[FFmpeg-devel] [PATCH 1/3] avcodec/ac3_parser: handle more header bits in ff_ac3_parse_header()
James Almer
jamrial at gmail.com
Fri Jun 6 00:49:36 EEST 2025
Signed-off-by: James Almer <jamrial at gmail.com>
---
libavcodec/ac3_parser.c | 218 +++++++++++++++++++++++++++++++
libavcodec/ac3_parser_internal.h | 19 +++
libavcodec/ac3dec.c | 88 +++----------
libavcodec/ac3dec.h | 4 +-
libavcodec/ac3defs.h | 2 +
libavcodec/eac3dec.c | 154 +++-------------------
6 files changed, 279 insertions(+), 206 deletions(-)
diff --git a/libavcodec/ac3_parser.c b/libavcodec/ac3_parser.c
index 69989690dd..1cba847eaa 100644
--- a/libavcodec/ac3_parser.c
+++ b/libavcodec/ac3_parser.c
@@ -73,6 +73,216 @@ int ff_ac3_find_syncword(const uint8_t *buf, int buf_size)
return i;
}
+/**
+ * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
+ * GetBitContext within AC3DecodeContext must point to
+ * the start of the synchronized AC-3 bitstream.
+ */
+static int ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
+{
+ /* read the rest of the bsi. read twice for dual mono mode. */
+ for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) {
+ hdr->dialog_normalization[i] = -get_bits(gbc, 5);
+ hdr->compression_exists[i] = get_bits1(gbc);
+ if (hdr->compression_exists[i])
+ hdr->heavy_dynamic_range[i] = get_bits(gbc, 8);
+ if (get_bits1(gbc))
+ skip_bits(gbc, 8); //skip language code
+ if (get_bits1(gbc))
+ skip_bits(gbc, 7); //skip audio production information
+ }
+
+ skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
+
+ /* skip the timecodes or parse the Alternate Bit Stream Syntax */
+ if (hdr->bitstream_id != 6) {
+ if (get_bits1(gbc))
+ skip_bits(gbc, 14); //skip timecode1
+ if (get_bits1(gbc))
+ skip_bits(gbc, 14); //skip timecode2
+ } else {
+ if (get_bits1(gbc)) {
+ hdr->preferred_downmix = get_bits(gbc, 2);
+ hdr->center_mix_level_ltrt = get_bits(gbc, 3);
+ hdr->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7);
+ hdr->center_mix_level = get_bits(gbc, 3);
+ hdr->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7);
+ }
+ if (get_bits1(gbc)) {
+ hdr->dolby_surround_ex_mode = get_bits(gbc, 2);
+ hdr->dolby_headphone_mode = get_bits(gbc, 2);
+ skip_bits(gbc, 10); // skip adconvtyp (1), xbsi2 (8), encinfo (1)
+ }
+ }
+
+ /* skip additional bitstream info */
+ if (get_bits1(gbc)) {
+ int i = get_bits(gbc, 6);
+ do {
+ skip_bits(gbc, 8);
+ } while (i--);
+ }
+
+ return 0;
+}
+
+static int eac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
+{
+ if (hdr->frame_type == EAC3_FRAME_TYPE_RESERVED)
+ return AC3_PARSE_ERROR_FRAME_TYPE;
+ if (hdr->substreamid)
+ return AC3_PARSE_ERROR_FRAME_TYPE;
+
+ skip_bits(gbc, 5); // skip bitstream id
+
+ /* volume control params */
+ for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) {
+ hdr->dialog_normalization[i] = -get_bits(gbc, 5);
+ hdr->compression_exists[i] = get_bits1(gbc);
+ if (hdr->compression_exists[i])
+ hdr->heavy_dynamic_range[i] = get_bits(gbc, 8);
+ }
+
+ /* dependent stream channel map */
+ if (hdr->frame_type == EAC3_FRAME_TYPE_DEPENDENT) {
+ if (get_bits1(gbc)) {
+ int64_t channel_layout = 0;
+ int channel_map = get_bits(gbc, 16);
