From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from perceval.ideasonboard.com ([95.142.166.194]:50899 "EHLO perceval.ideasonboard.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932134AbaDKNL4 (ORCPT ); Fri, 11 Apr 2014 09:11:56 -0400 From: Laurent Pinchart To: Sakari Ailus Cc: linux-media@vger.kernel.org Subject: Re: [yavta PATCH 7/9] Print timestamp type and source for dequeued buffers Date: Fri, 11 Apr 2014 15:11:55 +0200 Message-ID: <77625335.6btl6flutB@avalon> In-Reply-To: <53471CD3.3060306@iki.fi> References: <1393690690-5004-1-git-send-email-sakari.ailus@iki.fi> <1981061.t1Onuu4osC@avalon> <53471CD3.3060306@iki.fi> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Sender: linux-media-owner@vger.kernel.org List-ID: Hi Sakari, On Friday 11 April 2014 01:36:03 Sakari Ailus wrote: > Laurent Pinchart wrote: > > On Thursday 10 April 2014 21:58:41 Sakari Ailus wrote: > >> Laurent Pinchart wrote: > >>> Hi Sakari, > >>> > >>> Thank you for the patch. > >>> > >>> Given that the timestamp type and source are not supposed to change > >>> during streaming, do we really need to print them for every frame ? > >> > >> When processing frames from memory to memory (COPY timestamp type), the > >> it is entirely possible that the timestamp source changes as the flags > >> are copied from the OUTPUT buffer to the CAPTURE buffer. > > > > It's possible, but is it allowed by the V4L2 API ? > > The spec states that: > > "The V4L2_BUF_FLAG_TIMESTAMP_COPY timestamp type which is used by e.g. on > mem-to-mem devices is an exception to the rule: the timestamp source flags > are copied from the OUTPUT video buffer to the CAPTURE video buffer." > > >> These patches do not support it but it is allowed. > >> > >> One option would be to print the source on every frame only when the > >> type is COPY. For a program like yavta this might be overly > >> sophisticated IMO. :-) > > > > My concern is that this makes the lines output by yavta pretty long. > > True as well. I could remove "type/src " from the timestamp source > information. That's mostly redundant anyway. Then we shouldn't exceed 80 > characters per line that easily anymore. I think that would be better. > Could this be the time to add a "verbose" option? :-) Possibly, but then we'll need to discuss what information should be printed in verbose mode only :-) -- Regards, Laurent Pinchart