wmadec.c

Trolltech公司发布的图形界面操作系统。可在qt-embedded-2.3.10平台上编译为嵌入式图形界面操作系统。

                    level = level_table[code];
                }
                sign = get_bits(&s->gb, 1);
                if (!sign)
                    level = -level;
                ptr += run;
                if (ptr >= eptr)
                    return -1;
                *ptr++ = level;
                /* NOTE: EOB can be omitted */
                if (ptr >= eptr)
                    break;
            }
        }
        if (s->version == 1 && s->nb_channels >= 2) {
            align_get_bits(&s->gb);
        }
    }
     
    /* normalize */
    {
        int n4 = s->block_len / 2;
        mdct_norm = 1.0 / (float)n4;
        if (s->version == 1) {
            mdct_norm *= sqrt(n4);
        }
    }

    /* finally compute the MDCT coefficients */
    for(ch = 0; ch < s->nb_channels; ch++) {
        if (s->channel_coded[ch]) {
            int16_t *coefs1;
            float *coefs, *exponents, mult, mult1, noise, *exp_ptr;
            int i, j, n, n1, last_high_band;
            float exp_power[HIGH_BAND_MAX_SIZE];

            coefs1 = s->coefs1[ch];
            exponents = s->exponents[ch];
            mult = pow(10, total_gain * 0.05) / s->max_exponent[ch];
            mult *= mdct_norm;
            coefs = s->coefs[ch];
            if (s->use_noise_coding) {
                mult1 = mult;
                /* very low freqs : noise */
                for(i = 0;i < s->coefs_start; i++) {
                    *coefs++ = s->noise_table[s->noise_index] * (*exponents++) * mult1;
                    s->noise_index = (s->noise_index + 1) & (NOISE_TAB_SIZE - 1);
                }
                
                n1 = s->exponent_high_sizes[bsize];

                /* compute power of high bands */
                exp_ptr = exponents + 
                    s->high_band_start[bsize] - 
                    s->coefs_start;
                last_high_band = 0; /* avoid warning */
                for(j=0;j<n1;j++) {
                    n = s->exponent_high_bands[s->frame_len_bits - 
                                              s->block_len_bits][j];
                    if (s->high_band_coded[ch][j]) {
                        float e2, v;
                        e2 = 0;
                        for(i = 0;i < n; i++) {
                            v = exp_ptr[i];
                            e2 += v * v;
                        }
                        exp_power[j] = e2 / n;
                        last_high_band = j;
                        tprintf("%d: power=%f (%d)\n", j, exp_power[j], n);
                    }
                    exp_ptr += n;
                }

                /* main freqs and high freqs */
                for(j=-1;j<n1;j++) {
                    if (j < 0) {
                        n = s->high_band_start[bsize] - 
                            s->coefs_start;
                    } else {
                        n = s->exponent_high_bands[s->frame_len_bits - 
                                                  s->block_len_bits][j];
                    }
                    if (j >= 0 && s->high_band_coded[ch][j]) {
                        /* use noise with specified power */
                        mult1 = sqrt(exp_power[j] / exp_power[last_high_band]);
                        /* XXX: use a table */
                        mult1 = mult1 * pow(10, s->high_band_values[ch][j] * 0.05);
                        mult1 = mult1 / (s->max_exponent[ch] * s->noise_mult);
                        mult1 *= mdct_norm;
                        for(i = 0;i < n; i++) {
                            noise = s->noise_table[s->noise_index];
                            s->noise_index = (s->noise_index + 1) & (NOISE_TAB_SIZE - 1);
                            *coefs++ = (*exponents++) * noise * mult1;
                        }
                    } else {
                        /* coded values + small noise */
                        for(i = 0;i < n; i++) {
                            noise = s->noise_table[s->noise_index];
                            s->noise_index = (s->noise_index + 1) & (NOISE_TAB_SIZE - 1);
                            *coefs++ = ((*coefs1++) + noise) * (*exponents++) * mult;
                        }
                    }
                }

                /* very high freqs : noise */
                n = s->block_len - s->coefs_end[bsize];
                mult1 = mult * exponents[-1];
                for(i = 0; i < n; i++) {
                    *coefs++ = s->noise_table[s->noise_index] * mult1;
                    s->noise_index = (s->noise_index + 1) & (NOISE_TAB_SIZE - 1);
                }
            } else {
                /* XXX: optimize more */
                for(i = 0;i < s->coefs_start; i++)
                    *coefs++ = 0.0;
                n = nb_coefs[ch];
                for(i = 0;i < n; i++) {
                    *coefs++ = coefs1[i] * exponents[i] * mult;
                }
                n = s->block_len - s->coefs_end[bsize];
                for(i = 0;i < n; i++)
                    *coefs++ = 0.0;
            }
        }
    }

