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@dweekly dweekly/mp3acm.c
Created Oct 19, 2010

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Windows Snippet To Use Built-in ACM MP3 Decoder
#include <windows.h>
#include <stdio.h>
#include <assert.h>
#include <mmreg.h>
#include <msacm.h>
#define MP3_BLOCK_SIZE 522
#define SOURCE_MP3 "C:\\audiograbber\\At The Club Last Night\\At_The_Club_Last_Night_-_Haven't_You_Heard.mp3"
#define OUTPUT_PCM_FILE "c:\\dump.pcm"
int g_mp3Drivers = 0;
BOOL CALLBACK acmDriverEnumCallback( HACMDRIVERID hadid, DWORD dwInstance, DWORD fdwSupport ){
if( fdwSupport & ACMDRIVERDETAILS_SUPPORTF_CODEC ) {
MMRESULT mmr;
ACMDRIVERDETAILS details;
details.cbStruct = sizeof(ACMDRIVERDETAILS);
mmr = acmDriverDetails( hadid, &details, 0 );
HACMDRIVER driver;
mmr = acmDriverOpen( &driver, hadid, 0 );
int i;
for(i = 0; i < details.cFormatTags; i++ ){
ACMFORMATTAGDETAILS fmtDetails;
ZeroMemory( &fmtDetails, sizeof(fmtDetails) );
fmtDetails.cbStruct = sizeof(ACMFORMATTAGDETAILS);
fmtDetails.dwFormatTagIndex = i;
mmr = acmFormatTagDetails( driver, &fmtDetails, ACM_FORMATTAGDETAILSF_INDEX );
if( fmtDetails.dwFormatTag == WAVE_FORMAT_MPEGLAYER3 ){
OutputDebugString( L"Found an MP3-capable ACM codec: " );
OutputDebugString( details.szLongName );
OutputDebugString( L"\n" );
g_mp3Drivers++;
}
}
mmr = acmDriverClose( driver, 0 );
}
return true;
}
HACMSTREAM g_mp3stream = NULL;
convertMP3(){
MMRESULT mmr;
// try to find an MP3 codec
acmDriverEnum( acmDriverEnumCallback, 0, 0 );
if(g_mp3Drivers == 0){
OutputDebugString( L"No MP3 decoders found!\n" );
return E_FAIL;
}
// find the biggest format size
DWORD maxFormatSize = 0;
mmr = acmMetrics( NULL, ACM_METRIC_MAX_SIZE_FORMAT, &maxFormatSize );
// define desired output format
LPWAVEFORMATEX waveFormat = (LPWAVEFORMATEX) LocalAlloc( LPTR, maxFormatSize );
waveFormat->wFormatTag = WAVE_FORMAT_PCM;
waveFormat->nChannels = 2; // stereo
waveFormat->nSamplesPerSec = 44100; // 44.1kHz
waveFormat->wBitsPerSample = 16; // 16 bits
waveFormat->nBlockAlign = 4; // 4 bytes of data at a time are useful (1 sample)
waveFormat->nAvgBytesPerSec = 4 * 44100; // byte-rate
waveFormat->cbSize = 0; // no more data to follow
// define MP3 input format
LPMPEGLAYER3WAVEFORMAT mp3format = (LPMPEGLAYER3WAVEFORMAT) LocalAlloc( LPTR, maxFormatSize );
mp3format->wfx.cbSize = MPEGLAYER3_WFX_EXTRA_BYTES;
mp3format->wfx.wFormatTag = WAVE_FORMAT_MPEGLAYER3;
mp3format->wfx.nChannels = 2;
mp3format->wfx.nAvgBytesPerSec = 128 * (1024 / 8); // not really used but must be one of 64, 96, 112, 128, 160kbps
mp3format->wfx.wBitsPerSample = 0; // MUST BE ZERO
mp3format->wfx.nBlockAlign = 1; // MUST BE ONE
mp3format->wfx.nSamplesPerSec = 44100; // 44.1kHz
mp3format->fdwFlags = MPEGLAYER3_FLAG_PADDING_OFF;
mp3format->nBlockSize = MP3_BLOCK_SIZE; // voodoo value #1
mp3format->nFramesPerBlock = 1; // MUST BE ONE
mp3format->nCodecDelay = 1393; // voodoo value #2
mp3format->wID = MPEGLAYER3_ID_MPEG;
g_mp3stream = NULL;
mmr = acmStreamOpen( &g_mp3stream, // open an ACM conversion stream
NULL, // querying all ACM drivers
(LPWAVEFORMATEX) mp3format, // converting from MP3
waveFormat, // to WAV
NULL, // with no filter
0, // or async callbacks
0, // (and no data for the callback)
0 // and no flags
);
LocalFree( mp3format );
LocalFree( waveFormat );
switch( mmr ) {
case MMSYSERR_NOERROR:
break; // success!
