int exss_parse(struct exss_parser *exss, uint8_t *data, int size)
{
int i, j, ret;
bits_init(&exss->bits, data, size);
// Extension substream sync word
bits_skip(&exss->bits, 32);
// User defined bits
bits_skip(&exss->bits, 8);
// Extension substream index
exss->exss_index = bits_get(&exss->bits, 2);
// Flag indicating short or long header size
bool wide_hdr = bits_get1(&exss->bits);
// Extension substream header length
int header_size = bits_get(&exss->bits, 8 + 4 * wide_hdr) + 1;
// Check CRC
if ((ret = bits_check_crc(&exss->bits, 32 + 8, header_size * 8)) < 0) {
exss_err("Invalid EXSS header checksum");
return ret;
}
exss->exss_size_nbits = 16 + 4 * wide_hdr;
// Number of bytes of extension substream
exss->exss_size = bits_get(&exss->bits, exss->exss_size_nbits) + 1;
if (exss->exss_size > size) {
exss_err("Packet too short for EXSS frame");
return -DCADEC_EBADDATA;
}
// Per stream static fields presence flag
exss->static_fields_present = bits_get1(&exss->bits);
if (exss->static_fields_present) {
// Reference clock code
bits_skip(&exss->bits, 2);
// Extension substream frame duration
bits_skip(&exss->bits, 3);
// Timecode presence flag
if (bits_get1(&exss->bits)) {
// Timecode data
bits_skip(&exss->bits, 32);
bits_skip(&exss->bits, 4);
}
// Number of defined audio presentations
exss->npresents = bits_get(&exss->bits, 3) + 1;
// Number of audio assets in extension substream
exss->nassets = bits_get(&exss->bits, 3) + 1;
// Reject unsupported features for now
if (exss->npresents > 1 || exss->nassets > 1) {
exss_err_once("Multiple audio presentations "
"and/or assets are not supported");
return -DCADEC_ENOSUP;
}
// Active extension substream mask for audio presentation
int active_exss_mask[8];
for (i = 0; i < exss->npresents; i++)
active_exss_mask[i] = bits_get(&exss->bits, exss->exss_index + 1);
// Active audio asset mask
for (i = 0; i < exss->npresents; i++)
for (j = 0; j <= exss->exss_index; j++)
if (active_exss_mask[i] & (1 << j))
bits_skip(&exss->bits, 8);
// Mixing metadata enable flag
exss->mix_metadata_enabled = bits_get1(&exss->bits);
if (exss->mix_metadata_enabled) {
// Mixing metadata adjustment level
bits_skip(&exss->bits, 2);
// Number of bits for mixer output speaker activity mask
int spkr_mask_nbits = (bits_get(&exss->bits, 2) + 1) << 2;
// Number of mixing configurations
exss->nmixoutconfigs = bits_get(&exss->bits, 2) + 1;
// Speaker layout mask for mixer output channels
for (i = 0; i < exss->nmixoutconfigs; i++)
exss->nmixoutchs[i] = count_chs_for_mask(bits_get(&exss->bits, spkr_mask_nbits));
}
} else {
exss->npresents = 1;
exss->nassets = 1;
}
// Reallocate assets
if (ta_zalloc_fast(exss, &exss->assets, exss->nassets, sizeof(struct exss_asset)) < 0)
return -DCADEC_ENOMEM;
// Size of encoded asset data in bytes
int offset = header_size;
for (i = 0; i < exss->nassets; i++) {
exss->assets[i].asset_offset = offset;
exss->assets[i].asset_size = bits_get(&exss->bits, exss->exss_size_nbits) + 1;
offset += exss->assets[i].asset_size;
if (offset > exss->exss_size) {
exss_err("Asset out of bounds");
return -DCADEC_EBADDATA;
}
}
// Audio asset descriptor
for (i = 0; i < exss->nassets; i++) {
exss->assets[i].parser = exss;
if ((ret = parse_descriptor(&exss->assets[i])) < 0)
return ret;
if ((ret = set_exss_offsets(&exss->assets[i])) < 0) {
exss_err("Invalid extension size in asset descriptor");
return ret;
}
}
// Backward compatible core present
// Backward compatible core substream index
// Backward compatible core asset index
// Reserved
// Byte align
// CRC16 of extension substream header
