FFmpeg
Data Structures | Macros | Enumerations | Functions | Variables
af_atempo.c File Reference
#include <float.h>
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/channel_layout.h"
#include "libavutil/eval.h"
#include "libavutil/opt.h"
#include "libavutil/samplefmt.h"
#include "libavutil/tx.h"
#include "avfilter.h"
#include "audio.h"
#include "internal.h"

Go to the source code of this file.

Data Structures

struct  AudioFragment
 A fragment of audio waveform. More...
 
struct  ATempoContext
 Filter state machine. More...
 

Macros

#define YAE_ATEMPO_MIN   0.5
 
#define YAE_ATEMPO_MAX   100.0
 
#define OFFSET(x)   offsetof(ATempoContext, x)
 
#define RE_MALLOC_OR_FAIL(field, field_size)
 
#define yae_init_xdat(scalar_type, scalar_max)
 A helper macro for initializing complex data buffer with scalar data of a given type. More...
 
#define yae_blend(scalar_type)
 A helper macro for blending the overlap region of previous and current audio fragment. More...
 

Enumerations

enum  FilterState {
  YAE_LOAD_FRAGMENT, YAE_ADJUST_POSITION, YAE_RELOAD_FRAGMENT, YAE_OUTPUT_OVERLAP_ADD,
  YAE_FLUSH_OUTPUT
}
 Filter state machine states. More...
 

Functions

 AVFILTER_DEFINE_CLASS (atempo)
 
static AudioFragmentyae_curr_frag (ATempoContext *atempo)
 
static AudioFragmentyae_prev_frag (ATempoContext *atempo)
 
static void yae_clear (ATempoContext *atempo)
 Reset filter to initial state, do not deallocate existing local buffers. More...
 
static void yae_release_buffers (ATempoContext *atempo)
 Reset filter to initial state and deallocate all buffers. More...
 
static int yae_reset (ATempoContext *atempo, enum AVSampleFormat format, int sample_rate, int channels)
 Prepare filter for processing audio data of given format, sample rate and number of channels. More...
 
static int yae_update (AVFilterContext *ctx)
 
static void yae_downmix (ATempoContext *atempo, AudioFragment *frag)
 Initialize complex data buffer of a given audio fragment with down-mixed mono data of appropriate scalar type. More...
 
static int yae_load_data (ATempoContext *atempo, const uint8_t **src_ref, const uint8_t *src_end, int64_t stop_here)
 Populate the internal data buffer on as-needed basis. More...
 
static int yae_load_frag (ATempoContext *atempo, const uint8_t **src_ref, const uint8_t *src_end)
 Populate current audio fragment data buffer. More...
 
static void yae_advance_to_next_frag (ATempoContext *atempo)
 Prepare for loading next audio fragment. More...
 
static void yae_xcorr_via_rdft (float *xcorr_in, float *xcorr, AVTXContext *complex_to_real, av_tx_fn c2r_fn, const AVComplexFloat *xa, const AVComplexFloat *xb, const int window)
 Calculate cross-correlation via rDFT. More...
 
static int yae_align (AudioFragment *frag, const AudioFragment *prev, const int window, const int delta_max, const int drift, float *correlation_in, float *correlation, AVTXContext *complex_to_real, av_tx_fn c2r_fn)
 Calculate alignment offset for given fragment relative to the previous fragment. More...
 
static int yae_adjust_position (ATempoContext *atempo)
 Adjust current fragment position for better alignment with previous fragment. More...
 
static int yae_overlap_add (ATempoContext *atempo, uint8_t **dst_ref, uint8_t *dst_end)
 Blend the overlap region of previous and current audio fragment and output the results to the given destination buffer. More...
 
static void yae_apply (ATempoContext *atempo, const uint8_t **src_ref, const uint8_t *src_end, uint8_t **dst_ref, uint8_t *dst_end)
 Feed as much data to the filter as it is able to consume and receive as much processed data in the destination buffer as it is able to produce or store. More...
 
static int yae_flush (ATempoContext *atempo, uint8_t **dst_ref, uint8_t *dst_end)
 Flush any buffered data from the filter. More...
 
