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ac3enc: simplify stereo rematrixing decision options

This commit is contained in:
Justin Ruggles 2011-04-15 19:22:42 -04:00
parent a28b058745
commit e0b33d479c
2 changed files with 25 additions and 35 deletions
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12
doc/encoders.texi
View File

@ -353,4 +353,16 @@ HDCD A/D Converter
@end table
@subheading Other AC-3 Encoding Options
@table @option
@item -stereo_rematrixing @var{boolean}
Stereo Rematrixing. Enables/Disables use of rematrixing for stereo input. This
is an optional AC-3 feature that increases quality by selectively encoding
the left/right channels as mid/side. This option is enabled by default, and it
is highly recommended that it be left as enabled except for testing purposes.
@end table
@c man end ENCODERS

48
libavcodec/ac3enc.c
View File

@ -52,12 +52,6 @@
/** Maximum number of exponent groups. +1 for separate DC exponent. */
#define AC3_MAX_EXP_GROUPS 85
/* stereo rematrixing algorithms */
#define AC3_REMATRIXING_IS_STATIC 0x1
#define AC3_REMATRIXING_SUMS 0
#define AC3_REMATRIXING_NONE 1
#define AC3_REMATRIXING_ALWAYS 3
#if CONFIG_AC3ENC_FLOAT
#define MAC_COEF(d,a,b) ((d)+=(a)*(b))
typedef float SampleType;
@ -103,6 +97,7 @@ typedef struct AC3EncOptions {
/* other encoding options */
int allow_per_frame_metadata;
int stereo_rematrixing;
} AC3EncOptions;
/**
@ -170,7 +165,7 @@ typedef struct AC3EncodeContext {
int bandwidth_code[AC3_MAX_CHANNELS]; ///< bandwidth code (0 to 60) (chbwcod)
int nb_coefs[AC3_MAX_CHANNELS];
int rematrixing; ///< determines how rematrixing strategy is calculated
int rematrixing_enabled; ///< stereo rematrixing enabled
int num_rematrixing_bands; ///< number of rematrixing bands
/* bitrate allocation control */
@ -269,6 +264,8 @@ static const AVOption options[] = {
{"ad_conv_type", "A/D Converter Type", OFFSET(ad_converter_type), FF_OPT_TYPE_INT, -1, -1, 1, AC3ENC_PARAM, "ad_conv_type"},
{"standard", "Standard (default)", 0, FF_OPT_TYPE_CONST, 0, INT_MIN, INT_MAX, AC3ENC_PARAM, "ad_conv_type"},
{"hdcd", "HDCD", 0, FF_OPT_TYPE_CONST, 1, INT_MIN, INT_MAX, AC3ENC_PARAM, "ad_conv_type"},
/* Other Encoding Options */
{"stereo_rematrixing", "Stereo Rematrixing", OFFSET(stereo_rematrixing), FF_OPT_TYPE_INT, 1, 0, 1, AC3ENC_PARAM},
{NULL}
};
@ -430,28 +427,6 @@ static void apply_mdct(AC3EncodeContext *s)
}
/**
* Initialize stereo rematrixing.
* If the strategy does not change for each frame, set the rematrixing flags.
*/
static void rematrixing_init(AC3EncodeContext *s)
{
if (s->channel_mode == AC3_CHMODE_STEREO)
s->rematrixing = AC3_REMATRIXING_SUMS;
else
s->rematrixing = AC3_REMATRIXING_NONE;
/* NOTE: AC3_REMATRIXING_ALWAYS might be used in
the future in conjunction with channel coupling. */
if (s->rematrixing & AC3_REMATRIXING_IS_STATIC) {
int flag = (s->rematrixing == AC3_REMATRIXING_ALWAYS);
s->blocks[0].new_rematrixing_strategy = 1;
memset(s->blocks[0].rematrixing_flags, flag,
sizeof(s->blocks[0].rematrixing_flags));
}
}
/**
* Determine rematrixing flags for each block and band.
*/
@ -461,16 +436,18 @@ static void compute_rematrixing_strategy(AC3EncodeContext *s)
int blk, bnd, i;
AC3Block *block, *block0;
s->num_rematrixing_bands = 4;
if (s->rematrixing & AC3_REMATRIXING_IS_STATIC)
if (s->channel_mode != AC3_CHMODE_STEREO)
return;
s->num_rematrixing_bands = 4;
nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
for (blk = 0; blk < AC3_MAX_BLOCKS; blk++) {
block = &s->blocks[blk];
block->new_rematrixing_strategy = !blk;
if (!s->rematrixing_enabled)
continue;
for (bnd = 0; bnd < s->num_rematrixing_bands; bnd++) {
/* calculate calculate sum of squared coeffs for one band in one block */
int start = ff_ac3_rematrix_band_tab[bnd];
@ -514,7 +491,7 @@ static void apply_rematrixing(AC3EncodeContext *s)
int start, end;
uint8_t *flags;
if (s->rematrixing == AC3_REMATRIXING_NONE)
if (!s->rematrixing_enabled)
return;
nb_coefs = FFMIN(s->nb_coefs[0], s->nb_coefs[1]);
@ -2088,6 +2065,9 @@ static av_cold int validate_options(AVCodecContext *avctx, AC3EncodeContext *s)
if (ret)
return ret;
s->rematrixing_enabled = s->options.stereo_rematrixing &&
(s->channel_mode == AC3_CHMODE_STEREO);
return 0;
}
@ -2246,8 +2226,6 @@ static av_cold int ac3_encode_init(AVCodecContext *avctx)
set_bandwidth(s);
rematrixing_init(s);
exponent_init(s);
bit_alloc_init(s);