Add some comments describing the fields in hdcd_state_t.
Signed-off-by: Burt P <pbu...@gmail.com>
---
libavfilter/af_hdcd.c | 34 +++++++++++++++++++++-------------
1 file changed, 21 insertions(+), 13 deletions(-)
diff --git a/libavfilter/af_hdcd.c b/libavfilter/af_hdcd.c
index f68a105..72560db 100644
--- a/libavfilter/af_hdcd.c
+++ b/libavfilter/af_hdcd.c
@@ -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;
+ unsigned char readahead;
+
+ /* 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;
- int code_counterC_unmatched; /* told to look for a code, but didn't find
one */
-
- /* For user information/stats, pulled up into HDCDContext
- * by filter_frame() */
- int count_peak_extend;
- int count_transient_filter;
+ 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
--
2.7.4
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