static av_cold int init (AVFilterContext *ctx)
 
static av_cold void uninit (AVFilterContext *ctx)
 
static int config_props (AVFilterLink *inlink)
 
static int push_samples (ATempoContext *atempo, AVFilterLink *outlink, int n_out)
 
static int filter_frame (AVFilterLink *inlink, AVFrame *src_buffer)
 
static int request_frame (AVFilterLink *outlink)
 
static int process_command (AVFilterContext *ctx, const char *cmd, const char *arg, char *res, int res_len, int flags)
 

Variables

static const AVOption atempo_options []
 
static enum AVSampleFormat sample_fmts []
 
static const AVFilterPad atempo_inputs []
 
static const AVFilterPad atempo_outputs []
 
const AVFilter ff_af_atempo
 

Detailed Description

tempo scaling audio filter – an implementation of WSOLA algorithm

Based on MIT licensed yaeAudioTempoFilter.h and yaeAudioFragment.h from Apprentice Video player by Pavel Koshevoy. https://sourceforge.net/projects/apprenticevideo/

An explanation of SOLA algorithm is available at http://www.surina.net/article/time-and-pitch-scaling.html

WSOLA is very similar to SOLA, only one major difference exists between these algorithms. SOLA shifts audio fragments along the output stream, where as WSOLA shifts audio fragments along the input stream.

The advantage of WSOLA algorithm is that the overlap region size is always the same, therefore the blending function is constant and can be precomputed.

Definition in file af_atempo.c.

Macro Definition Documentation

◆ YAE_ATEMPO_MIN

#define YAE_ATEMPO_MIN   0.5

Definition at line 158 of file af_atempo.c.

◆ YAE_ATEMPO_MAX

#define YAE_ATEMPO_MAX   100.0

Definition at line 159 of file af_atempo.c.

◆ OFFSET

#define OFFSET (   x)    offsetof(ATempoContext, x)

Definition at line 161 of file af_atempo.c.

◆ RE_MALLOC_OR_FAIL

#define RE_MALLOC_OR_FAIL (   field,
  field_size 
)
Value:
do { \
av_freep(&field); \
field = av_calloc(field_size, 1); \
if (!field) { \
yae_release_buffers(atempo); \
return AVERROR(ENOMEM); \
} \
} while (0)

Definition at line 250 of file af_atempo.c.

◆ yae_init_xdat

#define yae_init_xdat (   scalar_type,
  scalar_max 
)

A helper macro for initializing complex data buffer with scalar data of a given type.

Definition at line 350 of file af_atempo.c.

◆ yae_blend

#define yae_blend (   scalar_type)
Value:
do { \
const scalar_type *aaa = (const scalar_type *)a; \
const scalar_type *bbb = (const scalar_type *)b; \
\
scalar_type *out = (scalar_type *)dst; \
scalar_type *out_end = (scalar_type *)dst_end; \
int64_t i; \
for (i = 0; i < overlap && out < out_end; \
i++, atempo->position[1]++, wa++, wb++) { \
float w0 = *wa; \
float w1 = *wb; \
int j; \
for (j = 0; j < atempo->channels; \
j++, aaa++, bbb++, out++) { \
float t0 = (float)*aaa; \
float t1 = (float)*bbb; \
\
*out = \
frag->position[0] + i < 0 ? \
*aaa : \
(scalar_type)(t0 * w0 + t1 * w1); \
} \
} \
dst = (uint8_t *)out; \
} while (0)

A helper macro for blending the overlap region of previous and current audio fragment.

Definition at line 729 of file af_atempo.c.

Enumeration Type Documentation

◆ FilterState

Filter state machine states.

Enumerator
YAE_LOAD_FRAGMENT 
YAE_ADJUST_POSITION 
YAE_RELOAD_FRAGMENT 
YAE_OUTPUT_OVERLAP_ADD 
YAE_FLUSH_OUTPUT 

Definition at line 77 of file af_atempo.c.

Function Documentation

◆ AVFILTER_DEFINE_CLASS()

AVFILTER_DEFINE_CLASS ( atempo  )

◆ yae_curr_frag()

static AudioFragment* yae_curr_frag ( ATempoContext atempo)
inlinestatic

◆ yae_prev_frag()

static AudioFragment* yae_prev_frag ( ATempoContext atempo)
inlinestatic

◆ yae_clear()

static void yae_clear ( ATempoContext atempo)
static

Reset filter to initial state, do not deallocate existing local buffers.

