MP3 encoder/decoder?

[chronozphere]

Hey people,

I want to do a little audio project that involves cutting mp3's. Therefore I need not only a decoder but also an encoder. Does anyone know a good library? I prefer to use one single lib that can do both without too much hassle.

Thanks.

[chronozphere]

I've just looked at LAME:

Download link

But there's one thing I cant figure out. There is a pascal header in there, containing the following functions:

Function beInitStream(var pbeConfig: TBE_CONFIG; var dwSample: LongWord; var dwBufferSize: LongWord; var phbeStream: THBE_STREAM ): BE_Err; cdecl; external 'Lame_enc.dll';
//Function beEncodeChunk(hbeStream: THBE_STREAM; nSamples: LongWord; pSample: PSmallInt;pOutput: PByte; var pdwOutput: LongWord): BE_Err; cdecl; external 'Lame_enc.dll';
Function beEncodeChunk(hbeStream: THBE_STREAM; nSamples: LongWord; var pSample;var pOutput; var pdwOutput: LongWord): BE_Err; cdecl; external 'Lame_enc.dll';
Function beDeinitStream(hbeStream: THBE_STREAM; var pOutput; var pdwOutput: LongWord): BE_Err; cdecl; external 'Lame_enc.dll';
Function beCloseStream(hbeStream: THBE_STREAM): BE_Err; cdecl; external 'Lame_enc.dll';
Procedure beVersion(var pbeVersion: TBE_VERSION); cdecl; external 'Lame_enc.dll';

However, there's also an include directory in the archive, containing a C++ header. I quickly scanned through it and I found out that it enables you to decode MP3 aswell. For example:

/* required call to initialize decoder */
hip_t CDECL hip_decode_init(void);

/* cleanup call to exit decoder  */
int CDECL hip_decode_exit(hip_t gfp);

int CDECL hip_decode( hip_t           gfp
                    , unsigned char * mp3buf
                    , size_t          len
                    , short           pcm_l[]
                    , short           pcm_r[]
                    );

/* same as hip_decode, and also returns mp3 header data */
int CDECL hip_decode_headers( hip_t           gfp
                            , unsigned char*  mp3buf
                            , size_t          len
                            , short           pcm_l[]
                            , short           pcm_r[]
                            , mp3data_struct* mp3data
                            );

Just wondering why the pascal header doesn't have these defs. Is there any translation somewhere?

Thanks

[JSoftware]

I'm not aware of any newer units, but it looks like those are newer versions of some lame_decode_* functions

But should be easy enough

type
 lameInt = longint; // Use cint from ctypes in fpc, or smallint on linux
 
 mp3data_struct = packed record
  header_parsed,
  stereo,
  samplerate,
  bitrate,
  mode,
  mode_ext,
  framesize: lameInt;
  
  nsamp: longword;
  
  totalframes,
  framenum: lameInt;
 end;

function hip_decode_init: pointer; cdecl; external 'Lame_enc.dll';
function hip_decode_exit(gfp: pointer): longint; cdecl; external 'Lame_enc.dll';
function hip_decode(gfp: pointer; mp3buf: pointer; len: longint; PcmL, PcmR: pword): longint; cdecl; external 'Lame_enc.dll';
function hip_decode_headers(gfp: pointer; mp3buf: pointer; len: longint; PcmL, PcmR: pword; var mp3data: mp3data_struct): longint; cdecl; external 'Lame_enc.dll';

[chronozphere]

Thanks.

I'm not very good at porting C(++) yet. I'm afraid to make subtle mistakes that will cost me hours of my precious time to fix. Well, maybe I should just try it someday.

As you may expect: The actual header is way bigger that that sample. About 1200 lines. It might be good to have a pascal version of it. However, the decode functionality of LAME is based on mpg123 code that was released under GPL, so some people may want to go down other paths instead.

Thus far, I think that using mpg123 for decoding and LAME for encoding might be "easiest". I can also attempt a header port and use LAME for both encoding and decoding.

Does anyone know any alternatives? I'm sure I have more options, but I'd like to know more of them.

[JSoftware]

You could write a decoder yourself...

That might be a too big undertaking. I'm not well aware of any other good decoders

I would write one if it wasn't so hard to get my hands on a real and complete specification. Just for the sake of getting rid of irritating semi-crossplatform dependencies. I got MP1 working, but I haven't even been able to test it since I can't find an encoder for it...

[chronozphere]

lol. This supposed to be a project for a few weeks, so writing my own decoder is out of the question.