在上一篇中简单设计了一个视频播放器，但是没有声音，于是本篇的代码就是在上一篇的基础上加上声音。
在ffmpeg给的官方例程中，给视频添加声音是有问题的，这一块可以参考下面的这篇博客：
其中播放声音比较ffmpeg以前版本增加了重采样的概念，而我添加声音这块代码也是参考这篇博客得来。
代码是在上一篇的基础上添加，对于之前的代码几乎没有删改，程序最终运行效果为视频跑的很快，但是声音则正常播放。
开发环境：
操作系统：ubuntu14
ffmpeg版本：3.2.2
sdl版本：2
编译与运行：
gcc -g main.c -o test -I /usr/local/ffmpeg/include -L /usr/local/ffmpeg/lib -lavutil -lavformat -lavcodec -lz -lavutil -lswscale -L /usr/lib/x86_64-linux-gnu -lSDL2 -lSDL2main
（其中路径按照自己的安装路径来 -g 是加GDB调试）
./test
1 #ifdef _cplusplus
2 extern "C"
3 {
4 #endif
5
6 #include<stdio.h>
7 #include<assert.h>
8 #include<libavcodec/avcodec.h>
9 #include<libavformat/avformat.h>
10 #include<libavutil/avutil.h>
11 #include<libswscale/swscale.h>
12 #include <libswresample/swresample.h>
13 #include<libavutil/avutil.h>
14 #include<libavutil/imgutils.h>
15 #include<SDL2/SDL.h>
16 #include<SDL2/SDL_thread.h>
17
18 //是否将YUV420P内容输出到文件
19 #define OUTPUT_YUV420P 0
20 //要播放的文件路径
21 #define filename "/home/sns/test.flv"
22 //要输出YUV420P内容的文件路径
23 #define outfilename "/home/sns/output.yuv"
24
25 #define SDL_AUDIO_BUFFER_SIZE 1024
26 #define MAX_AUDIO_FRAME_SIZE 192000
27 //结构体定义
28 typedef struct PacketQueue{
29 AVPacketList *first_pkt,*last_pkt;//队首、队尾
30 int nb_packets; //包的个数
31 int size;//队列的字节数
32 SDL_mutex *mutex;//互斥量
33 SDL_cond *cond;//条件变量
34 }PacketQueue;
35
36 typedef struct AudioParams {
37 int freq;
38 int channels;
39 int64_t channel_layout;
40 enum AVSampleFormat fmt;
41 int frame_size;
42 int bytes_per_sec;
43 } AudioParams;
44 //函数定义
45 static void audio_callback(void *userdata, Uint8 * stream, int len);//
46 static int packet_queue_get(PacketQueue *q,AVPacket *pkt,int block);
47 int packet_queue_put(PacketQueue *q,AVPacket *pkt);
48 void packet_queue_init(PacketQueue *q);
49 static int audio_decode_frame(AVCodecContext *aCodecCtx,uint8_t *audio_buf,int buf_size);
50 int resample(AVFrame *af,uint8_t *audio_buf,int *audio_buf_size);
51
52 //全局变量定义
53 int quit =0;
54 PacketQueue audioQ;
55 int sample_rate, nb_channels;
56 int64_t channel_layout;
57 struct SwrContext * swr_ctx = NULL;
58 AudioParams audio_hw_params_tgt;
59 AudioParams audio_hw_params_src;
60
61 //主函数
62 int main(int argc, char **argv)
63 {
64 //变量定义*********************************************************************
65 AVFormatContext *pFormatCtx;
66 int i=0;
67 int videoStream;
68 int audioStream;
69 AVCodecContext *pCodecCtx;
70 AVCodecContext *aCodecCtxOrig;
71 AVCodecContext *aCodecCtx;
72 AVCodec *pCodec;
73 AVCodec *aCodec;
74 AVFrame *pFrame;
75 AVFrame *pFrameYUV;
76 uint8_t *buffer;
77 int numBytes;
78
79 SDL_Window *screen;
80 SDL_Renderer *sdlRender;
81 SDL_Texture *sdlTexture;
82 SDL_Rect sdlRect;
83 int frameFinished;
84 AVPacket packet;
85 struct SwsContext *img_convert_ctx;
86 int err_code;
87 char buf[1024];
88 FILE *fp_yuv;
89 int y_size;
90 SDL_AudioSpec audioSpec;