Definition at line 187 of file af_atempo.c.

Referenced by yae_release_buffers(), and yae_reset().

◆ yae_release_buffers()

static void yae_release_buffers ( ATempoContext atempo)
static

Reset filter to initial state and deallocate all buffers.

Definition at line 228 of file af_atempo.c.

Referenced by uninit(), and yae_reset().

◆ yae_reset()

static int yae_reset ( ATempoContext atempo,
enum AVSampleFormat  format,
int  sample_rate,
int  channels 
)
static

Prepare filter for processing audio data of given format, sample rate and number of channels.

Definition at line 264 of file af_atempo.c.

Referenced by config_props().

◆ yae_update()

static int yae_update ( AVFilterContext ctx)
static

Definition at line 335 of file af_atempo.c.

Referenced by process_command().

◆ yae_downmix()

static void yae_downmix ( ATempoContext atempo,
AudioFragment frag 
)
static

Initialize complex data buffer of a given audio fragment with down-mixed mono data of appropriate scalar type.

Definition at line 400 of file af_atempo.c.

Referenced by yae_apply(), and yae_flush().

◆ yae_load_data()

static int yae_load_data ( ATempoContext atempo,
const uint8_t **  src_ref,
const uint8_t *  src_end,
int64_t  stop_here 
)
static

Populate the internal data buffer on as-needed basis.

Returns
0 if requested data was already available or was successfully loaded, AVERROR(EAGAIN) if more input data is required.

Definition at line 428 of file af_atempo.c.

Referenced by yae_load_frag().

◆ yae_load_frag()

static int yae_load_frag ( ATempoContext atempo,
const uint8_t **  src_ref,
const uint8_t *  src_end 
)
static

Populate current audio fragment data buffer.

Returns
0 when the fragment is ready, AVERROR(EAGAIN) if more input data is required.

Definition at line 503 of file af_atempo.c.

Referenced by yae_apply(), and yae_flush().

◆ yae_advance_to_next_frag()

static void yae_advance_to_next_frag ( ATempoContext atempo)
static

Prepare for loading next audio fragment.

Definition at line 583 of file af_atempo.c.

Referenced by yae_apply(), and yae_flush().

◆ yae_xcorr_via_rdft()

static void yae_xcorr_via_rdft ( float xcorr_in,
float xcorr,
AVTXContext complex_to_real,
av_tx_fn  c2r_fn,
const AVComplexFloat xa,
const AVComplexFloat xb,
const int  window 
)
static

Calculate cross-correlation via rDFT.

Multiply two vectors of complex numbers (result of real_to_complex rDFT) and transform back via complex_to_real rDFT.

Definition at line 605 of file af_atempo.c.

Referenced by yae_align().

◆ yae_align()

static int yae_align ( AudioFragment frag,
const AudioFragment prev,
const int  window,
const int  delta_max,
const int  drift,
float correlation_in,
float correlation,
AVTXContext complex_to_real,
av_tx_fn  c2r_fn 
)
static

Calculate alignment offset for given fragment relative to the previous fragment.

Returns
alignment offset of current fragment relative to previous.

Definition at line 631 of file af_atempo.c.

Referenced by yae_adjust_position().

◆ yae_adjust_position()

static int yae_adjust_position ( ATempoContext atempo)
static

Adjust current fragment position for better alignment with previous fragment.

Returns
alignment correction.

Definition at line 689 of file af_atempo.c.

Referenced by yae_apply(), and yae_flush().

◆ yae_overlap_add()

static int yae_overlap_add ( ATempoContext atempo,
uint8_t **  dst_ref,
uint8_t *  dst_end 
)
static

Blend the overlap region of previous and current audio fragment and output the results to the given destination buffer.

Returns
0 if the overlap region was completely stored in the dst buffer, AVERROR(EAGAIN) if more destination buffer space is required.

Definition at line 766 of file af_atempo.c.

Referenced by yae_apply(), and yae_flush().

