sbr_syntax.c

这是著名的TCPMP播放器在WINDWOWS,和WINCE下编译通过的源程序.笔者对其中的LIBMAD库做了针对ARM MPU的优化. 并增加了词幕功能.

/*
** FAAD2 - Freeware Advanced Audio (AAC) Decoder including SBR decoding
** Copyright (C) 2003-2004 M. Bakker, Ahead Software AG, http://www.nero.com
**  
** This program is free software; you can redistribute it and/or modify
** it under the terms of the GNU General Public License as published by
** the Free Software Foundation; either version 2 of the License, or
** (at your option) any later version.
** 
** This program is distributed in the hope that it will be useful,
** but WITHOUT ANY WARRANTY; without even the implied warranty of
** MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
** GNU General Public License for more details.
** 
** You should have received a copy of the GNU General Public License
** along with this program; if not, write to the Free Software 
** Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
**
** Any non-GPL usage of this software or parts of this software is strictly
** forbidden.
**
** Commercial non-GPL licensing of this software is possible.
** For more info contact Ahead Software through [e-mail].
**
** $Id: sbr_syntax.c,v 1.34 2004/09/04 14:56:28 menno Exp $
**/

#include "common.h"
#include "structs.h"

#ifdef SBR_DEC

#include "sbr_syntax.h"
#include "syntax.h"
#include "sbr_huff.h"
#include "sbr_fbt.h"
#include "sbr_tf_grid.h"
#include "sbr_e_nf.h"
#include "bits.h"
#ifdef PS_DEC
#include "ps_dec.h"
#endif
#ifdef DRM_PS
#include "drm_dec.h"
#endif
#include "analysis.h"

/* static function declarations */
static void sbr_header(bitfile *ld, sbr_info *sbr);
static uint8_t calc_sbr_tables(sbr_info *sbr, uint8_t start_freq, uint8_t stop_freq,
                               uint8_t samplerate_mode, uint8_t freq_scale,
                               uint8_t alter_scale, uint8_t xover_band);
static uint8_t sbr_data(bitfile *ld, sbr_info *sbr);
static uint16_t sbr_extension(bitfile *ld, sbr_info *sbr,
                              uint8_t bs_extension_id, uint16_t num_bits_left);
static uint8_t sbr_single_channel_element(bitfile *ld, sbr_info *sbr);
static uint8_t sbr_channel_pair_element(bitfile *ld, sbr_info *sbr);
static uint8_t sbr_grid(bitfile *ld, sbr_info *sbr, uint8_t ch);
static void sbr_dtdf(bitfile *ld, sbr_info *sbr, uint8_t ch);
static void invf_mode(bitfile *ld, sbr_info *sbr, uint8_t ch);
static void sinusoidal_coding(bitfile *ld, sbr_info *sbr, uint8_t ch);


static void sbr_reset(sbr_info *sbr)
{
#if 0
    printf("%d\n", sbr->bs_start_freq_prev);
    printf("%d\n", sbr->bs_stop_freq_prev);
    printf("%d\n", sbr->bs_freq_scale_prev);
    printf("%d\n", sbr->bs_alter_scale_prev);
    printf("%d\n", sbr->bs_xover_band_prev);
    printf("%d\n\n", sbr->bs_noise_bands_prev);
#endif

    /* if these are different from the previous frame: Reset = 1 */
    if ((sbr->bs_start_freq != sbr->bs_start_freq_prev) ||
        (sbr->bs_stop_freq != sbr->bs_stop_freq_prev) ||
        (sbr->bs_freq_scale != sbr->bs_freq_scale_prev) ||
        (sbr->bs_alter_scale != sbr->bs_alter_scale_prev) ||
        (sbr->bs_xover_band != sbr->bs_xover_band_prev) ||
        (sbr->bs_noise_bands != sbr->bs_noise_bands_prev))
    {
        sbr->Reset = 1;
    } else {
        sbr->Reset = 0;
    }

    sbr->bs_start_freq_prev = sbr->bs_start_freq;
    sbr->bs_stop_freq_prev = sbr->bs_stop_freq;
    sbr->bs_freq_scale_prev = sbr->bs_freq_scale;
    sbr->bs_alter_scale_prev = sbr->bs_alter_scale;
    sbr->bs_xover_band_prev = sbr->bs_xover_band;
    sbr->bs_noise_bands_prev = sbr->bs_noise_bands;
}

static uint8_t calc_sbr_tables(sbr_info *sbr, uint8_t start_freq, uint8_t stop_freq,
                               uint8_t samplerate_mode, uint8_t freq_scale,
                               uint8_t alter_scale, uint8_t xover_band)
{
    uint8_t result = 0;
    uint8_t k2;

