mad-dev April 2004

mad-dev@lists.mars.org

10 participants
7 discussions

mp3gain vs madplay
by Bruce Fitzsimons 15 Sep '04

15 Sep '04

Peoples, I'm about to launch into a debugging session to see why mp3gain (http://mp3gain.sourceforge.net/ ) and madplay 0.15.1b don't seem to be playing together (no pun intended). I thought I'd ask if anyone has used the two together yet, or if there is another linux-based replaygain processor (for adding replaygain to existing mp3s) that is more reliable. map3gain does appear to be adding a tag, as it finds it again if rerun over the same file. "# mp3gain /tmp/Abracadabra.mp3 /tmp/Abracadabra.mp3 Recommended "Track" dB change: -1.690000 Recommended "Track" mp3 gain change: -1 Max PCM sample at current gain: 28533.063680 Max mp3 global gain field: 180 Min mp3 global gain field: 116 Recommended "Album" dB change for all files: -7.490000 Recommended "Album" mp3 gain change for all files: -5" madplay doesn't appear to find it: "# madplay -G -Tv /tmp/Abracadabra.mp3 MPEG Audio Decoder 0.15.1 (beta) - Copyright (C) 2000-2004 Robert Leslie et al. Title: Abracadabra Artist: The Steve Miller Band Album: Golds Greatest Hits Track: 11 Year: 1982 Genre: Vocal Encoder Version: LAME 3.92 VBR Method: constant Bitrate: 255+ kbps Stereo Mode: normal Preset: none Unwise Settings: no Encoding Flags: Lowpass Filter: 19500 Hz ATH Type: 2 Noise Shaping: 1 Surround: none Start Delay: 576 samples End Padding: 1503 samples Source Rate: 44.1 kHz Music Length: 9948263 bytes Audio Frames: 11900" (note the missing "Replay Gain" printout I expect after reading the source) I'd hasten to add that I suspect mp3gain of doing something wrong, not madplay. I'm guessing the tag is wrong or in the wrong place. Any info would be appreciated, otherwise I'll report my findings to the list when I discover the root cause. /Bruce

5 8

Progress meter
by Hamish Allan 30 Apr '04

30 Apr '04

Hi folks, I've just started writing an audio processing utility, using libmad to read from MP3 files. I've modelled my code on minimad.c and it works fine, but as I'm decoding each file all at once, I want to provide a progress meter. In minimad.c the whole file is mmapped, so the read function only gets called once. I figured I would change my read function to make available a small fraction of the data, update the progress bar, then make the next block available, etc. Unfortunately this doesn't work, I get "lost synchronisation" , "reserved sample frequency value", "bad main_data_begin pointer", "forbidden bitrate value" and "Huffman data overrun" errors each time I return a new block of data. As far as I can tell, my code is doing the right thing (I've included it below). In madllc.c, there is provision for when a frame is not wholly included by a buffer, but I would expect in the case of the high-level functions that this would be detected by mad_decoder_run and the input function would be polled for more data automatically. Am I missing something obvious? Also, is there a better way to implement a progress bar? Thanks in advance, Hamish P.S. this code is in Objective-C: "[inputData length]" does what the C++ "inputdata.length()" would do, and "id" is like "NSObject *" (NSObject is the root object). struct dataDescriptor { NSData *inputData; NSMutableData *outputData; unsigned int bytesRead; unsigned int byteChunk; // number of bytes to read at a time id progressObject; }; static enum mad_flow madInput(void *data, struct mad_stream *stream) { struct dataDescriptor *descriptor = data; NSData *inputData = descriptor->inputData; unsigned int bytesTotal = [inputData length]; unsigned int bytesLeft = bytesTotal - descriptor->bytesRead; double progress = (double)(descriptor->bytesRead) / (double)bytesTotal; [descriptor->progressObject showProgress:progress] if (bytesLeft == 0) return MAD_FLOW_STOP; fprintf(stderr, "Bytes read=%d, left=%d\n", descriptor->bytesRead, bytesLeft); if (bytesLeft > descriptor->byteChunk) bytesLeft = descriptor->byteChunk; mad_stream_buffer(stream, [inputData bytes] + (descriptor->bytesRead), bytesLeft); descriptor->bytesRead += bytesLeft; return MAD_FLOW_CONTINUE; }