+
+ for (int i = 0; i < 16; i++)
+ if (channel_map & (1 << (EAC3_MAX_CHANNELS - i - 1)))
+ channel_layout |= ff_eac3_custom_channel_map_locations[i][1];
+
+ if (av_popcount64(channel_layout) > EAC3_MAX_CHANNELS) {
+ return AC3_PARSE_ERROR_CHANNEL_MAP;
+ }
+ hdr->channel_map = channel_map;
+ }
+ }
+
+ /* mixing metadata */
+ if (get_bits1(gbc)) {
+ /* center and surround mix levels */
+ if (hdr->channel_mode > AC3_CHMODE_STEREO) {
+ hdr->preferred_downmix = get_bits(gbc, 2);
+ if (hdr->channel_mode & 1) {
+ /* if three front channels exist */
+ hdr->center_mix_level_ltrt = get_bits(gbc, 3);
+ hdr->center_mix_level = get_bits(gbc, 3);
+ }
+ if (hdr->channel_mode & 4) {
+ /* if a surround channel exists */
+ hdr->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7);
+ hdr->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7);
+ }
+ }
+
+ /* lfe mix level */
+ if (hdr->lfe_on && (hdr->lfe_mix_level_exists = get_bits1(gbc))) {
+ hdr->lfe_mix_level = get_bits(gbc, 5);
+ }
+
+ /* info for mixing with other streams and substreams */
+ if (hdr->frame_type == EAC3_FRAME_TYPE_INDEPENDENT) {
+ for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) {
+ // TODO: apply program scale factor
+ if (get_bits1(gbc)) {
+ skip_bits(gbc, 6); // skip program scale factor
+ }
+ }
+ if (get_bits1(gbc)) {
+ skip_bits(gbc, 6); // skip external program scale factor
+ }
+ /* skip mixing parameter data */
+ switch(get_bits(gbc, 2)) {
+ case 1: skip_bits(gbc, 5); break;
+ case 2: skip_bits(gbc, 12); break;
+ case 3: {
+ int mix_data_size = (get_bits(gbc, 5) + 2) << 3;
+ skip_bits_long(gbc, mix_data_size);
+ break;
+ }
+ }
+ /* skip pan information for mono or dual mono source */
+ if (hdr->channel_mode < AC3_CHMODE_STEREO) {
+ for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) {
+ if (get_bits1(gbc)) {
+ /* note: this is not in the ATSC A/52B specification
+ reference: ETSI TS 102 366 V1.1.1
+ section: E.1.3.1.25 */
+ skip_bits(gbc, 8); // skip pan mean direction index
+ skip_bits(gbc, 6); // skip reserved paninfo bits
+ }
+ }
+ }
+ /* skip mixing configuration information */
+ if (get_bits1(gbc)) {
+ for (int i = 0; i < hdr->num_blocks; i++) {
+ if (hdr->num_blocks == 1 || get_bits1(gbc)) {
+ skip_bits(gbc, 5);
+ }
+ }
+ }
+ }
+ }
+
+ /* informational metadata */
+ if (get_bits1(gbc)) {
+ hdr->bitstream_mode = get_bits(gbc, 3);
+ skip_bits(gbc, 2); // skip copyright bit and original bitstream bit
+ if (hdr->channel_mode == AC3_CHMODE_STEREO) {
+ hdr->dolby_surround_mode = get_bits(gbc, 2);
+ hdr->dolby_headphone_mode = get_bits(gbc, 2);
+ }
+ if (hdr->channel_mode >= AC3_CHMODE_2F2R) {
+ hdr->dolby_surround_ex_mode = get_bits(gbc, 2);
+ }
+ for (int i = 0; i < (hdr->channel_mode ? 1 : 2); i++) {
+ if (get_bits1(gbc)) {
+ skip_bits(gbc, 8); // skip mix level, room type, and A/D converter type
+ }
+ }
+ if (hdr->sr_code != EAC3_SR_CODE_REDUCED) {
+ skip_bits1(gbc); // skip source sample rate code
+ }
+ }
+
+ /* converter synchronization flag
+ If frames are less than six blocks, this bit should be turned on
+ once every 6 blocks to indicate the start of a frame set.