91 SDL_AudioSpec spec;
92 SDL_Event event;
93 //*******************************************************************************
94 av_register_all();
95 //1、打开视频文件*************************************************
96 pFormatCtx = avformat_alloc_context();
97 err_code = avformat_open_input(&pFormatCtx, filename, NULL, NULL);
98 if (err_code != 0)
99 {//打开文件失败
100 av_strerror(err_code, buf, 1024);
101 printf("coundn't open the file!,error code = %d(%s)\n", err_code, buf);
102 return -1;
103 }
104 if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
105 {
106 printf("Couldn't find stream information.\n");
107 return -1;
108 }
109 // 打印信息
110 av_dump_format(pFormatCtx, 0, filename, 0);
111 //2、找到第一个视频流和第一个音频流****************************
112 videoStream = -1;
113 audioStream = -1;
114 for (i = 0; i < pFormatCtx->nb_streams; i++)
115 {
116 if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO && videoStream<0)
117 {
118 videoStream = i;//得到视频流的索引
119 }
120 if(pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO &&audioStream < 0)
121 {
122 audioStream = i;//得到音频流的索引
123 }
124 }
125 if (videoStream == -1)
126 {
127 printf("Didn't find a video stream.\n");
128 return -1;
129 }
130 if(audioStream == -1)
131 {
132 printf("coundn't find a audio stream!\n");
133 return -1;
134 }
135 /* 3、从视频流中得到一个音频和视频编解码上下文,里面包含了编解码器的所有信息和一个
136 指向真正的编解码器 ,然后我们找到音频和视频编解码器*/
137 pCodecCtx = pFormatCtx->streams[videoStream]->codec;
138 aCodecCtxOrig = pFormatCtx->streams[audioStream]->codec;
139 pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
140 aCodec = avcodec_find_decoder(aCodecCtxOrig->codec_id);
141 if (pCodec == NULL)
142 {
143 fprintf(stderr, "Unsupported codec !\n");
144 return -1;
145 }
146 if(aCodec == NULL)
147 {
148 fprintf(stderr,"Unsupported codec!\n");
149 return -1;
150 }
151 //拷贝上下文
152 aCodecCtx = avcodec_alloc_context3(aCodec);
153 if(avcodec_copy_context(aCodecCtx,aCodecCtxOrig) != 0)
154 {
155 fprintf(stderr,"couldn't copy codec context!\n");
156 return -1;
157 }
158 //4、打开音频和视频编解码器
159 if (avcodec_open2(pCodecCtx, pCodec, NULL) < 0)
160 {
161 printf("cann't open the codec!\n");
162 return -1;
163 }
164 if(avcodec_open2(aCodecCtx,aCodec,NULL) < 0 )
165 {
166 printf("cann't open the audio codec!\n");
167 return -1;
168 }
169 //设置声音参数
170 sample_rate = aCodecCtx->sample_rate;
171 nb_channels = aCodecCtx->channels;
172 channel_layout = aCodecCtx->channel_layout;
173
174 // printf("channel_layout=%" PRId64 "\n", channel_layout);
175 printf("nb_channels=%d\n", nb_channels);
176 printf("freq=%d\n", sample_rate);
177
178 if (!channel_layout|| nb_channels != av_get_channel_layout_nb_channels(channel_layout))
179 {
180 channel_layout = av_get_default_channel_layout(nb_channels);
181 channel_layout &= ~AV_CH_LAYOUT_STEREO_DOWNMIX;
182 printf("correction\n");
183 }
184 /*通故编解码上下文中的所有信息来建立音频的信息*/
