lame.c

音频编码

    /* make a copy of input buffer, changing type to sample_t */
    for (i = 0; i < nsamples; i++) {
        in_buffer[0][i] = buffer_l[i];
        if (gfc->channels_in>1)
	    in_buffer[1][i] = buffer_r[i];
    }

    return lame_encode_buffer_sample_t(gfp,in_buffer[0],in_buffer[1],
				      nsamples, mp3buf, mp3buf_size);
}











int
lame_encode_buffer_interleaved(lame_global_flags * gfp,
                               short int buffer[],
                               int nsamples,
                               unsigned char *mp3buf, int mp3buf_size)
{
    lame_internal_flags *gfc = gfp->internal_flags;
    int     i;
    sample_t *in_buffer[2];

    if (update_inbuffer_size( gfc, nsamples ) != 0) {
        return -2;
    }

    in_buffer[0] = gfc->in_buffer_0;
    in_buffer[1] = gfc->in_buffer_1;

    for (i = 0; i < nsamples; i++) {
        in_buffer[0][i] = buffer[2 * i];
        in_buffer[1][i] = buffer[2 * i + 1];
    }
    return lame_encode_buffer_sample_t(gfp, in_buffer[0], in_buffer[1], nsamples, mp3buf,
                           mp3buf_size);
}


int
lame_encode(lame_global_flags * const gfp,
            const short int in_buffer[2][1152],
            unsigned char *const mp3buf, const int size)
{
    lame_internal_flags *gfc = gfp->internal_flags;

    if (gfc->Class_ID != LAME_ID)
        return -3;

    return lame_encode_buffer(gfp, in_buffer[0], in_buffer[1], gfp->framesize,
                              mp3buf, size);
}

/*****************************************************************
 Flush mp3 buffer, pad with ancillary data so last frame is complete.
 Reset reservoir size to 0                  
 but keep all PCM samples and MDCT data in memory             
 This option is used to break a large file into several mp3 files 
 that when concatenated together will decode with no gaps         
 Because we set the reservoir=0, they will also decode seperately 
 with no errors. 
*********************************************************************/
int
lame_encode_flush_nogap(lame_global_flags * gfp,
                  unsigned char *mp3buffer, int mp3buffer_size)
{
    lame_internal_flags *gfc = gfp->internal_flags;
    flush_bitstream(gfp);
    return copy_buffer(gfc,mp3buffer, mp3buffer_size,1);
}


/* called by lame_init_params.  You can also call this after flush_nogap 
   if you want to write new id3v2 and Xing VBR tags into the bitstream */
int
lame_init_bitstream(lame_global_flags * gfp)
{
    lame_internal_flags *gfc = gfp->internal_flags;
    gfp->frameNum=0;

    id3tag_write_v2(gfp);
#ifdef BRHIST
    /* initialize histogram data optionally used by frontend */
    memset(gfc->bitrate_stereoMode_Hist, 0,
	   sizeof(gfc->bitrate_stereoMode_Hist));
    memset(gfc->bitrate_blockType_Hist, 0,
	   sizeof(gfc->bitrate_blockType_Hist));
#endif

    gfc->PeakSample = 0.0;

    /* Write initial VBR Header to bitstream and init VBR data */
    if (gfp->bWriteVbrTag) 
        InitVbrTag(gfp);


    return 0;
}


/*****************************************************************/
/* flush internal PCM sample buffers, then mp3 buffers           */
/* then write id3 v1 tags into bitstream.                        */
/*****************************************************************/

int
lame_encode_flush(lame_global_flags * gfp,
                  unsigned char *mp3buffer, int mp3buffer_size)
{
    lame_internal_flags *gfc = gfp->internal_flags;
    short int buffer[2][1152];
    int     imp3 = 0, mp3count, mp3buffer_size_remaining;

    /* we always add POSTDELAY=288 padding to make sure granule with real
     * data can be complety decoded (because of 50% overlap with next granule */
    int end_padding=POSTDELAY;  

    memset(buffer, 0, sizeof(buffer));
    mp3count = 0;


    while (gfc->mf_samples_to_encode > 0) {

        mp3buffer_size_remaining = mp3buffer_size - mp3count;

        /* if user specifed buffer size = 0, dont check size */
        if (mp3buffer_size == 0)
            mp3buffer_size_remaining = 0;

        /* send in a frame of 0 padding until all internal sample buffers
         * are flushed 
         */
        imp3 = lame_encode_buffer(gfp, buffer[0], buffer[1], gfp->framesize,
                                  mp3buffer, mp3buffer_size_remaining);

