#include?“Audio.h“

#include?
#include?
extern?“C“?{

#include?

}

extern?bool?quit;

AudioState::AudioState（）
	:BUFFER_SIZE（192000）
{
	audio_ctx?=?nullptr;
	stream_index?=?-1;
	stream?=?nullptr;
	audio_clock?=?0;

	audio_buff?=?new?uint8_t[BUFFER_SIZE];
	audio_buff_size?=?0;
	audio_buff_index?=?0;
}

AudioState::AudioState（AVCodecContext?*audioCtx?int?index）
	:BUFFER_SIZE（192000）
{
	audio_ctx?=?audioCtx;
	stream_index?=?index;
	

	audio_buff?=?new?uint8_t[BUFFER_SIZE];
	audio_buff_size?=?0;
	audio_buff_index?=?0;
}

AudioState::~AudioState（）
{
	if?（audio_buff）
		delete[]?audio_buff;
}

bool?AudioState::audio_play（）
{
	SDL_AudioSpec?desired;
	desired.freq?=?audio_ctx->sample_rate;
	desired.channels?=?audio_ctx->channels;
	desired.format?=?AUDIO_S16SYS;
	desired.samples?=?1024;
	desired.silence?=?0;
	desired.userdata?=?this;
	desired.callback?=?audio_callback;

	if?（SDL_OpenAudio（&desired?nullptr）?	{
		return?false;
	}

	SDL_PauseAudio（0）;?//?playing

	return?true;
}

double?AudioState::get_audio_clock（）
{
	int?hw_buf_size?=?audio_buff_size?-?audio_buff_index;
	int?bytes_per_sec?=?stream->codec->sample_rate?*?audio_ctx->channels?*?2;

	double?pts?=?audio_clock?-?static_cast（hw_buf_size）?/?bytes_per_sec;

	
	return?pts;
}

/**
*?向設備發送audio數據的回調函數
*/
void?audio_callback（void*?userdata?Uint8?*stream?int?len）
{
	AudioState?*audio_state?=?（AudioState*）userdata;

	SDL_memset（stream?0?len）;

	int?audio_size?=?0;
	int?len1?=?0;
	while?（len?>?0）//?向設備發送長度為len的數據
	{
		if?（audio_state->audio_buff_index?>=?audio_state->audio_buff_size）?//?緩沖區中無數據
		{
			//?從packet中解碼數據
			audio_size?=?audio_decode_frame（audio_state?audio_state->audio_buff?sizeof（audio_state->audio_buff））;
			if?（audio_size?			{
				audio_state->audio_buff_size?=?0;
				memset（audio_state->audio_buff?0?audio_state->audio_buff_size）;
			}
			else
				audio_state->audio_buff_size?=?audio_size;

			audio_state->audio_buff_index?=?0;
		}
		len1?=?audio_state->audio_buff_size?-?audio_state->audio_buff_index;?//?緩沖區中剩下的數據長度
		if?（len1?>?len）?//?向設備發送的數據長度為len
			len1?=?len;

		SDL_MixAudio（stream?audio_state->audio_buff?+?audio_state->audio_buff_index?len?SDL_MIX_MAXVOLUME）;

		len?-=?len1;
		stream?+=?len1;
		audio_state->audio_buff_index?+=?len1;
	}
}

int?audio_decode_frame（AudioState?*audio_state?uint8_t?*audio_buf?int?buf_size）
{
	AVframe?*frame?=?av_frame_alloc（）;
	int?data_size?=?0;
	AVPacket?pkt;
	SwrContext?*swr_ctx?=?nullptr;
	static?double?clock?=?0;
	
	if?（quit）
		return?-1;
	if?（!audio_state->audioq.deQueue（&pkt?true））
		return?-1;

	if?（pkt.pts?!=?AV_NOPTS_VALUE）
	{
		audio_state->audio_clock?=?av_q2d（audio_state->stream->time_base）?*?pkt.pts;
	}
	int?ret?=?avcodec_send_packet（audio_state->audio_ctx?&pkt）;
	if?（ret?		return?-1;

	ret?=?avcodec_receive_frame（audio_state->audio_ctx?frame）;
	if?（ret?		return?