◆ yae_apply()

static void yae_apply ( ATempoContext atempo,
const uint8_t **  src_ref,
const uint8_t *  src_end,
uint8_t **  dst_ref,
uint8_t *  dst_end 
)
static

Feed as much data to the filter as it is able to consume and receive as much processed data in the destination buffer as it is able to produce or store.

Definition at line 821 of file af_atempo.c.

Referenced by filter_frame().

◆ yae_flush()

static int yae_flush ( ATempoContext atempo,
uint8_t **  dst_ref,
uint8_t *  dst_end 
)
static

Flush any buffered data from the filter.

Returns
0 if all data was completely stored in the dst buffer, AVERROR(EAGAIN) if more destination buffer space is required.

Definition at line 895 of file af_atempo.c.

Referenced by request_frame().

◆ init()

static av_cold int init ( AVFilterContext ctx)
static

Definition at line 984 of file af_atempo.c.

◆ uninit()

static av_cold void uninit ( AVFilterContext ctx)
static

Definition at line 992 of file af_atempo.c.

◆ config_props()

static int config_props ( AVFilterLink inlink)
static

Definition at line 1013 of file af_atempo.c.

◆ push_samples()

static int push_samples ( ATempoContext atempo,
AVFilterLink outlink,
int  n_out 
)
static

Definition at line 1024 of file af_atempo.c.

Referenced by filter_frame(), and request_frame().

◆ filter_frame()

static int filter_frame ( AVFilterLink inlink,
AVFrame src_buffer 
)
static

Definition at line 1050 of file af_atempo.c.

◆ request_frame()

static int request_frame ( AVFilterLink outlink)
static

Definition at line 1098 of file af_atempo.c.

◆ process_command()

static int process_command ( AVFilterContext ctx,
const char *  cmd,
const char *  arg,
char *  res,
int  res_len,
int  flags 
)
static

Definition at line 1144 of file af_atempo.c.

Variable Documentation

◆ atempo_options

const AVOption atempo_options[]
static
Initial value:
= {
{ "tempo", "set tempo scale factor",
OFFSET(tempo), AV_OPT_TYPE_DOUBLE, { .dbl = 1.0 },
{ NULL }
}

Definition at line 163 of file af_atempo.c.

◆ sample_fmts

enum AVSampleFormat sample_fmts[]
static

◆ atempo_inputs

const AVFilterPad atempo_inputs[]
static
Initial value:
= {
{
.name = "default",
.filter_frame = filter_frame,
.config_props = config_props,
},
}

Definition at line 1159 of file af_atempo.c.

◆ atempo_outputs

const AVFilterPad atempo_outputs[]
static
Initial value:
= {
{
.name = "default",
.request_frame = request_frame,
},
}

Definition at line 1168 of file af_atempo.c.

◆ ff_af_atempo

const AVFilter ff_af_atempo
Initial value:
= {
.name = "atempo",
.description = NULL_IF_CONFIG_SMALL("Adjust audio tempo."),
.init = init,
.uninit = uninit,
.process_command = process_command,
.priv_size = sizeof(ATempoContext),
.priv_class = &atempo_class,
}

Definition at line 1176 of file af_atempo.c.

