From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161027AbcANTCd (ORCPT ); Thu, 14 Jan 2016 14:02:33 -0500 Received: from bhuna.collabora.co.uk ([46.235.227.227]:42642 "EHLO bhuna.collabora.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932300AbcANTCb (ORCPT ); Thu, 14 Jan 2016 14:02:31 -0500 Message-ID: <1452798133.3306.3.camel@collabora.com> Subject: Re: [PATCH] v4l: add V4L2_CID_MPEG_VIDEO_FORCE_FRAME_TYPE. From: Nicolas Dufresne Reply-To: Nicolas Dufresne To: Kamil Debski , "'Wu-Cheng Li'" , pawel@osciak.com, mchehab@osg.samsung.com, hverkuil@xs4all.nl, crope@iki.fi, standby24x7@gmail.com, ricardo.ribalda@gmail.com, ao2@ao2.it, bparrot@ti.com, "'Andrzej Hajda'" Cc: linux-media@vger.kernel.org, linux-kernel@vger.kernel.org, linux-api@vger.kernel.org Date: Thu, 14 Jan 2016 14:02:13 -0500 In-Reply-To: <00ac01d14ef0$0702b2f0$150818d0$@samsung.com> References: <1452686611-145620-1-git-send-email-wuchengli@chromium.org> <1452686611-145620-2-git-send-email-wuchengli@chromium.org> <003f01d14e21$78f7ad40$6ae707c0$@samsung.com> <1452783743.10009.18.camel@collabora.com> <00ac01d14ef0$0702b2f0$150818d0$@samsung.com> Organization: Collabora Ltd. Content-Type: multipart/signed; micalg="pgp-sha1"; protocol="application/pgp-signature"; boundary="=-brlVbyPf4xej2aoZ8DtX" X-Mailer: Evolution 3.18.3 (3.18.3-1.fc23) Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --=-brlVbyPf4xej2aoZ8DtX Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Le jeudi 14 janvier 2016 =C3=A0 18:21 +0100, Kamil Debski a =C3=A9crit=C2= =A0: > I had a look into the documentation of MFC. It is possible to force > two types of a frame to be coded. > The one is a keyframe, the other is a not coded frame. As I > understand this is a type of frame that means that image did not > change from previous frame. I am sure I seen it in an MPEG4 stream in > a movie trailer. The initial board with the age rating is displayed > for a couple of seconds and remains static. Thus there is one I-frame=20 > and a number of non-coded frames. >=20 > That is the reason why the control was implemented in MFC as a menu > and not a button. Thus the question remains - is it better to leave > it as a menu, or should there be two (maybe more in the future) > buttons? Then I believe we need both. Because with the menu, setting I-Frame, I would expect to only receive keyframes from now-on. While the useful feature we are looking for here, is to get the next buffer (or nearby) to be a keyframe. It's the difference between creating an I-Frame only stream and requesting a key-frame manually for recovery (RTP use case). In this end, we should probably take that time to review the features we have as we need: - A way to trigger a key frame to be produce - A way to produce a I-Frame only stream - A way to set the key-frame distance (in frames) even though this could possibly be emulated using the trigger. cheers, Nicolas --=-brlVbyPf4xej2aoZ8DtX Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part Content-Transfer-Encoding: 7bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v1 iEYEABECAAYFAlaX8LUACgkQcVMCLawGqBy+NgCgz5q9VWw+FIGC6xKtcn0MSEWn e9AAn0NzyR4+QkHx8o160oqZcv92dGoM =7kPt -----END PGP SIGNATURE----- --=-brlVbyPf4xej2aoZ8DtX--