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Mp3 File Format

General and Gameplay Programming Programming

Started by Great Milenko August 27, 2001 09:33 PM

12 comments, last by Great Milenko 23 years, 5 months ago

Great Milenko

Author

122

August 27, 2001 09:33 PM

I''m looking for some info on the mp3 file format... not finding what I need... I''m fineding lots on reading in the headers... frame headers VBR headers ID3Tag..... hummm great I can chance the name of the song.... Thats not what I want... I want to beable to read in the file extract playable music from it... and then beable to write it back to file... I''m not finding anything on how the data is actualy compressed... anyone got a link for me?

The Great Milenko"Don't stick a pretzel up your ass, it might get stuck in there.""Computer Programming is findding the right wrench to hammer in the correct screw."

Shannon Barber

1,684

August 27, 2001 11:22 PM

You can use DirectShow to play MP3 files if that''s all you want to do.

Or go look up CDex and LAME at SourceForge. CDex is mostly the UI, and LAME is mostly the encoder.

Magmai Kai Holmlor
- Not For Rent

- The trade-off between price and quality does not exist in Japan. Rather, the idea that high quality brings on cost reduction is widely accepted.-- Tajima & Matsubara

Anonymous

August 28, 2001 01:16 AM

Ask KierenJ (or something like that). He knows aeverything about mp3''s and compression...

granat

122

August 28, 2001 01:16 AM

Ask KierenJ (or something like that). He knows everything about mp3's and compression...

Edited by - granat on August 28, 2001 2:17:26 AM

-------------Ban KalvinB !

Jasun220

122

August 28, 2001 06:56 AM

Or you can use the windows media player. I have the full source code that i use in my game, if you would like it, just ask

Boltimus

100

August 28, 2001 08:41 AM

I thought that if you wanted to get into the guts of MP3 you had to buy the license from them, as it is proprietery(sp ?). Unless others already have the info.. hehe

~ Boltimus ~

~Bolt"All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find that it was vanity: but the dreamers of the day are dangerous men, for they may act their dreams with open eyes, to make it possible." This I did...

python_regious

929

August 28, 2001 09:00 AM

Jasun220, I would like that source code if you don't mind! cheers!

Phil ( phil.dadd@btinternet.com )

Edited by - python_regious on August 28, 2001 10:01:09 AM

If at first you don't succeed, redefine success.

Great Milenko

Author

122

August 28, 2001 11:19 AM

jasun220 ok send away =)

smccurdy@milanandnews.com

The Great Milenko"Don't stick a pretzel up your ass, it might get stuck in there.""Computer Programming is findding the right wrench to hammer in the correct screw."

Jasun220

122

August 28, 2001 09:35 PM

Ok, ill send it, but ill have to convert it because some of i is written in Genesis code

Jasun220

122

August 28, 2001 09:49 PM

I decided to post it in the forum, so anyone else can use it. Its not plug and use code

, but im sure you can figure it out

Even included is fading code, but i dont think it works, let me know if you can get it working

First of all, the header file:

  #ifndef MP3MGR_H#define MP3MGR_Htypedef signed int rcBool;typedef signed float geFloat;#define RC_FALSE	(0)#define RC_TRUE		(1)// For MP3 and video#include <stdlib.h>#include <strmif.h>#include <control.h>#include <uuids.h>#include <evcode.h>////////////////////class RCMP3{public:	RCMP3();	virtual ~RCMP3();	rcBool					LoadMP3s(HWND hWnd);	rcBool					UnloadAllMP3s();	long					MP3Volume;	rcBool					SwitchMP3(char *NewMP3, BOOL DoFade2);	rcBool					UpdateM(geFloat Time);	rcBool					DoFade(geFloat Time, BOOL FadeIn);	rcBool					SetVolume(int NewVol);private:	rcBool					BuildGraph(char *FileName);	rcBool					OpenMP3(char *FileName);	rcBool					IsMP3Playing();	rcBool					CloseMP3();	rcBool					StopMP3();	rcBool					PlayMP3();};#endif

Now, look into that, and im sure you can figure the structure of it out

Now the C++ file:

