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 9C43742C5E for ; Mon, 2 May 2022 22:51:20 +0000 (UTC) Received: from [127.0.1.1] (localhost [127.0.0.1]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTP id 07FA168B2B5; Tue, 3 May 2022 01:51:18 +0300 (EEST) Received: from avasout-ptp-003.plus.net (avasout-ptp-003.plus.net [84.93.230.244]) by ffbox0-bg.mplayerhq.hu (Postfix) with ESMTPS id 50DB468B294 for ; Tue, 3 May 2022 01:51:10 +0300 (EEST) Received: from sparrow.collectfair.co.uk ([80.229.167.224]) by smtp with SMTP id lesinKiUTGjO8lesjnY8AT; Mon, 02 May 2022 23:51:10 +0100 X-Clacks-Overhead: "GNU Terry Pratchett" X-CM-Score: 0.00 X-CNFS-Analysis: v=2.4 cv=HttlpmfS c=1 sm=1 tr=0 ts=6270605e a=kGmXhoCkr3jB6KbzR35ddQ==:117 a=kGmXhoCkr3jB6KbzR35ddQ==:17 a=8nJEP1OIZ-IA:10 a=oZkIemNP1mAA:10 a=emhf11hzAAAA:8 a=x6GE8WT5UgPu2nJ_AsAA:9 a=wPNLvfGTeEIA:10 a=HLUCug_QN4oeKp6PugZw:22 Received: (qmail 4870 invoked from network); 2 May 2022 22:50:01 -0000 Received: from localhost (HELO webmail.megapico.co.uk) (127.0.0.1) by sparrow.collectfair.co.uk with SMTP; 2 May 2022 22:50:01 -0000 Received: from 192.168.0.1 (auth. user dif@localhost) by webmail.megapico.co.uk with HTTP; Mon, 02 May 2022 22:50:01 +0000 To: "FFmpeg development discussions and patches" Date: Mon, 02 May 2022 22:50:01 +0000 X-Mailer: IlohaMail/0.8.14 Message-ID: <9QyOO8W2.1651531801.9277750.dif@localhost> In-Reply-To: From: "David Fletcher" Bounce-To: "David Fletcher" MIME-Version: 1.0 X-CMAE-Envelope: MS4xfDN3vfbOp4CYXRSi/+5xnLv+a5JOOeFcVhHbLDWXiq51VgTLic//TB0aEenJstS40MBn8vyt8xUHKmYv/JyezFcwzFixxavZ+LiTd2XpArbHBRlhrEhQ QOpTPaNfFvhVl9iQzl2s1Xls5sNg2ph706Hxyy0E9xwnKf4qh08uQvEW6jIcyByroFnadDZBwcMqAS+WoO25OvJJVdjmWuuhQ0Y= Subject: Re: [FFmpeg-devel] PATCH - libmad MP3 decoding support 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="iso-8859-1" Content-Transfer-Encoding: quoted-printable Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" Archived-At: List-Archive: List-Post: On 2/5/2022, "Martin Storsj=F6" martin at martin.st wrote: > That sounds like there's an issue with some of the ARM implementations of = > DSP functions, that only exists in implementations for less featureful AR= M = > instruction sets. > = > (It could theoretically be a compiler bug also but I think it's much more = > probable that it's a bug in a seldom used codepath in ffmpeg.) > = > If you pass "-cpuflags 0" to ffmpeg, does the issue vanish? (If it does, = > it would suggest an issue in e.g. an armv5/armv6 specific implementation = > of some DSP functions.) Does if vanish if you configure with = > --arch=3Dgeneric? (That would omit all ARM specific DSP routines and just = > use plain C code.) > = > On a more modern ARM cpu, if it works correctly normally, does the issue = > appear if you use "-cpuflags 0"? That would indicate an issue in one of = > the ARM specific routines that are enabled without cpuflags (e.g. that = > don't require anything above armv4). > = Hi Martin, Thanks for these tips. I've posted a bug tracker about this issue, and also created some sample audio files that demonstrate things working well on ARMv7, but with distortion on ARMv4. https://trac.ffmpeg.org/ticket/9764 So far I've been using the libav libraries rather than ffmpeg so it's not so easy to pass "-cpuflags 0". But this is I think doing the same thing I've been doing with when configuring to compile FFmpeg. I tried a range of --disable-vfp --disable-neon --enable-asm or --disable-asm. I could not find a combination that makes the issue go away. As you say, that could well indicate something in an ARM routine that always runs, and is not superseded by an ARM5 or higher alternative when the CPU can handle that. I've not tried --arch=3Dgeneric. I'm cross-compiling on x86 targeting ARMv4 so the cross-compile will stop working properly if I take out --arch=3Darmv4t. I'll do some further investigation and see if I can create ffmpeg through the cross-compilation rather than the transcode program I've been using (this is based on the example transcode_aac). Many thanks, David. _______________________________________________ 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".