        /* don't count the above padding: */
        gfc->mf_samples_to_encode -= gfp->framesize;
        if (gfc->mf_samples_to_encode < 0) {
            /* we added extra padding to the end */
            end_padding += -gfc->mf_samples_to_encode;  
        }


        if (imp3 < 0) {
            /* some type of fatal error */
            return imp3;
        }
        mp3buffer += imp3;
        mp3count += imp3;
    }

    mp3buffer_size_remaining = mp3buffer_size - mp3count;
    /* if user specifed buffer size = 0, dont check size */
    if (mp3buffer_size == 0)
        mp3buffer_size_remaining = 0;

    /* mp3 related stuff.  bit buffer might still contain some mp3 data */
    flush_bitstream(gfp);
    imp3 = copy_buffer(gfc,mp3buffer, mp3buffer_size_remaining, 1);
    if (imp3 < 0) {
	/* some type of fatal error */
	return imp3;
    }
    mp3buffer += imp3;
    mp3count += imp3;
    mp3buffer_size_remaining = mp3buffer_size - mp3count;
    /* if user specifed buffer size = 0, dont check size */
    if (mp3buffer_size == 0)
	mp3buffer_size_remaining = 0;

    /* write a id3 tag to the bitstream */
    id3tag_write_v1(gfp);
    imp3 = copy_buffer(gfc,mp3buffer, mp3buffer_size_remaining, 0);

    if (imp3 < 0) {
        return imp3;
    }
    mp3count += imp3;
    gfp->encoder_padding=end_padding;
    return mp3count;
}

/***********************************************************************
 *
 *      lame_close ()
 *
 *  frees internal buffers
 *
 ***********************************************************************/

int
lame_close(lame_global_flags * gfp)
{
    lame_internal_flags *gfc = gfp->internal_flags;

    if (gfc->Class_ID != LAME_ID)
        return -3;

    if (gfp->exp_nspsytune2.pointer[0]) {
      fclose((FILE *)gfp->exp_nspsytune2.pointer[0]);
      gfp->exp_nspsytune2.pointer[0] = NULL;
    }

    gfc->Class_ID = 0;

    /* this routien will free all malloc'd data in gfc, and then free gfc: */
    freegfc(gfc);

    gfp->internal_flags = NULL;

    if (gfp->lame_allocated_gfp) {
        gfp->lame_allocated_gfp = 0;
        free(gfp);
    }

    return 0;
}

/*****************************************************************/
/* flush internal mp3 buffers, and free internal buffers         */
/*****************************************************************/

int
lame_encode_finish(lame_global_flags * gfp,
                   unsigned char *mp3buffer, int mp3buffer_size)
{
    int     ret = lame_encode_flush(gfp, mp3buffer, mp3buffer_size);

    lame_close(gfp);

    return ret;
}

/*****************************************************************/
/* write VBR Xing header, and ID3 version 1 tag, if asked for    */
/*****************************************************************/
void
lame_mp3_tags_fid(lame_global_flags * gfp, FILE * fpStream)
{
    if (gfp->bWriteVbrTag) {
        /* Map VBR_q to Xing quality value: 0=worst, 100=best */
        int     nQuality = ((9-gfp->VBR_q) * 100) / 9;

        /* Write Xing header again */
        if (fpStream && !fseek(fpStream, 0, SEEK_SET))
            PutVbrTag(gfp, fpStream, nQuality);
    }
}

lame_global_flags *
lame_init(void)
{
    lame_global_flags *gfp;
    int     ret;

    init_log_table();

    gfp = calloc(1, sizeof(lame_global_flags));
    if (gfp == NULL)
        return NULL;

    ret = lame_init_old(gfp);
    if (ret != 0) {
        free(gfp);
        return NULL;
    }

    gfp->lame_allocated_gfp = 1;
    return gfp;
}

/* initialize mp3 encoder */
int
lame_init_old(lame_global_flags * gfp)
{
    lame_internal_flags *gfc;

    disable_FPE();      /* disable floating point exceptions */

    memset(gfp, 0, sizeof(lame_global_flags));

    if (NULL ==
        (gfc = gfp->internal_flags =
         calloc(1, sizeof(lame_internal_flags)))) return -1;

