_REGISTER",
[_IOC_NR(VIDIOC_INT_G_REGISTER)] = "VIDIOC_INT_G_REGISTER",
[_IOC_NR(VIDIOC_INT_RESET)] = "VIDIOC_INT_RESET",
[_IOC_NR(VIDIOC_INT_AUDIO_CLOCK_FREQ)] = "VIDIOC_INT_AUDIO_CLOCK_FREQ",
[_IOC_NR(VIDIOC_INT_DECODE_VBI_LINE)] = "VIDIOC_INT_DECODE_VBI_LINE",
[_IOC_NR(VIDIOC_INT_S_VBI_DATA)] = "VIDIOC_INT_S_VBI_DATA",
[_IOC_NR(VIDIOC_INT_G_VBI_DATA)] = "VIDIOC_INT_G_VBI_DATA",
[_IOC_NR(VIDIOC_INT_G_CHIP_IDENT)] = "VIDIOC_INT_G_CHIP_IDENT",
[_IOC_NR(VIDIOC_INT_I2S_CLOCK_FREQ)] = "VIDIOC_INT_I2S_CLOCK_FREQ",
[_IOC_NR(VIDIOC_INT_S_STANDBY)] = "VIDIOC_INT_S_STANDBY",
[_IOC_NR(VIDIOC_INT_S_AUDIO_ROUTING)] = "VIDIOC_INT_S_AUDIO_ROUTING",
[_IOC_NR(VIDIOC_INT_G_AUDIO_ROUTING)] = "VIDIOC_INT_G_AUDIO_ROUTING",
[_IOC_NR(VIDIOC_INT_S_VIDEO_ROUTING)] = "VIDIOC_INT_S_VIDEO_ROUTING",
[_IOC_NR(VIDIOC_INT_G_VIDEO_ROUTING)] = "VIDIOC_INT_G_VIDEO_ROUTING",
[_IOC_NR(VIDIOC_INT_S_CRYSTAL_FREQ)] = "VIDIOC_INT_S_CRYSTAL_FREQ"
};
可见，V4L的ioctl支持的命令字与V4L2的ioctl支持的命令字是不同的。当在内核配置时选中了兼容V4L，则应用程序调用ioctl时如果使用V4L的命令字，则在驱动中会被转换成V4L2的命令字，v4l_compat_translate_ioctl()负责这一转换。常用的摄像头驱动gspca是符合V4L的驱动（至少gspcav1-20071224之前是）。

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