Port & Audio
结构体
pjmedia_port
/**
* Port interface.
*/
typedef struct pjmedia_port
{
pjmedia_port_info info; /**< Port information. */
/** Port data can be used by the port creator to attach arbitrary
* value to be associated with the port.
*/
struct port_data {
void *pdata; /**< Pointer data. */
long ldata; /**< Long data. */
} port_data;
/**
* Group lock.
*
* This is optional, but if this port is registered to the audio/video
* conference bridge, the bridge will create one if the port has none.
*/
pj_grp_lock_t *grp_lock;
/**
* Get clock source.
* This should only be called by #pjmedia_port_get_clock_src().
*/
pjmedia_clock_src* (*get_clock_src)(struct pjmedia_port *this_port,
pjmedia_dir dir);
/**
* Sink interface.
* This should only be called by #pjmedia_port_put_frame().
*/
pj_status_t (*put_frame)(struct pjmedia_port *this_port,
pjmedia_frame *frame);
/**
* Source interface.
* This should only be called by #pjmedia_port_get_frame().
*/
pj_status_t (*get_frame)(struct pjmedia_port *this_port,
pjmedia_frame *frame);
/**
* Called to destroy this port.
*/
pj_status_t (*on_destroy)(struct pjmedia_port *this_port);
} pjmedia_port;
pjmedia_snd_port
struct pjmedia_snd_port
{
int rec_id;
int play_id;
pj_uint32_t aud_caps;
pjmedia_aud_param aud_param;
pjmedia_aud_stream *aud_stream;
pjmedia_dir dir;
pjmedia_port *port;
pjmedia_clock_src cap_clocksrc,
play_clocksrc;
unsigned clock_rate;
unsigned channel_count;
unsigned samples_per_frame;
unsigned bits_per_sample;
unsigned options;
unsigned prm_ec_options;
/* audio frame preview callbacks */
void *user_data;
pjmedia_aud_play_cb on_play_frame;
pjmedia_aud_rec_cb on_rec_frame;
};
pjmedia_snd_port_param
/**
* This structure specifies the parameters to create the sound port.
* Use pjmedia_snd_port_param_default() to initialize this structure with
* default values (mostly zeroes)
*/
typedef struct pjmedia_snd_port_param
{
/**
* Base structure.
*/
pjmedia_aud_param base;
/**
* Sound port creation options.
*/
unsigned options;
/**
* Echo cancellation options/flags.
*/
unsigned ec_options;
/**
* Arbitrary user data for playback and record preview callbacks below.
*/
void *user_data;
/**
* Optional callback for audio frame preview right before queued to
* the speaker.
* Notes:
* - application MUST NOT block or perform long operation in the callback
* as the callback may be executed in sound device thread
* - when using software echo cancellation, application MUST NOT modify
* the audio data from within the callback, otherwise the echo canceller
* will not work properly.
* - the return value of the callback will be ignored
*/
pjmedia_aud_play_cb on_play_frame;
/**
* Optional callback for audio frame preview recorded from the microphone
* before being processed by any media component such as software echo
* canceller.
* Notes:
* - application MUST NOT block or perform long operation in the callback
* as the callback may be executed in sound device thread
* - when using software echo cancellation, application MUST NOT modify
* the audio data from within the callback, otherwise the echo canceller
* will not work properly.
* - the return value of the callback will be ignored
*/
pjmedia_aud_rec_cb on_rec_frame;
} pjmedia_snd_port_param;
pjmedia_aud_param
/**
* This structure specifies the parameters to open the audio stream.
*/
typedef struct pjmedia_aud_param
{
/**
* The audio direction. This setting is mandatory.
*/
pjmedia_dir dir;
/**
* The audio recorder device ID. This setting is mandatory if the audio
* direction includes input/capture direction.
*/
pjmedia_aud_dev_index rec_id;
/**
* The audio playback device ID. This setting is mandatory if the audio
* direction includes output/playback direction.
*/
pjmedia_aud_dev_index play_id;
/**
* Clock rate/sampling rate. This setting is mandatory.
*/
unsigned clock_rate;
/**
* Number of channels. This setting is mandatory.
*/
unsigned channel_count;
/**
* Number of samples per frame. This setting is mandatory.
*/
unsigned samples_per_frame;
/**
* Number of bits per sample. This setting is mandatory.
*/
unsigned bits_per_sample;
/**
* This flags specifies which of the optional settings are valid in this
* structure. The flags is bitmask combination of pjmedia_aud_dev_cap.