185 audioSpec.freq = aCodecCtx->sample_rate;
186 audioSpec.format = AUDIO_S16SYS;
187 audioSpec.channels = aCodecCtx->channels;
188 audioSpec.silence = 0;
189 audioSpec.samples = SDL_AUDIO_BUFFER_SIZE;
190 audioSpec.callback = audio_callback;
191 audioSpec.userdata = aCodecCtx;
192 //打开音频设备和初始化
193 if(SDL_OpenAudio(&audioSpec,&spec) < 0)
194 //其中回调函数在需要更多音频数据的时候被调用（即播放完后需要从回调取数据播放）
195 {
196 fprintf(stderr,"SDL_OpenAudio: %s\n",SDL_GetError());
197 return -1;
198 }
199 printf("freq: %d\tchannels: %d\n", spec.freq, spec.channels);
200 //5、分配两个视频帧，一个保存得到的原始视频帧，一个保存为指定格式的视频帧（该帧通过原始帧转换得来）
201 pFrame = av_frame_alloc();
202 if (pFrame == NULL)
203 {
204 printf("pFrame alloc fail!\n");
205 return -1;
206 }
207 pFrameYUV = av_frame_alloc();
208 if (pFrameYUV == NULL)
209 {
210 printf("pFrameYUV alloc fail!\n");
211 return -1;
212 }
213 //6、得到一帧视频截图的内存大小并分配内存，并将YUV数据填充进去
214 numBytes = av_image_get_buffer_size(AV_PIX_FMT_YUV420P, pCodecCtx->width,
215 pCodecCtx->height,1);
216 buffer = (uint8_t*) av_mallocz(numBytes * sizeof(uint8_t));
217 if (!buffer)
218 {
219 printf("numBytes :%d , buffer malloc 's mem \n", numBytes);
220 return -1;
221 }
222 //打印信息
223 printf("--------------- File Information ----------------\n");
224 av_dump_format(pFormatCtx, 0, filename, 0);
225 printf("-------------------------------------------------\n");
226 av_image_fill_arrays(pFrameYUV->data, pFrameYUV->linesize,buffer,
227 AV_PIX_FMT_YUV420P,pCodecCtx->width, pCodecCtx->height,1);
228 //7、得到指定转换格式的上下文**********************************
229 img_convert_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height,
230 pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height,
231 AV_PIX_FMT_YUV420P,
232 SWS_BICUBIC,
233 NULL, NULL, NULL);
234 if (img_convert_ctx == NULL)
235 {
236 fprintf(stderr, "Cannot initialize the conversion context!\n");
237 return -1;
238 }
239 //***********************************************************
240 #if OUTPUT_YUV420P
241 fp_yuv = fopen(outfilename, "wb+");
242 #endif
243 //8、SDL初始化和创建多重windows等准备工作
244 if (SDL_Init(SDL_INIT_AUDIO | SDL_INIT_TIMER | SDL_INIT_VIDEO))
245 {
246 fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
247 return -1;
248 }
249 //使用SDL_CreateWindow代替SDL_SetVideoMode
250 //创建一个给定高度和宽度、位置和标示的windows。
251 screen = SDL_CreateWindow("Simplest ffmpeg player's Window",
252 SDL_WINDOWPOS_UNDEFINED, SDL_WINDOWPOS_UNDEFINED, pCodecCtx->width,
253 pCodecCtx->height, SDL_WINDOW_OPENGL);
254 if (!screen)
255 {
256 fprintf(stderr, "SDL: could not create window - exiting - %s\n",SDL_GetError());
257 return -1;
258 }
259 //对该window创建一个2D渲染上下文
260 sdlRender = SDL_CreateRenderer(screen, -1, 0);
261 if (!sdlRender)
262 {
263 fprintf(stderr, "SDL:cound not create render : %s\n", SDL_GetError());
264 return -1;
265 }
266 //Create a texture for a rendering context.