+ reference: RFC 4598, Section 2.1.3 Frame Sets */
+ if (hdr->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && hdr->num_blocks != 6) {
+ skip_bits1(gbc); // skip converter synchronization flag
+ }
+
+ /* original frame size code if this stream was converted from AC-3 */
+ if (hdr->frame_type == EAC3_FRAME_TYPE_AC3_CONVERT &&
+ (hdr->num_blocks == 6 || get_bits1(gbc))) {
+ skip_bits(gbc, 6); // skip frame size code
+ }
+
+ /* additional bitstream info */
+ if (get_bits1(gbc)) {
+ int addbsil = get_bits(gbc, 6);
+ for (int i = 0; i < addbsil + 1; i++) {
+ if (i == 0) {
+ /* In this 8 bit chunk, the LSB is equal to flag_ec3_extension_type_a
+ which can be used to detect Atmos presence */
+ skip_bits(gbc, 7);
+ hdr->eac3_extension_type_a = get_bits1(gbc);
+ if (hdr->eac3_extension_type_a) {
+ hdr->complexity_index_type_a = get_bits(gbc, 8);
+ i++;
+ }
+ } else {
+ skip_bits(gbc, 8); // skip additional bit stream info
+ }
+ }
+ }
+
+ return 0;
+}
+
int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
{
int frame_size_code;
@@ -133,6 +343,10 @@ int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
hdr->frame_size = ff_ac3_frame_size_tab[frame_size_code][hdr->sr_code] * 2;
hdr->frame_type = EAC3_FRAME_TYPE_AC3_CONVERT; //EAC3_FRAME_TYPE_INDEPENDENT;
hdr->substreamid = 0;
+
+ int ret = ac3_parse_header(gbc, hdr);
+ if (ret < 0)
+ return ret;
} else {
/* Enhanced AC-3 */
hdr->crc1 = 0;
@@ -165,6 +379,10 @@ int ff_ac3_parse_header(GetBitContext *gbc, AC3HeaderInfo *hdr)
hdr->bit_rate = 8LL * hdr->frame_size * hdr->sample_rate /
(hdr->num_blocks * 256);
hdr->channels = ff_ac3_channels_tab[hdr->channel_mode] + hdr->lfe_on;
+
+ int ret = eac3_parse_header(gbc, hdr);
+ if (ret < 0)
+ return ret;
}
hdr->channel_layout = ff_ac3_channel_layout_tab[hdr->channel_mode];
if (hdr->lfe_on)
diff --git a/libavcodec/ac3_parser_internal.h b/libavcodec/ac3_parser_internal.h
index 46814bfb1f..ab5df34003 100644
--- a/libavcodec/ac3_parser_internal.h
+++ b/libavcodec/ac3_parser_internal.h
@@ -46,6 +46,7 @@ typedef struct AC3HeaderInfo {
int substreamid; ///< substream identification
int center_mix_level; ///< Center mix level index
int surround_mix_level; ///< Surround mix level index
+ uint8_t channel_map_present;
uint16_t channel_map;
int num_blocks; ///< number of audio blocks
int dolby_surround_mode;
@@ -62,6 +63,23 @@ typedef struct AC3HeaderInfo {
uint64_t channel_layout;
int8_t ac3_bit_rate_code;
/** @} */
+
+ /** @name enhanced eac3 extension coded elements
+ * @{
+ */
+ int8_t dialog_normalization[2];
+ uint8_t compression_exists[2];
+ uint8_t heavy_dynamic_range[2];
+ uint8_t center_mix_level_ltrt; ///< Center mix level index
+ uint8_t surround_mix_level_ltrt; ///< Surround mix level index
+ uint8_t dolby_headphone_mode;
+ uint8_t dolby_surround_ex_mode;
+ uint8_t lfe_mix_level_exists;
+ uint8_t lfe_mix_level;
