mad-dev

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682 discussions

need you help
by lizhan 30 Apr '06

30 Apr '06

Dear Sir/Madam: Recently, I take part in developing a mp3 decoder, and we come across a questios that is: How to test the mp3 LIBMAD decoder compliance with respect to the ISO/IEC 11172 international standard, which are stated in http://www.underbit.com/resources/mpeg/audio/compliance/. To test the decoder compliance, our method are taken as follows: 1. we get a test case (layer 3 test bitstreams), which we got from the web ftp://ftp.fhg.de/pub/layer3/ at Fraunhofer Institut. The case consists of: compl.bit the test bitstream (10Hz-10kHz/-20dB sine sweep) mono, 48 kHz compl.hex reference output in 24bit ascii hex format (mono) These two files are mp3 test bitstreams whice are designed to help verify that an mpeg decoder works properly.These conformance bitstreams are the official test bitstreams provided by the MPEG committee. 2. next we catch the audio output data by decoding the bitstream "compl.bit" with our player. 3. then compare this output with the reference output "compl.hex". However we found the two output are totally different. I wonder if somebody are kindly enough to share us with what is your test method and test case to do the compliance test. Looking forward your response. Best regards! leon email:lizhan@amoi.com.cn

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MAD/ARM archeology..
by john cooper 14 Apr '06

14 Apr '06

Hello, I've been lugging around a 0.13 version of libmad for about 5 years for use in a back burner project. I've ported the works to PPC about a year ago and just today to ARM. With 0.13 libmad there seems to be some really funky decode artifacts in libmad 0.13/ARM (but not in 0.15.1) which I couldn't explain. I noticed a few ARM-specific changes in fixed.h between 0.15.1 and 0.13 as well as what appear to be some tweaks called out in the CHANGES file. But the echo-like decode artifacts were so dramatic I can't believe they would have gone unnoticed nor unaddressed. I suppose it could be some odd build issue local to my work but that seems rather remote. Anyone encounter any similar issue specific to ARM in or around that vintage? Thanks, -john -- john.cooper(a)third-harmonic.com

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VBR headers, and even ID3v2
by Cameron Gorrie 09 Apr '06

09 Apr '06

In a March 2004 post on this list, this little snippet came up: > On Mar 30, 2004, at 2:17 PM, Glenn Maynard wrote: > >>* There's no support for reading Xing/LAME VBR header tags in libmad, > *>>* but > *>>* the code to do it can be found in madplay (see tag.c). > *>* > *>* Note that this code doesn't parse "Info" tags, which are just Xing > *>* tags but are usually written for CBR files (probably to not confuse > *>* players which assume existance a Xing tag means VBR). > * > Actually since version 0.15.1b, it does -- at your suggestion, in fact. > It also reads any LAME tag following the Xing info, which contains > Replay Gain information. > > Now I have version 0.15.1b, but I don't know how to access this data - specifically, the computed length of the file. Also, I read somewhere that support for ID3v2 headers was being built into MAD. Is there any truth in this, or should I be doing it on my own?

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cross-compile libmad for ARM
by waseim mohamed 05 Apr '06

05 Apr '06

i just need help in exact steps to cross compile libmad for arm. and whatoptions should be used when configuring? Thanks in advance.. _________________________________________________________________ On the road to retirement? Check out MSN Life Events for advice on how to get there! http://lifeevents.msn.com/category.aspx?cid=Retirement

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Documentation
by MUNDOALEM.com 17 Mar '06

17 Mar '06

Hi, I'm starting to code with libmad and libid3tag now builting and mp3 player with my need just for studying purposes. I'm coding with ANSI C, I don't program in C++. And I have found lack or none documentation of libmad and libid3tag. So if o you know any website or even doc files which explains how to use this libs I'll apreciate it. So thank you very much. --------------------- MUNDOALEM.com Entreternimento Digital

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Compiling zlib library
by Arpita Ghosh 10 Mar '06

10 Mar '06

We are trying to compile the zlib library using DSP16k compiler - cc16k. I get an error saying the symbol "__vsnprintf" was not found. Can anyone tell me how I can get around this problem? Thanks.

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The test code for mp3 decoder compliance
by Li Xiaochao.Jeff 12 Feb '06

12 Feb '06

Hello, Does anyone has the ideal about how to test the libmad output quality or compliant test? Or did anyone write the similar test for Libmad before? Best regards, Li xiaochao.Jeff

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How to use the libmad low-level API
by Håvard Engebretsen 10 Feb '06

10 Feb '06

Hi! I am currently decoding mp3 files using the minimad mp3-decoder and the high-level API. Can anybody tell me how to use the low-level API instead of the high-level? Regards Håvard.

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Re: mad-dev Digest, Vol 9, Issue 2
by Li Xiaochao.Jeff 08 Feb '06

08 Feb '06

Lowering the precision might affect the final quality of audio output. "defining MAD_F_FRACBITS to 16 bits" might cause the inferior quality, while the original precision is 28bits for Libmad. I am wondering if the song could be acceptable that way. Best regards, Li xiaochao.Jeff ----- Original Message ----- From: <mad-dev-request(a)lists.mars.org> To: <mad-dev(a)lists.mars.org> Sent: Friday, February 03, 2006 4:00 AM Subject: mad-dev Digest, Vol 9, Issue 2 > Send mad-dev mailing list submissions to > mad-dev(a)lists.mars.org > > To subscribe or unsubscribe via the World Wide Web, visit > http://www.mars.org/bin/mailman/listinfo/mad-dev > or, via email, send a message with subject or body 'help' to > mad-dev-request(a)lists.mars.org > > You can reach the person managing the list at > mad-dev-owner(a)lists.mars.org > > When replying, please edit your Subject line so it is more specific > than "Re: Contents of mad-dev digest..." > > > Today's Topics: > > 1. Reducing preision on intermediate data in minimad during > decoding (H?vard Engebretsen) > > > ---------------------------------------------------------------------- > > Message: 1 > Date: Thu, 2 Feb 2006 15:37:53 +0100 > From: H?vard Engebretsen <havardsp(a)stud.ntnu.no> > Subject: [mad-dev] Reducing preision on intermediate data in minimad > during decoding > To: <mad-dev(a)lists.mars.org> > Message-ID: <20060202143738.045A913C480(a)merke.itea.ntnu.no> > Content-Type: text/plain; charset="iso-8859-1" > > Hi! > > > > I am looking into the possibility of lowering the precision of the > intermediate data in minimad during decoding (i.e. defining MAD_F_FRACBITS > to 16 bits). Does anyone know if this will work, or will the lowered > precision corrupt the decoded data? > > > > Regards, > > Haavard > >

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Reducing preision on intermediate data in minimad during decoding
by Håvard Engebretsen 02 Feb '06

02 Feb '06

Hi! I am looking into the possibility of lowering the precision of the intermediate data in minimad during decoding (i.e. defining MAD_F_FRACBITS to 16 bits). Does anyone know if this will work, or will the lowered precision corrupt the decoded data? Regards, Haavard

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