libavcodec/libspeexenc.c File Reference

libspeex Speex audio encoder More...

#include <speex/speex.h>
#include <speex/speex_header.h>
#include <speex/speex_stereo.h>
#include "libavutil/mathematics.h"
#include "libavutil/opt.h"
#include "avcodec.h"
#include "internal.h"

Go to the source code of this file.

Data Structures

struct  LibSpeexEncContext


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


static av_cold void print_enc_params (AVCodecContext *avctx, LibSpeexEncContext *s)
static av_cold int encode_init (AVCodecContext *avctx)
static int encode_frame (AVCodecContext *avctx, uint8_t *frame, int buf_size, void *data)
static av_cold int encode_close (AVCodecContext *avctx)


static const AVOption options []
class {
      class_name = "libspeex"
      item_name = av_default_item_name
      option = options
static const AVCodecDefault defaults []
AVCodec ff_libspeex_encoder

Detailed Description

libspeex Speex audio encoder

Usage Guide This explains the values that need to be set prior to initialization in order to control various encoding parameters.

Channels Speex only supports mono or stereo, so avctx->channels must be set to 1 or 2.

Sample Rate / Encoding Mode Speex has 3 modes, each of which uses a specific sample rate. narrowband : 8 kHz wideband : 16 kHz ultra-wideband : 32 kHz avctx->sample_rate must be set to one of these 3 values. This will be used to set the encoding mode.

Rate Control VBR mode is turned on by setting CODEC_FLAG_QSCALE in avctx->flags. avctx->global_quality is used to set the encoding quality. For CBR mode, avctx->bit_rate can be used to set the constant bitrate. Alternatively, the 'cbr_quality' option can be set from 0 to 10 to set a constant bitrate based on quality. For ABR mode, set avctx->bit_rate and set the 'abr' option to 1. Approx. Bitrate Range: narrowband : 2400 - 25600 bps wideband : 4000 - 43200 bps ultra-wideband : 4400 - 45200 bps

Complexity Encoding complexity is controlled by setting avctx->compression_level. The valid range is 0 to 10. A higher setting gives generally better quality at the expense of encoding speed. This does not affect the bit rate.

Frames-per-Packet The encoder defaults to using 1 frame-per-packet. However, it is sometimes desirable to use multiple frames-per-packet to reduce the amount of container overhead. This can be done by setting the 'frames_per_packet' option to a value 1 to 8.

Definition in file libspeexenc.c.

Define Documentation


Definition at line 292 of file libspeexenc.c.

#define OFFSET (  )     offsetof(LibSpeexEncContext, x)

Definition at line 291 of file libspeexenc.c.

Function Documentation

static av_cold int encode_close ( AVCodecContext avctx  )  [static]

Definition at line 278 of file libspeexenc.c.

static int encode_frame ( AVCodecContext avctx,
uint8_t *  frame,
int  buf_size,
void *  data 
) [static]

Definition at line 234 of file libspeexenc.c.

static av_cold int encode_init ( AVCodecContext avctx  )  [static]

Definition at line 122 of file libspeexenc.c.

static av_cold void print_enc_params ( AVCodecContext avctx,
LibSpeexEncContext s 
) [static]

Definition at line 90 of file libspeexenc.c.

Referenced by encode_init().

Variable Documentation

const { ... } [static]

class_name = "libspeex"

Definition at line 301 of file libspeexenc.c.

Referenced by av_opt_show2().

const AVCodecDefault defaults[] [static]

Initial value:

    { "b",                 "0" },
    { "compression_level", "3" },
    { NULL },

Definition at line 307 of file libspeexenc.c.

Initial value:

    .name           = "libspeex",
    .type           = AVMEDIA_TYPE_AUDIO,
    .id             = CODEC_ID_SPEEX,
    .priv_data_size = sizeof(LibSpeexEncContext),
    .init           = encode_init,
    .encode         = encode_frame,
    .close          = encode_close,
    .capabilities   = CODEC_CAP_DELAY,
    .sample_fmts    = (const enum SampleFormat[]){ AV_SAMPLE_FMT_S16, AV_SAMPLE_FMT_NONE },
    .long_name      = NULL_IF_CONFIG_SMALL("libspeex Speex"),
    .priv_class     = &class,
    .defaults       = defaults,

Definition at line 313 of file libspeexenc.c.

item_name = av_default_item_name

Definition at line 302 of file libspeexenc.c.

Definition at line 303 of file libspeexenc.c.

Referenced by pp_get_mode_by_name_and_quality().

const AVOption options[] [static]

Initial value:

    { "abr",               "Use average bit rate",                      OFFSET(abr),               AV_OPT_TYPE_INT, { 0 }, 0,   1, AE },
    { "cbr_quality",       "Set quality value (0 to 10) for CBR",       OFFSET(cbr_quality),       AV_OPT_TYPE_INT, { 8 }, 0,  10, AE },
    { "frames_per_packet", "Number of frames to encode in each packet", OFFSET(frames_per_packet), AV_OPT_TYPE_INT, { 1 }, 1,   8, AE },
    { NULL },

Definition at line 293 of file libspeexenc.c.

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