Hello , mr @FBL
iam also facing same problem above explained.
1. As requested, I’m sharing the USB UVC packet trace captured using Wireshark .
2. Below is a brief explanation of how I'm preparing and sending UVC packets:
Resolution: 640x480
Format: YUV2 (16 bits per pixel)
Frame size : UVC_MAX_FRAME_SIZE (UVC_FRAME_WIDTH * UVC_FRAME_HEIGHT * 16U / 8U)
Max packet size : USBD_VIDEO_EPIN_HS_MPS 2044U
Payload header: 2 bytes (0x02 ,0x00)
Once all packets for a frame are sent, I reset packet_index and wait for the next frame (indicated by usb_tx_complete = 1 ( which is poll from DCMI frame interrupt ) ).
Logic :
VOID video_write_payload(UX_DEVICE_CLASS_VIDEO_STREAM *stream)
{
static uint8_t payload_header[2] = {0x02U, 0x00U};
uint8_t *Pcktdata;
uint16_t PcktSze, PcktIdx;
UCHAR *buffer;
ULONG buffer_length;
static uint32_t packet_index = 0;
uint32_t packet_count = UVC_MAX_FRAME_SIZE / (USBD_VIDEO_EPIN_HS_MPS - 2U); //
uint32_t packet_remainder = UVC_MAX_FRAME_SIZE % (USBD_VIDEO_EPIN_HS_MPS - 2U);
/* Get payload buffer */
ux_device_class_video_write_payload_get(stream, &buffer, &buffer_length);
/* Check if streaming is active */
if (uvc_state == UVC_PLAY_STATUS_STREAMING)
{
if (usb_tx_complete == 1)
{
if (packet_index < packet_count)
{
PcktIdx = packet_index;
PcktSze = USBD_VIDEO_EPIN_HS_MPS;
Pcktdata = Rx_B_Temp + packet_index * (USBD_VIDEO_EPIN_HS_MPS - 2U);
packet_index++;
}
else if (packet_index == packet_count)
{
PcktIdx = packet_index;
PcktSze = packet_remainder + 2U;
Pcktdata = Rx_B_Temp + packet_index * (USBD_VIDEO_EPIN_HS_MPS - 2U);
packet_index++;
}
else
{
usb_tx_complete = 0;
packet_index = 0;
PcktSze = 2; // Send only the header
}
}
if (PcktSze > 2U)
{
if (PcktIdx == 0U)
{
/* Toggle frame start flag for the first packet */
payload_header[1] ^= 0x01U;
}
/* Add header and copy video data into the transmission buffer */
ux_utility_memory_copy(buffer, payload_header, sizeof(payload_header));
ux_utility_memory_copy(buffer + 2U, Pcktdata, PcktSze - 2U);
/* Commit the payload */
ux_device_class_video_write_payload_commit(stream, PcktSze);
}
else
{
// /* Send only the header for the final packet */
ux_utility_memory_copy(buffer, payload_header, sizeof(payload_header));
ux_device_class_video_write_payload_commit(stream, 2U);
}
}
else if (uvc_state == UVC_PLAY_STATUS_READY)
{
/* Prepare an empty payload with just a header */
payload_header[1] = 0x00; // Clear flags
ux_utility_memory_copy(buffer, payload_header, sizeof(payload_header));
ux_device_class_video_write_payload_commit(stream, sizeof(payload_header));
}
}
please unzip and filter ( usb.src== "1.14.3" ) . for easy monitoring.
thank you,