267 //为一个渲染上下文创建一个纹理
268 //IYUV: Y + U + V (3 planes)
269 //YV12: Y + V + U (3 planes)
270 sdlTexture = SDL_CreateTexture(sdlRender, SDL_PIXELFORMAT_IYUV,
271 SDL_TEXTUREACCESS_STREAMING, pCodecCtx->width, pCodecCtx->height);
272 if (!sdlTexture)
273 {
274 fprintf(stderr, "SDL:cound not create Texture : %s\n", SDL_GetError());
275 return -1;
276 }
277 //建立一个矩形变量，提供后面使用
278 sdlRect.x = 0;
279 sdlRect.y = 0;
280 sdlRect.w = pCodecCtx->width;
281 sdlRect.h = pCodecCtx->height;
282 //*****************************************************
283 //声音部分代码
284 audio_hw_params_tgt.fmt = AV_SAMPLE_FMT_S16;
285 audio_hw_params_tgt.freq = spec.freq;
286 audio_hw_params_tgt.channel_layout = channel_layout;
287 audio_hw_params_tgt.channels = spec.channels;
288 audio_hw_params_tgt.frame_size = av_samples_get_buffer_size(NULL,
289 audio_hw_params_tgt.channels, 1, audio_hw_params_tgt.fmt, 1);
290 audio_hw_params_tgt.bytes_per_sec = av_samples_get_buffer_size(NULL,
291 audio_hw_params_tgt.channels, audio_hw_params_tgt.freq,
292 audio_hw_params_tgt.fmt, 1);
293 if (audio_hw_params_tgt.bytes_per_sec <= 0|| audio_hw_params_tgt.frame_size <= 0)
294 {
295 printf("size error\n");
296 return -1;
297 }
298 audio_hw_params_src = audio_hw_params_tgt;
299 //*****************************************************
300 packet_queue_init(&audioQ);
301 SDL_PauseAudio(0);
302 //9、正式开始读取数据*****************************************
303 while (av_read_frame(pFormatCtx, &packet) >= 0)
304 {
305 //如果读取的包来自视频流
306 if (packet.stream_index == videoStream)
307 {
308 //从包中得到解码后的帧
309 if (avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished,&packet) < 0)
310 {
311 printf("Decode Error!\n");
312 return -1;
313 }
314 //如果确定完成得到该视频帧
315 if (frameFinished)
316 {
317 //转换帧数据格式
318 sws_scale(img_convert_ctx, pFrame->data, pFrame->linesize, 0,
319 pCodecCtx->height,
320 pFrameYUV->data,
321 pFrameYUV->linesize);
322 #if OUTPUT_YUV420P
323 y_size = pCodecCtx->width * pCodecCtx->height;
324 fwrite(pFrameYUV->data[0], 1, y_size, fp_yuv); //Y
325 fwrite(pFrameYUV->data[1], 1, y_size / 4, fp_yuv); //U
326 fwrite(pFrameYUV->data[2], 1, y_size / 4, fp_yuv); //V
327 #endif
328 //SDL显示~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
329 #if 0
330 SDL_UpdateTexture(sdlTexture,NULL,pFrameYUV->data[0],pFrameYUV->linesize[0]);
331 #else
332 SDL_UpdateYUVTexture(sdlTexture, &sdlRect, pFrameYUV->data[0],
333 pFrameYUV->linesize[0], pFrameYUV->data[1],
334 pFrameYUV->linesize[1], pFrameYUV->data[2],
335 pFrameYUV->linesize[2]);
336 #endif
337 SDL_RenderClear(sdlRender);
338 SDL_RenderCopy(sdlRender, sdlTexture, NULL, &sdlRect);
339 SDL_RenderPresent(sdlRender);
340 //结束SDL~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
341 }
342 }
343 else if(packet.stream_index == audioStream)
344 {
345 packet_queue_put(&audioQ,&packet);
346 }else{
347 av_free_packet(&packet);//释放读出来的包
348 }
349 SDL_PollEvent(&event);
350 switch (event.type)
351 {
352 case SDL_QUIT:
353 quit = 1;
354 SDL_Quit();
355 exit(0);
356 break;
357 default:
358 break;
359 }
360 }
361 while(1) SDL_Delay(1000);
362 //**************************************************************************************
363 //10、释放分配的内存或关闭文件等操作
364 #if OUTPUT_YUV420P
365 fclose(fp_yuv);
366 #endif
367 sws_freeContext(img_convert_ctx);
368 SDL_Quit();
369 av_free(buffer);
370 av_free(pFrame);
371 av_free(pFrameYUV);
372 avcodec_close(pCodecCtx);
373 avcodec_close(aCodecCtxOrig);
374 avcodec_close(aCodecCtx);
375 avformat_close_input(&pFormatCtx);
376 return EXIT_SUCCESS;
377 }
378
379
380 static void audio_callback(void *userdata, Uint8 * stream, int len)
381 {
382 AVCodecContext *aCodecCtx = (AVCodecContext*)userdata;
383 int len1,audio_size;
