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[68.41.54.207]) by smtp.gmail.com with ESMTPSA id r26-20020a5d96da000000b00654b214def9sm10996589iol.52.2022.04.27.05.28.31 for (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 27 Apr 2022 05:28:31 -0700 (PDT) Message-ID: <52349af0-efb6-e5ed-9e20-ad4c03faa2f0@gmail.com> Date: Wed, 27 Apr 2022 08:28:30 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:91.0) Gecko/20100101 Thunderbird/91.8.1 Content-Language: en-US-large To: ffmpeg-devel@ffmpeg.org References: <20220426210834.314078-1-leo.izen@gmail.com> From: Leo Izen In-Reply-To: Subject: Re: [FFmpeg-devel] [PATCH] doc/encoders: document libjxl encoder options 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 4/27/22 04:39, Gyan Doshi wrote: > > > On 2022-04-27 02:38 am, Leo Izen wrote: >> >> + >> +@item modular >> +Force the encoder to use Modular mode. The default is to let the >> encoder pick >> +between VarDCT and Modular encoding modes based on encoding settings >> and the >> +type of input content. > > What happens in these two modes? Why would the user want to force > modular? Is there a way and reason to force VarDCT? > > VarDCT uses a fourier-DCT-based transform in essence. Modular uses a variety of transforms that can be combined like Lego bricks into patches, including a modified Haar transform. In general, VarDCT will be superior to Modular for lossy encoding, but VarDCT doesn't support lossless, so Modular is required for lossless encoding. Currently, the library always chooses VarDCT for lossy and Modular for lossless, although this could potentially be subject to change. A user will have very little reason to force modular unless they're testing the two modes against each other. The library API does not provide a way to force VarDCT. Or rather, it does, but if you force VarDCT and tell it to encode losslessly it will silently use modular rather than fail. You generally won't have a reason to force VarDCT anyway, since it's chosen by default if you pick lossy, so this isn't an issue. Leo Izen (thebombzen) _______________________________________________ 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".