AVERROR
Filter the word “frame” indicates either a video frame or a group of audio as stored in an AVFrame structure Format for each input and each output the list of supported formats For video that means pixel format For audio that means channel sample they are references to shared objects When the negotiation mechanism computes the intersection of the formats supported at each end of a all references to both lists are replaced with a reference to the intersection And when a single format is eventually chosen for a link amongst the remaining all references to the list are updated That means that if a filter requires that its input and output have the same format amongst a supported all it has to do is use a reference to the same list of formats query_formats can leave some formats unset and return AVERROR(EAGAIN) to cause the negotiation mechanism toagain later. That can be used by filters with complex requirements to use the format negotiated on one link to set the formats supported on another. Frame references ownership and permissions
out
FILE * out
Definition: movenc.c:54
config_props
static int config_props(AVFilterLink *inlink)
Definition: af_atempo.c:1013
t0
#define t0
Definition: regdef.h:28
b
#define b
Definition: input.c:34
AV_OPT_FLAG_RUNTIME_PARAM
#define AV_OPT_FLAG_RUNTIME_PARAM
a generic parameter which can be set by the user at runtime
Definition: opt.h:296
t1
#define t1
Definition: regdef.h:29
OFFSET
#define OFFSET(x)
Definition: af_atempo.c:161
AV_OPT_FLAG_FILTERING_PARAM
#define AV_OPT_FLAG_FILTERING_PARAM
a generic parameter which can be set by the user for filtering
Definition: opt.h:297
init
static av_cold int init(AVFilterContext *ctx)
Definition: af_atempo.c:984
ATempoContext
Filter state machine.
Definition: af_atempo.c:88
atempo_outputs
static const AVFilterPad atempo_outputs[]
Definition: af_atempo.c:1168
float
float
Definition: af_crystalizer.c:122
AV_OPT_TYPE_DOUBLE
@ AV_OPT_TYPE_DOUBLE
Definition: opt.h:227
AVMEDIA_TYPE_AUDIO
@ AVMEDIA_TYPE_AUDIO
Definition: avutil.h:202
YAE_ATEMPO_MAX
#define YAE_ATEMPO_MAX
Definition: af_atempo.c:159
field
it s the only field you need to keep assuming you have a context There is some magic you don t need to care about around this field
Definition: writing_filters.txt:78
FILTER_INPUTS
#define FILTER_INPUTS(array)
Definition: internal.h:190
AV_OPT_FLAG_AUDIO_PARAM
#define AV_OPT_FLAG_AUDIO_PARAM
Definition: opt.h:283
NULL
#define NULL
Definition: coverity.c:32
filter_frame
static int filter_frame(AVFilterLink *inlink, AVFrame *src_buffer)
Definition: af_atempo.c:1050
process_command
static int process_command(AVFilterContext *ctx, const char *cmd, const char *arg, char *res, int res_len, int flags)
Definition: af_atempo.c:1144
NULL_IF_CONFIG_SMALL
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification.
Definition: internal.h:116
for
for(k=2;k<=8;++k)
Definition: h264pred_template.c:425
AV_SAMPLE_FMT_NONE
@ AV_SAMPLE_FMT_NONE
Definition: samplefmt.h:56
FILTER_SAMPLEFMTS_ARRAY
#define FILTER_SAMPLEFMTS_ARRAY(array)
Definition: internal.h:173
a
The reader does not expect b to be semantically here and if the code is changed by maybe adding a a division or other the signedness will almost certainly be mistaken To avoid this confusion a new type was SUINT is the C unsigned type but it holds a signed int to use the same example SUINT a
Definition: undefined.txt:41
i
#define i(width, name, range_min, range_max)
Definition: cbs_h2645.c:271
YAE_ATEMPO_MIN
#define YAE_ATEMPO_MIN
Definition: af_atempo.c:158
AV_SAMPLE_FMT_U8
@ AV_SAMPLE_FMT_U8
unsigned 8 bits
Definition: samplefmt.h:57
sample_fmts
static enum AVSampleFormat sample_fmts[]
Definition: af_atempo.c:1004
AV_SAMPLE_FMT_S16
@ AV_SAMPLE_FMT_S16
signed 16 bits
Definition: samplefmt.h:58
av_calloc
void * av_calloc(size_t nmemb, size_t size)
Definition: mem.c:272
atempo_inputs
static const AVFilterPad atempo_inputs[]
Definition: af_atempo.c:1159
request_frame
static int request_frame(AVFilterLink *outlink)
Definition: af_atempo.c:1098
FILTER_OUTPUTS
#define FILTER_OUTPUTS(array)
Definition: internal.h:191
uninit
static av_cold void uninit(AVFilterContext *ctx)
Definition: af_atempo.c:992
AV_SAMPLE_FMT_DBL
@ AV_SAMPLE_FMT_DBL
double
Definition: samplefmt.h:61
AV_SAMPLE_FMT_S32
@ AV_SAMPLE_FMT_S32
signed 32 bits
Definition: samplefmt.h:59
AV_SAMPLE_FMT_FLT
@ AV_SAMPLE_FMT_FLT
float
Definition: samplefmt.h:60