384 static uint8_t audio_buf[(MAX_AUDIO_FRAME_SIZE*3)/2];
385 static unsigned int audio_buf_size = 0;
386 static unsigned int audio_buf_index =0;
387 while(len>0){
388 if(audio_buf_index >= audio_buf_size){
389 audio_size = audio_decode_frame(aCodecCtx,audio_buf,sizeof(audio_buf));
390 if(audio_size < 0){
391 audio_buf_size = 1024;
392 memset(audio_buf,0,audio_buf_size);
393 }else{
394 audio_buf_size = audio_size;
395 }
396 audio_buf_index = 0;
397 }
398 len1 = audio_buf_size - audio_buf_index;
399 if(len1 > len)
400 len1 = len;
401 memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);
402 len -= len1;
403 stream += len1;
404 audio_buf_index += len1;
405 }
406 }
407
408 void packet_queue_init(PacketQueue *q)
409 {
410 memset(q,0,sizeof(PacketQueue));
411 q->mutex = SDL_CreateMutex();
412 q->cond = SDL_CreateCond();
413 }
414
415 int packet_queue_put(PacketQueue *q,AVPacket *pkt)
416 {
417 AVPacketList *pkt1;
418 if(av_dup_packet(pkt)<0)
419 {
420 printf("dup packet error!\n");
421 return -1;
422 }
423 pkt1 = av_malloc(sizeof(AVPacketList));
424 if(!pkt1)
425 {
426 printf("malloc AVPacketList error!\n");
427 return -1;
428 }
429 pkt1->pkt = *pkt;
430 pkt1->next = NULL;
431 SDL_LockMutex(q->mutex);
432 if(!q->last_pkt){
433 q->first_pkt = pkt1;
434 }else{
435 q->last_pkt->next = pkt1;
436 }
437 q->last_pkt = pkt1;
438 q->nb_packets ++;
439 q->size +=pkt1->pkt.size;
440 SDL_CondSignal(q->cond);
441 SDL_UnlockMutex(q->mutex);
442 return 0;
443 }
444 static int packet_queue_get(PacketQueue *q,AVPacket *pkt,int block){
445 int ret;
446 AVPacketList *pkt1;
447 SDL_LockMutex(q->mutex);
448 for(;;){
449 if(quit){
450 printf("packet_queue has quit!\n");
451 ret =-1;
452 break;
453 }
454 pkt1 = q->first_pkt;
455 if(pkt1){
456 q->first_pkt = pkt1->next;
457 if(!q->first_pkt){
458 q->last_pkt = NULL;
459 }
460 q->nb_packets--;
461 q->size -= pkt1->pkt.size;
462 *pkt = pkt1->pkt;
463 av_free(pkt1);
464 ret =1;
465 break;
466 }else if(!block){
467 ret =0;
468 break;
469 }else{
470 SDL_CondWait(q->cond,q->mutex);//做了解锁互斥量的动作
471 }
472 }
473 SDL_UnlockMutex(q->mutex);
474 return ret;
475 }
476 static int audio_decode_frame(AVCodecContext *aCodecCtx,uint8_t *audio_buf,int buf_size)
477 {
478 static AVPacket pkt;
479 static uint8_t *audio_pkt_data = NULL;
480 static int audio_pkt_size = 0;
481 int len1,data_size=0;
482 static AVFrame frame;
483 int got_frame=0;
484
485 for(;;){
486 while(audio_pkt_size >0 ){
487 len1 = avcodec_decode_audio4(aCodecCtx, &frame, &got_frame, &pkt);
488 if (len1 < 0)
489 {
490 /* if error, skip frame */
491 audio_pkt_size = 0;
492 break;
493 }
494 audio_pkt_data += len1;
495 audio_pkt_size -= len1;
496 data_size =0;
497 if(got_frame){
498 data_size = resample(&frame, audio_buf, &buf_size);
499 assert(data_size <= buf_size);
500 }
501 if (data_size <= 0)
502 {
503 /* No data yet, get more frames */
504 continue;
505 }
506 /* We have data, return it and come back for more later */
507 return data_size;
508 }
509 if (pkt.data)
510 av_free_packet(&pkt);
511 if (quit)
512 {
513 return -1;
514 }
515 if (packet_queue_get(&audioQ, &pkt, 1) < 0)
516 {
517 printf("packet_queue_get error!\n");
518 return -1;
519 }
520 audio_pkt_data = pkt.data;
521 audio_pkt_size = pkt.size;
522 }
523 return 1;
524 }
525
526 //重采样
527 int resample(AVFrame *af, uint8_t *audio_buf, int *audio_buf_size)
528 {
529 int data_size = 0;
530 int resampled_data_size = 0;
531 int64_t dec_channel_layout;
532 data_size = av_samples_get_buffer_size(NULL,
533 av_frame_get_channels(af),
534 af->nb_samples,
535 af->format, 1);
536 dec_channel_layout =(af->channel_layout&&
537 av_frame_get_channels(af)== av_get_channel_layout_nb_channels(
538 af->channel_layout)) ?