+ uint8_t preferred_downmix;
+ uint8_t eac3_extension_type_a;
+ uint8_t complexity_index_type_a;
+ /** @} */
} AC3HeaderInfo;
typedef enum {
@@ -71,6 +89,7 @@ typedef enum {
AC3_PARSE_ERROR_FRAME_SIZE = -0x4030c0a,
AC3_PARSE_ERROR_FRAME_TYPE = -0x5030c0a,
AC3_PARSE_ERROR_CRC = -0x6030c0a,
+ AC3_PARSE_ERROR_CHANNEL_MAP = -0x7030c0a,
} AC3ParseError;
/**
diff --git a/libavcodec/ac3dec.c b/libavcodec/ac3dec.c
index 5eacab4475..2f0e7f5344 100644
--- a/libavcodec/ac3dec.c
+++ b/libavcodec/ac3dec.c
@@ -156,72 +156,6 @@ static av_cold void ac3_decode_flush(AVCodecContext *avctx)
av_lfg_init(&s->dith_state, 0);
}
-/**
- * Parse the 'sync info' and 'bit stream info' from the AC-3 bitstream.
- * GetBitContext within AC3DecodeContext must point to
- * the start of the synchronized AC-3 bitstream.
- */
-static int ac3_parse_header(AC3DecodeContext *s)
-{
- GetBitContext *gbc = &s->gbc;
- int i;
-
- /* read the rest of the bsi. read twice for dual mono mode. */
- i = !s->channel_mode;
- do {
- s->dialog_normalization[(!s->channel_mode)-i] = -get_bits(gbc, 5);
- if (s->dialog_normalization[(!s->channel_mode)-i] == 0) {
- s->dialog_normalization[(!s->channel_mode)-i] = -31;
- }
- if (s->target_level != 0) {
- s->level_gain[(!s->channel_mode)-i] = powf(2.0f,
- (float)(s->target_level -
- s->dialog_normalization[(!s->channel_mode)-i])/6.0f);
- }
- if (s->compression_exists[(!s->channel_mode)-i] = get_bits1(gbc)) {
- s->heavy_dynamic_range[(!s->channel_mode)-i] =
- AC3_HEAVY_RANGE(get_bits(gbc, 8));
- }
- if (get_bits1(gbc))
- skip_bits(gbc, 8); //skip language code
- if (get_bits1(gbc))
- skip_bits(gbc, 7); //skip audio production information
- } while (i--);
-
- skip_bits(gbc, 2); //skip copyright bit and original bitstream bit
-
- /* skip the timecodes or parse the Alternate Bit Stream Syntax */
- if (s->bitstream_id != 6) {
- if (get_bits1(gbc))
- skip_bits(gbc, 14); //skip timecode1
- if (get_bits1(gbc))
- skip_bits(gbc, 14); //skip timecode2
- } else {
- if (get_bits1(gbc)) {
- s->preferred_downmix = get_bits(gbc, 2);
- s->center_mix_level_ltrt = get_bits(gbc, 3);
- s->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7);
- s->center_mix_level = get_bits(gbc, 3);
- s->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7);
- }
- if (get_bits1(gbc)) {
- s->dolby_surround_ex_mode = get_bits(gbc, 2);
- s->dolby_headphone_mode = get_bits(gbc, 2);
- skip_bits(gbc, 10); // skip adconvtyp (1), xbsi2 (8), encinfo (1)
- }
- }
-
- /* skip additional bitstream info */
- if (get_bits1(gbc)) {
- i = get_bits(gbc, 6);
- do {
- skip_bits(gbc, 8);
- } while (i--);
- }
-
- return 0;
-}
-
/**
* Common function to parse AC-3 or E-AC-3 frame header
*/
@@ -281,10 +215,25 @@ static int parse_frame_header(AC3DecodeContext *s)
s->dba_syntax = 1;
s->skip_syntax = 1;
memset(s->channel_uses_aht, 0, sizeof(s->channel_uses_aht));