    /* Global flags.  set defaults here for non-zero values */
    /* see lame.h for description */
    /* set integer values to -1 to mean that LAME will compute the
     * best value, UNLESS the calling program as set it
     * (and the value is no longer -1)
     */


    gfp->mode = NOT_SET;
    gfp->original = 1;
    gfp->in_samplerate = 1000 * 44.1;
    gfp->num_channels = 2;
    gfp->num_samples = MAX_U_32_NUM;

    gfp->bWriteVbrTag = 1;
    gfp->quality = -1;
    gfp->short_blocks = short_block_not_set;
    gfc->subblock_gain = -1;

    gfp->lowpassfreq = 0;
    gfp->highpassfreq = 0;
    gfp->lowpasswidth = -1;
    gfp->highpasswidth = -1;

    gfp->VBR = vbr_off;
    gfp->VBR_q = 4;
    gfp->ATHcurve = -1;
    gfp->VBR_mean_bitrate_kbps = 128;
    gfp->VBR_min_bitrate_kbps = 0;
    gfp->VBR_max_bitrate_kbps = 0;
    gfp->VBR_hard_min = 0;
    gfc->VBR_min_bitrate = 1; /* not  0 ????? */
    gfc->VBR_max_bitrate = 13; /* not 14 ????? */

    gfp->quant_comp = -1;
    gfp->quant_comp_short = -1;

    gfp->msfix = -1;

    gfc->resample_ratio = 1;

    gfc->OldValue[0] = 180;
    gfc->OldValue[1] = 180;
    gfc->CurrentStep[0] = 4;
    gfc->CurrentStep[1] = 4;
    gfc->masking_lower = 1;
    gfc->nsPsy.attackthre   = -1;
    gfc->nsPsy.attackthre_s = -1;

    gfp->scale = -1;

    gfp->athaa_type = -1;
    gfp->ATHtype = -1;  /* default = -1 = set in lame_init_params */
    gfp->athaa_loudapprox = -1;	/* 1 = flat loudness approx. (total energy) */
                                /* 2 = equal loudness curve */
    gfp->athaa_sensitivity = 0.0; /* no offset */
    gfp->useTemporal = -1;
    gfp->interChRatio = -1;

    /* The reason for
     *       int mf_samples_to_encode = ENCDELAY + POSTDELAY;
     * ENCDELAY = internal encoder delay.  And then we have to add POSTDELAY=288
     * because of the 50% MDCT overlap.  A 576 MDCT granule decodes to
     * 1152 samples.  To synthesize the 576 samples centered under this granule
     * we need the previous granule for the first 288 samples (no problem), and
     * the next granule for the next 288 samples (not possible if this is last
     * granule).  So we need to pad with 288 samples to make sure we can
     * encode the 576 samples we are interested in.
     */
    gfc->mf_samples_to_encode = ENCDELAY + POSTDELAY;
    gfp->encoder_padding = 0;
    gfc->mf_size = ENCDELAY - MDCTDELAY; /* we pad input with this many 0's */

    gfp->findReplayGain = 0;
    gfp->decode_on_the_fly = 0;

    gfc->decode_on_the_fly = 0;
    gfc->findReplayGain = 0;
    gfc->findPeakSample = 0;

    gfc->RadioGain = 0;
    gfc->AudiophileGain = 0;
    gfc->noclipGainChange = 0;
    gfc->noclipScale = -1.0;

    gfp->asm_optimizations.mmx = 1;
    gfp->asm_optimizations.amd3dnow = 1;
    gfp->asm_optimizations.sse = 1;

    gfp->preset = 0;
    
    gfp->psymodel = -1;

    gfp->sparsing = 0;
    gfp->sparse_low = 9.0;
    gfp->sparse_high = 3.0;
    
    return 0;
}

/***********************************************************************
 *
 *  some simple statistics
 *
 *  Robert Hegemann 2000-10-11
 *
 ***********************************************************************/

/*  histogram of used bitrate indexes:
 *  One has to weight them to calculate the average bitrate in kbps
 *
 *  bitrate indices:
 *  there are 14 possible bitrate indices, 0 has the special meaning 
 *  "free format" which is not possible to mix with VBR and 15 is forbidden
 *  anyway.
 *
 *  stereo modes:
 *  0: LR   number of left-right encoded frames
 *  1: LR-I number of left-right and intensity encoded frames
 *  2: MS   number of mid-side encoded frames
 *  3: MS-I number of mid-side and intensity encoded frames
 *
 *  4: number of encoded frames
 *
 */

void
lame_bitrate_kbps(const lame_global_flags * const gfp, int bitrate_kbps[14])
{
    const lame_internal_flags *gfc;
    int     i;

    if (NULL == bitrate_kbps)
        return;
    if (NULL == gfp)
        return;
    gfc = gfp->internal_fl