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 084DD49F55 for ; Thu, 16 May 2024 18:30:14 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 4D76268D476; Thu, 16 May 2024 21:30:11 +0300 (EEST) Received: from relay3-d.mail.gandi.net (relay3-d.mail.gandi.net [217.70.183.195]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 01CA768D25B for ; Thu, 16 May 2024 21:30:04 +0300 (EEST) Received: by mail.gandi.net (Postfix) with ESMTPSA id D4CB56000C for ; Thu, 16 May 2024 18:30:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=niedermayer.cc; s=gm1; t=1715884204; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=mUu/wYNiyeVfkMt8OYB6uwbl5VVKtqa+U1ddxaYUZ5o=; b=U3K9DIzlDr+1/HljnIBorOMbE0O2wX1T9yvcSANt4AMwO34GsB67PlG5NmEgGhu+Yw7cQH LU1bJ0e/sIK3ssHrXg9ZSc6XerP7yOwtnqg4Y1emyFDK4+Vxro/x3yMkEZmlmUj0Q6D9kA VIDnHN04gnWstQYhsV56dyczPc1vSBo1JndGKi75pWFNTyks6Kc9Tu0+FdwAo0e0ErSf+u deOBBkrWZOqDveq/OBkhTnnDfKQdfGtjkqSnZVWwNT8C591oPwZ7ow7TKnaHUTm/fJSZkg k0JiqCQuuvSD+cl0HVwzNfkzH8r3CjLq0jU2PlJbAAs53mcy6hUTAQjQ82rfug== Date: Thu, 16 May 2024 20:30:02 +0200 From: Michael Niedermayer To: FFmpeg development discussions and patches Message-ID: <20240516183002.GP6420@pb2> References: <20240516100818.246162-1-dev@lynne.ee> <20240516100818.246162-2-dev@lynne.ee> MIME-Version: 1.0 In-Reply-To: <20240516100818.246162-2-dev@lynne.ee> X-GND-Sasl: michael@niedermayer.cc Subject: Re: [FFmpeg-devel] [PATCH 1/8] aacdec: move from scalefactor ranged arrays to flat arrays 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: multipart/mixed; boundary="===============4910342538213160024==" Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: --===============4910342538213160024== Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="37j9J1DThWDabdWS" Content-Disposition: inline --37j9J1DThWDabdWS Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, May 16, 2024 at 12:08:11PM +0200, Lynne via ffmpeg-devel wrote: > AAC uses an unconventional system to send scalefactors > (the volume+quantization value for each band). > Each window is split into either 1 or 8 blocks (long vs short), > and transformed separately from one another, with the coefficients > for each being also completely independent. The scalefactors > slightly increase from 64 (long) to 128 (short) to accomodate > better per-block-per-band volume for each window. >=20 > To reduce overhead, the codec signals scalefactor sizes in an obtuse way, > where each group's scalefactor types are sent via a variable length decod= ing, > with a range. > But our decoder was written in a way where those ranges were carried thro= ugh > the entire decoder, and to actually read them you had to use the range. >=20 > Instead of having a dedicated array with a range for each scalefactor, > just let the decoder directly index each scalefactor. >=20 > This also switches the form of quantized scalefactors to the format > the spec uses, where for intensity stereo and regular, scalefactors > are stored in a scalefactor - 100 form, rather than as-is. >=20 > USAC gets rid of the complex scalefactor handling. This commit permits > for code sharing between both. > --- > libavcodec/aac/Makefile | 3 +- > libavcodec/aac/aacdec.c | 100 ++++++++++++--------------- > libavcodec/aac/aacdec.h | 5 +- > libavcodec/aac/aacdec_dsp_template.c | 95 ++++++++++--------------- > 4 files changed, 85 insertions(+), 118 deletions(-) >=20 > diff --git a/libavcodec/aac/Makefile b/libavcodec/aac/Makefile > index c3e525d373..8b0bfff3e5 100644 > --- a/libavcodec/aac/Makefile > +++ b/libavcodec/aac/Makefile > @@ -2,6 +2,7 @@ clean:: > $(RM) $(CLEANSUFFIXES:%=3Dlibavcodec/aac/%) > =20 > OBJS-$(CONFIG_AAC_DECODER) +=3D aac/aacdec.o aac/aacdec_tab.o \ > - aac/aacdec_float.o > + aac/aacdec_float.o aac/aacdec_us= ac.o \ > + aac/aacdec_ac.o AR libavcodec/libavcodec.a ar: libavcodec/aac/aacdec_ac.o: No such file or directory make: *** [ffbuild/library.mak:38: libavcodec/libavcodec.a] Error 1 [...] --=20 Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB In fact, the RIAA has been known to suggest that students drop out of college or go to community college in order to be able to afford settlements. -- The RIAA --37j9J1DThWDabdWS Content-Type: application/pgp-signature; name="signature.asc" -----BEGIN PGP SIGNATURE----- iF0EABEKAB0WIQSf8hKLFH72cwut8TNhHseHBAsPqwUCZkZQpAAKCRBhHseHBAsP q6emAJ91DojfSm3tpFZ935qne2GCfaeEZwCeJ3UlmWneXHu+IqaG6FwgCCJGrzk= =2F88 -----END PGP SIGNATURE----- --37j9J1DThWDabdWS-- --===============4910342538213160024== Content-Type: text/plain; charset="us-ascii" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Content-Disposition: inline _______________________________________________ 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". --===============4910342538213160024==--