2 1

Reordering question
by Grigory A. 21 Apr '04

21 Apr '04

Hi! MAD for sp3r5m 3DSP core www.3dsp.com is ready. In average up to 256 kb/s 27MHz is more than enough to decode any mp3 bitstream. But 320 kb/s - required calculation is very close to available resources (and maybe even worst) Only - I want to improve performance in some places Now I am looking on void III_reorder(mad_fixed_t xr[576], struct channel const *channel, unsigned char const sfbwidth[39]) C implementation takes ~30 000 cycles - it is too much. So could you tell me can I use for reordering this one simple scheme for sb=0 to 31 do //For all 32 subbands for window=0 to 2 do //For each of the 3 windows for ws=0 to 5 do //For each sample within a window Xro[18*sb + ss] = Xdis[18*sb + window + 3*ws] //Reorder end for end for end for If answer is "no" - so could you explain the role of unsigned char const sfbwidth[39] in original MAD reordering function very shortly of course. Thanks for answers -- Best regards, Grigory mailto:Ryhor@tut.by

2 1

save PCM
by Гурин Олег 18 Apr '04

18 Apr '04

Hello. Why do I get PCM with loud noise while decoding? I receive Mp3 stream using HTTP. After mad_synth_frame I record 16-bit values on disk (as in the madlld example). During playback of the PCM obtained the music itself can hardly be heard because of noise ? (Win 2000 platform, libmad ver.0.15.1) --- Ваш легкий поиск ТУТ! http://go.tut.by

2 1

huffman.c macros
by Ian MacIntosh 14 Apr '04

14 Apr '04

I was building this on Solaris and noticed the macros for PTR and V only work for little-endian or gcc compilers. So I made a few changes, below are the macros rewritten for more portability: for huffquad # if defined(__GNUC__) || (__SUNPRO_C >= 0x556) # define PTR(offs, bits) { .ptr = { 0, bits, offs } } # define V(v, w, x, y, hlen) { .value = { 1, hlen, v, w, x, y } } #elif defined(WORDS_BIGENDIAN) # define PTR(offs, bits) { { 0, bits, offs } } # define V(v, w, x, y, hlen) { { 1, hlen, (v << 11) | (w << 10) | \ (x << 9) | (y << 8) } } #else # define PTR(offs, bits) { { 0, bits, offs } } # define V(v, w, x, y, hlen) { { 1, hlen, (v << 0) | (w << 1) | \ (x << 2) | (y << 3) } } # endif for huffpair # if defined(__GNUC__) || (__SUNPRO_C >= 0x556) # define PTR(offs, bits) { .ptr= { 0, bits, offs } } # define V(x, y, hlen) { .value= { 1, hlen, x, y } } # elif defined(WORDS_BIGENDIAN) # define PTR(offs, bits) { { 0, bits, offs } } # define V(x, y, hlen) { { 1, hlen, (x << 8) | (y << 4) } } # else # define PTR(offs, bits) { { 0, bits, offs } } # define V(x, y, hlen) { { 1, hlen, (x << 0) | (y << 4) } } # endif instead of the ptr: and value: it uses the C99 designator syntax, also I've changed the shifts for big-endian. obviously the WORDS_BIGENDIAN needs to come from the config.h. regards, Ian

1 0

Intensity stereo
by Grigory A. 12 Apr '04

12 Apr '04

Hi! Could someone give me or tell where can I take mp3 bitstream with joint stereo Intensity_Stereo_LSF_EXT all other bitsreams have been successfully tested. Only this one is question. If in MAD decoder there is such portion of code - I think it is tested. Thanks. Best regards, Grigory mailto:Ryhor@tut.by

1 0

unsusbcribe
by Alain 02 Apr '04

02 Apr '04

unsusbcribe ___________________________________________________________ WIN FREE WORLDWIDE FLIGHTS - nominate a cafe in the Yahoo! Mail Internet Cafe Awards www.yahoo.co.uk/internetcafes

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mad-dev April 2004