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ffmpeg学习---7.音视频同步之视频同步音频

分类： LINUX

2016-05-23 17:14:06

http://dranger.com/ffmpeg/tutorial05.html
1. 根据上面的教程学习音视频同步

2. 代码基于ffmpeg-3.0.1
2.1 注:同步新加的部分用绿色标出
  1. #include <libavcodec/avcodec.h>
  2. #include <libavformat/avformat.h>
  3. #include <libswscale/swscale.h>
  4. #include <libswresample/swresample.h>
  5. #include <libavutil/avstring.h>
  6. #include <libavutil/pixfmt.h>
  7. #include <libavutil/log.h>
  8. #include <libavutil/time.h>              //要使用函数av_gettime
  9. #include <SDL/SDL.h>
  10. #include <SDL/SDL_thread.h>
  11. #include <stdio.h>
  12. #include <math.h>

  14. #define SDL_AUDIO_BUFFER_SIZE 4096
  15. #define AVCODEC_MAX_AUDIO_FRAME_SIZE 192000

  17. #define MAX_AUDIOQ_SIZE (5 * 16 * 1024)
  18. #define MAX_VIDEOQ_SIZE (5 * 256 * 1024)

  20. #define AV_SYNC_THRESHOLD 0.01
  21. #define AV_NOSYNC_THRESHOLD 10.0

  23. #define FF_REFRESH_EVENT (SDL_USEREVENT)
  24. #define FF_QUIT_EVENT (SDL_USEREVENT + 1)

  26. typedef struct PacketQueue
  27. {
  28.     AVPacketList * first_pkt, *last_pkt;
  29.     int nb_packets;
  30.     int size;
  31.     SDL_mutex *mutex;
  32.     SDL_cond * cond;
  33. }PacketQueue;

  35. static int signal_quit = 0;
  36. SDL_mutex *affmutex;
  37. SDL_Event sdlevent;

  39. #define VIDEO_PICTURE_QUEUE_SIZE 1

  41. typedef struct VideoState {
  42.     int videoindex;
  43.     int sndindex;
  44.     int frameFinished;
  45.     int wanted_freq;
  46.     int wanted_samples;
  47.     int wanted_channels;
  48.     int pictq_size, pictq_rindex, pictq_windex;
  49.     unsigned int audio_buf_size;
  50.     unsigned int audio_buf_index;
  51.     double frame_timer;
  52.     double frame_last_pts;
  53.     double now_video_pts;
  54.     double frame_last_delay;
  55.     double video_clock;
  56.     double              audio_clock;
  57.     SDL_Thread* video_tid;
  58.     AVFormatContext* pFormatCtx;
  59.     AVCodecContext* vdoCodecCtx;
  60.     AVCodecContext* sndCodecCtx;
  61.     AVCodec* vdoCodec;
  62.     AVCodec* sndCodec;
  63.     AVStream* vdoStream;
  64.     AVStream* sndStream;
  65.     AVFrame* pFrameYUV;
  66.     AVPacket* packet;
  67.     struct SwsContext *img_convert_ctx;
  68.     struct SwrContext *swr_ctx;
  69.     SDL_mutex *pictq_mutex;
  70.     SDL_cond *pictq_cond;
  71.     SDL_Surface* psscreen;
  72.     SDL_Overlay* overlay;
  73.     SDL_Rect rect;
  74.     SDL_mutex *screen_mutex;
  75.     enum AVSampleFormat wanted_fmt;
  76.     int64_t wanted_channel_layout;
  77.     PacketQueue audioq;
  78.     PacketQueue videoq;
  79.     DECLARE_ALIGNED(16,uint8_t,audio_buf2) [AVCODEC_MAX_AUDIO_FRAME_SIZE * 4];
  80. }VideoState;

  82. static void video_refresh_timer(void* arg);

  83.
  84. double synchronize_video(VideoState *is, AVFrame *src_frame, double pts) ;  //这两个函数是新加的
  85. double get_audio_clock(VideoState *is);
  86. static int sdl_event_thread(void* data)
  87. {
  88.     while((0==signal_quit))
  89.     {
  90.         SDL_LockMutex(affmutex);
  91.         while(SDL_PollEvent(&sdlevent))
  92.         {
  93.             switch(sdlevent.type)
  94.             {
  95.                 case FF_QUIT_EVENT:
  96.                 case SDL_QUIT:
  97.                     {
  98.                         signal_quit = 1;
  99.                         SDL_Quit();
  100.                         exit(0);
  101.                     }
  102.                     break;
  103.                 case FF_REFRESH_EVENT:
  104.                   video_refresh_timer(sdlevent.user.data1);
  105.                   break;
  106.                 default:
  107.                     break;
  108.             }
  109.         }
  110.         SDL_UnlockMutex(affmutex);
  111.     }
  112.     return 0;
  113. }

