check_wav.c File Reference

Macros
#define	WAV_HEADER_LEN   44

Enumerations
enum	check_wav_state { CWS_NEED_HEADER, CWS_HAVE_HEADER, CWS_NO_HEADER }

Functions
void	check_wav_pre_monitor (struct sched *s, struct check_wav_context *cwc)
int	check_wav_post_monitor (struct check_wav_context *cwc)
struct check_wav_context *	check_wav_init (struct btr_node *parent, struct btr_node *child, struct wav_params *params, struct btr_node **cw_btrn)
void	check_wav_shutdown (struct check_wav_context *cwc)

Detailed Description

Detect and delete a wav header.

Macro Definition Documentation

WAV_HEADER_LEN

#define WAV_HEADER_LEN   44

Length of a standard wav header.

Enumeration Type Documentation

check_wav_state

enum check_wav_state

The possible states of a check_wav instance.

Enumerator
CWS_NEED_HEADER	Initial state, less than WAV_HEADER_LEN bytes available.
CWS_HAVE_HEADER	Wav hader was detected.
CWS_NO_HEADER	First part of the stream did not look like a wav header.

Function Documentation

check_wav_pre_monitor()

void check_wav_pre_monitor	(	struct sched *	s,
		struct check_wav_context *	cwc
	)

Request a minimal timeout if not idle.

Parameters

s	The scheduler instance.
cwc	The buffer tree node is derived from this.

If no data is available and the buffer tree node is not in error state, the function does nothing.

References btr_node_status(), BTR_NT_INTERNAL, and sched_min_delay().

check_wav_post_monitor()

int check_wav_post_monitor

(

struct check_wav_context *

cwc

)

Filter out the wav header, pushdown everything else.

Parameters

cwc	The context of this instance.

This function looks at the first WAV_HEADER_SIZE bytes of the input queue of the btrn of cwc. If they look like a wav header, the function extracts the information of interest and swallows this part of the stream. Otherwise it is pushed down to all children. In either case the rest of the input is pushed down as well.

Once the first part has been processed this way, the state of the instance changes from CWS_NEED_HEADER to CWS_HAVE_HEADER or CWS_NO_HEADER.

Returns

Standard.

References btr_merge(), btr_next_buffer(), btr_node_status(), BTR_NT_INTERNAL, CWS_HAVE_HEADER, CWS_NEED_HEADER, CWS_NO_HEADER, PARA_INFO_LOG, PARA_NOTICE_LOG, and SAMPLE_FORMATS.

check_wav_init()

struct check_wav_context* check_wav_init	(	struct btr_node *	parent,
		struct btr_node *	child,
		struct wav_params *	params,
		struct btr_node **	cw_btrn
	)

Allocate and set up a new check_wav instance.

Parameters

parent	This buffer tree node will be the parent of the new node.
child	The child of the new node.
params	Default values and options.
cw_btrn	A pointer to the check wav node is returned here.

This function also sets up the ->execute handler of the btrn so that all children of this node can figure out channel count, sample rate, etc.

Returns

The (opaque) handle of the newly created check_wav instance. It is supposed to be passed to check_wav_pre_monitor() and check_wav_post_monitor().

See also

btr_new_node.

References btr_new_node(), CWS_NEED_HEADER, EMBRACE, WAV_HEADER_LEN, and zalloc().

check_wav_shutdown()

void check_wav_shutdown

(

struct check_wav_context *

cwc

)

Dellocate all ressources of a check_wav instance.

Parameters

cwc	Determines the instance to shut down.

This function may only be called after check_wav_post_monitor() has returned negative.