vgmstream/src/meta/rage_aud_streamfile.h

#ifndef _RAGE_AUD_STREAMFILE_H_
#define _RAGE_AUD_STREAMFILE_H_
#include "deblock_streamfile.h"
#include "../util/endianness.h"
#include "../util/log.h"

#define RAGE_AUD_MAX_MUSIC_CHANNELS 7 /* max known */

/* ************************************************************************* */

typedef struct {
    int start_entry; /* innacurate! */
    int entries;
    int32_t channel_skip;
    int32_t channel_samples;

    uint32_t frame_size;

    /* derived */
    uint32_t chunk_start; /* relative to block offset */
    uint32_t chunk_size;  /* size of this channel's data (not including padding) */
} rage_aud_block_t;

typedef struct {
    int big_endian;
    uint8_t codec;
    int channels;
    uint32_t block_offset;
    uint32_t header_size;
    rage_aud_block_t blk[RAGE_AUD_MAX_MUSIC_CHANNELS];
} rage_aud_block_info_t;

/* Block format:
 * - block header for all channels (needed to find frame start)
 * - frames from channel 1
 * - ...
 * - frames from channel N
 * - usually there is padding between channels or blocks
 * 
 * Header format:
 * - base header (for all channels)
 *   0x00: seek info offset (within block)
 *   0x08: seek table offset
 *   0x10: seek table offset
 * - channel info (per channel)
 *   0x00: start entry for that channel?
 *         may be off by +1/+2?
 *   0x04: frames in this channel (may be different between channels)
 *   0x08: samples to discard in the beginning of this block (MPEG/XMA2)
 *         this seems to repeat XMA frames, which decoders don't like, so maybe they just skip whole frames
 *   0x0c: samples in channel without discard? (for MPEG/XMA2 can vary between channels)
 *   (next fields only exists for MPEG)
 *   0x10: close to number of frames but varies a bit?
 *   0x14: channel chunk size (not counting padding)
 * - seek table (entries for all channels)
 *   0x00: start?
 *   0x04: end?
 * - padding until this block's end
 */
static bool read_rage_aud_block(STREAMFILE* sf, rage_aud_block_info_t* bi) {
    read_s32_t read_s32 = bi->big_endian ? read_s32be : read_s32le;

    uint32_t channel_entry_size, seek_entry_size;
    uint32_t offset = bi->block_offset;
    int channels = bi->channels;
    /* read stupid block crap + derived info at once so hopefully it's a bit easier to understand */

    switch(bi->codec) {
        case 0x0000: /* XMA1 */
            channel_entry_size = 0x10;
            seek_entry_size = 0x08;
            break;
        default:
            goto fail;
    }

    /* base header */
    {
        offset += 0x18;
    }

    /* channel info table */
    for (int ch = 0; ch < bi->channels; ch++) {
        bi->blk[ch].start_entry        = read_s32(offset + 0x00, sf);
        bi->blk[ch].entries            = read_s32(offset + 0x04, sf);
        bi->blk[ch].channel_skip       = read_s32(offset + 0x08, sf);
        bi->blk[ch].channel_samples    = read_s32(offset + 0x0c, sf);
        /* others: optional */

        offset += channel_entry_size;
    }

    /* seek table */
    for (int ch = 0; ch < channels; ch++) {
        offset += bi->blk[ch].entries * seek_entry_size;
    }

    /* derived info */
    for (int ch = 0; ch < channels; ch++) {
        switch(bi->codec) {
            case 0x0000: /* XMA1 */
                bi->blk[ch].frame_size = 0x800;
                bi->blk[ch].chunk_size = bi->blk[ch].entries * bi->blk[ch].frame_size;
                break;

            /* in MPEG frames seem to be VBR, so would need channel chunk size */
            default:
                goto fail;
        }
    }

    /* detect block header size (aligned to 0x800) and adjust offset */
    {
        /* seek table size seems consistent for all blocks; last one defines less entries yet still writes
         * a table as big as prev blocks, repeating old values for unused entries, so final header size is consistent */
        if (!bi->header_size)
            bi->header_size = offset - bi->block_offset;
        offset = bi->block_offset + align_size_to_block(bi->header_size, 0x800);
    }

    /* set frame starts per channel */
    for (int ch = 0; ch < channels; ch++) {
        bi->blk[ch].chunk_start = offset - bi->block_offset;
        offset += bi->blk[ch].chunk_size;
    }

    /* beyond this is padding until chunk_start */

    return true;
fail:
    return false;
}

/* Find data that repeats in the beginning of a new block at the end of last block.
 * When a new block starts there is some repeated data + channel_skip (for seeking + encoder delay?).
 * Detect it so decoder may ignore it. */
static uint32_t get_block_repeated_size(STREAMFILE* sf, rage_aud_block_info_t* bi, int channel) {

    if (bi->blk[channel].channel_skip == 0)
        return 0;
    if (bi->block_offset >= get_streamfile_size(sf))
        return 0;

    switch(bi->codec) {
        case 0x0000: { /* XMA1 */
            /* when data repeats seems to clone the last (super-)frame */
            return bi->blk[channel].frame_size;
        }

        default: 
            ;VGM_LOG("RAGE_AUD: found channel skip in codec %x\n", bi->codec); /* not seen */
            return 0;
    }
}

/* ************************************************************************* */

static void block_callback(STREAMFILE *sf, deblock_io_data* data) {
    int channel = data->cfg.track_number;
    rage_aud_block_info_t bi = {0};

    bi.big_endian = data->cfg.big_endian;
    bi.block_offset = data->physical_offset;
    bi.channels = data->cfg.track_count;
    bi.codec = data->cfg.track_type;
    bi.header_size = data->cfg.config;

    if (!read_rage_aud_block(sf, &bi))
        return; //???
    data->cfg.config = bi.header_size; /* fixed for all blocks but calc'd on first one */

    uint32_t repeat_size = get_block_repeated_size(sf, &bi, channel);

    data->block_size = data->cfg.chunk_size;
    data->skip_size = bi.blk[channel].chunk_start + repeat_size;
    data->data_size = bi.blk[channel].chunk_size - repeat_size;
}

/* deblocks RAGE_AUD blocks */
static STREAMFILE* setup_rage_aud_streamfile(STREAMFILE* sf, uint32_t stream_offset, uint32_t stream_size, uint32_t block_size, int channels, int channel, uint8_t codec, int big_endian) {
    STREAMFILE* new_sf = NULL;
    deblock_config_t cfg = {0};

    if (channels > RAGE_AUD_MAX_MUSIC_CHANNELS || channel >= channels)
        return NULL;

    cfg.track_number = channel;
    cfg.track_count = channels;
    cfg.stream_start = stream_offset;
    cfg.stream_size = stream_size;
    cfg.chunk_size = block_size;
    cfg.track_type = codec;
    cfg.big_endian = big_endian;
    //cfg.physical_offset = stream_offset;
    //cfg.logical_size = rage_aud_io_size(sf, &cfg); /* force init */
    cfg.block_callback = block_callback;

    new_sf = open_wrap_streamfile(sf);
    new_sf = open_io_deblock_streamfile_f(new_sf, &cfg);
    //new_sf = open_buffer_streamfile_f(new_sf, 0);
    return new_sf;
}

#endif