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trishume / linux-track

Automatically exported from code.google.com/p/linux-track
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optional JPEG compression #36

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
can linux-track access optional JPEG compression directly?

ie Sony PS3 eye camera is stated to have optional JPEG compression,
is that on-chip or only via a subroutine that converts YUYV to jpeg?

Original issue reported on code.google.com by j...@peepo.com on 2 May 2013 at 11:59

GoogleCodeExporter commented 9 years ago 
Hello,
the compression is usually implemented in the camera itself, so the USB 
bandwidth is saved. Linuxtrack doesn't handle this directly, it accesses the 
webcam through libv4l, that should handle differences between 
requested/supported formats transparently to the application/user.

That said, using the jpeg format *might* impact the tracking precision, by 
introducing artifacts to the image so I'd incline to using uncompressed images 
(although there is a problem with bandwidth).

Is there a reason for you to need the jpeg format?
Kind regards,

Michal

Original comment by f.jo...@email.cz on 3 May 2013 at 7:24

GoogleCodeExporter commented 9 years ago 
[deleted comment]
GoogleCodeExporter commented 9 years ago 
Michal,

many thanks for your prompt response,

How can one request jpeg directly from PS3 eye camera?
ie using say libv4l**

Raspberry pi processor and others similar are not capable of compressing more 
than ~4 frames per second

**$ v4l2-ctl --list-formats
ioctl: VIDIOC_ENUM_FMT
    Index       : 0
    Type        : Video Capture
    Pixel Format: 'YUYV'
    Name        : YUYV

ie no jpeg is listed as supported??
yet Sony seem to suggest on chip compression available....

Original comment by j...@peepo.com on 3 May 2013 at 8:42

GoogleCodeExporter commented 9 years ago 
Hi,
I'd try to use guvcview - it should show you what formats are available...

Just out of curiosity - you are going to run linuxtrack on Raspberry Pi?
Kind regards,

Michal

Original comment by f.jo...@email.cz on 3 May 2013 at 9:57

GoogleCodeExporter commented 9 years ago 
guvcview does not list jpeg as an option...

baby steps, need to access jpeg first...

Original comment by j...@peepo.com on 3 May 2013 at 10:20

GoogleCodeExporter commented 9 years ago 
What pixelformats does the guvcview report (when run in terminal)?

Also command 'sudo lsusb -v -d XXXX:XXXX', where XXXX:XXXX is the ID of the 
device (obtained by 'lsusb' command) will show you all the descriptors - it 
contains all informations on the device...

If the MJPG fourcc is mentioned (this is the one that my old Creative Live! 
webcam knows), you have a chance, otherwise you are going to need to use 
different webcam.
Kind regards,

Michal

Original comment by f.jo...@email.cz on 3 May 2013 at 6:49

GoogleCodeExporter commented 9 years ago 
Linuxtrack uses libv4l and its conversion abilities, that silently does what is 
necessary to get the desired data format (YUYV, RGB, ...).

Original comment by f.jo...@email.cz on 12 Jul 2013 at 12:57