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3bbb0bf8
编写于
8月 04, 2007
作者:
J
Justin Ruggles
浏览文件
操作
浏览文件
下载
电子邮件补丁
差异文件
add support for downmixing to stereo or mono
Originally committed as revision 9916 to
svn://svn.ffmpeg.org/ffmpeg/trunk
上级
c0d2d806
变更
1
隐藏空白更改
内联
并排
Showing
1 changed file
with
110 addition
and
13 deletion
+110
-13
libavcodec/ac3dec.c
libavcodec/ac3dec.c
+110
-13
未找到文件。
libavcodec/ac3dec.c
浏览文件 @
3bbb0bf8
...
...
@@ -76,14 +76,45 @@ static float dynrng_tbl[256];
#define LEVEL_MINUS_3DB 0.7071067811865476
#define LEVEL_MINUS_4POINT5DB 0.5946035575013605
#define LEVEL_MINUS_6DB 0.5000000000000000
#define LEVEL_PLUS_3DB 1.4142135623730951
#define LEVEL_PLUS_6DB 2.0000000000000000
#define LEVEL_MINUS_9DB 0.3535533905932738
#define LEVEL_ZERO 0.0000000000000000
#define LEVEL_ONE 1.0000000000000000
static
const
float
gain_levels
[
6
]
=
{
LEVEL_ZERO
,
LEVEL_ONE
,
LEVEL_MINUS_3DB
,
LEVEL_MINUS_4POINT5DB
,
LEVEL_MINUS_6DB
,
LEVEL_MINUS_9DB
};
static
const
float
clevs
[
4
]
=
{
LEVEL_MINUS_3DB
,
LEVEL_MINUS_4POINT5DB
,
LEVEL_MINUS_6DB
,
LEVEL_MINUS_4POINT5DB
};
/**
* Table for center mix levels
* reference: Section 5.4.2.4 cmixlev
*/
static
const
uint8_t
clevs
[
4
]
=
{
2
,
3
,
4
,
3
};
static
const
float
slevs
[
4
]
=
{
LEVEL_MINUS_3DB
,
LEVEL_MINUS_6DB
,
LEVEL_ZERO
,
LEVEL_MINUS_6DB
};
/**
* Table for surround mix levels
* reference: Section 5.4.2.5 surmixlev
*/
static
const
uint8_t
slevs
[
4
]
=
{
2
,
4
,
0
,
4
};
/**
* Table for default stereo downmixing coefficients
* reference: Section 7.8.2 Downmixing Into Two Channels
*/
static
const
uint8_t
ac3_default_coeffs
[
8
][
5
][
2
]
=
{
{
{
1
,
0
},
{
0
,
1
},
},
{
{
2
,
2
},
},
{
{
1
,
0
},
{
0
,
1
},
},
{
{
1
,
0
},
{
3
,
3
},
{
0
,
1
},
},
{
{
1
,
0
},
{
0
,
1
},
{
4
,
4
},
},
{
{
1
,
0
},
{
3
,
3
},
{
0
,
1
},
{
5
,
5
},
},
{
{
1
,
0
},
{
0
,
1
},
{
4
,
0
},
{
0
,
4
},
},
{
{
1
,
0
},
{
3
,
3
},
{
0
,
1
},
{
4
,
0
},
{
0
,
4
},
},
};
/* override ac3.h to include coupling channel */
#undef AC3_MAX_CHANNELS
...
...
@@ -94,8 +125,6 @@ static const float slevs[4] = { LEVEL_MINUS_3DB, LEVEL_MINUS_6DB, LEVEL_ZERO, LE
typedef
struct
{
int
acmod
;
int
cmixlev
;
int
surmixlev
;
int
dsurmod
;
int
blksw
[
AC3_MAX_CHANNELS
];
...
...
@@ -129,6 +158,7 @@ typedef struct {
int
output_mode
;
///< output channel configuration
int
out_channels
;
///< number of output channels
float
downmix_coeffs
[
AC3_MAX_CHANNELS
][
2
];
///< stereo downmix coefficients
float
dynrng
;
//dynamic range gain
float
dynrng2
;
//dynamic range gain for 1+1 mode
float
cplco
[
AC3_MAX_CHANNELS
][
18
];
//coupling coordinates
...
