From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]:16397 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754691AbZKHRLQ (ORCPT ); Sun, 8 Nov 2009 12:11:16 -0500 Message-ID: <4AF6FCFD.6000200@redhat.com> Date: Sun, 08 Nov 2009 18:16:45 +0100 From: Hans de Goede MIME-Version: 1.0 To: =?ISO-8859-2?Q?N=E9meth_M=E1rton?= CC: V4L Mailing List Subject: Re: libv4l problem decoding frames from pac7302 References: <4AF6C7D1.6040000@freemail.hu> In-Reply-To: <4AF6C7D1.6040000@freemail.hu> Content-Type: text/plain; charset=ISO-8859-2; format=flowed Content-Transfer-Encoding: 8bit Sender: linux-media-owner@vger.kernel.org List-ID: Hi, On 11/08/2009 02:29 PM, Németh Márton wrote: > Hi, > > I have some problem that libv4l cannot decode all image coming from the > Labtec Webcam 2200. There are some cases when no image at all can be decoded. > This case can be reproduced always for example by setting the camera to test > mode to produce a color test bar. The raw data arrives from the driver (41472 > bytes, see attached) and v4lconvert_convert() returns -1 and the errno is set > to EAGAIN. In this case the v4lconvert_get_error_message() reports the > following error message: > > v4l-convert: error decompressing JPEG: Pixart JPEG error: invalid MCU marker: 0xff > See: libv4lconvert/tinyjpeg.c, lines 1611-1620 for some info on the magical byte pixart puts between Huffman data blocks. The 0xff value probably is normal for the test mode, so I would start with trying to change the MCU test to also except 0xff as a valid MCU marker Regards, hans > Steps to reproduce: > 1. get 13327:19c0469c02c3 from http://linuxtv.org/hg/v4l-dvb/ > 2. apply the patch http://www.spinics.net/lists/linux-media/msg11841.html > 3. apply the patch http://www.spinics.net/lists/linux-media/msg11842.html > 4. compile and install the new driver > 5. plug Labtec Webcam 2200 > 6. start capturing > 7. execute "v4l2-dbg --set-register=0x72 9", this will switch on the color > test card of the webcam. > > Current result: v4lconvert_convert() always return -1 and errno is EAGAIN until > the olor test card is not switched off with "v4l2-dbg --set-register=0x72 0". > > How would you start to fix this? > > Regards, > > Márton Németh >