    /* calculate the Master Frequency Table */
    sbr->k0 = qmf_start_channel(start_freq, samplerate_mode, sbr->sample_rate);
    k2 = qmf_stop_channel(stop_freq, sbr->sample_rate, sbr->k0);

    /* check k0 and k2 */
    if (sbr->sample_rate >= 48000)
    {
        if ((k2 - sbr->k0) > 32)
            result += 1;
    } else if (sbr->sample_rate <= 32000) {
        if ((k2 - sbr->k0) > 48)
            result += 1;
    } else { /* (sbr->sample_rate == 44100) */
        if ((k2 - sbr->k0) > 45)
            result += 1;
    }

    if (freq_scale == 0)
    {
        result += master_frequency_table_fs0(sbr, sbr->k0, k2, alter_scale);
    } else {
        result += master_frequency_table(sbr, sbr->k0, k2, freq_scale, alter_scale);
    }
    result += derived_frequency_table(sbr, xover_band, k2);

    result = (result > 0) ? 1 : 0;

    return result;
}

/* table 2 */
uint8_t sbr_extension_data(bitfile *ld, sbr_info *sbr, uint16_t cnt)
{
    uint8_t result = 0;
    uint16_t num_align_bits = 0;
    uint16_t num_sbr_bits = (uint16_t)faad_get_processed_bits(ld);

    uint8_t saved_start_freq, saved_samplerate_mode;
    uint8_t saved_stop_freq, saved_freq_scale;
    uint8_t saved_alter_scale, saved_xover_band;

#ifdef DRM
    if (!sbr->Is_DRM_SBR)
#endif
    {
        uint8_t bs_extension_type = (uint8_t)faad_getbits(ld, 4
            DEBUGVAR(1,198,"sbr_bitstream(): bs_extension_type"));

        if (bs_extension_type == EXT_SBR_DATA_CRC)
        {
            sbr->bs_sbr_crc_bits = (uint16_t)faad_getbits(ld, 10
                DEBUGVAR(1,199,"sbr_bitstream(): bs_sbr_crc_bits"));
        }
    }

    /* save old header values, in case the new ones are corrupted */
    saved_start_freq = sbr->bs_start_freq;
    saved_samplerate_mode = sbr->bs_samplerate_mode;
    saved_stop_freq = sbr->bs_stop_freq;
    saved_freq_scale = sbr->bs_freq_scale;
    saved_alter_scale = sbr->bs_alter_scale;
    saved_xover_band = sbr->bs_xover_band;

    sbr->bs_header_flag = faad_get1bit(ld
        DEBUGVAR(1,200,"sbr_bitstream(): bs_header_flag"));

    if (sbr->bs_header_flag)
        sbr_header(ld, sbr);

    /* Reset? */
    sbr_reset(sbr);

    /* first frame should have a header */
    //if (!(sbr->frame == 0 && sbr->bs_header_flag == 0))
    if (sbr->header_count != 0)
    {
        if (sbr->Reset || (sbr->bs_header_flag && sbr->just_seeked))
        {
            uint8_t rt = calc_sbr_tables(sbr, sbr->bs_start_freq, sbr->bs_stop_freq,
                sbr->bs_samplerate_mode, sbr->bs_freq_scale,
                sbr->bs_alter_scale, sbr->bs_xover_band);

            /* if an error occured with the new header values revert to the old ones */
            if (rt > 0)
            {
                calc_sbr_tables(sbr, saved_start_freq, saved_stop_freq,
                    saved_samplerate_mode, saved_freq_scale,
                    saved_alter_scale, saved_xover_band);
            }
        }

        if (result == 0)
        {
            result = sbr_data(ld, sbr);

            /* sbr_data() returning an error means that there was an error in
               envelope_time_border_vector().
               In this case the old time border vector is saved and all the previous
               data normally read after sbr_grid() is saved.
            */
            /* to be on the safe side, calculate old sbr tables in case of error */
            if ((result > 0) &&
                (sbr->Reset || (sbr->bs_header_flag && sbr->just_seeked)))
            {
                calc_sbr_tables(sbr, saved_start_freq, saved_stop_freq,
                    saved_samplerate_mode, saved_freq_scale,
                    saved_alter_scale, saved_xover_band);
            }

            /* we should be able to safely set result to 0 now */
            result = 0;
        }
    } else {
        result = 1;
    }