*/
unsigned flags;
/**
* Set the audio format. This setting is optional, and will only be used
* if PJMEDIA_AUD_DEV_CAP_EXT_FORMAT is set in the flags.
*/
pjmedia_format ext_fmt;
/**
* Input latency, in milliseconds. This setting is optional, and will
* only be used if PJMEDIA_AUD_DEV_CAP_INPUT_LATENCY is set in the flags.
*/
unsigned input_latency_ms;
/**
* Input latency, in milliseconds. This setting is optional, and will
* only be used if PJMEDIA_AUD_DEV_CAP_OUTPUT_LATENCY is set in the flags.
*/
unsigned output_latency_ms;
/**
* Input volume setting, in percent. This setting is optional, and will
* only be used if PJMEDIA_AUD_DEV_CAP_INPUT_VOLUME_SETTING is set in
* the flags.
*/
unsigned input_vol;
/**
* Output volume setting, in percent. This setting is optional, and will
* only be used if PJMEDIA_AUD_DEV_CAP_OUTPUT_VOLUME_SETTING is set in
* the flags.
*/
unsigned output_vol;
/**
* Set the audio input route/source. This setting is optional, and
* will only be used if PJMEDIA_AUD_DEV_CAP_INPUT_ROUTE/
* PJMEDIA_AUD_DEV_CAP_INPUT_SOURCE is set in the flags.
*/
pjmedia_aud_dev_route input_route;
/**
* Set the audio output route. This setting is optional, and will only be
* used if PJMEDIA_AUD_DEV_CAP_OUTPUT_ROUTE is set in the flags.
*/
pjmedia_aud_dev_route output_route;
/**
* Enable/disable echo canceller, if the device supports it. This setting
* is optional, and will only be used if PJMEDIA_AUD_DEV_CAP_EC is set in
* the flags.
*/
pj_bool_t ec_enabled;
/**
* Set echo canceller tail length in milliseconds, if the device supports
* it. This setting is optional, and will only be used if
* PJMEDIA_AUD_DEV_CAP_EC_TAIL is set in the flags.
*/
unsigned ec_tail_ms;
/**
* Enable/disable PLC. This setting is optional, and will only be used
* if PJMEDIA_AUD_DEV_CAP_PLC is set in the flags.
*/
pj_bool_t plc_enabled;
/**
* Enable/disable CNG. This setting is optional, and will only be used
* if PJMEDIA_AUD_DEV_CAP_CNG is set in the flags.
*/
pj_bool_t cng_enabled;
/**
* Enable/disable VAD. This setting is optional, and will only be used
* if PJMEDIA_AUD_DEV_CAP_VAD is set in the flags.
*/
pj_bool_t vad_enabled;
} pjmedia_aud_param;
设备抽象
pjmedia_aud_stream 在设备的进一步抽象中绑定rec_cb play_cb
/**
* This structure describes the audio device stream.
*/
struct pjmedia_aud_stream
{
/** Internal data to be initialized by audio subsystem */
struct {
/** Driver index */
unsigned drv_idx;
} sys;
/** Operations */
pjmedia_aud_stream_op *op;
};
pjmedia_aud_stream_op
/**
* Sound stream operations.
*/
typedef struct pjmedia_aud_stream_op
{
/**
* See #pjmedia_aud_stream_get_param()
*/
pj_status_t (*get_param)(pjmedia_aud_stream *strm,
pjmedia_aud_param *param);
/**
* See #pjmedia_aud_stream_get_cap()
*/
pj_status_t (*get_cap)(pjmedia_aud_stream *strm,
pjmedia_aud_dev_cap cap,
void *value);
/**
* See #pjmedia_aud_stream_set_cap()
*/
pj_status_t (*set_cap)(pjmedia_aud_stream *strm,
pjmedia_aud_dev_cap cap,
const void *value);
/**
* See #pjmedia_aud_stream_start()
*/
pj_status_t (*start)(pjmedia_aud_stream *strm);
/**
* See #pjmedia_aud_stream_stop().
*/
pj_status_t (*stop)(pjmedia_aud_stream *strm);
/**
* See #pjmedia_aud_stream_destroy().
*/
pj_status_t (*destroy)(pjmedia_aud_stream *strm);
} pjmedia_aud_stream_op;
factory相关
/**
* Sound device factory operations.
*/
typedef struct pjmedia_aud_dev_factory_op
{
/**
* Initialize the audio device factory.
*
* @param f The audio device factory.
*/
pj_status_t (*init)(pjmedia_aud_dev_factory *f);
/**
* Close this audio device factory and release all resources back to the
* operating system.
*
* @param f The audio device factory.