...
@@ -286,6 +316,7 @@ static int ac3_parse_header(AC3DecodeContext *ctx)
{
AC3HeaderInfo
hdr
;
GetBitContext
*
gb
=
&
ctx
->
gb
;
float
cmixlev
,
surmixlev
;
int
err
,
i
;
err
=
ff_ac3_parse_header
(
gb
->
buffer
,
&
hdr
);
...
...
@@ -295,8 +326,8 @@ static int ac3_parse_header(AC3DecodeContext *ctx)
/* get decoding parameters from header info */
ctx
->
bit_alloc_params
.
fscod
=
hdr
.
fscod
;
ctx
->
acmod
=
hdr
.
acmod
;
c
tx
->
cmixlev
=
hdr
.
cmixlev
;
ctx
->
surmixlev
=
hdr
.
surmixlev
;
c
mixlev
=
gain_levels
[
clevs
[
hdr
.
cmixlev
]]
;
surmixlev
=
gain_levels
[
slevs
[
hdr
.
surmixlev
]]
;
ctx
->
dsurmod
=
hdr
.
dsurmod
;
ctx
->
lfeon
=
hdr
.
lfeon
;
ctx
->
bit_alloc_params
.
halfratecod
=
hdr
.
halfratecod
;
...
...
@@ -355,6 +386,24 @@ static int ac3_parse_header(AC3DecodeContext *ctx)
}
while
(
i
--
);
}
/* set stereo downmixing coefficients
reference: Section 7.8.2 Downmixing Into Two Channels */
for
(
i
=
0
;
i
<
ctx
->
nfchans
;
i
++
)
{
ctx
->
downmix_coeffs
[
i
][
0
]
=
gain_levels
[
ac3_default_coeffs
[
ctx
->
acmod
][
i
][
0
]];
ctx
->
downmix_coeffs
[
i
][
1
]
=
gain_levels
[
ac3_default_coeffs
[
ctx
->
acmod
][
i
][
1
]];
}
if
(
ctx
->
acmod
>
1
&&
ctx
->
acmod
&
1
)
{
ctx
->
downmix_coeffs
[
1
][
0
]
=
ctx
->
downmix_coeffs
[
1
][
1
]
=
cmixlev
;
}
if
(
ctx
->
acmod
==
AC3_ACMOD_2F1R
||
ctx
->
acmod
==
AC3_ACMOD_3F1R
)
{
int
nf
=
ctx
->
acmod
-
2
;
ctx
->
downmix_coeffs
[
nf
][
0
]
=
ctx
->
downmix_coeffs
[
nf
][
1
]
=
surmixlev
*
LEVEL_MINUS_3DB
;
}
if
(
ctx
->
acmod
==
AC3_ACMOD_2F2R
||
ctx
->
acmod
==
AC3_ACMOD_3F2R
)
{
int
nf
=
ctx
->
acmod
-
4
;
ctx
->
downmix_coeffs
[
nf
][
0
]
=
ctx
->
downmix_coeffs
[
nf
+
1
][
1
]
=
surmixlev
;
}
return
0
;
}
...
...
@@ -662,12 +711,40 @@ static inline void do_imdct(AC3DecodeContext *ctx)
ctx
->
tmp_imdct
);
}
ctx
->
dsp
.
vector_fmul_add_add
(
ctx
->
output
[
ch
-
1
],
ctx
->
tmp_output
,
ctx
->
window
,
ctx
->
delay
[
ch
-
1
],
ctx
->
add_bias
,
256
,
1
);
ctx
->
window
,
ctx
->
delay
[
ch
-
1
],
0
,
256
,
1
);
ctx
->
dsp
.
vector_fmul_reverse
(
ctx
->
delay
[
ch
-
1
],
ctx
->
tmp_output
+
256
,
ctx
->
window
,
256
);
}
}
/**
* Downmixes the output to stereo.