#ifdef DRM
    if (!sbr->Is_DRM_SBR)
#endif
    {
        num_sbr_bits = (uint16_t)faad_get_processed_bits(ld) - num_sbr_bits;

        /* check if we read more bits then were available for sbr */
        if (8*cnt < num_sbr_bits)
            return 1;

        /* -4 does not apply, bs_extension_type is re-read in this function */
        num_align_bits = 8*cnt /*- 4*/ - num_sbr_bits;

        while (num_align_bits > 7)
        {
            faad_getbits(ld, 8
                DEBUGVAR(1,999,"sbr_bitstream(): num_align_bits"));
            num_align_bits -= 8;
        }
        faad_getbits(ld, num_align_bits
            DEBUGVAR(1,999,"sbr_bitstream(): num_align_bits"));
    }

    return result;
}

/* table 3 */
static void sbr_header(bitfile *ld, sbr_info *sbr)
{
    uint8_t bs_header_extra_1, bs_header_extra_2;

    sbr->header_count++;

    sbr->bs_amp_res = faad_get1bit(ld
        DEBUGVAR(1,203,"sbr_header(): bs_amp_res"));

    /* bs_start_freq and bs_stop_freq must define a fequency band that does
       not exceed 48 channels */
    sbr->bs_start_freq = (uint8_t)faad_getbits(ld, 4
        DEBUGVAR(1,204,"sbr_header(): bs_start_freq"));
    sbr->bs_stop_freq = (uint8_t)faad_getbits(ld, 4
        DEBUGVAR(1,205,"sbr_header(): bs_stop_freq"));
    sbr->bs_xover_band = (uint8_t)faad_getbits(ld, 3
        DEBUGVAR(1,206,"sbr_header(): bs_xover_band"));
    faad_getbits(ld, 2
        DEBUGVAR(1,207,"sbr_header(): bs_reserved_bits_hdr"));
    bs_header_extra_1 = (uint8_t)faad_get1bit(ld
        DEBUGVAR(1,208,"sbr_header(): bs_header_extra_1"));
    bs_header_extra_2 = (uint8_t)faad_get1bit(ld
        DEBUGVAR(1,209,"sbr_header(): bs_header_extra_2"));

    if (bs_header_extra_1)
    {
        sbr->bs_freq_scale = (uint8_t)faad_getbits(ld, 2
            DEBUGVAR(1,211,"sbr_header(): bs_freq_scale"));
        sbr->bs_alter_scale = (uint8_t)faad_get1bit(ld
            DEBUGVAR(1,212,"sbr_header(): bs_alter_scale"));
        sbr->bs_noise_bands = (uint8_t)faad_getbits(ld, 2
            DEBUGVAR(1,213,"sbr_header(): bs_noise_bands"));
    } else {
        /* Default values */
        sbr->bs_freq_scale = 2;
        sbr->bs_alter_scale = 1;
        sbr->bs_noise_bands = 2;
    }

    if (bs_header_extra_2)
    {
        sbr->bs_limiter_bands = (uint8_t)faad_getbits(ld, 2
            DEBUGVAR(1,214,"sbr_header(): bs_limiter_bands"));
        sbr->bs_limiter_gains = (uint8_t)faad_getbits(ld, 2
            DEBUGVAR(1,215,"sbr_header(): bs_limiter_gains"));
        sbr->bs_interpol_freq = (uint8_t)faad_get1bit(ld
            DEBUGVAR(1,216,"sbr_header(): bs_interpol_freq"));
        sbr->bs_smoothing_mode = (uint8_t)faad_get1bit(ld
            DEBUGVAR(1,217,"sbr_header(): bs_smoothing_mode"));
    } else {
        /* Default values */
        sbr->bs_limiter_bands = 2;
        sbr->bs_limiter_gains = 2;
        sbr->bs_interpol_freq = 1;
        sbr->bs_smoothing_mode = 1;
    }

#if 0
    /* print the header to screen */
    printf("bs_amp_res: %d\n", sbr->bs_amp_res);
    printf("bs_start_freq: %d\n", sbr->bs_start_freq);
    printf("bs_stop_freq: %d\n", sbr->bs_stop_freq);
    printf("bs_xover_band: %d\n", sbr->bs_xover_band);
    if (bs_header_extra_1)
    {
        printf("bs_freq_scale: %d\n", sbr->bs_freq_scale);
        printf("bs_alter_scale: %d\n", sbr->bs_alter_scale);
        printf("bs_noise_bands: %d\n", sbr->bs_noise_bands);
    }
    if (bs_header_extra_2)
    {
        printf("bs_limiter_bands: %d\n", sbr->bs_limiter_bands);
        printf("bs_limiter_gains: %d\n", sbr->bs_limiter_gains);
        printf("bs_interpol_freq: %d\n", sbr->bs_interpol_freq);
        printf("bs_smoothing_mode: %d\n", sbr->bs_smoothing_mode);
    }
    printf("\n");
#endif
}