*/
pj_status_t (*destroy)(pjmedia_aud_dev_factory *f);
/**
* Get the number of audio devices installed in the system.
*
* @param f The audio device factory.
*/
unsigned (*get_dev_count)(pjmedia_aud_dev_factory *f);
/**
* Get the audio device information and capabilities.
*
* @param f The audio device factory.
* @param index Device index.
* @param info The audio device information structure which will be
* initialized by this function once it returns
* successfully.
*/
pj_status_t (*get_dev_info)(pjmedia_aud_dev_factory *f,
unsigned index,
pjmedia_aud_dev_info *info);
/**
* Initialize the specified audio device parameter with the default
* values for the specified device.
*
* @param f The audio device factory.
* @param index Device index.
* @param param The audio device parameter.
*/
pj_status_t (*default_param)(pjmedia_aud_dev_factory *f,
unsigned index,
pjmedia_aud_param *param);
/**
* Open the audio device and create audio stream. See
* #pjmedia_aud_stream_create()
*/
pj_status_t (*create_stream)(pjmedia_aud_dev_factory *f,
const pjmedia_aud_param *param,
pjmedia_aud_rec_cb rec_cb,
pjmedia_aud_play_cb play_cb,
void *user_data,
pjmedia_aud_stream **p_aud_strm);
/**
* Refresh the list of audio devices installed in the system.
*
* @param f The audio device factory.
*/
pj_status_t (*refresh)(pjmedia_aud_dev_factory *f);
} pjmedia_aud_dev_factory_op;
/**
* This structure describes an audio device factory.
*/
struct pjmedia_aud_dev_factory
{
/** Internal data to be initialized by audio subsystem. */
struct {
/** Driver index */
unsigned drv_idx;
} sys;
/** Operations */
pjmedia_aud_dev_factory_op *op;
};
相关方法
初始化方法
（snd_port_param）pjmedia_snd_port_param_default
/* Initialize with default values (zero) */
PJ_DEF(void) pjmedia_snd_port_param_default(pjmedia_snd_port_param *prm)
{
pj_bzero(prm, sizeof(*prm));
}
pjmedia_stream_get_port
PJ_DEF(pj_status_t) pjmedia_stream_get_port( pjmedia_stream *stream,
pjmedia_port **p_port )
{
*p_port = &stream->port;
return PJ_SUCCESS;
}
stream->port，返回p_port
（aud_dev_default_param）pjmedia_aud_dev_default_param
/* API: Initialize the audio device parameters with default values for the
* specified device.
*/
PJ_DEF(pj_status_t) pjmedia_aud_dev_default_param(pjmedia_aud_dev_index id,
pjmedia_aud_param *param)
{
pjmedia_aud_dev_factory *f;
unsigned index;
pj_status_t status;
PJ_ASSERT_RETURN(param && id!=PJMEDIA_AUD_INVALID_DEV, PJ_EINVAL);
PJ_ASSERT_RETURN(aud_subsys.pf, PJMEDIA_EAUD_INIT);
status = lookup_dev(id, &f, &index); //Internal: lookup valid device id
if (status != PJ_SUCCESS)
return status;
status = f->op->default_param(f, index, param);
if (status != PJ_SUCCESS)
return status;
/* Normalize device IDs */
make_global_index(f->sys.drv_idx, ¶m->rec_id);
make_global_index(f->sys.drv_idx, ¶m->play_id);
return PJ_SUCCESS;
}
Create port
pjmedia_snd_port_create
初始化pjmedia_snd_port_param的各种信息，调用pjmedia_snd_port_create2
pj_status_t pjmedia_snd_port_create_player(pj_pool_t *pool, int dev_id, unsigned int clock_rate, unsigned int channel_count, unsigned int samples_per_frame, unsigned int bits_per_sample, unsigned int options, pjmedia_snd_port **p_port)
Create unidirectional sound device port for playing audio streams with the specified parameters.