  115. static void packet_queue_init(PacketQueue *q)
  116. {
  117.     memset(q, 0, sizeof(PacketQueue));
  118.     q->mutex = SDL_CreateMutex();
  119.     q->cond = SDL_CreateCond();
  120. }

  122. static int packet_queue_put(PacketQueue *q, AVPacket *pkt)
  123. {
  124.     AVPacketList *pkt1;
  125.     pkt1 = av_malloc(sizeof(AVPacketList));
  126.     if (!pkt1)
  127.         return -1;
  128.     pkt1->pkt = *pkt;
  129.     pkt1->next = NULL;

  131.     SDL_LockMutex(q->mutex);
  132.     if (!q->last_pkt)
  133.         q->first_pkt = pkt1;
  134.     else
  135.         q->last_pkt->next = pkt1;
  136.     q->last_pkt = pkt1;
  137.     q->nb_packets++;
  138.     q->size += pkt1->pkt.size;
  139.     //dbmsg("put_queue and send singal");
  140.     SDL_CondSignal(q->cond);
  141.     SDL_UnlockMutex(q->mutex);
  142.     return 0;
  143. }

  145. static int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block)
  146. {
  147.     AVPacketList *pkt1;
  148.     int ret;
  149.     SDL_LockMutex(q->mutex);
  150.     for(;;)
  151.     {
  152.         pkt1 = q->first_pkt;
  153.         if (pkt1)
  154.         {
  155.             q->first_pkt = pkt1->next;
  156.             if (!q->first_pkt)
  157.                 q->last_pkt = NULL;
  158.             q->nb_packets--;
  159.             q->size -= pkt1->pkt.size;
  160.             *pkt = pkt1->pkt;
  161.             av_free(pkt1);
  162.             ret = 1;
  163.             break;
  164.         } else if (!block) {
  165.             ret = 0;
  166.             break;
  167.         } else {
  168.             SDL_CondWait(q->cond, q->mutex);
  169.          }
  170.     }
  171.     SDL_UnlockMutex(q->mutex);
  172.     return ret;
  173. }
  174. double get_audio_clock(VideoState *is) {
  175.     double pts;
  176.     int hw_buf_size, bytes_per_sec, n;

  178.     pts = is->audio_clock; /* maintained in the audio thread */
  179.     hw_buf_size = is->audio_buf_size - is->audio_buf_index;
  180.     bytes_per_sec = 0;
  181.     n = is->sndCodecCtx->channels * 2;
  182.     bytes_per_sec = is->sndCodecCtx->sample_rate * n;
  183.     if(bytes_per_sec) {
  184.         pts -= (double)hw_buf_size / bytes_per_sec;
  185.     }
  186.     return pts;
  187. }

  189. static int audio_decode_frame(VideoState* is)
  190. {
  191.     int len1,len2, data_size, got_frame;
  192.     int new_packet;
  193.     int n;
  194.     int64_t dec_channel_layout;
  195.     uint8_t *out[] = { is->audio_buf2 };
  196.     AVPacket *pkt = av_mallocz(sizeof(AVPacket));
  197.     AVPacket *pkt_temp = av_mallocz(sizeof(AVPacket));
  198.     AVFrame *frame = av_frame_alloc();
  199.     for(;;)
  200.     {
  201.         while(pkt_temp->size>0 || (!pkt_temp->data && new_packet))
  202.         {
  203.             if(frame)
  204.             {
  205.                 //dbmsg("av_get default frame");
  206.                 av_frame_unref(frame); //reset frame
  207.             }
  208.             new_packet = 0;
  209.             len1 = avcodec_decode_audio4(is->sndCodecCtx, frame, &got_frame, pkt_temp); //decode data is store in frame
  210.             if(len1 < 0)
  211.             {
  212.                 pkt_temp->size = 0;
  213.                 break;
  214.             }
  215.             //dbmsg("len1=%d, linesize=%d",len1, frame->linesize[0]);

  217.             pkt_temp->data += len1;
  218.             pkt_temp->size -= len1;

