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af_hdcd: Code comments update

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Signed-off-by: Burt P <pburt0@gmail.com>
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Burt P 2016-08-21 13:00:22 -05:00
parent 45e5d5f547
commit 400e2acd11
1 changed files with 95 additions and 86 deletions
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139
libavfilter/af_hdcd.c
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@ -1,40 +1,46 @@
/* /*
Copyright (C) 2010, Chris Moeller, * Copyright (C) 2010, Chris Moeller,
All rights reserved. * All rights reserved.
Optimizations by Gumboot * Optimizations by Gumboot
Redistribution and use in source and binary forms, with or without modification, * Additional work by Burt P.
are permitted provided that the following conditions are met: * Original code reverse engineered from HDCD decoder library by Christopher Key,
1. Redistributions of source code must retain the above copyright * which was likely reverse engineered from Windows Media Player.
notice, this list of conditions and the following disclaimer. *
2. Redistributions in binary form must reproduce the above copyright * Redistribution and use in source and binary forms, with or without modification,
notice, this list of conditions and the following disclaimer in the * are permitted provided that the following conditions are met:
documentation and/or other materials provided with the distribution. * 1. Redistributions of source code must retain the above copyright
3. The names of its contributors may not be used to endorse or promote * notice, this list of conditions and the following disclaimer.
products derived from this software without specific prior written * 2. Redistributions in binary form must reproduce the above copyright
permission. * notice, this list of conditions and the following disclaimer in the
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS * documentation and/or other materials provided with the distribution.
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT * 3. The names of its contributors may not be used to endorse or promote
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR * products derived from this software without specific prior written
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR * permission.
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
* LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
* NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
* SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/ */
/* /*
Original code reverse engineered from HDCD decoder library by Christopher Key, * HDCD is High Definition Compatible Digital
which was likely reverse engineered from Windows Media Player. * http://wiki.hydrogenaud.io/index.php?title=High_Definition_Compatible_Digital
*
* More information about HDCD-encoded audio CDs:
* http://www.audiomisc.co.uk/HFN/HDCD/Enigma.html
* http://www.audiomisc.co.uk/HFN/HDCD/Examined.html
*/ */
/* /**
HDCD is High Definition Compatible Digital * @file
More information about HDCD-encoded audio CDs: * HDCD decoding filter
http://www.audiomisc.co.uk/HFN/HDCD/Enigma.html
http://www.audiomisc.co.uk/HFN/HDCD/Examined.html
*/ */
#include "libavutil/opt.h" #include "libavutil/opt.h"
@ -820,33 +826,33 @@ typedef struct {
uint64_t window; uint64_t window;
unsigned char readahead; unsigned char readahead;
/* arg is set when a packet prefix is found. /** arg is set when a packet prefix is found.
* control is the active control code, where * control is the active control code, where
* bit 0-3: target_gain, 4-bit (3.1) fixed-point value * bit 0-3: target_gain, 4-bit (3.1) fixed-point value
* bit 4 : peak_extend * bit 4 : peak_extend
* bit 5 : transient_filter * bit 5 : transient_filter
* bit 6,7: always zero */ * bit 6,7: always zero */
unsigned char arg, control; uint8_t arg, control;
unsigned sustain, sustain_reset; /* code detect timer */ unsigned int sustain, sustain_reset; /**< code detect timer */
int running_gain; /* 11-bit (3.8) fixed point, extended from target_gain */ int running_gain; /**< 11-bit (3.8) fixed point, extended from target_gain */
/* counters */ /* counters */
int code_counterA; /* 8-bit format packet */ 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_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; /**< 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_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; /**< packet prefix was found, expect a code */
int code_counterC_unmatched; /* told to look for a code, but didn't find one */ 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_peak_extend; /**< valid packets where peak_extend was enabled */
int count_transient_filter; /* valid packets where filter was detected */ int count_transient_filter; /**< valid packets where filter was detected */
/* target_gain is a 4-bit (3.1) fixed-point value, always /** target_gain is a 4-bit (3.1) fixed-point value, always
* negative, but stored positive. * negative, but stored positive.
