Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756805AbcJ2C4w (ORCPT ); Fri, 28 Oct 2016 22:56:52 -0400 Received: from mail-qk0-f195.google.com ([209.85.220.195]:36195 "EHLO mail-qk0-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756491AbcJ2C4s (ORCPT ); Fri, 28 Oct 2016 22:56:48 -0400 MIME-Version: 1.0 X-Originating-IP: [73.25.156.150] In-Reply-To: <00f453e4-4a58-f01f-c68e-80c88554c3c1@denx.de> References: <00f453e4-4a58-f01f-c68e-80c88554c3c1@denx.de> From: Matt Ranostay Date: Fri, 28 Oct 2016 19:56:47 -0700 Message-ID: Subject: Re: [RFC] v4l2 support for thermopile devices To: Marek Vasut Cc: Devin Heitmueller , Linux Media Mailing List , Linux Kernel , Jonathan Cameron , Lars-Peter Clausen , Attila Kinali Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2063 Lines: 40 On Fri, Oct 28, 2016 at 1:40 PM, Marek Vasut wrote: > On 10/28/2016 10:30 PM, Devin Heitmueller wrote: >> Hi Matt, >> >>> Need some input for the video pixel data types, which the device we >>> are using (see datasheet links below) is outputting pixel data in >>> little endian 16-bit of which a 12-bits signed value is used. Does it >>> make sense to do some basic processing on the data since greyscale is >>> going to look weird with temperatures under 0C degrees? Namely a cold >>> object is going to be brighter than the hottest object it could read. >>> Or should a new V4L2_PIX_FMT_* be defined and processing done in >>> software? Another issue is how to report the scaling value of 0.25 C >>> for each LSB of the pixels to the respecting recording application. >> >> Regarding the format for the pixel data: I did some research into >> this when doing some driver work for the Seek Thermal (a product >> similar to the FLIR Lepton). While it would be nice to be able to use >> an existing application like VLC or gStreamer to just take the video >> and capture from the V4L2 interface with no additional userland code, >> the reality is that how you colorize the data is going to be highly >> user specific (e.g. what thermal ranges to show with what colors, >> etc). If your goal is really to do a V4L2 driver which returns the >> raw data, then you're probably best returning it in the native >> greyscale format (whether that be an existing V4L2 PIX_FMT or a new >> one needs to be defined), and then in software you can figure out how >> to colorize it. > > All true, I also did my share of poking into SEEK Thermal USB and it is > an excellent candidate for a V4L2 driver, that one. But I think this > device here is producing much smaller images, something like 8x8 pixels. Yes this is only 64 pixel (8x8 grid) but it is video still. Does have some major pluses over a FLIR camera though, mainly power usage is really low, and cost is lower (although that reason is decreasing everyday). > > -- > Best regards, > Marek Vasut