在本篇 blog 中，我们学习如何在同一个分辨率下支持多个帧率的视频传输。
- 首先，我们需要对 frame descriptor 进行修改。此处，我们配置分辨率为 1920 x 1080，帧率分别为 30 fps 和 60 fps。
0x22, /* Descriptor size */
CX3_CS_INTRFC_DESCR, /* Descriptor type*/
0x05, /* Subtype: frame interface*/
0x01, /* Frame Descriptor Index: 1 */
0x00, /* No Still image capture method supported */
0x80,0x07, /* Width in pixel: 1920 */
0x38,0x04, /* Height in pixel: 1080 */
0x00,0x00,0xa7,0x76, /* Max bit rate (bits/s): 1920 x 1080 x 16 x 60 = 0x76a70000 */
0x00,0x80,0x53,0x3b, /* Min bit rate (bits/s): 1920 x 1080 x 16 x 30 = 995328000 */
0x00,0x48,0x3f,0x00, /* Maximum video or still frame size in bytes(Deprecated): 1920 x 1080 x 2 */
0x15,0x16,0x05,0x00, /* Default frame interval (in 100ns units): (1/30)x10^7 */
0x02, /* Frame interval type : No of discrete intervals */
0x0a,0x8b,0x02,0x00, /* 60 fps */
0x15,0x16,0x05,0x00, /* 30 fps */
2.随后修改 Class-specific Video Streaming Input Header Descriptor 中的长度值。
0x56,0x00, /* Total size of Class specific VS descr */
和 CyCx3USBSSConfigDscr 中的总长度值。
0xe9,0x00, /* Length of this descriptor and all sub descriptors */
3. 分别配置 30fps 和 60fps 对应的 probe 结构体
/* UVC Probe Control Setting - 1080p_60fps*/
uint8_t const gl1080pProbeCtrl_60fps[CX3_UVC_MAX_PROBE_SETTING] = {
0x00, 0x00, /* bmHint : No fixed parameters */
0x01, /* Use 1st Video format index */
0x01, /* Use 1st Video frame index */
0x0a,0x8b,0x02,0x00, /* Desired frame interval in 100ns = (1/30)x10^7 */
0x00, 0x00, /* Key frame rate in key frame/video frame units */
0x00, 0x00, /* PFrame rate in PFrame / key frame units */
0x00, 0x00, /* Compression quality control */
0x00, 0x00, /* Window size for average bit rate */
0x00, 0x00, /* Internal video streaming i/f latency in ms */
0x00,0x48,0x3f,0x00, /* Max video frame size in bytes = 1920 x 1080 x 2 */
#ifdef CX3_UVC_1_0_SUPPORT
0x00, 0x90, 0x00, 0x00 /* No. of bytes device can rx in single payload: 36KB */
#else
/* UVC 1.1 Probe Control has additional fields from UVC 1.0 */
0x00, 0x90, 0x00, 0x00, /* No. of bytes device can rx in single payload: 36KB */
0x00, 0x60, 0xE3, 0x16, /* Device Clock */
0x00, /* Framing Information - Ignored for uncompressed format*/
0x00, /* Preferred payload format version */
0x00, /* Minimum payload format version */
0x00 /* Maximum payload format version */
#endif
};
/* UVC Probe Control Setting - 1080p_30fps*/
uint8_t const gl1080pProbeCtrl_30fps[CX3_UVC_MAX_PROBE_SETTING] = {
0x00, 0x00, /* bmHint : No fixed parameters */
0x01, /* Use 1st Video format index */
0x01, /* Use 1st Video frame index */
0x15,0x16,0x05,0x00, /* Desired frame interval in 100ns = (1/30)x10^7 */
0x00, 0x00, /* Key frame rate in key frame/video frame units */
0x00, 0x00, /* PFrame rate in PFrame / key frame units */
0x00, 0x00, /* Compression quality control */
0x00, 0x00, /* Window size for average bit rate */
0x00, 0x00, /* Internal video streaming i/f latency in ms */
0x00,0x48,0x3f,0x00, /* Max video frame size in bytes = 1920 x 1080 x 2 */
#ifdef CX3_UVC_1_0_SUPPORT
0x00, 0x90, 0x00, 0x00 /* No. of bytes device can rx in single payload: 36KB */
#else
/* UVC 1.1 Probe Control has additional fields from UVC 1.0 */
0x00, 0x90, 0x00, 0x00, /* No. of bytes device can rx in single payload: 36KB */
0x00, 0x60, 0xE3, 0x16, /* Device Clock */
