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Linshizhi
ffmpeg.wasm-core
Commits
ba6bce51
Commit
ba6bce51
authored
Apr 16, 2011
by
Justin Ruggles
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ac3enc: merge compute_exp_strategy_ch() into compute_exp_strategy()
parent
4142487d
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1 changed file
with
33 additions
and
42 deletions
+33
-42
ac3enc.c
libavcodec/ac3enc.c
+33
-42
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libavcodec/ac3enc.c
View file @
ba6bce51
...
...
@@ -560,56 +560,47 @@ static void extract_exponents(AC3EncodeContext *s)
#define EXP_DIFF_THRESHOLD 500
/**
* Calculate exponent strategies for all blocks in a single channel.
*/
static
void
compute_exp_strategy_ch
(
AC3EncodeContext
*
s
,
uint8_t
*
exp_strategy
,
uint8_t
*
exp
)
{
int
blk
,
blk1
;
int
exp_diff
;
/* estimate if the exponent variation & decide if they should be
reused in the next frame */
exp_strategy
[
0
]
=
EXP_NEW
;
exp
+=
AC3_MAX_COEFS
;
for
(
blk
=
1
;
blk
<
AC3_MAX_BLOCKS
;
blk
++
)
{
exp_diff
=
s
->
dsp
.
sad
[
0
](
NULL
,
exp
,
exp
-
AC3_MAX_COEFS
,
16
,
16
);
if
(
exp_diff
>
EXP_DIFF_THRESHOLD
)
exp_strategy
[
blk
]
=
EXP_NEW
;
else
exp_strategy
[
blk
]
=
EXP_REUSE
;
exp
+=
AC3_MAX_COEFS
;
}
/* now select the encoding strategy type : if exponents are often
recoded, we use a coarse encoding */
blk
=
0
;
while
(
blk
<
AC3_MAX_BLOCKS
)
{
blk1
=
blk
+
1
;
while
(
blk1
<
AC3_MAX_BLOCKS
&&
exp_strategy
[
blk1
]
==
EXP_REUSE
)
blk1
++
;
switch
(
blk1
-
blk
)
{
case
1
:
exp_strategy
[
blk
]
=
EXP_D45
;
break
;
case
2
:
case
3
:
exp_strategy
[
blk
]
=
EXP_D25
;
break
;
default:
exp_strategy
[
blk
]
=
EXP_D15
;
break
;
}
blk
=
blk1
;
}
}
/**
* Calculate exponent strategies for all channels.
* Array arrangement is reversed to simplify the per-channel calculation.
*/
static
void
compute_exp_strategy
(
AC3EncodeContext
*
s
)
{
int
ch
,
blk
;
int
ch
,
blk
,
blk1
;
for
(
ch
=
0
;
ch
<
s
->
fbw_channels
;
ch
++
)
{
compute_exp_strategy_ch
(
s
,
s
->
exp_strategy
[
ch
],
s
->
blocks
[
0
].
exp
[
ch
]);
uint8_t
*
exp_strategy
=
s
->
exp_strategy
[
ch
];
uint8_t
*
exp
=
s
->
blocks
[
0
].
exp
[
ch
];
int
exp_diff
;
/* estimate if the exponent variation & decide if they should be
reused in the next frame */
exp_strategy
[
0
]
=
EXP_NEW
;
exp
+=
AC3_MAX_COEFS
;
for
(
blk
=
1
;
blk
<
AC3_MAX_BLOCKS
;
blk
++
)
{
exp_diff
=
s
->
dsp
.
sad
[
0
](
NULL
,
exp
,
exp
-
AC3_MAX_COEFS
,
16
,
16
);
if
(
exp_diff
>
EXP_DIFF_THRESHOLD
)
exp_strategy
[
blk
]
=
EXP_NEW
;
else
exp_strategy
[
blk
]
=
EXP_REUSE
;
exp
+=
AC3_MAX_COEFS
;
}
/* now select the encoding strategy type : if exponents are often
recoded, we use a coarse encoding */
blk
=
0
;
while
(
blk
<
AC3_MAX_BLOCKS
)
{
blk1
=
blk
+
1
;
while
(
blk1
<
AC3_MAX_BLOCKS
&&
exp_strategy
[
blk1
]
==
EXP_REUSE
)
blk1
++
;
switch
(
blk1
-
blk
)
{
case
1
:
exp_strategy
[
blk
]
=
EXP_D45
;
break
;
case
2
:
case
3
:
exp_strategy
[
blk
]
=
EXP_D25
;
break
;
default:
exp_strategy
[
blk
]
=
EXP_D15
;
break
;
}
blk
=
blk1
;
}
}
if
(
s
->
lfe_on
)
{
ch
=
s
->
lfe_channel
;
...
...
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