539 af->channel_layout :
540 av_get_default_channel_layout(av_frame_get_channels(af));
541 if (af->format != audio_hw_params_src.fmt
542 || af->sample_rate != audio_hw_params_src.freq
543 || dec_channel_layout != audio_hw_params_src.channel_layout
544 || !swr_ctx)
545 {
546 swr_free(&swr_ctx);
547 swr_ctx = swr_alloc_set_opts(NULL, audio_hw_params_tgt.channel_layout,
548 audio_hw_params_tgt.fmt, audio_hw_params_tgt.freq,
549 dec_channel_layout, af->format, af->sample_rate, 0, NULL);
550 if (!swr_ctx || swr_init(swr_ctx) < 0)
551 {
552 av_log(NULL, AV_LOG_ERROR,
553 "Cannot create sample rate converter for conversion of %d Hz %s %d channels to %d Hz %s %d channels!\n",
554 af->sample_rate, av_get_sample_fmt_name(af->format),
555 av_frame_get_channels(af), audio_hw_params_tgt.freq,
556 av_get_sample_fmt_name(audio_hw_params_tgt.fmt),
557 audio_hw_params_tgt.channels);
558 swr_free(&swr_ctx);
559 return -1;
560 }
561 printf("swr_init\n");
562 audio_hw_params_src.channels = av_frame_get_channels(af);
563 audio_hw_params_src.fmt = af->format;
564 audio_hw_params_src.freq = af->sample_rate;
565 }
566
567 if (swr_ctx)
568 {
569 const uint8_t **in = (const uint8_t **) af->extended_data;
570 uint8_t **out = &audio_buf;
571 int out_count = (int64_t) af->nb_samples * audio_hw_params_tgt.freq
572 / af->sample_rate + 256;
573 int out_size = av_samples_get_buffer_size(NULL,
574 audio_hw_params_tgt.channels, out_count,
575 audio_hw_params_tgt.fmt, 0);
576 int len2;
577 if (out_size < 0)
578 {
579 av_log(NULL, AV_LOG_ERROR, "av_samples_get_buffer_size() failed\n");
580 return -1;
581 }
582 av_fast_malloc(&audio_buf, audio_buf_size, out_size);
583 if (!audio_buf)
584 return AVERROR(ENOMEM);
585 len2 = swr_convert(swr_ctx, out, out_count, in, af->nb_samples);
586 if (len2 < 0)
587 {
588 av_log(NULL, AV_LOG_ERROR, "swr_convert() failed\n");
589 return -1;
590 }
591 if (len2 == out_count)
592 {
593 av_log(NULL, AV_LOG_WARNING,
594 "audio buffer is probably too small\n");
595 if (swr_init(swr_ctx) < 0)
596 swr_free(&swr_ctx);
597 }
598 resampled_data_size = len2 * audio_hw_params_tgt.channels
599 * av_get_bytes_per_sample(audio_hw_params_tgt.fmt);
600 }
601 else
602 {
603 audio_buf = af->data[0];
604 resampled_data_size = data_size;
605 }
606
607 return resampled_data_size;
608 }
609
610 #ifdef _cplusplus
611 }
612 #endif
代码那么多，不好理解呀～～～～～
所以程序还是最好模块化和分文件来做才行，或者封装成一个类。
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