0x00, /* Framing Information - Ignored for uncompressed format*/
0x00, /* Preferred payload format version */
0x00, /* Minimum payload format version */
0x00 /* Maximum payload format version */
#endif
};
4.修改 CyCx3UvcAppGetProbeControlData 以返回相应的 probe 结构体
/*Returns the pointer to the Probe Control structure for the corresponding frame index.*/
uint8_t *
CyCx3UvcAppGetProbeControlData (
CyU3PUSBSpeed_t usbConType,
uint8_t frameIndex,
uint32_t glCurrentFrameInterval
)
{
uint32_t frame_fps = 10000000 / glCurrentFrameInterval;
if (usbConType == CY_U3P_SUPER_SPEED)
{
if (frameIndex == 1)
{
if(frame_fps == 30)
{
/* 1920 x 1080 @30.0 fps */
CyU3PDebugPrint(4,"\n Line:%d: Return 30 fps structure",__LINE__);
return ((uint8_t *) gl1080pProbeCtrl_30fps);
}
else if(frame_fps == 60)
{ /* 1920 x 1080 @60.0 fps */
CyU3PDebugPrint(4,"\n Line:%d Return 60 fps structure",__LINE__);
return ((uint8_t *) gl1080pProbeCtrl_60fps);
}
}
}
else if (usbConType == CY_U3P_HIGH_SPEED)
{
}
else
{
}
return NULL;
}
5. 在 Callback 函数中修改 Set_cur 的代码
/* Set Probe Control */
if (wValue == CX3_UVC_VS_PROBE_CONTROL)
{
glCurrentFrameIndex = glCommitCtrl[3];
#ifdef Two_frame_rate
glCurrentFrameInterval = ((uint32_t)glCommitCtrl[7] << 24) | ((uint32_t)glCommitCtrl[6] << 16) |
((uint32_t)glCommitCtrl[5] << 😎 | ((uint32_t)glCommitCtrl[4] << 0);
CyU3PDebugPrint(4,"\r\n Line:%d: glCurrentFrameInterval = 0x%x",__LINE__,glCurrentFrameInterval);
#endif
}
6. 修改 SetVideoResolution 函数的实现
/* Set the video resolution through this function. This function lists all the
* supported resolutions in SuperSpeed and HighSpeed. The frame index of resolutions
* supported in Still Capture can be different from the frame index of resolutions supported
* in Video streaming.
*/
static void
CyCx3UvcAppImageSensorSetVideoResolution(
uint8_t resolution_index,
uint32_t frame_Interval
)
{
CyU3PReturnStatus_t status = CY_U3P_SUCCESS;
uint32_t frameRate= 10000000/frame_Interval;
switch (CyU3PUsbGetSpeed ())
{
case CY_U3P_SUPER_SPEED:
switch (resolution_index)
{
case 0x01:
{
if(frameRate == 30)
{
CyU3PDebugPrint(4,"\r\n Line:%d: Set 30 fps",__LINE__);
/* Write 1080pSettings */
#ifndef FX3_STREAMING
status = CyU3PMipicsiSetIntfParams (&OV5640_YUY2_1080p, CyFalse);
if (status != CY_U3P_SUCCESS)
{
CyU3PDebugPrint (4, "\n\rUSBStpCB:SetIntfParams SS1 Err = 0x%x", status);
}
#endif
CyCx3_ImageSensor_Set_1080p ();
}
else if (frameRate == 60)
{
CyU3PDebugPrint(4,"\r\n Line:%d: Set 60 fps",__LINE__);
/* Write 1080pSettings */
#ifndef FX3_STREAMING
status = CyU3PMipicsiSetIntfParams (&OV5640_YUY2_1080p, CyFalse);
if (status != CY_U3P_SUCCESS)
{
CyU3PDebugPrint (4, "\n\rUSBStpCB:SetIntfParams SS1 Err = 0x%x", status);
}
#endif
CyCx3_ImageSensor_Set_1080p ();
}
}
break;
}
break;
case CY_U3P_HIGH_SPEED:
switch (resolution_index)
{
}
break;
}
}
按以上的步骤修改后，将固件下载至Demo 板，进行测试。
可以看到，用户可以在主机端软件中对不同 fps 的配置进行正常切换。用户可以参考附件的工程获取更多细节信息。
注：
- 出于演示的目的，本篇文档所附的固件中，只配置了USB3.0 的配置描述符（以及其他所有相关的 处理函数），没有 设置 USB2.0 及以下速度对应的配置描述符。如有需要，用户可以自行进行添加。
- 同上，本篇 blog 所附的固件中，实际上当主机设置不同的 fps 时，固件采用相同的参数对 MIPI CSI 模块和 sensor进行配置（即执行相同的代码），只是采用 UART 打印的方式演示函数分支可以正常执行。实际使用中，用户当然需要做不同的配置。
- 在主机软件的分辨率列表中，同一分辨率只会显示默认的帧率，不会同时列出所有帧率。
- 在第一步中，需要先定义Max bits/s 后 Min bits/s，先 高帧率 后低帧率，否则烧录固件后不能正常工作。参考 CX3 multiple framerate support in same resolution