  220.             if(got_frame <= 0) /* No data yet, get more frames */
  221.                 continue;
  222.             data_size = av_samples_get_buffer_size(NULL, is->sndCodecCtx->channels, frame->nb_samples, is->sndCodecCtx->sample_fmt, 1);
  223.             dec_channel_layout = (frame->channel_layout && frame->channels==av_get_channel_layout_nb_channels(frame->channel_layout))?
  224.                 frame->channel_layout: is->wanted_channel_layout;
  225. #if 0
  226.             dbmsg("format=%d:%d,layout=%lld:%lld,rate=%d:%d,samples=%d:%d",frame->format,is->wanted_fmt,
  227.                    (long long) dec_channel_layout,(long long)av_get_default_channel_layout(is->wanted_channels),
  228.               frame->sample_rate,is->wanted_freq,frame->nb_samples,is->wanted_samples );

  230.             dbmsg("wanted_channel_layout=%lld", (long long)is->wanted_channel_layout);
  231.             dbmsg("wanted_fmt=%d", is->wanted_fmt);
  232.             dbmsg("spec.freq=%d", is->wanted_freq);
  233. #endif
  234.             //check: format,channel_layout,rate,sample
  235.             if((NULL==is->swr_ctx) && ( (frame->format!=is->wanted_fmt) || (dec_channel_layout!=av_get_default_channel_layout(is->wanted_channels)) ||
  236.               (frame->sample_rate!=is->wanted_freq) || (frame->nb_samples!=is->wanted_samples)) )
  237.             {
  238.                 if(is->swr_ctx != NULL)
  239.                     swr_free(&is->swr_ctx);
  240. #if 0
  241.                 dbmsg("wanted_channel_layout=%lld, wanted_fmt=%d, wanted_sample=%d, dec_channel_layout=%lld, frame->format=%d, frame->sample_rate=%d",
  242.                 (long long)is->wanted_channel_layout, is->wanted_fmt, is->wanted_samples, (long long)dec_channel_layout, frame->format, frame->sample_rate);
  243. #endif
  244.                 is->swr_ctx = swr_alloc_set_opts(NULL, is->wanted_channel_layout, is->wanted_fmt, is->wanted_freq, dec_channel_layout, frame->format, frame->sample_rate, 0, NULL);
  245.                 if(is->swr_ctx == NULL)
  246.                 {
  247.                     dbmsg("swr_ctx == NULL");
  248.                 }
  249.                 swr_init(is->swr_ctx);
  250.             }
  251.             if(is->swr_ctx)
  252.             {
  253.                 len2 = swr_convert(is->swr_ctx, out, sizeof(is->audio_buf2)/is->wanted_channels/av_get_bytes_per_sample(frame->format),(const uint8_t **)frame->extended_data, frame->nb_samples);
  254.                 data_size = len2 * is->wanted_channels * av_get_bytes_per_sample(is->wanted_fmt);
  255.             }else {
  256.                 memcpy(is->audio_buf2, frame->data[0], frame->linesize[0]);
  257.             }
  258.             n = 2*is->sndCodecCtx->channels;
  259.             is->audio_clock += (double)data_size/(double)(n*is->sndCodecCtx->sample_rate);    //下面获取的audio的pts与下一个sample的时间相加得到下一个sample的pts
  260.             dbmsg("data_size=%d,sample_rate=%d, audio_clock=%lf, n=%d",data_size,is->sndCodecCtx->sample_rate, is->audio_clock, n);
  261.             return data_size;
  262.         }
  263.         if(pkt->data)
  264.             av_freep(pkt);
  265.         memset(pkt_temp, 0, sizeof(*pkt_temp));
  266.         if(signal_quit)
  267.             return -1;
  268.         if((new_packet = packet_queue_get(&is->audioq, pkt, 1)) < 0)
  269.         {
  270.             dbmsg("get packet=%d", new_packet);
  271.             return -1;
  272.         }
  273.         if(pkt->pts != AV_NOPTS_VALUE)
  274.         {
  275.             is->audio_clock = av_q2d(is->sndCodecCtx->time_base)*pkt->pts;   //这儿获取的是audio的pts单位是s
  276.             dbmsg("audio_clock=%lf", is->audio_clock);
  277.         }

  279.         *pkt_temp = *pkt;
  280.     }
  281. }

  283. static void audio_callback(void *userdata, Uint8 *stream, int len)
  284. {
  285.     VideoState* is = (VideoState*)userdata;
  286.     int len1, audio_size;

  288.     //static unsigned int audio_buf_size = 0;
  289.     //static unsigned int audio_buf_index = 0;