/* table 4 */
static uint8_t sbr_data(bitfile *ld, sbr_info *sbr)
{
    uint8_t result;
#if 0
    sbr->bs_samplerate_mode = faad_get1bit(ld
        DEBUGVAR(1,219,"sbr_data(): bs_samplerate_mode"));
#endif

    sbr->rate = (sbr->bs_samplerate_mode) ? 2 : 1;

    switch (sbr->id_aac)
    {
    case ID_SCE:
		if ((result = sbr_single_channel_element(ld, sbr)) > 0)
			return result;
        break;
    case ID_CPE:
		if ((result = sbr_channel_pair_element(ld, sbr)) > 0)
			return result;
        break;
    }

	return 0;
}

/* table 5 */
static uint8_t sbr_single_channel_element(bitfile *ld, sbr_info *sbr)
{
    uint8_t result;

    if (faad_get1bit(ld
        DEBUGVAR(1,220,"sbr_single_channel_element(): bs_data_extra")))
    {
        faad_getbits(ld, 4
            DEBUGVAR(1,221,"sbr_single_channel_element(): bs_reserved_bits_data"));
    }

#ifdef DRM
    /* bs_coupling, from sbr_channel_pair_base_element(bs_amp_res) */
    if (sbr->Is_DRM_SBR)
        faad_get1bit(ld);
#endif

    if ((result = sbr_grid(ld, sbr, 0)) > 0)
        return result;
    sbr_dtdf(ld, sbr, 0);
    invf_mode(ld, sbr, 0);
    sbr_envelope(ld, sbr, 0);
    sbr_noise(ld, sbr, 0);

#ifndef FIXED_POINT
    envelope_noise_dequantisation(sbr, 0);
#endif

    memset(sbr->bs_add_harmonic[0], 0, 64*sizeof(uint8_t));

    sbr->bs_add_harmonic_flag[0] = faad_get1bit(ld
        DEBUGVAR(1,223,"sbr_single_channel_element(): bs_add_harmonic_flag[0]"));
    if (sbr->bs_add_harmonic_flag[0])
        sinusoidal_coding(ld, sbr, 0);

    sbr->bs_extended_data = faad_get1bit(ld
        DEBUGVAR(1,224,"sbr_single_channel_element(): bs_extended_data[0]"));

    if (sbr->bs_extended_data)
    {
        uint16_t nr_bits_left;
#if (defined(PS_DEC) || defined(DRM_PS))
        uint8_t ps_ext_read = 0;
#endif
        uint16_t cnt = (uint16_t)faad_getbits(ld, 4
            DEBUGVAR(1,225,"sbr_single_channel_element(): bs_extension_size"));
        if (cnt == 15)
        {
            cnt += (uint16_t)faad_getbits(ld, 8
                DEBUGVAR(1,226,"sbr_single_channel_element(): bs_esc_count"));
        }

        nr_bits_left = 8 * cnt;
        while (nr_bits_left > 7)
        {
            uint16_t tmp_nr_bits = 0;

            sbr->bs_extension_id = (uint8_t)faad_getbits(ld, 2
                DEBUGVAR(1,227,"sbr_single_channel_element(): bs_extension_id"));
            tmp_nr_bits += 2;

            /* allow only 1 PS extension element per extension data */
#if (defined(PS_DEC) || defined(DRM_PS))
#if (defined(PS_DEC) && defined(DRM_PS))
            if (sbr->bs_extension_id == EXTENSION_ID_PS || sbr->bs_extension_id == DRM_PARAMETRIC_STEREO)
#else
#ifdef PS_DEC
            if (sbr->bs_extension_id == EXTENSION_ID_PS)
#else
#ifdef DRM_PS
            if (sbr->bs_extension_id == DRM_PARAMETRIC_STEREO)
#endif
#endif
#endif
            {
                if (ps_ext_read == 0)
                {
                    ps_ext_read = 1;
                } else {
                    /* to be safe make it 3, will switch to "default"
                     * in sbr_extension() */
                    sbr->bs_extension_id = 3;
                }
            }