From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from ffbox0-bg.mplayerhq.hu (ffbox0-bg.ffmpeg.org [79.124.17.100]) by master.gitmailbox.com (Postfix) with ESMTP id 75EF14A575 for ; Thu, 2 May 2024 10:17:02 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 0D5B068D72B; Thu, 2 May 2024 13:16:59 +0300 (EEST) Received: from haasn.dev (haasn.dev [78.46.187.166]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id A68DA68D72B for ; Thu, 2 May 2024 13:16:51 +0300 (EEST) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=haasn.xyz; s=mail; t=1714645011; bh=w7tPivhyzXsdcJe+Mu9CFcrynuQaxWlO//mkP0zPFks=; h=Date:From:To:Subject:In-Reply-To:References:From; b=lhyCpG71r9deVMCdmOF43JF9C+AXVK/d9WSWNFxftISY9rHSJq6T6nlmCg8PAAYFu 2h1F4mMaCdAJMutRioWjrcYll9sm2BwudXTk5K+FlhowvW9qTIM/KFxZdSOTkHGpmG COftWmw/Ne+8zSRguZLrF+J4GwwCKw20SI8c4pJg= Received: from haasn.dev (unknown [10.30.0.2]) by haasn.dev (Postfix) with ESMTP id 7280F40356 for ; Thu, 2 May 2024 12:16:51 +0200 (CEST) Date: Thu, 2 May 2024 12:16:51 +0200 Message-ID: <20240502121651.GG10830@haasn.xyz> From: Niklas Haas To: FFmpeg development discussions and patches In-Reply-To: <20240410220905.GS6420@pb2> References: <20240405185721.111072-1-ffmpeg@haasn.xyz> <20240408201833.GI6420@pb2> <20240408235502.GB24382@haasn.xyz> <20240410220905.GS6420@pb2> MIME-Version: 1.0 Content-Disposition: inline Subject: Re: [FFmpeg-devel] [PATCH 01/11] avcodec: add avcodec_get_supported_config() X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: On Thu, 11 Apr 2024 00:09:05 +0200 Michael Niedermayer wrote: > On Mon, Apr 08, 2024 at 11:55:02PM +0200, Niklas Haas wrote: > > On Mon, 08 Apr 2024 22:18:33 +0200 Michael Niedermayer wrote: > > > On Fri, Apr 05, 2024 at 08:57:11PM +0200, Niklas Haas wrote: > > > > From: Niklas Haas > > > > > > > > This replaces the myriad of existing lists in AVCodec by a unified API > > > > call, allowing us to (ultimately) trim down the sizeof(AVCodec) quite > > > > substantially, while also making this more trivially extensible. > > > > > > > > In addition to the already covered lists, add two new entries for color > > > > space and color range, mirroring the newly added negotiable fields in > > > > libavfilter. > > > > > > > > I decided to drop the explicit length field from the API proposed by > > > > Andreas Rheinhardt, because having it in place ended up complicating > > > > both the codec side and the client side implementations, while also > > > > being strictly less flexible (it's trivial to recover a length given > > > > a terminator, but requires allocation to add a terminator given > > > > a length). Using a terminator also presents less of a porting challenge > > > > for existing users of the current API. > > > > > > > > Once the deprecation period passes for the existing public fields, the > > > > rough plan is to move the commonly used fields (such as > > > > pix_fmt/sample_fmt) into FFCodec, possibly as a union of audio and video > > > > configuration types, and then implement the rarely used fields with > > > > custom callbacks. > > > > --- > > > > doc/APIchanges | 5 ++++ > > > > libavcodec/avcodec.c | 51 +++++++++++++++++++++++++++++++++++++ > > > > libavcodec/avcodec.h | 27 ++++++++++++++++++++ > > > > libavcodec/codec.h | 19 +++++++++++--- > > > > libavcodec/codec_internal.h | 21 +++++++++++++++ > > > > libavcodec/version.h | 4 +-- > > > > 6 files changed, 121 insertions(+), 6 deletions(-) > > > > > > This patchset seems to overlap a bit with AVOptionRanges > > > > > > I think ideally the user should at some point be able to query using some > > > API on a AVCodecContext/AVCodecParameters/AVFormatContex/AVStream > > > what for that specific instance are supported settings for each field > > > > > > The API here seems to use a enum, which can make sense but it differs from > > > how AVOption works which doesnt use enums to identify fields > > > > I didn't know AVOptionRanges exists; indeed it can be seen as somewhat > > overlapping here. That said, there is a vital distinction here: AVOptionRanges > > represents *static* limits on what options can be set (e.g. via > > `av_opt_set_int`), whereas this API represents *dynamic* limits on what can be > > coded. > > AVOptionRanges where definitly not intended to be static > > see the docs: > * The returned list may depend on other fields in obj like for example profile. > > that would not be static > > > > > > > In particular, the list of supported colorspaces etc. can *depend* on the value > > of other options. Currently, only strict_std_compliance, but I can easily see > > this list growing in the future (e.g. for different profiles, dolbyvision, > > ...). > > > > That aside, I personally find an API based on strings and doubles rather > > cumbersome to use, especially when downstream clients expect an enum list. > > AVOption* is intended to be a generic API. > For example something that an App can query to build a drop down menu in a GUI > for each parameter > > For this, it must be possible to iterate over all paremeters, then for each > iterate over all possible settings if its a discrete type or range if its a > continous type. And then present the user with the corresponding GUI elements > > thx Okay, then I do not present as strong an objection as I thought. That said, I still think that downstream API users will be very thankful for having a replacement API that's easy to migrate to, rather one that's IMO rather difficult to use (and which requires both FPU and malloc to access what used to be just a static list). What do other people think? Should we introduce this new API as-is, or should it be scrapped in favor of reusing AVOptionRanges? _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-request@ffmpeg.org with subject "unsubscribe".