[aklug] Re: FriLinux

On 11/22/2010 01:54 PM, Jeremy Austin wrote:
> On Mon, Nov 22, 2010 at 9:54 AM, Shane R. Spencer<shane@bogomip.com> wrote=
> :
>> I got 1280x1024 MJPEG video chat working the other day. =A0Required 10mbi=
> t :) Most UVC video
>> cameras will let you receive a MJPEG stream encoded on the camera.. then =
> you just run
>> gstreamer or VLC to do the rest. =A0I wouldn't recommend transcoding at t=
> hat resolution :)
>>
>> In a week or so I will be doing this with 1920x1080 if all goes well :)
>
> What live camera are you using that output 1920x1080?
>
> The current crop of HD cameras is greatly inferior for live video to
> the previous standard def DV-based generation that used Firewire. Any
> suggestions for live USB-based HD capture?
>
> I have an HDMI capture card, so I can easily capture 4:4:4 video from
> any of my HD camcorders with HDMI output, but that's not practical for
> the average person, or portable setup, since PCI-E or USB 3 is needed.
>
> I do have the horsepower to live transcode from anything to anything on te=
> fly.
>

Most of the new Logitech cameras support MJPEG over the wire. When you're not too
concerned with super high quality (out of a USB web cam with a tiny little lens) this
method works very well. The JPEG quality is pretty high on the models I've tested. I've
been able to use several utilities, even python, to connect to UVC USB cameras and fetch
MJPEG streams and record live or transmit over the network. The is often a "chroma"
option recording programs use. MJPEG should be one of the options if compatible.

I'm not sure what chroma downsampling is used with MJPEG streams. I don't have one handy
so I can't do a query on it.

- Shane
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Received on Mon Nov 22 15:17:02 2010