From owner-freebsd-questions@FreeBSD.ORG Tue Jun 13 15:09:30 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 2F55D16A41A for ; Tue, 13 Jun 2006 15:09:30 +0000 (UTC) (envelope-from cswiger@mac.com) Received: from pi.codefab.com (pi.codefab.com [199.103.21.227]) by mx1.FreeBSD.org (Postfix) with ESMTP id 7B06A43D53 for ; Tue, 13 Jun 2006 15:09:29 +0000 (GMT) (envelope-from cswiger@mac.com) Received: from localhost (localhost [127.0.0.1]) by pi.codefab.com (Postfix) with ESMTP id 861C55DBA; Tue, 13 Jun 2006 11:09:28 -0400 (EDT) X-Virus-Scanned: amavisd-new at codefab.com Received: from pi.codefab.com ([127.0.0.1]) by localhost (pi.codefab.com [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id RLR8nL2rQeEy; Tue, 13 Jun 2006 11:09:27 -0400 (EDT) Received: from [192.168.1.251] (pool-68-160-201-170.ny325.east.verizon.net [68.160.201.170]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by pi.codefab.com (Postfix) with ESMTP id 49C705C27; Tue, 13 Jun 2006 11:09:27 -0400 (EDT) Message-ID: <448ED58E.7010402@mac.com> Date: Tue, 13 Jun 2006 11:11:10 -0400 From: Chuck Swiger User-Agent: Thunderbird 1.5.0.4 (Windows/20060516) MIME-Version: 1.0 To: Howard Jones References: <7.0.1.0.2.20060613145307.023662b0@broadpark.no> <448EC879.1010603@mac.com> <448ECAB3.5090900@thingy.com> In-Reply-To: <448ECAB3.5090900@thingy.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-questions@freebsd.org Subject: Re: [freebsd-questions] Scanning MP3 files for skips X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 Jun 2006 15:09:30 -0000 Howard Jones wrote: > Chuck Swiger wrote: [ ...ID'ing skips in music... ] >> Sort of...GraceNote and a few other companies ("Shazam", seems to be >> from India?) sell a service where music files can be fingerprinted and >> identified. Good audio files ought to ID as what they are; bad music >> files with skips or garbage will fail to ID. >> > Shazam (at least) works on a fragment the song. In the UK they provide a > phone-based service, which only needs 20-30 seconds of clear music to > identify a song. Yeah, that's right. But there's also a fingerprinting tool which creates something called QCF files (Qualcom something-or-other) which analyses the entire song and should notice major skips or distortions better. [ ... ] > I'm also looking for a blip-detecting MP3 tool. I haven't had time to > look at it yet, but I was going to try something like libmad on the > assumption that somewhere internally it knows when it's only had half an > frame of data, even if there is no CRC. That way, it'll work on any > obscure music I have, without relying on some external giant database of > correctness. That's the rub of the matter: most home-grown tools are going to find it hard to recognize a skip from Trent Reznor or a lot of rap music, or a dropout with silences common in classic music, etc. :-) With the external giant database of correctness, you've got something which actually can tell that a song isn't correct, rather than making guesses, even if you have to break your samples down into 10 to 30 second pieces and check them all individually. [ Again, I would try using the QCF fingerprinting tool instead of exhaustive submatch checking. On the other hand, if you can manage to put together something which can guess well, I'd be interested in seeing it... ] -- -Chuck