- return ac3_parse_header(s);
+ /* volume control params */
+ for (int i = 0; i < (s->channel_mode ? 1 : 2); i++) {
+ s->dialog_normalization[i] = hdr.dialog_normalization[i];
+ if (s->dialog_normalization[i] == 0) {
+ s->dialog_normalization[i] = -31;
+ }
+ if (s->target_level != 0) {
+ s->level_gain[i] = powf(2.0f,
+ (float)(s->target_level - s->dialog_normalization[i])/6.0f);
+ }
+ s->compression_exists[i] = hdr.compression_exists[i];
+ if (s->compression_exists[i]) {
+ s->heavy_dynamic_range[i] = AC3_HEAVY_RANGE(hdr.heavy_dynamic_range[i]);
+ }
+ }
+ return 0;
} else if (CONFIG_EAC3_DECODER) {
s->eac3 = 1;
- return ff_eac3_parse_header(s);
+ return ff_eac3_parse_header(s, &hdr);
} else {
av_log(s->avctx, AV_LOG_ERROR, "E-AC-3 support not compiled in\n");
return AVERROR(ENOSYS);
@@ -1469,6 +1418,9 @@ dependent_frame:
av_log(avctx, AV_LOG_ERROR, "invalid frame type\n");
}
break;
+ case AC3_PARSE_ERROR_CHANNEL_MAP:
+ av_log(avctx, AV_LOG_ERROR, "invalid channel map\n");
+ return AVERROR_INVALIDDATA;
case AC3_PARSE_ERROR_CRC:
break;
default: // Normal AVERROR do not try to recover.
diff --git a/libavcodec/ac3dec.h b/libavcodec/ac3dec.h
index 4042a99b80..a099264475 100644
--- a/libavcodec/ac3dec.h
+++ b/libavcodec/ac3dec.h
@@ -260,11 +260,13 @@ typedef struct AC3DecodeContext {
///@}
} AC3DecodeContext;
+struct AC3HeaderInfo;
+
/**
* Parse the E-AC-3 frame header.
* This parses both the bit stream info and audio frame header.
*/
-static int ff_eac3_parse_header(AC3DecodeContext *s);
+static int ff_eac3_parse_header(AC3DecodeContext *s, const struct AC3HeaderInfo *hdr);
/**
* Decode mantissas in a single channel for the entire frame.
diff --git a/libavcodec/ac3defs.h b/libavcodec/ac3defs.h
index f9b1be059f..8d6a58d21f 100644
--- a/libavcodec/ac3defs.h
+++ b/libavcodec/ac3defs.h
@@ -34,6 +34,8 @@
#define AC3_CRITICAL_BANDS 50
#define AC3_MAX_CPL_BANDS 18
+#define EAC3_SR_CODE_REDUCED 3
+
/* pre-defined gain values */
#define LEVEL_PLUS_3DB M_SQRT2
#define LEVEL_PLUS_1POINT5DB 1.1892071150027209
diff --git a/libavcodec/eac3dec.c b/libavcodec/eac3dec.c
index 2b3bffda6e..c5095b1917 100644
--- a/libavcodec/eac3dec.c
+++ b/libavcodec/eac3dec.c
@@ -53,8 +53,6 @@ typedef enum {
EAC3_GAQ_124
} EAC3GaqMode;
-#define EAC3_SR_CODE_REDUCED 3
-
static void ff_eac3_apply_spectral_extension(AC3DecodeContext *s)
{
int bin, bnd, ch, i;
@@ -287,7 +285,7 @@ static void ff_eac3_decode_transform_coeffs_aht_ch(AC3DecodeContext *s, int ch)
}
}
-static int ff_eac3_parse_header(AC3DecodeContext *s)
+static int ff_eac3_parse_header(AC3DecodeContext *s, const AC3HeaderInfo *hdr)
{
int i, blk, ch;
int ac3_exponent_strategy, parse_aht_info, parse_spx_atten_data;
@@ -323,11 +321,10 @@ static int ff_eac3_parse_header(AC3DecodeContext *s)
avpriv_request_sample(s->avctx, "Reduced sampling rate");
return AVERROR_PATCHWELCOME;
