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af_amix.c File Reference

Audio Mix Filter. More...

#include "libavutil/attributes.h"
#include "libavutil/audio_fifo.h"
#include "libavutil/avassert.h"
#include "libavutil/avstring.h"
#include "libavutil/channel_layout.h"
#include "libavutil/common.h"
#include "libavutil/float_dsp.h"
#include "libavutil/mathematics.h"
#include "libavutil/opt.h"
#include "libavutil/samplefmt.h"
#include "audio.h"
#include "avfilter.h"
#include "formats.h"
#include "internal.h"

Go to the source code of this file.

Data Structures

struct  FrameInfo
 
struct  FrameList
 Linked list used to store timestamps and frame sizes of all frames in the FIFO for the first input. More...
 
struct  MixContext
 

Macros

#define INPUT_ON   1
 input is active More...
 
#define INPUT_EOF   2
 input has reached EOF (may still be active) More...
 
#define DURATION_LONGEST   0
 
#define DURATION_SHORTEST   1
 
#define DURATION_FIRST   2
 
#define OFFSET(x)   offsetof(MixContext, x)
 
#define A   AV_OPT_FLAG_AUDIO_PARAM
 
#define F   AV_OPT_FLAG_FILTERING_PARAM
 

Functions

static void frame_list_clear (FrameList *frame_list)
 
static int frame_list_next_frame_size (FrameList *frame_list)
 
static int64_t frame_list_next_pts (FrameList *frame_list)
 
static void frame_list_remove_samples (FrameList *frame_list, int nb_samples)
 
static int frame_list_add_frame (FrameList *frame_list, int nb_samples, int64_t pts)
 
 AVFILTER_DEFINE_CLASS (amix)
 
static void calculate_scales (MixContext *s, int nb_samples)
 Update the scaling factors to apply to each input during mixing. More...
 
static int config_output (AVFilterLink *outlink)
 
static int calc_active_inputs (MixContext *s)
 Calculates the number of active inputs and determines EOF based on the duration option. More...
 
static int output_frame (AVFilterLink *outlink)
 Read samples from the input FIFOs, mix, and write to the output link. More...
 
static int request_samples (AVFilterContext *ctx, int min_samples)
 Requests a frame, if needed, from each input link other than the first. More...
 
static int request_frame (AVFilterLink *outlink)
 
static int filter_frame (AVFilterLink *inlink, AVFrame *buf)
 
static av_cold int init (AVFilterContext *ctx)
 
static av_cold void uninit (AVFilterContext *ctx)
 
static int query_formats (AVFilterContext *ctx)
 

Variables

static const AVOption amix_options []
 
static const AVFilterPad avfilter_af_amix_outputs []
 
AVFilter ff_af_amix
 

Detailed Description

Audio Mix Filter.

Mixes audio from multiple sources into a single output. The channel layout, sample rate, and sample format will be the same for all inputs and the output.

Definition in file af_amix.c.

Macro Definition Documentation

#define INPUT_ON   1

input is active

Definition at line 47 of file af_amix.c.

Referenced by calc_active_inputs(), calculate_scales(), config_output(), output_frame(), request_frame(), and request_samples().

#define INPUT_EOF   2

input has reached EOF (may still be active)

Definition at line 48 of file af_amix.c.

Referenced by output_frame(), and request_samples().

#define DURATION_LONGEST   0

Definition at line 50 of file af_amix.c.

#define DURATION_SHORTEST   1

Definition at line 51 of file af_amix.c.

Referenced by calc_active_inputs().

#define DURATION_FIRST   2

Definition at line 52 of file af_amix.c.

Referenced by calc_active_inputs().

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

Definition at line 175 of file af_amix.c.

#define A   AV_OPT_FLAG_AUDIO_PARAM

Definition at line 176 of file af_amix.c.

Definition at line 177 of file af_amix.c.

Function Documentation

static void frame_list_clear ( FrameList frame_list)
static

Definition at line 76 of file af_amix.c.

Referenced by frame_list_remove_samples(), and uninit().

static int frame_list_next_frame_size ( FrameList frame_list)
static

Definition at line 90 of file af_amix.c.

Referenced by output_frame(), and request_frame().

static int64_t frame_list_next_pts ( FrameList frame_list)
static

Definition at line 97 of file af_amix.c.

Referenced by output_frame().

static void frame_list_remove_samples ( FrameList frame_list,
int  nb_samples 
)
static

Definition at line 104 of file af_amix.c.

Referenced by output_frame().

static int frame_list_add_frame ( FrameList frame_list,
int  nb_samples,
int64_t  pts 
)
static

Definition at line 131 of file af_amix.c.

Referenced by filter_frame().

AVFILTER_DEFINE_CLASS ( amix  )
static void calculate_scales ( MixContext s,
int  nb_samples 
)
static

Update the scaling factors to apply to each input during mixing.

This balances the full volume range between active inputs and handles volume transitions when EOF is encountered on an input but mixing continues with the remaining inputs.

