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af_hdcd: add force_pe filter option 

Used to attempt replication of some results from
http://www.audiomisc.co.uk/HFN/HDCD/Examined.html
May not be generally useful, defaults to off.

Signed-off-by: Burt P <pburt0@gmail.com>
Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
This commit is contained in:
Burt P 2016-07-29 12:36:19 -05:00 committed by Michael Niedermayer
parent 6517177d97
commit b90d0ab4be
1 changed files with 22 additions and 4 deletions
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26
libavfilter/af_hdcd.c
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@ -867,6 +867,12 @@ typedef struct HDCDContext {
const AVClass *class;
hdcd_state_t state[2];
/* always extend peaks above -3dBFS even if PE isn't signaled
* -af hdcd=force_pe=0 for off
* -af hdcd=force_pe=1 for on
* default is off */
int force_pe;
AVFilterContext *fctx; /* filter context for logging errors */
int sample_count; /* used in error logging */
@ -878,7 +884,10 @@ typedef struct HDCDContext {
float max_gain_adjustment; /* in dB, expected in the range -6.0 to 0.0 */
} HDCDContext;
#define OFFSET(x) offsetof(HDCDContext, x)
static const AVOption hdcd_options[] = {
{ "force_pe", "Always extend peaks above -3dBFS even when PE is not signaled.",
OFFSET(force_pe), AV_OPT_TYPE_INT, { .i64 = 0 }, 0, 1, 0 },
{NULL}
};
@ -1093,14 +1102,21 @@ static int hdcd_envelope(int32_t *samples, int count, int stride, int gain, int
return gain;
}
/* extract fields from control code */
static void hdcd_control(HDCDContext *ctx, hdcd_state_t *state, int *peak_extend, int *target_gain)
{
*peak_extend = (ctx->force_pe || state->control & 16);
*target_gain = (state->control & 15) << 7;
}
static void hdcd_process(HDCDContext *ctx, hdcd_state_t *state, int32_t *samples, int count, int stride)
{
int32_t *samples_end = samples + count * stride;
int gain = state->running_gain;
int peak_extend = (state->control & 16);
int target_gain = (state->control & 15) << 7;
int peak_extend, target_gain;
int lead = 0;
hdcd_control(ctx, state, &peak_extend, &target_gain);
while (count > lead) {
int envelope_run;
int run;
@ -1115,8 +1131,7 @@ static void hdcd_process(HDCDContext *ctx, hdcd_state_t *state, int32_t *samples
samples += envelope_run * stride;
count -= envelope_run;
lead = run - envelope_run;
peak_extend = (state->control & 16);
target_gain = (state->control & 15) << 7;
hdcd_control(ctx, state, &peak_extend, &target_gain);
}
if (lead > 0) {
av_assert0(samples + lead * stride <= samples_end);
@ -1285,6 +1300,9 @@ static av_cold int init(AVFilterContext *ctx)
hdcd_reset(&s->state[c], 44100);
}
av_log(ctx, AV_LOG_VERBOSE, "Force PE: %s\n",
(s->force_pe) ? "on" : "off");
return 0;
}