adpcm.c

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.7平台上编译为嵌入式图形界面操作系统。

    c->status[0].step = c->status[1].step = 0;

    switch(avctx->codec->id) {
    default:
        break;
    }
    return 0;
}

static inline short adpcm_ima_expand_nibble(ADPCMChannelStatus *c, char nibble)
{
    int step_index;
    int predictor;
    int sign, delta, diff, step;

    predictor = c->predictor;
    step_index = c->step_index + index_table[(unsigned)nibble];
    if (step_index < 0) step_index = 0;
    if (step_index > 88) step_index = 88;

    step = c->step;

/*
    diff = ((signed)((nibble & 0x08)?(nibble | 0xF0):(nibble)) + 0.5) * step / 4;
    predictor += diff;
*/
    sign = nibble & 8;
    delta = nibble & 7;
    diff = step >> 3;
    if (delta & 4) diff += step;
    if (delta & 2) diff += step >> 1;
    if (delta & 1) diff += step >> 2;
    if (sign) predictor -= diff;
    else predictor += diff;

    CLAMP_TO_SHORT(predictor);
    c->predictor = predictor;
    c->step_index = step_index;
    c->step = step_table[step_index];
    
    return (short)predictor;
}

static inline short adpcm_ms_expand_nibble(ADPCMChannelStatus *c, char nibble)
{
    int predictor;

    predictor = (((c->sample1) * (c->coeff1)) + ((c->sample2) * (c->coeff2))) / 256;
    predictor += (signed)((nibble & 0x08)?(nibble - 0x10):(nibble)) * c->idelta;
    CLAMP_TO_SHORT(predictor);

    c->sample2 = c->sample1;
    c->sample1 = predictor;
    c->idelta = (AdaptationTable[(int)nibble] * c->idelta) / 256;
    if (c->idelta < 16) c->idelta = 16;

    return (short)predictor;
}

static int adpcm_decode_frame(AVCodecContext *avctx,
			    void *data, int *data_size,
			    UINT8 *buf, int buf_size)
{
    ADPCMContext *c = avctx->priv_data;
    ADPCMChannelStatus *cs;
    int n, m, channel;
    int block_predictor[2];
    short *samples;
    UINT8 *src;
    int st; /* stereo */

    samples = data;
    src = buf;

    st = avctx->channels == 2;

    switch(avctx->codec->id) {
    case CODEC_ID_ADPCM_IMA_QT:
        n = (buf_size - 2);/* >> 2*avctx->channels;*/
        channel = c->channel;
        cs = &(c->status[channel]);
        /* (pppppp) (piiiiiii) */

        /* Bits 15-7 are the _top_ 9 bits of the 16-bit initial predictor value */
        cs->predictor = (*src++) << 8;
        cs->predictor |= (*src & 0x80);
        cs->predictor &= 0xFF80;

        /* sign extension */
        if(cs->predictor & 0x8000)
            cs->predictor -= 0x10000;

        CLAMP_TO_SHORT(cs->predictor);

        cs->step_index = (*src++) & 0x7F;

        if (cs->step_index > 88) fprintf(stderr, "ERROR: step_index = %i\n", cs->step_index);
        if (cs->step_index > 88) cs->step_index = 88;

        cs->step = step_table[cs->step_index];

        if (st && channel)
            samples++;

        *samples++ = cs->predictor;
        samples += st;

        for(m=32; n>0 && m>0; n--, m--) { /* in QuickTime, IMA is encoded by chuncks of 34 bytes (=64 samples) */
            *samples = adpcm_ima_expand_nibble(cs, src[0] & 0x0F);
            samples += avctx->channels;
            *samples = adpcm_ima_expand_nibble(cs, (src[0] >> 4) & 0x0F);
            samples += avctx->channels;
            src ++;
        }

        if(st) { /* handle stereo interlacing */
            c->channel = (channel + 1) % 2; /* we get one packet for left, then one for right data */
            if(channel == 0) { /* wait for the other packet before outputing anything */
                *data_size = 0;
                return src - buf;
            }
        }
        break;
    case CODEC_ID_ADPCM_IMA_WAV:
        if (buf_size > BLKSIZE) {
            if (avctx->block_align != 0)
                buf_size = avctx->block_align;
            else
                buf_size = BLKSIZE;
        }
        n = buf_size - 4 * avctx->channels;
        cs = &(c->status[0]);
        cs->predictor = (*src++) & 0x0FF;
        cs->predictor |= ((*src++) << 8) & 0x0FF00;
        if(cs->predictor & 0x8000)
            cs->predictor -= 0x10000;
        CLAMP_TO_SHORT(cs->predictor);

        *samples++ = cs->predictor;

        cs->step_index = *src++;
        if (cs->step_index < 0) cs->step_index = 0;
        if (cs->step_index > 88) cs->step_index = 88;
        if (*src++) fprintf(stderr, "unused byte should be null !!\n"); /* unused */

        if (st) {
            cs = &(c->status[1]);
            cs->predictor = (*src++) & 0x0FF;
            cs->predictor |= ((*src++) << 8) & 0x0FF00;
            if(cs->predictor & 0x8000)
                cs->predictor -= 0x10000;
            CLAMP_TO_SHORT(cs->predictor);