}
- skip_bits(gbc, 5); // skip bitstream id
/* volume control params */
for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
- s->dialog_normalization[i] = -get_bits(gbc, 5);
+ s->dialog_normalization[i] = hdr->dialog_normalization[i];
if (s->dialog_normalization[i] == 0) {
s->dialog_normalization[i] = -31;
}
@@ -335,147 +332,30 @@ static int ff_eac3_parse_header(AC3DecodeContext *s)
s->level_gain[i] = powf(2.0f,
(float)(s->target_level - s->dialog_normalization[i])/6.0f);
}
- s->compression_exists[i] = get_bits1(gbc);
- if (s->compression_exists[i]) {
- s->heavy_dynamic_range[i] = AC3_HEAVY_RANGE(get_bits(gbc, 8));
+ if (hdr->compression_exists[i]) {
+ s->heavy_dynamic_range[i] = AC3_HEAVY_RANGE(hdr->heavy_dynamic_range[i]);
}
}
- /* dependent stream channel map */
- if (s->frame_type == EAC3_FRAME_TYPE_DEPENDENT) {
- if (get_bits1(gbc)) {
- int64_t channel_layout = 0;
- int channel_map = get_bits(gbc, 16);
- av_log(s->avctx, AV_LOG_DEBUG, "channel_map: %0X\n", channel_map);
-
- for (i = 0; i < 16; i++)
- if (channel_map & (1 << (EAC3_MAX_CHANNELS - i - 1)))
- channel_layout |= ff_eac3_custom_channel_map_locations[i][1];
-
- if (av_popcount64(channel_layout) > EAC3_MAX_CHANNELS) {
- return AVERROR_INVALIDDATA;
- }
- s->channel_map = channel_map;
- }
- }
+ s->channel_map = hdr->channel_map;
/* mixing metadata */
- if (get_bits1(gbc)) {
- /* center and surround mix levels */
- if (s->channel_mode > AC3_CHMODE_STEREO) {
- s->preferred_downmix = get_bits(gbc, 2);
- if (s->channel_mode & 1) {
- /* if three front channels exist */
- s->center_mix_level_ltrt = get_bits(gbc, 3);
- s->center_mix_level = get_bits(gbc, 3);
- }
- if (s->channel_mode & 4) {
- /* if a surround channel exists */
- s->surround_mix_level_ltrt = av_clip(get_bits(gbc, 3), 3, 7);
- s->surround_mix_level = av_clip(get_bits(gbc, 3), 3, 7);
- }
- }
-
- /* lfe mix level */
- if (s->lfe_on && (s->lfe_mix_level_exists = get_bits1(gbc))) {
- s->lfe_mix_level = get_bits(gbc, 5);
- }
-
- /* info for mixing with other streams and substreams */
- if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT) {
- for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
- // TODO: apply program scale factor
- if (get_bits1(gbc)) {
- skip_bits(gbc, 6); // skip program scale factor
- }
- }
- if (get_bits1(gbc)) {
- skip_bits(gbc, 6); // skip external program scale factor
- }
- /* skip mixing parameter data */
- switch(get_bits(gbc, 2)) {
- case 1: skip_bits(gbc, 5); break;
- case 2: skip_bits(gbc, 12); break;
- case 3: {
- int mix_data_size = (get_bits(gbc, 5) + 2) << 3;
- skip_bits_long(gbc, mix_data_size);
- break;
- }
- }
- /* skip pan information for mono or dual mono source */
- if (s->channel_mode < AC3_CHMODE_STEREO) {
- for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
- if (get_bits1(gbc)) {