* The 16 possible values range from -7.5 to 0.0 dB in * The 16 possible values range from -7.5 to 0.0 dB in
* steps of 0.5, but no value below -6.0 dB should appear. */ * steps of 0.5, but no value below -6.0 dB should appear. */
int gain_counts[16]; /* for cursiosity, mostly */ int gain_counts[16];
int max_gain; int max_gain;
/* occurences of code detect timer expiring without detecting /** occurences of code detect timer expiring without detecting
* a code. -1 for timer never set. */ * a code. -1 for timer never set. */
int count_sustain_expired; int count_sustain_expired;
} hdcd_state_t; } hdcd_state_t;
@ -866,7 +872,7 @@ static const char * const pe_str[] = {
#define HDCD_PROCESS_STEREO_DEFAULT 1 #define HDCD_PROCESS_STEREO_DEFAULT 1
#define HDCD_MAX_CHANNELS 2 #define HDCD_MAX_CHANNELS 2
/* convert to float from 4-bit (3.1) fixed-point /** convert to float from 4-bit (3.1) fixed-point
* the always-negative value is stored positive, so make it negative */ * the always-negative value is stored positive, so make it negative */
#define GAINTOFLOAT(g) (g) ? -(float)(g>>1) - ((g & 1) ? 0.5 : 0.0) : 0.0 #define GAINTOFLOAT(g) (g) ? -(float)(g>>1) - ((g & 1) ? 0.5 : 0.0) : 0.0
@ -894,38 +900,40 @@ typedef struct HDCDContext {
const AVClass *class; const AVClass *class;
hdcd_state_t state[HDCD_MAX_CHANNELS]; hdcd_state_t state[HDCD_MAX_CHANNELS];
/* use hdcd_*_stereo() functions to process both channels together. /* AVOption members */
/** use hdcd_*_stereo() functions to process both channels together.
* -af hdcd=process_stereo=0 for off * -af hdcd=process_stereo=0 for off
* -af hdcd=process_stereo=1 for on * -af hdcd=process_stereo=1 for on
* default is HDCD_PROCESS_STEREO_DEFAULT */ * default is HDCD_PROCESS_STEREO_DEFAULT */
int process_stereo; int process_stereo;
/* always extend peaks above -3dBFS even if PE isn't signaled /** always extend peaks above -3dBFS even if PE isn't signaled
* -af hdcd=force_pe=0 for off * -af hdcd=force_pe=0 for off
* -af hdcd=force_pe=1 for on * -af hdcd=force_pe=1 for on
* default is off */ * default is off */
int force_pe; int force_pe;
/* analyze mode replaces the audio with a solid tone and adjusts /** analyze mode replaces the audio with a solid tone and adjusts
* the amplitude to signal some specific aspect of the decoding * the amplitude to signal some specific aspect of the decoding
* process. See docs or HDCD_ANA_* defines. */ * process. See docs or HDCD_ANA_* defines. */
int analyze_mode; int analyze_mode;
int ana_snb; /* used in tone generation */ int ana_snb; /**< used in tone generation */
/* end AVOption members */
/* config_input() and config_output() scan links for any resampling /** config_input() and config_output() scan links for any resampling
* or format changes. If found, warnings are issued and bad_config * or format changes. If found, warnings are issued and bad_config
* is set. */ * is set. */
int bad_config; int bad_config;
AVFilterContext *fctx; /* filter context for logging errors */ AVFilterContext *fctx; /**< filter context for logging errors */
int sample_count; /* used in error logging */ int sample_count; /**< used in error logging */
int val_target_gain; /* last matching target_gain in both channels */ int val_target_gain; /**< last matching target_gain in both channels */
/* User information/stats */ /* User information/stats */
int hdcd_detected; int hdcd_detected; /**< Valid HDCD coding was detected */
int det_errors; /* detectable errors */ int det_errors; /**< detectable errors */
hdcd_pe_t peak_extend; hdcd_pe_t peak_extend; /**< peak exted used */
