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682 discussions

Re: [mad-dev] Calculation error
by Tim Dylla 24 Aug '07

24 Aug '07

Andre schrieb: > Tim Dylla <tim.dylla(a)gmx.net> wrote: >> MAD in contrast introduces a perceivable error right on the first >> half wave of the sine sweep. I think, it's an overflow in the >> requantization or the IMDCT (when I remember right, the huffman >> decoder produces very high output at this moment). > > Just a hunch, but if you are able to build MAD from source, maybe you > could try the follow patch posted to the list a few years back... > perhaps it helps ?? > > diff -ruN mad-0.14.2b_orig/libmad/layer3.c > mad-0.14.2b/libmad/layer3.c > --- mad-0.14.2b_orig/libmad/layer3.c Thu Nov 8 15:28:02 2001 > +++ mad-0.14.2b/libmad/layer3.c Tue Mar 25 15:21:12 2003 > @@ -910,7 +910,7 @@ > fprintf(stderr, "requantize overflow (%f * 2^%d)\n", > mad_f_todouble(requantized), exp); > # endif > - requantized = MAD_F_MAX; > + requantized = MAD_F_MAX / 2; > } > else > requantized <<= exp; Nope, same Result. I'm sorry, I'm still sticking with my diploma, so I don't have the time for extensive tests right now. Maybe someone can confirm the problem and have a look at? Feel free to contact me for the Bitstream in Question and the correct decoder output. Best, Tim Dylla > > > Andre > -- > >

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[Offtopic] Stories about Process Change
by Christopher Oezbek 23 Aug '07

23 Aug '07

Hi MAD-Hackers, Hi Rob, I am researching what happens if a developer attempts to change the way a project works (in contrast to changing the software being developed) and have picked MAD as a small OSS project in long-term existence that seems to use a closed development strategy. I would be very interested in hearing if there was ever the need to modify the development process and if yes how successful have those changes been. I put up a survey of 13 questions (should take between 10 and 20 minutes) at http://survey.mi.fu-berlin.de/public/survey.php?name=changeEpisodeSurvey but you can also email me directly if you prefer. Thank you very much, Christopher Oezbek P.S.: If you are thinking about making such a change or are currently on it, feel free to drop me a note so I can share what I have learned so far. P.P.S.: Results will be made available at http://www.inf.fu-berlin.de/w/SE/SurveyChange over the next month, where you can also find further information. -- Christopher Oezbek Freie Universität Berlin http://www.inf.fu-berlin.de/~oezbek/

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problem with the seeking over
by cab 17 Aug '07

17 Aug '07

Hi, Ok, I managed to seek in a frame Thanks for your help Cab

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Re: [mad-dev] mad-dev Digest, seeking problem with libmad
by cab 16 Aug '07

16 Aug '07

Hi, You said I had to map the current file at a seek point but I just can't do itn there's a problem with the function mmap itself here's my source: (from minimad) int main(int argc, char *argv[]) { struct stat stat; void *fdm; if (argc != 1) return 1; int fd; FILE*fichier=fopen("essai.mp3","r+"); fd=fileno(fichier); lseek(fd,10,SEEK_SET); if (fstat(fd, &stat) == -1 || stat.st_size == 0) return 2; fdm = mmap(0,stat.st_size/2-1 , PROT_READ, MAP_SHARED, fd,stat.st_size/2); if (fdm == MAP_FAILED) return 3; decode(fdm, stat.st_size/2-1); if (munmap(fdm, stat.st_size/2-1) == -1) return 4; return 0; } I've got an error return 22 I know it's because the offset is not set to 0 thanks for your help

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test-bitstreams
by Tim Dylla 30 Jul '07

30 Jul '07

Hi list, since I'm doing final tests on my mp3-decoder implementation for a Blackfin DSP, I'm searching for teststreams coming with a decoded reference. The original ISO/IEC/Fraunhofer-teststream package contains only the decoded reference of the compliance bitstream. But (as you certainly know) it doesn't test the whole functionality of MP3 (not even short blocks), and the decoder in this package is crap (limited compliance, far away from being a reference). I'm searching for more bitstreams in company with their decoded reference to avoid adding up deviance of the used Encoder to my test results. Has anyone some resource regarding this? I'm interested in MPEG1 and 2 - Layer III bitstreams. Thanks in advance, Tim

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Computation Speed
by Tim Dylla 23 Jul '07

23 Jul '07

Hello List, I'm new to this list, let me introduce myself. I'm working on my Diploma for Applied Informatics, I have to implement the MP3-Decoder for the Analog Devices BF-533 DSP. It's the the final testphase regarding accuracy, where MAD really convinces. Since I want to leave the needed MIPS of my Algorithm low, I had to make some compromise between Accuracy and Speed. Now I wonder: how much MIPS needs MAD? Say, for the x86-Version optimized for Accuracy? Has anyone measured this? Or is there a Webpage with all that info, and I was just dumb? :) Best Regards, Tim Dylla

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compiling libmad in c++
by julien ricard 05 Jul '07

05 Jul '07

hi, how can I compile libmad using a c++ compiler? using g++ and -D__cplusplus gives errors. For example: $ g++ -c -D__cplusplus -DFPM_INTEL decoder.c decoder.c: In function 'void mad_decoder_init(mad_decoder*, void*, mad_flow (*)(void*, mad_stream*), mad_flow (*)(void*, const mad_header*), mad_flow (*)(void*, const mad_stream*, mad_frame*), mad_flow (*)(void*, const mad_header*, mad_pcm*), mad_flow (*)(void*, mad_stream*, mad_frame*), mad_flow (*)(void*, void*, unsigned int*))': decoder.c:76: error: invalid conversion from 'int' to 'mad_decoder_mode' decoder.c: In function 'mad_flow error_default(void*, mad_stream*, mad_frame*)': decoder.c:299: error: invalid conversion from 'void*' to 'int*' decoder.c: In function 'int mad_decoder_run(mad_decoder*, mad_decoder_mode)': decoder.c:553: error: invalid conversion from 'void*' to 'mad_decoder::<anonymous struct>*' thanks jul

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mad_stream_skip to seek to a new frame
by www.bigcab＠free.fr 19 Jun '07

19 Jun '07

I think I can use mad_stream_skip to seek a new frame but I always got a lost sync error I don't understand?

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libmad know the current bytes read or decoded
by www.bigcab＠free.fr 18 Jun '07

18 Jun '07

here I would like to know if it could be possible to know if we could retrive the current byte read (an equivalent of ftell) aren't there any functions for it? thanks very much

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problem with the seeking
by www.bigcab＠free.fr 18 Jun '07

18 Jun '07

Hi here I've got a VBR (variable bitrate file ) so I can't seek the right frame It's not as if I had a Pcm file can someone help me?

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