  291.     while(len > 0)
  292.     {
  293.         if(is->audio_buf_index >= is->audio_buf_size)
  294.         {
  295.             audio_size = audio_decode_frame(is); //decode data is store in is->audio_buf2
  296.             //dbmsg("audio_size=%d", audio_size);
  297.             if(audio_size < 0)
  298.             {
  299.                 /* If error, output silence */
  300.                 is->audio_buf_size = 1024;
  301.                 memset(is->audio_buf2, 0, is->audio_buf_size);
  302.             } else {
  303.                 is->audio_buf_size = audio_size;
  304.             }
  305.             is->audio_buf_index = 0;
  306.         }
  307.         //dbmsg("len=%d, audio_buf_size=%d, audio_buf_index=%d", len, audio_buf_size, audio_buf_index);
  308.         len1 = is->audio_buf_size - is->audio_buf_index;
  309.         //dbmsg("len1=%d", len1);
  310.         if(len1 > len)
  311.             len1 = len;
  312.         //dbmsg("len1 = %d", len1);
  313.         memcpy(stream, (uint8_t *)is->audio_buf2 + is->audio_buf_index, len1);
  314.         len -= len1;
  315.         stream += len1;
  316.         is->audio_buf_index += len1;
  317.     }
  318. }

  320. static Uint32 sdl_refresh_timer_cb(Uint32 interval, void *opaque) {
  321.   SDL_Event event;
  322.   event.type = FF_REFRESH_EVENT;
  323.   event.user.data1 = opaque;
  324.   SDL_PushEvent(&event);
  325.   return 0; /* 0 means stop timer */
  326. }

  328. /* schedule a video refresh in 'delay' ms */
  329. static void schedule_refresh(VideoState *is, int delay) {
  330.   dbmsg("schedule_delay = %d", delay);
  331.   SDL_AddTimer(delay, sdl_refresh_timer_cb, is);
  332. }

  334. static void video_display(VideoState *is) {
  335.     SDL_LockMutex(is->screen_mutex);
  336.     SDL_DisplayYUVOverlay(is->overlay, &is->rect);
  337.     SDL_UnlockMutex(is->screen_mutex);
  338. }

  340. static void video_refresh_timer(void *data)
  341. {
  342.     VideoState *is = (VideoState *)data;
  343.     double actual_delay, delay, sync_threshold, ref_clock, diff;
  344.     if(is->pictq_size == 0) {
  345.         schedule_refresh(is, 1);
  346.     } else {
  347.         delay = is->now_video_pts - is->frame_last_pts;   //当前帧的pts与上一帧的pts的差就是两帧的时间间隔，单位是s
  348.         dbmsg("delay=%lf", delay);
  349.         if(delay<=0 || delay>=1.0)                        //前后两帧的间隔不能小于0,也不能大于1s
  350.         {
  351.             delay = is->frame_last_delay;
  352.             dbmsg("delay=is->frame_last_delay=%lf", delay);
  353.         }
  354.         is->frame_last_delay = delay;                     //保存上一次的delay结果
  355.         is->frame_last_pts = is->now_video_pts;           //保存上一次的pts结果 

  357.         ref_clock = get_audio_clock(is);                  //获取当前audio的pts
  358.         dbmsg("now_video_pts=%lf, ref_clock=%lf",is->now_video_pts, ref_clock);
  359.         diff = is->now_video_pts - ref_clock;             //视频相对于音频提前或落后了多长时间

  361.         //每次同步的时间间隔不能小于这个阀值
  362.         sync_threshold = (delay > AV_SYNC_THRESHOLD) ? delay : AV_SYNC_THRESHOLD;
  363.         if( fabs(diff) < AV_NOSYNC_THRESHOLD)
  364.         {
  365.             if(diff <= -sync_threshold)           //视频比音频慢了，就让视频快点跑delay=0
  366.                 delay = 0;
  367.             else if( diff >= sync_threshold)      //视频比音频快了，就让视频慢点跑delay=2*delay
  368.                 delay = 2 * delay;
  369.         }
  370.         is->frame_timer += delay;
  371.         actual_delay = is->frame_timer - (av_gettime() / 1000000.0); //单位是s
  372.         if(actual_delay < 0.010) {
  373.                actual_delay = 0.010;
  374.         }
  375.         dbmsg("actual_delay=%lf", actual_delay);
  376.         schedule_refresh(is, (int)(actual_delay * 1000 + 0.5));     //刷新的单位是ms,这儿加0.5的作用是四舍五入吗？
  377.         //schedule_refresh(is, 40);
  378.         video_display(is);