参数:
pool – Pool to allocate sound port structure.
index – Device index, or -1 to let the library choose the first available device.
clock_rate – Sound device's clock rate to set.
channel_count – Set number of channels, 1 for mono, or 2 for stereo. The channel count determines the format of the frame.
samples_per_frame – Number of samples per frame.
bits_per_sample – Set the number of bits per sample. The normal value for this parameter is 16 bits per sample.
options – Options flag.
p_port – Pointer to receive the sound device port instance.
pjmedia_snd_port_create2
用pjmedia_snd_port_creat中传入的pjmedia_snd_port_param，初始化pjmedia_snd_port（此时声音port创建），最后调用start_sound_device，Start the sound stream.
start_sound_device
-
Get device caps：获取dev_id，根据id调用函数pjmedia_aud_dev_get_info获取pjmedia_aud_dev_info
-
Process EC settings
-
Open the device
设置了两个回调snd_rec_cb、snd_play_cb分别为 rec_cb、play_cb
status = pjmedia_aud_stream_create(¶m_copy, snd_rec_cb, snd_play_cb, snd_port, &snd_port->aud_stream); -
Start sound stream.：pjmedia_aud_stream_start(snd_port->aud_stream);
pjmedia_aud_stream_create
先通过lookup_dev搜索rec_id、play_id设备对应的工厂，然后通过工厂创建设备f->op->create_stream并设置给设备两个回调函数 rec_cb、play_cb给设备抽象pjmedia_aud_stream的ca_cb、pb_cb，lookup_dev中aud_subsys已经存储了所有的音频设备是在创建媒体端点endpoint时初始化举例来说：初始化的时候创建媒体端点pjmedia_endpt，同时初始化了音频子系统aud_subsys，把各种类型的音频设备工厂添加到全局变量static pjmedia_aud_subsys aud_subsys;。这样当创建设备时，就可以遍历这些工厂，寻找合适的工厂，通过工厂创建设备实例。比如alsa类型的设备在alsa_dev.c
pjmedia_aud_stream_start
以alsa为例，在alsa_dev.c中，调用alsa_stream_start函数，在alsa_dev.c alsa_stream_start中，会创建播放和采集两条线程。
static pj_status_t alsa_stream_start (pjmedia_aud_stream *s)
{
struct alsa_stream *stream = (struct alsa_stream*)s;
pj_status_t status = PJ_SUCCESS;
stream->quit = 0;
if (stream->param.dir & PJMEDIA_DIR_PLAYBACK) {
status = pj_thread_create (stream->pool,
"alsasound_playback",
pb_thread_func,
stream,
0, //ZERO,
0,
&stream->pb_thread);
if (stream->param.dir & PJMEDIA_DIR_CAPTURE) {
status = pj_thread_create (stream->pool,
"alsasound_playback",
ca_thread_func,
stream,
0, //ZERO,
0,
&stream->ca_thread);
}
return status;
}
以播放线程为例
static int pb_thread_func (void *arg)
{
struct alsa_stream* stream = (struct alsa_stream*) arg;
snd_pcm_t* pcm = stream->pb_pcm;
int size = stream->pb_buf_size;
snd_pcm_uframes_t nframes = stream->pb_frames;
void* user_data = stream->user_data;
char* buf = stream->pb_buf;
pj_timestamp tstamp;
int result;
pj_bzero (buf, size);
tstamp.u64 = 0;
snd_pcm_prepare (pcm);
while (!stream->quit) {
pjmedia_frame frame;
frame.type = PJMEDIA_FRAME_TYPE_AUDIO;
frame.buf = buf;
frame.size = size;
frame.timestamp.u64 = tstamp.u64;
frame.bit_info = 0;
result = stream->pb_cb (user_data, &frame);
if (result != PJ_SUCCESS || stream->quit)
break;
if (frame.type != PJMEDIA_FRAME_TYPE_AUDIO)
pj_bzero (buf, size);
result = snd_pcm_writei (pcm, buf, nframes);
if (result == -EPIPE) {
PJ_LOG (4,(THIS_FILE, "pb_thread_func: underrun!"));
snd_pcm_prepare (pcm);
} else if (result < 0) {
PJ_LOG (4,(THIS_FILE, "pb_thread_func: error writing data!"));
}
tstamp.u64 += nframes;
}
snd_pcm_drain (pcm);
TRACE_((THIS_FILE, "pb_thread_func: Stopped"));
return PJ_SUCCESS;
}
播放线程先通过回调拿到待播放的音频数据stream->pb_cb ，然后写到声卡snd_pcm_writei。pb_cb就是sound_port.c中的play_cb，来看下play_cb的流程。
static pj_status_t play_cb(void *user_data, pjmedia_frame *frame)
{
pjmedia_snd_port *snd_port = (pjmedia_snd_port*) user_data;
pjmedia_port *port;
const unsigned required_size = (unsigned)frame->size;
pj_status_t status;
port = snd_port->port;
status = pjmedia_port_get_frame(port, frame);
/* Invoke preview callback */
if (snd_port->on_play_frame)
(*snd_port->on_play_frame)(snd_port->user_data, frame);
return PJ_SUCCESS;
}
通过pjmedia_port* port获取一帧数据