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Commit 400e2acd authored by Burt P's avatar Burt P
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af_hdcd: Code comments update 

Signed-off-by: 's avatarBurt P <pburt0@gmail.com>
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libavfilter/af_hdcd.c
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/*
Copyright (C) 2010, Chris Moeller,
All rights reserved.
Optimizations by Gumboot
Redistribution and use in source and binary forms, with or without modification,
are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright
notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
3. The names of its contributors may not be used to endorse or promote
products derived from this software without specific prior written
permission.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
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.
* Copyright (C) 2010, Chris Moeller,
* All rights reserved.
* Optimizations by Gumboot
* Additional work by Burt P.
* Original code reverse engineered from HDCD decoder library by Christopher Key,
* which was likely reverse engineered from Windows Media Player.
*
* Redistribution and use in source and binary forms, with or without modification,
* are permitted provided that the following conditions are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The names of its contributors may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* 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,
which was likely reverse engineered from Windows Media Player.
* HDCD is High Definition Compatible Digital
* 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
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
/**
* @file
* HDCD decoding filter
*/
#include "libavutil/opt.h"
......@@ -820,34 +826,34 @@ typedef struct {
uint64_t window;
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 */
/** 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 */
uint8_t arg, control;
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 */
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
* steps of 0.5, but no value below -6.0 dB should appear. */
int gain_counts[16]; /* for cursiosity, mostly */
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
* steps of 0.5, but no value below -6.0 dB should appear. */
int gain_counts[16];
int max_gain;
/* occurences of code detect timer expiring without detecting
* a code. -1 for timer never set. */
/** occurences of code detect timer expiring without detecting
* a code. -1 for timer never set. */
int count_sustain_expired;
} hdcd_state_t;
......@@ -866,8 +872,8 @@ static const char * const pe_str[] = {
#define HDCD_PROCESS_STEREO_DEFAULT 1
#define HDCD_MAX_CHANNELS 2
/* convert to float from 4-bit (3.1) fixed-point
* the always-negative value is stored positive, so make it negative */
/** convert to float from 4-bit (3.1) fixed-point
* 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 HDCD_ANA_OFF 0
......@@ -894,38 +900,40 @@ typedef struct HDCDContext {
const AVClass *class;
hdcd_state_t state[HDCD_MAX_CHANNELS];
/* use hdcd_*_stereo() functions to process both channels together.
* -af hdcd=process_stereo=0 for off
* -af hdcd=process_stereo=1 for on
* default is HDCD_PROCESS_STEREO_DEFAULT */
/* AVOption members */
/** use hdcd_*_stereo() functions to process both channels together.
* -af hdcd=process_stereo=0 for off
* -af hdcd=process_stereo=1 for on
* default is HDCD_PROCESS_STEREO_DEFAULT */
int process_stereo;
/* 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 */
/** 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;
/* analyze mode replaces the audio with a solid tone and adjusts
* the amplitude to signal some specific aspect of the decoding
* process. See docs or HDCD_ANA_* defines. */
/** analyze mode replaces the audio with a solid tone and adjusts
* the amplitude to signal some specific aspect of the decoding
* process. See docs or HDCD_ANA_* defines. */
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
* or format changes. If found, warnings are issued and bad_config
* is set. */
/** config_input() and config_output() scan links for any resampling
* or format changes. If found, warnings are issued and bad_config
* is set. */
int bad_config;
AVFilterContext *fctx; /* filter context for logging errors */
int sample_count; /* used in error logging */
int val_target_gain; /* last matching target_gain in both channels */
AVFilterContext *fctx; /**< filter context for logging errors */
int sample_count; /**< used in error logging */
int val_target_gain; /**< last matching target_gain in both channels */
/* User information/stats */
int hdcd_detected;
int det_errors; /* detectable errors */
hdcd_pe_t peak_extend;
int uses_transient_filter; /* detected, but not implemented */
float max_gain_adjustment; /* in dB, expected in the range -6.0 to 0.0 */
int hdcd_detected; /**< Valid HDCD coding was detected */
int det_errors; /**< detectable errors */
hdcd_pe_t peak_extend; /**< peak exted used */
int uses_transient_filter; /**< transient filter flag detected */
float max_gain_adjustment; /**< in dB, expected in the range -7.5 to 0.0 */
} HDCDContext;
#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;
}
/* update the user info/counters */
/** update the user info/counters */
static void hdcd_update_info(hdcd_state_t *state)
{
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;
}
/* 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)
{
float sflt = sample, vv = v;
......@@ -1252,8 +1260,8 @@ static int32_t hdcd_analyze_gen(int32_t sample, unsigned int v, unsigned int max
return (int32_t)sflt;
}
/* behaves like hdcd_envelope(), but encodes processing information in
* a way that is audible (and visible in an audio editor) to aid analysis. */
/** behaves like hdcd_envelope(), but encodes processing information in
* 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 const int maxg = 0xf << 7;
......@@ -1313,6 +1321,7 @@ static int hdcd_analyze(int32_t *samples, int count, int stride, int gain, int t
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)
{
int i;
......@@ -1372,7 +1381,7 @@ static int hdcd_envelope(int32_t *samples, int count, int stride, int gain, int
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)
{
*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];
}
/* 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)
static int filter_frame(AVFilterLink *inlink, AVFrame *in)
......
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