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 2295E47CBB for ; Thu, 15 Feb 2024 12:32:13 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 2996E68D230; Thu, 15 Feb 2024 14:32:11 +0200 (EET) Received: from mout-p-201.mailbox.org (mout-p-201.mailbox.org [80.241.56.171]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id AB4D968D1C1 for ; Thu, 15 Feb 2024 14:32:04 +0200 (EET) Received: from smtp2.mailbox.org (smtp2.mailbox.org [10.196.197.2]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (No client certificate requested) by mout-p-201.mailbox.org (Postfix) with ESMTPS id 4TbDw20ksBz9smn for ; Thu, 15 Feb 2024 13:32:02 +0100 (CET) Message-ID: <0c3c8b9b-927e-470d-9272-67536279ba15@gyani.pro> Date: Thu, 15 Feb 2024 18:01:59 +0530 MIME-Version: 1.0 From: Gyan Doshi To: ffmpeg-devel@ffmpeg.org References: <20240123064948.455-1-ffmpeg@gyani.pro> <36aab7a2-3590-4cc1-aeb4-8805d6484de9@gyani.pro> <677047fe-11e4-4a62-a003-912471ff81ef@gyani.pro> <170643927262.8914.6288212134706680203@lain.khirnov.net> <594a2da4-0693-483e-82ab-2924b16d8dbb@gyani.pro> <170799405543.32390.14003661310804711658@lain.khirnov.net> Content-Language: en-US In-Reply-To: <170799405543.32390.14003661310804711658@lain.khirnov.net> Subject: Re: [FFmpeg-devel] [PATCH 1/2] avcodec/s302m: enable non-PCM decoding 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-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: On 2024-02-15 04:17 pm, Anton Khirnov wrote: > Hi, > sorry for the delay, I've been busy fixing things for the release > Quoting Gyan Doshi via ffmpeg-devel (2024-01-29 05:00:33) >> On 2024-01-28 04:24 pm, Anton Khirnov wrote: >>>> a) it would mean essentially inlining this decoder in the demuxer. >>> Why is that a problem? This decoder seems like it shouldn't be a >>> decoder. >>> >>> I agree with Andreas that this seems like it's a demuxer pretending to >>> be a decoder. >> This module transforms the entire raw payload data to generate its >> output, even if the syntax is simple which >> essentially makes it a de-coder. The de-multiplexer aspect of multiple >> streams is an academic possibility allowed >> by the standard but not seen in any sample which makes me suspect it's >> used for carriage between broadcast >> facilities rather than something ever sent to an OTT provider, let alone >> an end user. > If it dynamically generates nested decoders, then it's not a proper > codec in our model. It should be either a part of the demuxer, or a > bitstream filter (possibly inserted automatically by the demuxer). s302m is a hybrid creature and does not slot cleanly into any role. So there is no theoretically proper place for this component - any choice is a least-out-of-place accommodation. But it is much more out of place inside a demuxer. Analyzing packet payload and then manipulating that entire payload is much closer to a decoding role than data chunk extraction for packetization. And the stream extracted from the container is meant to be SMPTE ST 302 not PCM* or Dolby-E/AC-3..etc, which will both misrepresent what the container carries and possibly discard S-ADM metadata, if present, in the packet. With passthrough demuxing, a stream can be mapped for both decoding and streamcopying. A bsf in principle would work but in practice, can't as Andreas clarified that bsfs can't set or alter codec_id after init. And resetting the codec id requires packet inspection. Nested decoders are used without issue in components like imm5 or ftr (upto 64 nested decoders!) among others. There's no breaking of new ground here. If you feel strongly about this, please refer this to the TC. Regards, Gyan _______________________________________________ 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".