int uses_transient_filter; /* detected, but not implemented */ int uses_transient_filter; /**< transient filter flag detected */
float max_gain_adjustment; /* in dB, expected in the range -6.0 to 0.0 */ float max_gain_adjustment; /**< in dB, expected in the range -7.5 to 0.0 */
} HDCDContext; } HDCDContext;
#define OFFSET(x) offsetof(HDCDContext, x) #define OFFSET(x) offsetof(HDCDContext, x)
@ -976,7 +984,7 @@ static void hdcd_reset(hdcd_state_t *state, unsigned rate)
state->count_sustain_expired = -1; state->count_sustain_expired = -1;
} }
/* update the user info/counters */ /** update the user info/counters */
static void hdcd_update_info(hdcd_state_t *state) static void hdcd_update_info(hdcd_state_t *state)
{ {
if (state->control & 16) state->count_peak_extend++; if (state->control & 16) state->count_peak_extend++;
@ -1242,7 +1250,7 @@ static int hdcd_scan_stereo(HDCDContext *ctx, const int32_t *samples, int max)
return result; return result;
} }
/* encode a value in the given sample by adjusting the amplitude */ /** encode a value in the given sample by adjusting the amplitude */
static int32_t hdcd_analyze_gen(int32_t sample, unsigned int v, unsigned int maxv) static int32_t hdcd_analyze_gen(int32_t sample, unsigned int v, unsigned int maxv)
{ {
float sflt = sample, vv = v; float sflt = sample, vv = v;
@ -1252,7 +1260,7 @@ static int32_t hdcd_analyze_gen(int32_t sample, unsigned int v, unsigned int max
return (int32_t)sflt; return (int32_t)sflt;
} }
/* behaves like hdcd_envelope(), but encodes processing information in /** behaves like hdcd_envelope(), but encodes processing information in
* a way that is audible (and visible in an audio editor) to aid analysis. */ * a way that is audible (and visible in an audio editor) to aid analysis. */
static int hdcd_analyze(int32_t *samples, int count, int stride, int gain, int target_gain, int extend, int mode, int cdt_active, int tg_mismatch) static int hdcd_analyze(int32_t *samples, int count, int stride, int gain, int target_gain, int extend, int mode, int cdt_active, int tg_mismatch)
{ {
@ -1313,6 +1321,7 @@ static int hdcd_analyze(int32_t *samples, int count, int stride, int gain, int t
return gain; return gain;
} }
/** apply HDCD decoding parameters to a series of samples */
static int hdcd_envelope(int32_t *samples, int count, int stride, int gain, int target_gain, int extend) static int hdcd_envelope(int32_t *samples, int count, int stride, int gain, int target_gain, int extend)
{ {
int i; int i;
@ -1372,7 +1381,7 @@ static int hdcd_envelope(int32_t *samples, int count, int stride, int gain, int
return gain; return gain;
} }
/* extract fields from control code */ /** extract fields from control code */
static void hdcd_control(HDCDContext *ctx, hdcd_state_t *state, int *peak_extend, int *target_gain) static void hdcd_control(HDCDContext *ctx, hdcd_state_t *state, int *peak_extend, int *target_gain)
{ {
*peak_extend = (ctx->force_pe || state->control & 16); *peak_extend = (ctx->force_pe || state->control & 16);
@ -1500,7 +1509,7 @@ static void hdcd_process_stereo(HDCDContext *ctx, int32_t *samples, int count)
ctx->state[1].running_gain = gain[1]; ctx->state[1].running_gain = gain[1];
} }
/* tone generator: sample_number, frequency, sample_rate, amplitude */ /** tone generator: sample_number, frequency, sample_rate, amplitude */
#define TONEGEN16(sn, f, sr, a) (int16_t)(sin((6.28318530718 * (sn) * (f)) /(sr)) * (a) * 0x7fff) #define TONEGEN16(sn, f, sr, a) (int16_t)(sin((6.28318530718 * (sn) * (f)) /(sr)) * (a) * 0x7fff)
static int filter_frame(AVFilterLink *inlink, AVFrame *in) static int filter_frame(AVFilterLink *inlink, AVFrame *in)