#ifdef TRACE
    for(ch = 0; ch < s->nb_channels; ch++) {
        if (s->channel_coded[ch]) {
            dump_floats("exponents", 3, s->exponents[ch], s->block_len);
            dump_floats("coefs", 1, s->coefs[ch], s->block_len);
        }
    }
#endif
    
    if (s->ms_stereo && s->channel_coded[1]) {
        float a, b;
        int i;

        /* nominal case for ms stereo: we do it before mdct */
        /* no need to optimize this case because it should almost
           never happen */
        if (!s->channel_coded[0]) {
            tprintf("rare ms-stereo case happened\n");
            memset(s->coefs[0], 0, sizeof(float) * s->block_len);
            s->channel_coded[0] = 1;
        }
        
        for(i = 0; i < s->block_len; i++) {
            a = s->coefs[0][i];
            b = s->coefs[1][i];
            s->coefs[0][i] = a + b;
            s->coefs[1][i] = a - b;
        }
    }

    /* build the window : we ensure that when the windows overlap
       their squared sum is always 1 (MDCT reconstruction rule) */
    /* XXX: merge with output */
    {
        int i, next_block_len, block_len, prev_block_len, n;
        float *wptr;

        block_len = s->block_len;
        prev_block_len = 1 << s->prev_block_len_bits;
        next_block_len = 1 << s->next_block_len_bits;

        /* right part */
        wptr = window + block_len;
        if (block_len <= next_block_len) {
            for(i=0;i<block_len;i++)
                *wptr++ = s->windows[bsize][i];
        } else {
            /* overlap */
            n = (block_len / 2) - (next_block_len / 2);
            for(i=0;i<n;i++)
                *wptr++ = 1.0;
            for(i=0;i<next_block_len;i++)
                *wptr++ = s->windows[s->frame_len_bits - s->next_block_len_bits][i];
            for(i=0;i<n;i++)
                *wptr++ = 0.0;
        }

        /* left part */
        wptr = window + block_len;
        if (block_len <= prev_block_len) {
            for(i=0;i<block_len;i++)
                *--wptr = s->windows[bsize][i];
        } else {
            /* overlap */
            n = (block_len / 2) - (prev_block_len / 2);
            for(i=0;i<n;i++)
                *--wptr = 1.0;
            for(i=0;i<prev_block_len;i++)
                *--wptr = s->windows[s->frame_len_bits - s->prev_block_len_bits][i];
            for(i=0;i<n;i++)
                *--wptr = 0.0;
        }
    }

    
    for(ch = 0; ch < s->nb_channels; ch++) {
        if (s->channel_coded[ch]) {
            FFTSample output[BLOCK_MAX_SIZE * 2] __attribute__((aligned(16)));
            float *ptr;
            int i, n4, index, n;

            n = s->block_len;
            n4 = s->block_len / 2;
            ff_imdct_calc(&s->mdct_ctx[bsize], 
                          output, s->coefs[ch], s->mdct_tmp);

            /* XXX: optimize all that by build the window and
               multipying/adding at the same time */
            /* multiply by the window */
            for(i=0;i<n * 2;i++) {
                output[i] *= window[i];
            }

            /* add in the frame */
            index = (s->frame_len / 2) + s->block_pos - n4;
            ptr = &s->frame_out[ch][index];
            for(i=0;i<n * 2;i++) {
                *ptr += output[i];
                ptr++;
            }

            /* specific fast case for ms-stereo : add to second
               channel if it is not coded */
            if (s->ms_stereo && !s->channel_coded[1]) {
                ptr = &s->frame_out[1][index];
                for(i=0;i<n * 2;i++) {
                    *ptr += output[i];
                    ptr++;
                }
            }
        }
    }
 next:
    /* update block number */
    s->block_num++;
    s->block_pos += s->block_len;
    if (s->block_pos >= s->frame_len)
        return 1;
    else
        return 0;
}

/* decode a frame of frame_len samples */
static int wma_decode_frame(WMADecodeContext *s, int16_t *samples)
{
    int ret, i, n, a, ch, incr;
    int16_t *ptr;
    float *iptr;

#ifdef TRACE
    tprintf("***decode_frame: %d size=%d\n", s->frame_count++, s->frame_len);
#endif

    /* read each block */
    s->block_num = 0;
    s->block_pos = 0;
    for(;;) {
        ret = wma_decode_block(s);
        if (ret < 0) 
            return -1;
        if (ret)
            break;
    }

    /* convert frame to integer */
    n = s->frame_len;
    incr = s->nb_channels;
    for(ch = 0; ch < s->nb_channels; ch++) {
        ptr = samples + ch;
        iptr = s->frame_out[ch];

        for(i=0;i<n;i++) {
            a = lrintf(*iptr++);
            if (a > 32767)
                a = 32767;
            else if (a < -32768)
                a = -32768;
            *ptr = a;
            ptr += incr;
        }
        /* prepare for next block */
        memmove(&s->frame_out[ch][0], &s->frame_out[ch][s->frame_len],
                s->frame_len * sizeof(float));
        /* XXX: suppress this */
        memset(&s->frame_out[ch][s->frame_len], 0, 
               s->frame_len * sizeof(float));
    }