Definition at line 201 of file af_amix.c.

Referenced by config_output(), and output_frame().

static int config_output ( AVFilterLink outlink)
static

Definition at line 218 of file af_amix.c.

static int calc_active_inputs ( MixContext s)
static

Calculates the number of active inputs and determines EOF based on the duration option.

Returns
0 if mixing should continue, or AVERROR_EOF if mixing should stop.

Definition at line 390 of file af_amix.c.

Referenced by output_frame(), and request_frame().

static int output_frame ( AVFilterLink outlink)
static

Read samples from the input FIFOs, mix, and write to the output link.

Definition at line 271 of file af_amix.c.

Referenced by filter_frame(), request_frame(), and request_samples().

static int request_samples ( AVFilterContext ctx,
int  min_samples 
)
static

Requests a frame, if needed, from each input link other than the first.

Definition at line 358 of file af_amix.c.

Referenced by request_frame().

static int request_frame ( AVFilterLink outlink)
static

Definition at line 405 of file af_amix.c.

static int filter_frame ( AVFilterLink inlink,
AVFrame buf 
)
static

Definition at line 436 of file af_amix.c.

Referenced by init().

static av_cold int init ( AVFilterContext ctx)
static

Definition at line 472 of file af_amix.c.

static av_cold void uninit ( AVFilterContext ctx)
static

Definition at line 498 of file af_amix.c.

static int query_formats ( AVFilterContext ctx)
static

Definition at line 518 of file af_amix.c.

Variable Documentation

const AVOption amix_options[]
static
Initial value:
= {
{ "inputs", "Number of inputs.",
OFFSET(nb_inputs), AV_OPT_TYPE_INT, { .i64 = 2 }, 1, 32, A|F },
{ "duration", "How to determine the end-of-stream.",
OFFSET(duration_mode), AV_OPT_TYPE_INT, { .i64 = DURATION_LONGEST }, 0, 2, A|F, "duration" },
{ "longest", "Duration of longest input.", 0, AV_OPT_TYPE_CONST, { .i64 = DURATION_LONGEST }, INT_MIN, INT_MAX, A|F, "duration" },
{ "shortest", "Duration of shortest input.", 0, AV_OPT_TYPE_CONST, { .i64 = DURATION_SHORTEST }, INT_MIN, INT_MAX, A|F, "duration" },
{ "first", "Duration of first input.", 0, AV_OPT_TYPE_CONST, { .i64 = DURATION_FIRST }, INT_MIN, INT_MAX, A|F, "duration" },
{ "dropout_transition", "Transition time, in seconds, for volume "
"renormalization when an input stream ends.",
OFFSET(dropout_transition), AV_OPT_TYPE_FLOAT, { .dbl = 2.0 }, 0, INT_MAX, A|F },
{ NULL }
}
#define NULL
Definition: coverity.c:32
#define DURATION_LONGEST
Definition: af_amix.c:50
#define A
Definition: af_amix.c:176
#define OFFSET(x)
Definition: af_amix.c:175
#define DURATION_SHORTEST
Definition: af_amix.c:51
#define F
Definition: af_amix.c:177
#define DURATION_FIRST
Definition: af_amix.c:52

Definition at line 178 of file af_amix.c.

const AVFilterPad avfilter_af_amix_outputs[]
static
Initial value:
= {
{
.name = "default",
.config_props = config_output,
.request_frame = request_frame
},
{ NULL }
}
#define NULL
Definition: coverity.c:32
static int request_frame(AVFilterLink *outlink)
Definition: af_amix.c:405
static int config_output(AVFilterLink *outlink)
Definition: af_amix.c:218

Definition at line 544 of file af_amix.c.

AVFilter ff_af_amix
Initial value:
= {
.name = "amix",
.description = NULL_IF_CONFIG_SMALL("Audio mixing."),
.priv_size = sizeof(MixContext),
.priv_class = &amix_class,
.init = init,
}
#define NULL
Definition: coverity.c:32
static av_cold void uninit(AVFilterContext *ctx)
Definition: af_amix.c:498
#define AVFILTER_FLAG_DYNAMIC_INPUTS
The number of the filter inputs is not determined just by AVFilter.inputs.
Definition: avfilter.h:105
static const AVFilterPad avfilter_af_amix_outputs[]
Definition: af_amix.c:544
static int flags
Definition: log.c:57
static int query_formats(AVFilterContext *ctx)
Definition: af_amix.c:518
#define NULL_IF_CONFIG_SMALL(x)
Return NULL if CONFIG_SMALL is true, otherwise the argument without modification. ...
Definition: internal.h:176
static const AVFilterPad outputs[]
Definition: af_afftfilt.c:386
static const AVFilterPad inputs[]
Definition: af_afftfilt.c:376
static av_cold int init(AVFilterContext *ctx)
Definition: af_amix.c:472

Definition at line 554 of file af_amix.c.