  #include "MP3Mgr.h"#define FADE_TIME		(300)	// half a second (in miliseconds)int						FadeVol = 0;BOOL					FirstTime = TRUE;IGraphBuilder			*pGraph;IMediaSeeking			*pMS;IMediaControl			*pMC;IBasicAudio				*pMA;int						CurMP3 = 0;BOOL					IsFading = FALSE;char					*MP3Name = "";RCMP3::RCMP3(){	pGraph					= NULL;	pMS						= NULL;	pMC						= NULL;	pMA						= NULL;	MP3Volume				= 0;	return;}RCMP3::~RCMP3(){	return;}rcBool RCMP3::LoadMP3s(HWND hWnd){	return RC_TRUE;}rcBool RCMP3::UnloadAllMP3s(){	if (IsMP3Playing() == RC_TRUE)	{		if (!StopMP3())		{			return RC_FALSE;		}		if (!CloseMP3())		{			return RC_FALSE;		}	}	return RC_TRUE;}rcBool RCMP3::SwitchMP3(char *NewMP3, BOOL DoFade2){	sprintf(MP3Name, "Data\\Music\\%s", NewMP3);	if (IsMP3Playing() == RC_TRUE)	{		if (DoFade2 == TRUE)		{			IsFading = TRUE;			FirstTime = TRUE;		}		else		{			StopMP3();			CloseMP3();		}	}	else	{		OpenMP3(MP3Name);	}	return RC_TRUE;}rcBool RCMP3::DoFade(geFloat Time, BOOL FadeIn){	if (FadeVol <= -10000)		return RC_FALSE;	if (FadeIn)	{		FadeVol -= (int)(FADE_TIME * Time);		if (!SetVolume(FadeVol))                     return RC_FALSE;	}	return RC_TRUE;}rcBool RCMP3::UpdateM(geFloat Time){	if (IsFading == TRUE)	{		if (FirstTime == TRUE)		{			FadeVol = MP3Volume;			FirstTime = FALSE;		}		if (DoFade(Time, TRUE) == RC_FALSE)		{			IsFading = FALSE;			FirstTime = FALSE;			return RC_TRUE;		}		return RC_TRUE;	}	if (IsMP3Playing() == RC_FALSE)		if (!PlayMP3())		{			return RC_FALSE;		}	return RC_TRUE;}rcBool RCMP3::BuildGraph(char *FileName){    WCHAR wPath[MAX_PATH];	MultiByteToWideChar(CP_ACP, 0, FileName, -1, wPath, MAX_PATH); 	if (FAILED(pGraph->RenderFile(wPath, NULL)))	{		return RC_FALSE;	}	return RC_TRUE;}rcBool RCMP3::OpenMP3(char *FileName){    if(FAILED(CoInitialize(NULL)))	{		return RC_FALSE;	}    if(FAILED(CoCreateInstance(CLSID_FilterGraph, NULL, CLSCTX_INPROC, IID_IGraphBuilder, (void **)&pGraph)))	{		return RC_FALSE;	}    if(FAILED(pGraph->QueryInterface(IID_IMediaControl,  (void **)&pMC)))	{		return RC_FALSE;	}    if(FAILED(pGraph->QueryInterface(IID_IMediaSeeking,  (void **)&pMS)))	{		return RC_FALSE;	}	if (FAILED(pGraph->QueryInterface(IID_IBasicAudio,(void**) &pMA)))	{		return RC_FALSE;	}	if (!BuildGraph(FileName))	{		return RC_FALSE;	}	return RC_TRUE;}rcBool RCMP3::CloseMP3(){	if (pMA != NULL)	{		pMA->Release();		pMA = NULL;	}	if (pMC != NULL)	{		pMC->Release();		pMC = NULL;	} 	if (pMS != NULL)	{		pMS->Release();		pMS = NULL;	}	if (pGraph != NULL)	{		pGraph->Release();		pGraph = NULL;	}	CoUninitialize();	return RC_TRUE;}rcBool RCMP3::PlayMP3(){	if (IsMP3Playing() == RC_FALSE)	{		if (pMA != NULL)			pMA->put_Volume( MP3Volume );		if (FAILED(pMS->SetPositions(0, AM_SEEKING_AbsolutePositioning, NULL, AM_SEEKING_NoPositioning)))		{			return RC_FALSE;		}		if (FAILED(pMC->Run()))		{			return RC_FALSE;		}	}	return RC_TRUE;}rcBool RCMP3::StopMP3(){	if (FAILED(pMC->StopWhenReady()))	{		return RC_FALSE;	}	return RC_TRUE;}rcBool RCMP3::IsMP3Playing(){	HRESULT				hr = S_OK;	IMediaPosition		*pMP = NULL;	REFTIME				Length, CurrentPos;	if (pGraph != NULL)	{		hr = pGraph->QueryInterface(IID_IMediaPosition, (void**) &pMP);		if (SUCCEEDED(hr))		{			hr = pMP->get_Duration(&Length);			if (SUCCEEDED(hr))			{				hr = pMP->get_CurrentPosition(&CurrentPos);				if (SUCCEEDED(hr))					if ((Length - CurrentPos) > 0)					{						return RC_TRUE;					}					else					{						return RC_FALSE;					}			}		}	}	return RC_FALSE;}rcBool RCMP3::SetVolume(int NewVol){	if (pMA)		if (!pMA->put_Volume((long)NewVol))		{			return RC_FALSE;		}	return RC_TRUE;}

Be sure to include winmm.lib and strmbasd.lib into ur project.

If you need some help in explaining how the code works, let me know

BTW: Brief explanation on how you use this code:

You call LoadMP3s() on program start (after the class is created of course)
and call UnloadMP3s() when shutting your program down (before you delete the class)

Call SwitchMP3() to change the MP3.
And you must call UpdateM() every frame inorder for the MP3 to play and repeat.

Have fun!

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