#ifdef TRACE
    dump_shorts("samples", samples, n * s->nb_channels);
#endif
    return 0;
}

static int wma_decode_superframe(AVCodecContext *avctx, 
                                 void *data, int *data_size,
                                 uint8_t *buf, int buf_size)
{
    WMADecodeContext *s = avctx->priv_data;
    int nb_frames, bit_offset, i, pos, len;
    uint8_t *q;
    int16_t *samples;
    
    tprintf("***decode_superframe:\n");

    samples = data;

    init_get_bits(&s->gb, buf, buf_size*8);
    
    if (s->use_bit_reservoir) {
        /* read super frame header */
        get_bits(&s->gb, 4); /* super frame index */
        nb_frames = get_bits(&s->gb, 4) - 1;

        bit_offset = get_bits(&s->gb, s->byte_offset_bits + 3);

        if (s->last_superframe_len > 0) {
            //        printf("skip=%d\n", s->last_bitoffset);
            /* add bit_offset bits to last frame */
            if ((s->last_superframe_len + ((bit_offset + 7) >> 3)) > 
                MAX_CODED_SUPERFRAME_SIZE)
                goto fail;
            q = s->last_superframe + s->last_superframe_len;
            len = bit_offset;
            while (len > 0) {
                *q++ = (get_bits)(&s->gb, 8);
                len -= 8;
            }
            if (len > 0) {
                *q++ = (get_bits)(&s->gb, len) << (8 - len);
            }
            
            /* XXX: bit_offset bits into last frame */
            init_get_bits(&s->gb, s->last_superframe, MAX_CODED_SUPERFRAME_SIZE*8);
            /* skip unused bits */
            if (s->last_bitoffset > 0)
                skip_bits(&s->gb, s->last_bitoffset);
            /* this frame is stored in the last superframe and in the
               current one */
            if (wma_decode_frame(s, samples) < 0)
                goto fail;
            samples += s->nb_channels * s->frame_len;
        }

        /* read each frame starting from bit_offset */
        pos = bit_offset + 4 + 4 + s->byte_offset_bits + 3;
        init_get_bits(&s->gb, buf + (pos >> 3), (MAX_CODED_SUPERFRAME_SIZE - (pos >> 3))*8);
        len = pos & 7;
        if (len > 0)
            skip_bits(&s->gb, len);
    
        s->reset_block_lengths = 1;
        for(i=0;i<nb_frames;i++) {
            if (wma_decode_frame(s, samples) < 0)
                goto fail;
            samples += s->nb_channels * s->frame_len;
        }

        /* we copy the end of the frame in the last frame buffer */
        pos = get_bits_count(&s->gb) + ((bit_offset + 4 + 4 + s->byte_offset_bits + 3) & ~7);
        s->last_bitoffset = pos & 7;
        pos >>= 3;
        len = buf_size - pos;
        if (len > MAX_CODED_SUPERFRAME_SIZE || len < 0) {
            goto fail;
        }
        s->last_superframe_len = len;
        memcpy(s->last_superframe, buf + pos, len);
    } else {
        /* single frame decode */
        if (wma_decode_frame(s, samples) < 0)
            goto fail;
        samples += s->nb_channels * s->frame_len;
    }
    *data_size = (int8_t *)samples - (int8_t *)data;
    return s->block_align;
 fail:
    /* when error, we reset the bit reservoir */
    s->last_superframe_len = 0;
    return -1;
}

static int wma_decode_end(AVCodecContext *avctx)
{
    WMADecodeContext *s = avctx->priv_data;
    int i;

    for(i = 0; i < s->nb_block_sizes; i++)
        ff_mdct_end(&s->mdct_ctx[i]);
    for(i = 0; i < s->nb_block_sizes; i++)
        av_free(s->windows[i]);

    if (s->use_exp_vlc) {
        free_vlc(&s->exp_vlc);
    }
    if (s->use_noise_coding) {
        free_vlc(&s->hgain_vlc);
    }
    for(i = 0;i < 2; i++) {
        free_vlc(&s->coef_vlc[i]);
        av_free(s->run_table[i]);
        av_free(s->level_table[i]);
    }
    
    return 0;
}

AVCodec wmav1_decoder =
{
    "wmav1",
    CODEC_TYPE_AUDIO,
    CODEC_ID_WMAV1,
    sizeof(WMADecodeContext),
    wma_decode_init,
    NULL,
    wma_decode_end,
    wma_decode_superframe,
};

AVCodec wmav2_decoder =
{
    "wmav2",
    CODEC_TYPE_AUDIO,
    CODEC_ID_WMAV2,
    sizeof(WMADecodeContext),
    wma_decode_init,
    NULL,
    wma_decode_end,
    wma_decode_superframe,
};