if ((ret = bits_seek(&exss->bits, header_size * 8)) < 0)
exss_err("Read past end of EXSS header");
return ret;
}
int ff_dca_exss_parse(DCAExssParser *s, uint8_t *data, int size)
{
int i, ret, offset, wide_hdr, header_size;
if ((ret = init_get_bits8(&s->gb, data, size)) < 0)
return ret;
// Extension substream sync word
skip_bits_long(&s->gb, 32);
// User defined bits
skip_bits(&s->gb, 8);
// Extension substream index
s->exss_index = get_bits(&s->gb, 2);
// Flag indicating short or long header size
wide_hdr = get_bits1(&s->gb);
// Extension substream header length
header_size = get_bits(&s->gb, 8 + 4 * wide_hdr) + 1;
// Check CRC
if (ff_dca_check_crc(s->avctx, &s->gb, 32 + 8, header_size * 8)) {
av_log(s->avctx, AV_LOG_ERROR, "Invalid EXSS header checksum\n");
return AVERROR_INVALIDDATA;
}
s->exss_size_nbits = 16 + 4 * wide_hdr;
// Number of bytes of extension substream
s->exss_size = get_bits(&s->gb, s->exss_size_nbits) + 1;
if (s->exss_size > size) {
av_log(s->avctx, AV_LOG_ERROR, "Packet too short for EXSS frame\n");
return AVERROR_INVALIDDATA;
}
// Per stream static fields presence flag
if (s->static_fields_present = get_bits1(&s->gb)) {
int active_exss_mask[8];
// Reference clock code
skip_bits(&s->gb, 2);
// Extension substream frame duration
skip_bits(&s->gb, 3);
// Timecode presence flag
if (get_bits1(&s->gb))
// Timecode data
skip_bits_long(&s->gb, 36);
// Number of defined audio presentations
s->npresents = get_bits(&s->gb, 3) + 1;
if (s->npresents > 1) {
avpriv_request_sample(s->avctx, "%d audio presentations", s->npresents);
return AVERROR_PATCHWELCOME;
}
// Number of audio assets in extension substream
s->nassets = get_bits(&s->gb, 3) + 1;
if (s->nassets > 1) {
avpriv_request_sample(s->avctx, "%d audio assets", s->nassets);
return AVERROR_PATCHWELCOME;
}
// Active extension substream mask for audio presentation
for (i = 0; i < s->npresents; i++)
active_exss_mask[i] = get_bits(&s->gb, s->exss_index + 1);
// Active audio asset mask
for (i = 0; i < s->npresents; i++)
skip_bits_long(&s->gb, av_popcount(active_exss_mask[i]) * 8);
// Mixing metadata enable flag
if (s->mix_metadata_enabled = get_bits1(&s->gb)) {
int spkr_mask_nbits;
// Mixing metadata adjustment level
skip_bits(&s->gb, 2);
// Number of bits for mixer output speaker activity mask
spkr_mask_nbits = (get_bits(&s->gb, 2) + 1) << 2;
// Number of mixing configurations
s->nmixoutconfigs = get_bits(&s->gb, 2) + 1;
// Speaker layout mask for mixer output channels
for (i = 0; i < s->nmixoutconfigs; i++)
s->nmixoutchs[i] = ff_dca_count_chs_for_mask(get_bits(&s->gb, spkr_mask_nbits));
}
} else {
s->npresents = 1;
s->nassets = 1;
}
// Size of encoded asset data in bytes
offset = header_size;
for (i = 0; i < s->nassets; i++) {
s->assets[i].asset_offset = offset;
s->assets[i].asset_size = get_bits(&s->gb, s->exss_size_nbits) + 1;
offset += s->assets[i].asset_size;
if (offset > s->exss_size) {
av_log(s->avctx, AV_LOG_ERROR, "EXSS asset out of bounds\n");
return AVERROR_INVALIDDATA;
}
}
// Audio asset descriptor
for (i = 0; i < s->nassets; i++) {
if ((ret = parse_descriptor(s, &s->assets[i])) < 0)
return ret;
if ((ret = set_exss_offsets(&s->assets[i])) < 0) {
av_log(s->avctx, AV_LOG_ERROR, "Invalid extension size in EXSS asset descriptor\n");
return ret;
}
}
// Backward compatible core present
// Backward compatible core substream index
// Backward compatible core asset index
// Reserved
// Byte align
// CRC16 of extension substream header
if (ff_dca_seek_bits(&s->gb, header_size * 8)) {
av_log(s->avctx, AV_LOG_ERROR, "Read past end of EXSS header\n");
return AVERROR_INVALIDDATA;
}
return 0;
}
