From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout3.w1.samsung.com ([210.118.77.13]:18818 "EHLO mailout3.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750753Ab3IIJKC (ORCPT ); Mon, 9 Sep 2013 05:10:02 -0400 Received: from eucpsbgm2.samsung.com (unknown [203.254.199.245]) by mailout3.w1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0MSU00M12PGH5Y40@mailout3.w1.samsung.com> for linux-media@vger.kernel.org; Mon, 09 Sep 2013 10:10:00 +0100 (BST) Message-id: <522D9065.3040209@samsung.com> Date: Mon, 09 Sep 2013 11:09:57 +0200 From: Sylwester Nawrocki MIME-version: 1.0 To: Kamil Debski Cc: 'Pawel Osciak' , 'Hans Verkuil' , linux-media@vger.kernel.org, 'Laurent Pinchart' Subject: Re: [PATCH v1 16/19] v4l: Add encoding camera controls. References: <1377829038-4726-1-git-send-email-posciak@chromium.org> <1377829038-4726-17-git-send-email-posciak@chromium.org> <52204058.6070008@xs4all.nl> <522D7E3E.8070104@xs4all.nl> <04c001cead3a$f8ea0dc0$eabe2940$%debski@samsung.com> In-reply-to: <04c001cead3a$f8ea0dc0$eabe2940$%debski@samsung.com> Content-type: text/plain; charset=ISO-8859-1 Content-transfer-encoding: 7bit Sender: linux-media-owner@vger.kernel.org List-ID: On 09/09/2013 11:00 AM, Kamil Debski wrote: [...] >>>> We have QP controls separately for H264, H263 and MPEG4. Why is that? >>>> Which one should I use for VP8? Shouldn't we unify them instead? >>> >>> I can't quite remember the details, so I've CCed Kamil since he added >> those controls. >>> At least the H264 QP controls are different from the others as they >>> have a different range. What's the range for VP8? >> >> Yes, it differs, 0-127. >> But I feel this is pretty unfortunate, is it a good idea to multiply >> controls to have one per format when they have different ranges >> depending on the selected format in general? Perhaps a custom handler >> would be better? >> >>> I'm not sure why the H263/MPEG4 controls weren't unified: it might be >>> that since the >>> H264 range was different we decided to split it up per codec. But I >>> seem to remember that there was another reason as well. > > We had a discussion about this on linux-media mailing list. It can be found > here: > http://comments.gmane.org/gmane.linux.drivers.video-input-infrastructure/32606 > In short, it is a mix of two reasons: one - the valid range is different for > different formats and second - implementing controls which have different > min/max values depending on format was not easy. Hmm, these seem pretty vague reasons. And since some time we have support for dynamic control range update [1]. > On the one hand I am thinking that now, when we have more codecs, it would > be better > to have a single control, on the other hand what about backward > compatibility? > Is there a graceful way to merge H263 and H264 QP controls? [1] https://patchwork.linuxtv.org/patch/16436/ -- Regards, Sylwester