Public bug reported:
Machine: HP Probook
Webcam: HP HD Webcam
OS Ver. Ubuntu 14.04 LTS
Architecture: amd64
Symptom:
The HP Probook has an HP HD Webcam and it supports various resolutions. Most of
them work fine, however, 960x540 has black preview and there is an error
message: Ther was an error playing video from the webcam shown in the cheese.
Diagnose:
According to some tests, the root cause results from the JPEG processing in
libv4l-0,
The source of v4l-utils-1.0.1/lib/libv4lconvert/jpeg.c, 377:
/* We don't want any padding as that may overflow our dest */
if (width % (8 * h_samp) || height % (8 * v_samp)) {
V4LCONVERT_ERR(
"resolution is not a multiple of dctsize");
errno = EIO;
return -1;
}
Because 540 is not a multiple of 8, so it fails.
I tried other video capture apps and set to the same resolution 960x540
and MJPEG format, the issue can be reproduced. But if the format changes
to YUYV, it works fine (preview/capture).
** Affects: cheese
Importance: Undecided
Status: New
** Affects: oem-priority
Importance: High
Status: New
** Also affects: cheese
Importance: Undecided
Status: New
** Package changed: cheese (Ubuntu) => oem-priority
** Changed in: oem-priority
Importance: Undecided => High
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https://bugs.launchpad.net/bugs/1326624
Title:
Error playing video from webcam
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