- /* note: this is not in the ATSC A/52B specification
- reference: ETSI TS 102 366 V1.1.1
- section: E.1.3.1.25 */
- skip_bits(gbc, 8); // skip pan mean direction index
- skip_bits(gbc, 6); // skip reserved paninfo bits
- }
- }
- }
- /* skip mixing configuration information */
- if (get_bits1(gbc)) {
- for (blk = 0; blk < s->num_blocks; blk++) {
- if (s->num_blocks == 1 || get_bits1(gbc)) {
- skip_bits(gbc, 5);
- }
- }
- }
- }
- }
+ s->preferred_downmix = hdr->preferred_downmix;
+ s->center_mix_level_ltrt = hdr->center_mix_level_ltrt;
+ s->center_mix_level = hdr->center_mix_level;
+ s->surround_mix_level_ltrt = hdr->surround_mix_level_ltrt;
+ s->surround_mix_level = hdr->surround_mix_level;
+ s->lfe_mix_level_exists = hdr->lfe_mix_level_exists;
+ s->lfe_mix_level = hdr->lfe_mix_level;
+ s->dolby_surround_mode = hdr->dolby_surround_mode;
+ s->dolby_headphone_mode = hdr->dolby_headphone_mode;
+ s->dolby_surround_ex_mode = hdr->dolby_surround_ex_mode;
/* informational metadata */
- if (get_bits1(gbc)) {
- s->bitstream_mode = get_bits(gbc, 3);
- skip_bits(gbc, 2); // skip copyright bit and original bitstream bit
- if (s->channel_mode == AC3_CHMODE_STEREO) {
- s->dolby_surround_mode = get_bits(gbc, 2);
- s->dolby_headphone_mode = get_bits(gbc, 2);
- }
- if (s->channel_mode >= AC3_CHMODE_2F2R) {
- s->dolby_surround_ex_mode = get_bits(gbc, 2);
- }
- for (i = 0; i < (s->channel_mode ? 1 : 2); i++) {
- if (get_bits1(gbc)) {
- skip_bits(gbc, 8); // skip mix level, room type, and A/D converter type
- }
- }
- if (s->bit_alloc_params.sr_code != EAC3_SR_CODE_REDUCED) {
- skip_bits1(gbc); // skip source sample rate code
- }
- }
-
- /* converter synchronization flag
- If frames are less than six blocks, this bit should be turned on
- once every 6 blocks to indicate the start of a frame set.
- reference: RFC 4598, Section 2.1.3 Frame Sets */
- if (s->frame_type == EAC3_FRAME_TYPE_INDEPENDENT && s->num_blocks != 6) {
- skip_bits1(gbc); // skip converter synchronization flag
- }
-
- /* original frame size code if this stream was converted from AC-3 */
- if (s->frame_type == EAC3_FRAME_TYPE_AC3_CONVERT &&
- (s->num_blocks == 6 || get_bits1(gbc))) {
- skip_bits(gbc, 6); // skip frame size code
- }
+ s->bitstream_mode = hdr->bitstream_mode;
/* additional bitstream info */
- if (get_bits1(gbc)) {
- int addbsil = get_bits(gbc, 6);
- for (i = 0; i < addbsil + 1; i++) {
- if (i == 0) {
- /* In this 8 bit chunk, the LSB is equal to flag_ec3_extension_type_a
- which can be used to detect Atmos presence */
- skip_bits(gbc, 7);
- if (get_bits1(gbc)) {
- s->eac3_extension_type_a = 1;
- }
- } else {
- skip_bits(gbc, 8); // skip additional bit stream info
- }
- }
- }
+ s->eac3_extension_type_a = hdr->eac3_extension_type_a;
/* audio frame syntax flags, strategy data, and per-frame data */
--
2.49.0
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