forked/ustreamer
1
0
Fork 0
mirror of https://github.com/pikvm/ustreamer.git synced 2026-02-27 04:06:30 +00:00
Code Issues Packages Projects Releases Wiki Activity

Discard truncated JPEG frames (#230)

Browse Source 
Hello! This patch works around an issue encountered with [ELP-USB100W03M]
cameras where they send a vast amount of invalid JPEGs when capturing
their MJPEG streams. These bad frames account for about 87% of captured
frames and cause issues for browsers and downstream applications.

Replaces #229

[ELP-USB100W03M]: https://www.webcamerausb.com/elp-10mp-free-driver-usb20-ov9712-cmos-sensor-hd-mjpeg-web-camera-board-720p-36mm-lens-p-116.html
This commit is contained in:
Stargirl Flowers
2023-09-16 16:27:08 -07:00
committed by Maxim Devaev
parent a52df47b29
commit c96559e4ac
1 changed files with 38 additions and 8 deletions
Download Patch File Download Diff File Expand all files Collapse all files

46
src/ustreamer/device.c
View File

@@ -54,7 +54,7 @@ static const struct {
};
static bool _device_is_buffer_valid(us_device_s *dev, const struct v4l2_buffer *buf);
static bool _device_is_buffer_valid(us_device_s *dev, const uint8_t *data, const struct v4l2_buffer *v4l2_buf);
static int _device_open_check_cap(us_device_s *dev);
static int _device_open_dv_timings(us_device_s *dev);
static int _device_apply_dv_timings(us_device_s *dev);
@@ -330,6 +330,7 @@ int us_device_grab_buffer(us_device_s *dev, us_hw_buffer_s **hw) {
}
# define GRABBED(x_buf) _RUN(hw_bufs)[x_buf.index].grabbed
# define FRAME_DATA(x_buf) _RUN(hw_bufs)[x_buf.index].raw.data
if (GRABBED(new)) {
US_LOG_ERROR("V4L2 error: grabbed device buffer=%u is already used", new.index);
@@ -337,7 +338,7 @@ int us_device_grab_buffer(us_device_s *dev, us_hw_buffer_s **hw) {
}
GRABBED(new) = true;
broken = !_device_is_buffer_valid(dev, &new);
broken = !_device_is_buffer_valid(dev, FRAME_DATA(new), &new);
if (broken) {
US_LOG_DEBUG("Releasing device buffer=%u (broken frame) ...", new.index);
if (_D_XIOCTL(VIDIOC_QBUF, &new) < 0) {
@@ -359,16 +360,20 @@ int us_device_grab_buffer(us_device_s *dev, us_hw_buffer_s **hw) {
}
# undef GRABBED
# undef FRAME_DATA
memcpy(&buf, &new, sizeof(struct v4l2_buffer));
buf_got = true;
} else {
if (buf_got && errno == EAGAIN) {
if (broken) {
if(errno == EAGAIN) {
if(broken) {
return -2;
} else if(buf_got) {
break;
} else {
continue;
}
break;
} else {
US_LOG_PERROR("Can't grab device buffer");
return -1;
@@ -425,17 +430,42 @@ int us_device_consume_event(us_device_s *dev) {
return 0;
}
bool _device_is_buffer_valid(us_device_s *dev, const struct v4l2_buffer *buf) {
bool _device_is_buffer_valid(us_device_s *dev, const uint8_t *data, const struct v4l2_buffer *v4l2_buf) {
// Workaround for broken, corrupted frames:
// Under low light conditions corrupted frames may get captured.
// The good thing is such frames are quite small compared to the regular frames.
// For example a VGA (640x480) webcam frame is normally >= 8kByte large,
// corrupted frames are smaller.
if (buf->bytesused < dev->min_frame_size) {
if (v4l2_buf->bytesused < dev->min_frame_size) {
US_LOG_DEBUG("Dropped too small frame, assuming it was broken: buffer=%u, bytesused=%u",
buf->index, buf->bytesused);
v4l2_buf->index, v4l2_buf->bytesused);
return false;
}
// Workaround for truncated JPEG frames:
// Some inexpensive CCTV-style USB webcams such as the ELP-USB100W03M send
// large amounts of these frames when using MJPEG streams. Checks that the
// buffer ends with either the JPEG end of image marker (0xFFD9), the last
// marker byte plus a padding byte (0xD900), or just padding bytes (0x0000)
// A more sophisticated method would scan for the end of image marker, but
// that takes precious CPU cycles and this should be good enough for most
// cases.
if (us_is_jpeg(dev->run->format)) {
const uint8_t *const end_ptr = data + v4l2_buf->bytesused;
const uint8_t *const eoi_ptr = end_ptr - 2;
if (eoi_ptr < data) {
US_LOG_DEBUG("Discarding invalid frame, too small to be a valid JPEG, bytesused=%u", v4l2_buf->bytesused);
return false;
}
const uint16_t eoi_marker = (((uint16_t)(eoi_ptr[0]) << 8) | eoi_ptr[1]);
if (eoi_marker != 0xFFD9 && eoi_marker != 0xD900 && eoi_marker != 0x0000) {
US_LOG_DEBUG("Discarding truncated JPEG frame, eoi_marker=0x%04x bytesused=%u", eoi_marker, v4l2_buf->bytesused);
return false;
}
}
return true;
}