            *samples++ = cs->predictor;

            cs->step_index = *src++;
            if (cs->step_index < 0) cs->step_index = 0;
            if (cs->step_index > 88) cs->step_index = 88;
            src++; /* unused */
        }
        cs = &(c->status[0]);


        for(m=3; n>0; n--, m--) {
            *samples++ = adpcm_ima_expand_nibble(&c->status[0], src[0] & 0x0F);
            if (st)
                *samples++ = adpcm_ima_expand_nibble(&c->status[1], src[4] & 0x0F);
            *samples++ = adpcm_ima_expand_nibble(&c->status[0], (src[0] >> 4) & 0x0F);
            if (st)
                *samples++ = adpcm_ima_expand_nibble(&c->status[1], (src[4] >> 4) & 0x0F);
            src ++;
            if (st && !m) {
                m=3;
                src+=4;
            }
        }
        break;
    case CODEC_ID_ADPCM_MS:

        if (buf_size > BLKSIZE) {
            if (avctx->block_align != 0)
                buf_size = avctx->block_align;
            else
                buf_size = BLKSIZE;
        }
        n = buf_size - 7 * avctx->channels;
        if (n < 0)
            return -1;
        block_predictor[0] = (*src++); /* should be bound */
        block_predictor[0] = (block_predictor[0] < 0)?(0):((block_predictor[0] > 7)?(7):(block_predictor[0]));
        block_predictor[1] = 0;
        if (st)
            block_predictor[1] = (*src++);
        block_predictor[1] = (block_predictor[1] < 0)?(0):((block_predictor[1] > 7)?(7):(block_predictor[1]));
        c->status[0].idelta = ((*src & 0xFF) | ((src[1] << 8) & 0xFF00));
        if (c->status[0].idelta & 0x08000)
            c->status[0].idelta -= 0x10000;
        src+=2;
        if (st)
            c->status[1].idelta = ((*src & 0xFF) | ((src[1] << 8) & 0xFF00));
        if (st && c->status[1].idelta & 0x08000)
            c->status[1].idelta |= 0xFFFF0000;
        if (st)
            src+=2;
        c->status[0].coeff1 = AdaptCoeff1[block_predictor[0]];
        c->status[0].coeff2 = AdaptCoeff2[block_predictor[0]];
        c->status[1].coeff1 = AdaptCoeff1[block_predictor[1]];
        c->status[1].coeff2 = AdaptCoeff2[block_predictor[1]];
        
        c->status[0].sample1 = ((*src & 0xFF) | ((src[1] << 8) & 0xFF00));
        src+=2;
        if (st) c->status[1].sample1 = ((*src & 0xFF) | ((src[1] << 8) & 0xFF00));
        if (st) src+=2;
        c->status[0].sample2 = ((*src & 0xFF) | ((src[1] << 8) & 0xFF00));
        src+=2;
        if (st) c->status[1].sample2 = ((*src & 0xFF) | ((src[1] << 8) & 0xFF00));
        if (st) src+=2;

        *samples++ = c->status[0].sample1;
        if (st) *samples++ = c->status[1].sample1;
        *samples++ = c->status[0].sample2;
        if (st) *samples++ = c->status[1].sample2;
        for(;n>0;n--) {
            *samples++ = adpcm_ms_expand_nibble(&c->status[0], (src[0] >> 4) & 0x0F);
            *samples++ = adpcm_ms_expand_nibble(&c->status[st], src[0] & 0x0F);
            src ++;
        }
        break;
    default:
        *data_size = 0;
        return -1;
    }
    *data_size = (UINT8 *)samples - (UINT8 *)data;
    return src - buf;
}

#define ADPCM_CODEC(id, name)                   \
AVCodec name ## _encoder = {                    \
    #name,                                      \
    CODEC_TYPE_AUDIO,                           \
    id,                                         \
    sizeof(ADPCMContext),                       \
    adpcm_encode_init,                          \
    adpcm_encode_frame,                         \
    adpcm_encode_close,                         \
    NULL,                                       \
};                                              \
AVCodec name ## _decoder = {                    \
    #name,                                      \
    CODEC_TYPE_AUDIO,                           \
    id,                                         \
    sizeof(ADPCMContext),                       \
    adpcm_decode_init,                          \
    NULL,                                       \
    NULL,                                       \
    adpcm_decode_frame,                         \
};

ADPCM_CODEC(CODEC_ID_ADPCM_IMA_QT, adpcm_ima_qt);
ADPCM_CODEC(CODEC_ID_ADPCM_IMA_WAV, adpcm_ima_wav);
ADPCM_CODEC(CODEC_ID_ADPCM_MS, adpcm_ms);

#undef ADPCM_CODEC