*/
static
void
ac3_downmix
(
float
samples
[
AC3_MAX_CHANNELS
][
256
],
int
nfchans
,
int
output_mode
,
float
coef
[
AC3_MAX_CHANNELS
][
2
])
{
int
i
,
j
;
float
v0
,
v1
,
s0
,
s1
;
for
(
i
=
0
;
i
<
256
;
i
++
)
{
v0
=
v1
=
s0
=
s1
=
0
.
0
f
;
for
(
j
=
0
;
j
<
nfchans
;
j
++
)
{
v0
+=
samples
[
j
][
i
]
*
coef
[
j
][
0
];
v1
+=
samples
[
j
][
i
]
*
coef
[
j
][
1
];
s0
+=
coef
[
j
][
0
];
s1
+=
coef
[
j
][
1
];
}
v0
/=
s0
;
v1
/=
s1
;
if
(
output_mode
==
AC3_ACMOD_MONO
)
{
samples
[
0
][
i
]
=
(
v0
+
v1
)
*
LEVEL_MINUS_3DB
;
}
else
if
(
output_mode
==
AC3_ACMOD_STEREO
)
{
samples
[
0
][
i
]
=
v0
;
samples
[
1
][
i
]
=
v1
;
}
}
}
/* Parse the audio block from ac3 bitstream.
* This function extract the audio block from the ac3 bitstream
* and produces the output for the block. This function must
...
...
@@ -945,8 +1022,18 @@ static int ac3_parse_audio_block(AC3DecodeContext *ctx, int blk)
do_imdct
(
ctx
);
/* downmix output if needed */
if
(
ctx
->
nchans
!=
ctx
->
out_channels
&&
!
((
ctx
->
output_mode
&
AC3_OUTPUT_LFEON
)
&&
ctx
->
nfchans
==
ctx
->
out_channels
))
{
ac3_downmix
(
ctx
->
output
,
ctx
->
nfchans
,
ctx
->
output_mode
,
ctx
->
downmix_coeffs
);
}
/* convert float to 16-bit integer */
for
(
ch
=
0
;
ch
<
ctx
->
out_channels
;
ch
++
)
{
for
(
i
=
0
;
i
<
256
;
i
++
)
{
ctx
->
output
[
ch
][
i
]
+=
ctx
->
add_bias
;
}
ctx
->
dsp
.
float_to_int16
(
ctx
->
int_output
[
ch
],
ctx
->
output
[
ch
],
256
);
}
...
...
@@ -981,14 +1068,24 @@ static int ac3_decode_frame(AVCodecContext * avctx, void *data, int *data_size,
avctx
->
bit_rate
=
ctx
->
bit_rate
;
/* channel config */
ctx
->
out_channels
=
ctx
->
nchans
;
if
(
avctx
->
channels
==
0
)
{
avctx
->
channels
=
ctx
->
out_channels
;
}
else
if
(
ctx
->
out_channels
<
avctx
->
channels
)
{
av_log
(
avctx
,
AV_LOG_ERROR
,
"Cannot upmix AC3 from %d to %d channels.
\n
"
,
ctx
->
out_channels
,
avctx
->
channels
);
return
-
1
;
}
if
(
avctx
->
channels
!=
ctx
->
out_channels
)
{
av_log
(
avctx
,
AV_LOG_ERROR
,
"Cannot mix AC3 to %d channels.
\n
"
,
avctx
->
channels
);
if
(
avctx
->
channels
==
2
)
{
ctx
->
output_mode
=
AC3_ACMOD_STEREO
;
}
else
if
(
avctx
->
channels
==
1
)
{
ctx
->
output_mode
=
AC3_ACMOD_MONO
;
}
else
if
(
avctx
->
channels
!=
ctx
->
out_channels
)
{
av_log
(
avctx
,
AV_LOG_ERROR
,
"Cannot downmix AC3 from %d to %d channels.
\n
"
,
ctx
->
out_channels
,
avctx
->
channels
);
return
-
1
;
}
ctx
->
out_channels
=
avctx
->
channels
;
//av_log(avctx, AV_LOG_INFO, "channels = %d \t bit rate = %d \t sampling rate = %d \n", avctx->channels, avctx->bit_rate * 1000, avctx->sample_rate);
...
...
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