I edit and compile the driver to filtering out some frames to get the FPS I want. For example, my camera only support 60 FPS, and I filter one in every two frames, then I will get a 30 FPS.
However, here is the results:
[16019.383083] Frame 1188 Duration: 15 ms, Total Frames: 3562
[16019.418196] Frame 1189 Start time recorded: 1732537841.015229658 seconds
[16019.433480] Frame 1189 Completion time (bulk): 1732537841.030515028 seconds
[16019.433491] Frame 1189 Duration: 15 ms, Total Frames: 3565
[16019.468593] Frame 1190 Start time recorded: 1732537841.065625954 seconds
[16019.483870] Frame 1190 Completion time (bulk): 1732537841.080905084 seconds
[16019.483881] Frame 1190 Duration: 15 ms, Total Frames: 3568
[16019.518984] Frame 1191 Start time recorded: 1732537841.116020811 seconds
[16019.534272] Frame 1191 Completion time (bulk): 1732537841.131310053 seconds
[16019.534283] Frame 1191 Duration: 15 ms, Total Frames: 3571
[16019.569385] Frame 1192 Start time recorded: 1732537841.166420915 seconds
[16019.584666] Frame 1192 Completion time (bulk): 1732537841.181704013 seconds
[16019.584677] Frame 1192 Duration: 15 ms, Total Frames: 3574
[16019.619783] Frame 1193 Start time recorded: 1732537841.216819196 seconds
[16019.635058] Frame 1193 Completion time (bulk): 1732537841.232098038 seconds
[16019.635069] Frame 1193 Duration: 15 ms, Total Frames: 3577
At the end I only get 1193 frames of 3577 for 60 seconds, it is nearly 20 FPS.
I edit the uvc_video.c as follows:
static int uvc_video_decode_start(struct uvc_streaming *stream,
struct uvc_buffer *buf, const u8 *data, int len)
{
u8 fid;
static unsigned int frame_counter = 0;
unsigned int interval = get_camera_fps() / get_user_fps();
total_frames++;
/* Sanity checks:
* - packet must be at least 2 bytes long
* - bHeaderLength value must be at least 2 bytes (see above)
* - bHeaderLength value can't be larger than the packet size.
*/
if (len < 2 || data[0] < 2 || data[0] > len) {
stream->stats.frame.nb_invalid++;
return -EINVAL;
}
fid = data[1] & UVC_STREAM_FID;
/* Skip current frames for FPS control */
if (frame_counter % interval != 0) {
frame_counter++;
return -ENODATA; // Skip current frame
}
/* Increase the sequence number regardless of any buffer states, so
* that discontinuous sequence numbers always indicate lost frames.
*/
if (stream->last_fid != fid) {
stream->sequence++;
if (stream->sequence)
uvc_video_stats_update(stream);
}
uvc_video_clock_decode(stream, buf, data, len);
uvc_video_stats_decode(stream, data, len);
/* Store the payload FID bit and return immediately when the buffer is
* NULL.
*/
if (buf == NULL) {
stream->last_fid = fid;
return -ENODATA;
}
/* Mark the buffer as bad if the error bit is set. */
if (data[1] & UVC_STREAM_ERR) {
uvc_trace(UVC_TRACE_FRAME, "Marking buffer as bad (error bit "
"set).\n");
buf->error = 1;
}
/* Synchronize to the input stream by waiting for the FID bit to be
* toggled when the the buffer state is not UVC_BUF_STATE_ACTIVE.
* stream->last_fid is initialized to -1, so the first isochronous
* frame will always be in sync.
*
* If the device doesn't toggle the FID bit, invert stream->last_fid
* when the EOF bit is set to force synchronisation on the next packet.
*/
if (buf->state != UVC_BUF_STATE_ACTIVE) {
if (fid == stream->last_fid) {
uvc_trace(UVC_TRACE_FRAME, "Dropping payload (out of "
"sync).\n");
if ((stream->dev->quirks & UVC_QUIRK_STREAM_NO_FID) &&
(data[1] & UVC_STREAM_EOF))
stream->last_fid ^= UVC_STREAM_FID;
return -ENODATA;
}
buf->buf.field = V4L2_FIELD_NONE;
buf->buf.sequence = stream->sequence;
buf->buf.vb2_buf.timestamp = ktime_to_ns(uvc_video_get_time());
buf->idx = ++frame_idx;
ktime_get_real_ts64(&buf->start_time);
pr_info("Frame %u Start time recorded: %ld.%09ld seconds\n",
buf->idx, (long)buf->start_time.tv_sec, buf->start_time.tv_nsec);
/* TODO: Handle PTS and SCR. */
buf->state = UVC_BUF_STATE_ACTIVE;
}
/* Mark the buffer as done if we're at the beginning of a new frame.
* End of frame detection is better implemented by checking the EOF
* bit (FID bit toggling is delayed by one frame compared to the EOF
* bit), but some devices don't set the bit at end of frame (and the
* last payload can be lost anyway). We thus must check if the FID has
* been toggled.
*
* stream->last_fid is initialized to -1, so the first isochronous
* frame will never trigger an end of frame detection.
*
* Empty buffers (bytesused == 0) don't trigger end of frame detection
* as it doesn't make sense to return an empty buffer. This also
* avoids detecting end of frame conditions at FID toggling if the
* previous payload had the EOF bit set.
*/
if (fid != stream->last_fid && buf->bytesused != 0) {
uvc_trace(UVC_TRACE_FRAME, "Frame complete (FID bit "
"toggled).\n");
buf->state = UVC_BUF_STATE_READY;
return -EAGAIN;
}
stream->last_fid = fid;
frame_counter++;
return data[0];
}
Does anyone know how to solve the problem? Thank you so much!
