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682 discussions

MAD performance
by Grigory A. 23 Dec '04

23 Dec '04

Hi! I want to a little discuss this topic - MAD performance. 1. The reason is - usage of MAD in embedded systems. In this case memory usage and cpu cycles consumption are become critical issues. Rewriting of 7-8 functions on asm can provide good compromise between software complexity and decoder performance. Yes it makes code platform specific - but I hope it is acceptable way for embedded systems. 2. some current results. Using such way I've ported MAD to 2 dsp platform: TI tms320vc55xx and 3DSP sp3r5m. Memory: Simple libmab + minimad application can be fitted in less than 16 000 DSP instructions and all data memory usage: constant tables + buffers + stack takes less than 64 kBytes. Cycles: there are functions with fixed "cycles requirements" - independent of input bitsream, slightly depended and highly. good example of first type is frame synthesis - mad_synth_frame() and last type - III_huffdecode(); now in average for these dsp synthesis takes ~100-120k cycles 3. interest. And finally I wanna ask only one thing: Is it possible to improve III_huffdecode() function in meaning of cycles usage? because right now average frame size of input mp3 bitstream is 300-400 bytes (128 kbps / 44 frames ) - and to decode this 350 bytes III_huffdecode() spends ~250k+ cycles! this is real bottleneck in calculation process. And at higher bitrates cycles consumption just growing up. What ways can you propose to overcome it? for example scenario: - "unpack necessary tables" : ~50k cycles - "look up" decoding process: less than ... cycles any proposal are highly welcome. -- Best regards, Grigory mailto:Ryhor@tut.by

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Re:
by Djslakor 29 Nov '04

29 Nov '04

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Re:
by Djslakor 29 Nov '04

29 Nov '04

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Re:
by Djslakor 29 Nov '04

29 Nov '04

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Could you add a function to check whether a file can be decoded by libmad?
by nikos＠altern.org 28 Nov '04

28 Nov '04

Hello, I was wondering if it was possible to you to add a function to check whether libmad can or not decode a file (something like mp3-check, but more simple, maybe by just checking the header). For more informations on why it may be useful, please see this bug report of mpg321 : http://sourceforge.net/tracker/index.php?func=detail&aid=948476&group_id=36… Thank you very much

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Problem with recent ALSA versions in madplay
by David Gómez 09 Nov '04

09 Nov '04

Hi all ;), I got this problem with latest madplay release: MPEG Audio Decoder 0.15.2 (beta) - Copyright (C) 2000-2004 Robert Leslie et al. ALSA lib pcm.c:826:(snd_pcm_sw_params) snd_pcm_sw_params: params->avail_min problem for start_threshold Unable to set sw params for playback: Invalid argument output: Invalid argument I asked in the alsa mailing lists and they told me that madplay is trying to set incosistent parameters. I looked for a developtment version or cvs with this problem fixed, in the underbit web but i didn't find it anything. Thanks in advance, -- David Gómez Jabber ID: davidge(a)jabber.org

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Re: [mad-user] madlld extension for proper 16bit pcm output
by Bertrand Petit 07 Nov '04

07 Nov '04

[Note: reply posted to mad-dev] On Sun, Nov 07, 2004 at 03:20:00AM +0000, Jens Lippmann wrote: > > Finally I wrote a header to be included in madlld.cpp. Thanks for you feedback. Unfortunately I can't accept your submission for inclusion in madlld as this would create a mix of BSD- and GPL-licensed code that is not permitted by the GPL. Also note that madlld is not a complete decoder example, it is intended to be a kind of documentation that explains how to use libmad's low level interface only. Other subjects such as rendition of the fixed point numbers, buffering, audio and video synchronization were left alone as these were not the subject of the discussion. However since there seems to be some applications using mad that are modeled after madlld and have not provided a correct conversion function, I may, if time permit, add one to the next release of madlld to avoid further spreading of bad implementations. -- %!PS 297.6 420.9 translate 90 rotate 0 setgray gsave 0 1 1{pop 0 180 moveto 100 180 170 100 170 -10 curveto 180 -9 180 -9 190 -10 curveto 190 100 100 180 0 180 curveto fill 180 rotate}for grestore/Bookman-LightItalic findfont 240 scalefont setfont -151.536392 -63.7998886 moveto (bp)show showpage

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Cross compiling for Win32
by David Barron 04 Nov '04

04 Nov '04

I keep seeing references to mad.dll for windows but I can't seem to find it anywhere. So I'm trying to build it myself (yeah, right). I'm using the Microsoft Visual C++ Toolkit, which is a free download from Microsoft. It does not include the Visual Studio IDE or the Nmake utility, so I have to compile and link manually. No problem I can work handle that, but the compile is failing with the following error: Fixed.h(446) : fatal error C1189: #error : "no FPM selected" I get this error several times, of course. And I'm also getting: Cannot open include file: 'sys/mman.h': No such file or directory And Cannot open include file: 'unistd.h': No such file or directory Am I wasting my time? By the way, my ultimate goal is to create a Java Native Interface to mad, so if anyone has been working on this I'd appreciate if you could let me know. Thanks David

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[patch] [libid3tag] handle general case when writing id3v2 tags
by Sam Clegg 31 Oct '04

31 Oct '04

I can remember whether I have submitted this patch before but I've had it knocking around for while. The patch is against 0.15.1b in debian/sid. It works for me and I would like to get it included in libid3tag as the current version will silently fail to write updated tags that are not the same size as the original. I've made rather crude use of malloc to handle moving the audio data to accommodate the new tag. If you'd rather I can rewrite it to use iteration and a fixed size buffer. It also relies on ftruncate for the case when a tag shrinks which i'm guessing will require a windows alternative. cheers, sam -- sam clegg :: sam(a)superduper.net :: http://superduper.net/ :: PGP : D91EE369 $superduper: .signature,v 1.13 2003/06/17 10:29:24 sam Exp $

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Programing a radio-station
by ALBERT.ALADID 18 Oct '04

18 Oct '04

end or -- I'm currently developing a radio-sation software. I want to add MP3 playback features. It is writen in Visual Basic. I've found that I can use libMAD and/or mpg321 or Directx. Has anyone experience at reproducing MP3? Note: I need complete control over the sound, and I'm not desiring to place a component like windows media player inside my aplication.

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