case MMSYSERR_INVALPARAM:
assert( !"Invalid parameters passed to acmStreamOpen" );
return E_FAIL;
case ACMERR_NOTPOSSIBLE:
assert( !"No ACM filter found capable of decoding MP3" );
return E_FAIL;
default:
assert( !"Some error opening ACM decoding stream!" );
return E_FAIL;
}
// MP3 stream converter opened correctly
// now, let's open a file, read in a bunch of MP3 data, and convert it!
// open file
FILE *fpIn = fopen( SOURCE_MP3, "rb" );
if( fpIn == NULL ){
assert( !"can't open MP3 file!" );
return E_FAIL;
}
// find out how big the decompressed buffer will be
unsigned long rawbufsize = 0;
mmr = acmStreamSize( g_mp3stream, MP3_BLOCK_SIZE, &rawbufsize, ACM_STREAMSIZEF_SOURCE );
assert( mmr == 0 );
assert( rawbufsize > 0 );
// allocate our I/O buffers
LPBYTE mp3buf = (LPBYTE) LocalAlloc( LPTR, MP3_BLOCK_SIZE );
LPBYTE rawbuf = (LPBYTE) LocalAlloc( LPTR, rawbufsize );
// prepare the decoder
ACMSTREAMHEADER mp3streamHead;
ZeroMemory( &mp3streamHead, sizeof(ACMSTREAMHEADER ) );
mp3streamHead.cbStruct = sizeof(ACMSTREAMHEADER );
mp3streamHead.pbSrc = mp3buf;
mp3streamHead.cbSrcLength = MP3_BLOCK_SIZE;
mp3streamHead.pbDst = rawbuf;
mp3streamHead.cbDstLength = rawbufsize;
mmr = acmStreamPrepareHeader( g_mp3stream, &mp3streamHead, 0 );
assert( mmr == 0 );
// let's dump this data off to disk (for debug checking!)
FILE *fpOut = fopen( OUTPUT_PCM_FILE, "wb" );
if( fpOut == NULL ){
assert( !"can't output output PCM!" );
return E_FAIL;
}
while(1) {
// suck in some MP3 data
int count = fread( mp3buf, 1, MP3_BLOCK_SIZE, fpIn );
if( count != MP3_BLOCK_SIZE )
break;
// convert the data
mmr = acmStreamConvert( g_mp3stream, &mp3streamHead, ACM_STREAMCONVERTF_BLOCKALIGN );
assert( mmr == 0 );
// write the decoded PCM to disk
count = fwrite( rawbuf, 1, mp3streamHead.cbDstLengthUsed, fpOut );
assert( count == mp3streamHead.cbDstLengthUsed );
};
// clean up after yourself like a good little boy
fclose( fpIn );
fclose( fpOut );
mmr = acmStreamUnprepareHeader( g_mp3stream, &mp3streamHead, 0 );
assert( mmr == 0 );
LocalFree(rawbuf);
LocalFree(mp3buf);
mmr = acmStreamClose( g_mp3stream, 0 );
assert( mmr == 0 );
return S_OK;
}
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