The VideoLAN Forums

Posted: **27 Dec 2013 14:53**

Hi!

and sorry for quite once-again topic.
I have 4 cameras which can run 12M (as lsusb -t told).
This is quite not much.

Dmesg sometimes claim there is not enough bandwith, but two cameras work (fair enough...).
But second started camera has lower quality than firs one (both are same models).

I'm searching webs for answer but none works..

From the begining: what can i try?

Command i use:

Code: Select all

vlc -I dummy v4l2:///dev/video2:width=640:height=480 --sout '#standard{access=http,mux=ts,dst=:8080}'

Posted: **27 Dec 2013 19:28**

What does not work:

Code: Select all

v4l2c:///dev/video1:width=320:height=240:chroma=mjpg:fps=5 
-v4l2-fps 5

sorry for two posts, forget about edit option.

Part of my VLC log:

Code: Select all

0xb6f005f0] main input debug: Creating an input for 'v4l2:///dev/video2'
[0xb6f005f0] main input debug: using timeshift granularity of 50 MiB, in path '/tmp'
[0xb6f005f0] main input debug: `v4l2:///dev/video2' gives access `v4l2' demux `' path `/dev/video2'
[0xb6f005f0] main input debug: creating demux: access='v4l2' demux='' location='/dev/video2' file='/dev/video2'
[0xb6d027d8] main demux debug: looking for access_demux module: 1 candidate
[0xb6d027d8] v4l2 demux debug: opening device '/dev/video2'
[0xb6d027d8] v4l2 demux debug: trying kernel V4L2
[0xb6d027d8] v4l2 demux debug: device PC Camera using driver gspca_zc3xx (version 3.12.6) on usb-0000:00:0f.4-1
[0xb6d027d8] v4l2 demux debug: the device has the capabilities: 0x85000001
[0xb6d027d8] v4l2 demux debug:  (X) Video Capture, ( ) Audio, ( ) Tuner, ( ) Radio
[0xb6d027d8] v4l2 demux debug:  (X) Read/Write, (X) Streaming, ( ) Asynchronous
[0xb6d027d8] v4l2 demux debug: video input 0 (gspca_zc3xx) has type: External analog input *
[0xb6d027d8] v4l2 demux debug: input set to 0
[0xb6d027d8] v4l2 demux debug: device supports chroma jpeg [JPEG, JPEG]
[0xb6d027d8] v4l2 demux debug: control class User Controls:
[0xb6d027d8] v4l2 demux debug:  integer  Brightness (00980900)
[0xb6d027d8] v4l2 demux debug:   current: 128, default: 128
[0xb6d027d8] v4l2 demux debug:  integer  Contrast (00980901)
[0xb6d027d8] v4l2 demux debug:   current: 128, default: 128
[0xb6d027d8] v4l2 demux debug:  integer  Gamma (00980910)
[0xb6d027d8] v4l2 demux debug:   current:   3, default:   3
[0xb6d027d8] v4l2 demux debug:  boolean  Gain, Automatic (00980912)
[0xb6d027d8] v4l2 demux debug:   current:  true, default:  true
[0xb6d027d8] v4l2 demux debug:  menu     Power Line Frequency (00980918)
[0xb6d027d8] v4l2 demux debug:   current: 0, default: 0
[0xb6d027d8] v4l2 demux debug:   choice 0) Disabled
[0xb6d027d8] v4l2 demux debug:   choice 1) 50 Hz
[0xb6d027d8] v4l2 demux debug:   choice 2) 60 Hz
[0xb6d027d8] v4l2 demux debug:  integer  Sharpness (0098091B)
[0xb6d027d8] v4l2 demux debug:   current:   2, default:   2
[0xb6d027d8] v4l2 demux debug: control class JPEG Compression Controls:
[0xb6d027d8] v4l2 demux debug:  integer  Compression Quality (009D0903)
[0xb6d027d8] v4l2 demux debug:   current:  75, default:  75
[0xb6d027d8] v4l2 demux debug: found default width and height of 640x480
[0xb6d027d8] v4l2 demux debug: will try to find optimal width and height
[0xb6d027d8] v4l2 demux debug: Found maximum framerate of -1.000000
[0xb6d027d8] v4l2 demux debug:  discrete size 320x240 supported
[0xb6d027d8] v4l2 demux debug:  discrete size 640x480 supported
[0xb6d027d8] v4l2 demux debug: Found optimal dimensions for framerate -1.000000 of 640x480
[0xb6d027d8] v4l2 demux debug: Driver requires at most 115790 bytes to store a complete image
[0xb6d027d8] v4l2 demux debug: Interlacing setting: progressive
[0xb6d027d8] v4l2 demux debug: added new video es jpeg 640x480
[0xb6d027d8] v4l2 demux debug:  frame rate: -1.000000
[0xb6f005f0] main input debug: selecting program id=0
[0xb6d027d8] main demux debug: using access_demux module "v4l2"
[0xb6d027d8] main demux debug: TIMER module_need() : 832.664 ms - Total 832.664 ms / 1 intvls (Avg 832.664 ms)
[0xb6d02a98] main decoder debug: looking for decoder module: 27 candidates
[0xb6d02a98] main decoder debug: no decoder module matching "any" could be loaded
[0xb6d02a98] main decoder debug: TIMER module_need() : 89.443 ms - Total 89.443 ms / 1 intvls (Avg 89.443 ms)
[0xb6d02a98] main decoder error: no suitable decoder module for fourcc `MJPG'. VLC probably does not support this sound or video format.
[0xb6d02a98] main decoder error: No suitable decoder module
[0xb6d02a98] main decoder error: VLC does not support the audio or video format "MJPG". Unfortunately there is no way for you to fix this.
[0xb6d02a98] main decoder debug: killing decoder fourcc `MJPG', 0 PES in FIFO

Does this mean i'm unable to change frameset?

Posted: **28 Dec 2013 12:08**

dmesg complains probably because you have saturated the USB bandwidth.

Note that VLC does not currently support selecting the V4L2 frame rate manually.

Posted: **28 Dec 2013 15:21**

Ok.

Is there any other way to set framerate?
Or any other way to make one-camera bandwith thinner?

Posted: **28 Dec 2013 15:51**

Yes, writing the missing code. Otherwise, you have to spread cameras through different USB buses.

Posted: **29 Dec 2013 17:38**

And how about manually setting quality?

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