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af_hdcd: more comments in state struct

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Add some comments describing the fields in hdcd_state_t.

Signed-off-by: Burt P <pburt0@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Burt P 2016-07-23 21:26:49 -05:00 committed by Michael Niedermayer
parent 91854b8ef6
commit c7ba34b6ea
1 changed files with 21 additions and 13 deletions
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34
libavfilter/af_hdcd.c
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@ -818,20 +818,28 @@ static const int32_t gaintab[] = {
typedef struct {
uint64_t window;
unsigned char readahead, arg, control;
int running_gain;
unsigned sustain, sustain_reset;
int code_counterA;
int code_counterA_almost; /* looks like an A code, but a bit expected to be 0 is 1 */
int code_counterB;
int code_counterB_checkfails; /* looks like a B code, but doesn't pass the XOR check */
int code_counterC;
int code_counterC_unmatched; /* told to look for a code, but didn't find one */
unsigned char readahead;
/* For user information/stats, pulled up into HDCDContext
* by filter_frame() */
int count_peak_extend;
int count_transient_filter;
/* arg is set when a packet prefix is found.
* control is the active control code, where
* bit 0-3: target_gain, 4-bit (3.1) fixed-point value
* bit 4 : peak_extend
* bit 5 : transient_filter
* bit 6,7: always zero */
unsigned char arg, control;
unsigned sustain, sustain_reset; /* code detect timer */
int running_gain; /* 11-bit (3.8) fixed point, extended from target_gain */
/* counters */
int code_counterA; /* 8-bit format packet */
int code_counterA_almost; /* looks like an A code, but a bit expected to be 0 is 1 */
int code_counterB; /* 16-bit format packet, 8-bit code, 8-bit XOR of code */
int code_counterB_checkfails; /* looks like a B code, but doesn't pass the XOR check */
int code_counterC; /* packet prefix was found, expect a code */
int code_counterC_unmatched; /* told to look for a code, but didn't find one */
int count_peak_extend; /* valid packets where peak_extend was enabled */
int count_transient_filter; /* valid packets where filter was detected */
/* target_gain is a 4-bit (3.1) fixed-point value, always
* negative, but stored positive.
* The 16 possible values range from -7.5 to 0.0 dB in