ao_sdl.c

DawnLightPlayer,一个新的基于ffmpeg的全功能播放器

/**********************************************
 * Dawn Light Player
 *
 *   ao_sdl.c
 *
 * Created by kf701
 * 13:48:35 02/29/08 CST
 *
 * $Id: ao_sdl.c 168 2008-03-21 02:50:01Z kf701 $
 **********************************************/

#if ENABLE_AO_SDL

#include <SDL/SDL.h>

#include "avcodec.h"
#include "avdecode.h"
#include "avformat.h"
#include "avoutput.h"
#include "global.h"

static volatile int need_new_packet = 0;

static AVSample *cur_s = NULL;
static int current_sample_pos = 0, current_sample_size = 0;

static int read_new_packet(void)
{
	if ( current_sample_size == 0 ||
	        (current_sample_pos && current_sample_pos == current_sample_size) )
	{
		if ( cur_s )
		{
			av_free_sample( cur_s );
			av_free( cur_s );
		}

		need_new_packet = 1;
		while ( need_new_packet )
		{
			usleep(20*1000);
		}

		current_sample_pos = 0;
		current_sample_size = cur_s->size;

		return current_sample_size;
	}
	return current_sample_size - current_sample_pos;
}

/* Prototype of our callback function */
static void sdl_audio_callback(void *userdata, Uint8 *stream, int len)
{
	int slen, copylen;
	while ( len > 0 )
	{
		slen = read_new_packet();
		copylen = len > slen ? slen : len;
		memcpy(stream, cur_s->data + current_sample_pos, copylen);
		len -= copylen;
		stream += copylen;
		current_sample_pos += copylen;
	}
}

static int ao_sdl_init(void)
{
	/* Open the audio device */
	SDL_AudioSpec desired, obtained;
	/* 22050Hz - FM Radio quality */
	desired.freq = dlpctxp->sample_rate;
	/* 16-bit signed audio */
	desired.format = AUDIO_S16SYS;
	/* Set channels */
	if ( dlpctxp->channels > 2 )
		dlpctxp->channels = 2;
	desired.channels = dlpctxp->channels;
	desired.silence = 0;
	/* Large audio buffer reduces risk of dropouts but increases response time */
	desired.samples = 1024;
	/* Our callback function */
	desired.callback = sdl_audio_callback;
	desired.userdata = NULL;
	/* Open the audio device */
	if ( SDL_OpenAudio(&desired, &obtained) < 0 )
	{
		av_log(NULL, AV_LOG_ERROR, "Couldn't open audio: %s\n", SDL_GetError());
		return -1;
	}

	SDL_PauseAudio(0);
	return 0;
}

static int ao_sdl_uninit(void)
{
	av_log(NULL, AV_LOG_INFO, "sdl audio close\n");
	SDL_CloseAudio();
	return 0;
}

static void ao_sdl_play(AVSample *s)
{
	while ( !need_new_packet )
		usleep(10*1000);

	need_new_packet = 0;

	cur_s = av_dup_sample(s);
}

static int ao_sdl_control(int cmd, void *arg)
{
	switch (cmd)
	{
	case AO_PAUSE:
		SDL_PauseAudio(1);
		break;
	case AO_RESUME:
		SDL_PauseAudio(0);
		break;
	default:
		av_log(NULL, AV_LOG_ERROR, "AO SDL not support volume control now!\n");
		break;
	}
	return 0;
}

ao_t ao_sdl =
{
	.id = AO_ID_SDL,
	.name = "sdl",
	.ao_init = ao_sdl_init,
	.ao_uninit = ao_sdl_uninit,
	.ao_play = ao_sdl_play,
	.ao_getspace = NULL,
	.ao_control = ao_sdl_control,
};

#endif