From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mailout4.w1.samsung.com ([210.118.77.14]:14962 "EHLO mailout4.w1.samsung.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754023AbaIPOUU (ORCPT ); Tue, 16 Sep 2014 10:20:20 -0400 Received: from eucpsbgm1.samsung.com (unknown [203.254.199.244]) by mailout4.w1.samsung.com (Oracle Communications Messaging Server 7u4-24.01(7.0.4.24.0) 64bit (built Nov 17 2011)) with ESMTP id <0NBZ008XOZYIO420@mailout4.w1.samsung.com> for linux-media@vger.kernel.org; Tue, 16 Sep 2014 15:23:06 +0100 (BST) From: Kamil Debski To: 'Kiran Avnd' Cc: 'Kiran AVND' , linux-media@vger.kernel.org, wuchengli@chromium.org, posciak@chromium.org, 'Arun Mankuzhi' , ihf@chromium.org, 'Prathyush' , 'Arun Kumar' References: <1410763393-12183-1-git-send-email-avnd.kiran@samsung.com> <1410763393-12183-4-git-send-email-avnd.kiran@samsung.com> <022a01cfd0f3$48185be0$d84913a0$%debski@samsung.com> In-reply-to: Subject: RE: [PATCH 03/17] [media] s5p-mfc: set B-frames as 2 while encoding Date: Tue, 16 Sep 2014 16:20:17 +0200 Message-id: <02ba01cfd1b9$57162de0$054289a0$%debski@samsung.com> MIME-version: 1.0 Content-type: text/plain; charset=UTF-8 Content-transfer-encoding: 7bit Content-language: pl Sender: linux-media-owner@vger.kernel.org List-ID: Hi Kiran, > From: Kiran Avnd [mailto:kiran@chromium.org] > Sent: Tuesday, September 16, 2014 10:10 AM > > Hi Kamil, > > > On Mon, Sep 15, 2014 at 8:12 PM, Kamil Debski > wrote: > > > Hi, > > > From: Kiran AVND [mailto:avnd.kiran@samsung.com] > > Sent: Monday, September 15, 2014 8:43 AM > > > > set default number of B-frames as 2 while encoding for better > > compression. This User can however change this setting using > > V4L2_CID_MPEG_VIDEO_B_FRAMES. > > The last sentence should be rephrased, as it is not clear. > > > > Sure. Will do. > > > The tougher question is what should be the default? > In my opinion the default should produce a stream that is as > simple as it gets. It should be playable on most hardware, > some of which may not support B frames. > > Anyway - this setting can be changed by the user to 2 using > V4L2_CID_MPEG_VIDEO_B_FRAMES ;) > > > > > Its empirical, and this setting has better compression quality and bit > rate than otherwise, in our testing. It doesn't surprise me - introducing B frames should increase both quality and compression efficiency at the cost of computation complexity and limiting compatibility. The thing I am against is changing the driver so that it forces such value of the encoding parameter on the user. Default number of B frames should remain 0. The application should consciously choose to use B frames. Best wishes, -- Kamil Debski Samsung R&D Institute Poland > > Regards, > Kiran > > > > > > > > Signed-off-by: Kiran AVND > > --- > > drivers/media/platform/s5p-mfc/s5p_mfc_enc.c | 2 +- > > 1 files changed, 1 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/media/platform/s5p-mfc/s5p_mfc_enc.c > > b/drivers/media/platform/s5p-mfc/s5p_mfc_enc.c > > index cd1b2a2..f7a6f68 100644 > > --- a/drivers/media/platform/s5p-mfc/s5p_mfc_enc.c > > +++ b/drivers/media/platform/s5p-mfc/s5p_mfc_enc.c > > @@ -280,7 +280,7 @@ static struct mfc_control controls[] = { > > .minimum = 0, > > .maximum = 2, > > .step = 1, > > - .default_value = 0, > > + .default_value = 2, > > }, > > { > > .id = V4L2_CID_MPEG_VIDEO_H264_PROFILE, > > -- > > 1.7.3.rc2 > > -- > To unsubscribe from this list: send the line "unsubscribe linux- > media" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo- > info.html > >