  380.         SDL_LockMutex(is->pictq_mutex);
  381.         is->pictq_size--;
  382.         SDL_CondSignal(is->pictq_cond);
  383.         SDL_UnlockMutex(is->pictq_mutex);
  384.     }
  385. }

  387. static int queue_picture(VideoState *is, AVFrame *pFrame)
  388. {
  389.     /* wait until we have space for a new pic */
  390.     SDL_LockMutex(is->pictq_mutex);
  391.     while(is->pictq_size >= VIDEO_PICTURE_QUEUE_SIZE && (0==signal_quit)) {
  392.         SDL_CondWait(is->pictq_cond, is->pictq_mutex);
  393.     }
  394.     SDL_UnlockMutex(is->pictq_mutex);

  396.     if(signal_quit)
  397.       return -1;

  399.     /* We have a place to put our picture on the queue */
  400.     SDL_LockYUVOverlay(is->overlay);
  401.     is->pFrameYUV->data[0] = is->overlay->pixels[0];
  402.     is->pFrameYUV->data[1] = is->overlay->pixels[2];
  403.     is->pFrameYUV->data[2] = is->overlay->pixels[1];
  404.     is->pFrameYUV->linesize[0] = is->overlay->pitches[0];
  405.     is->pFrameYUV->linesize[1] = is->overlay->pitches[2];
  406.     is->pFrameYUV->linesize[2] = is->overlay->pitches[1];
  407.     sws_scale(is->img_convert_ctx, (const uint8_t* const*)pFrame->data, pFrame->linesize, 0,
  408.     is->vdoCodecCtx->height, is->pFrameYUV->data, is->pFrameYUV->linesize);
  409.     SDL_UnlockYUVOverlay(is->overlay);
  410.     SDL_LockMutex(is->pictq_mutex);
  411.     is->pictq_size++;
  412.     SDL_UnlockMutex(is->pictq_mutex);
  413.     return 0;
  414. }

  416. double synchronize_video(VideoState *is, AVFrame *src_frame, double pts) {
  417.     double frame_delay;
  418.     //函数的作用是为了修正video_clock,对需要重复的帧修正video_clock
  419.     if(pts != 0) {
  420.         /* if we have pts, set video clock to it */
  421.         is->video_clock = pts;
  422.     } else {
  423.         /* if we aren't given a pts, set it to the clock */
  424.         pts = is->video_clock;         //但是video_clock只在这儿用了一次，当pts==0时把pts设为vidoe_clock
  425.     }                                  //pts只有在第1帧时pts才会为0,那时video_clock也是0,作用就是把0赋给pts,也就是没有用处  
  426.     /* update the video clock */       //所以感觉这个函数有没有都无所谓，现在是这么理解的，不知对不对？
  427.     frame_delay = av_q2d(is->vdoStream->time_base);
  428.     /* if we are repeating a frame, adjust clock accordingly */
  429.     frame_delay += src_frame->repeat_pict * (frame_delay * 0.5);
  430.     is->video_clock += frame_delay;
  431.     return pts;
  432. }
  433. static int video_thread(void* data)
  434. {
  435.     VideoState *is = (VideoState *)data;
  436.     AVPacket pkt1, *packet = &pkt1;
  437.     AVFrame *pFrame;
  438.     double pts;
  439.     int ret;
  440.     pFrame = av_frame_alloc();

  442.    for(;;)
  443.    {
  444.       if(signal_quit)
  445.           break;
  446.       if(packet_queue_get(&is->videoq, packet, 1) < 0) {
  447.           // means we quit getting packets
  448.           dbmsg("packet_queue_get < 0");
  449.           break;
  450.         }
  451.         // Decode video frame
  452.         if((ret=avcodec_decode_video2(is->vdoCodecCtx, pFrame, &is->frameFinished, packet)) < 0)
  453.         {
  454.             dbmsg("decocode video error");
  455.             continue;
  456.         }
  457.         if((pts = av_frame_get_best_effort_timestamp(pFrame)) == AV_NOPTS_VALUE) {
  458.             pts = 0;
  459.         }
  460.         //这儿的pts是0 3003 5005 6006 8008这样的
  461.         dbmsg("video: before_pts = %lf", pts);
  462.         pts *= av_q2d(is->vdoStream->time_base);     //time_base[1,24002],即pts=pts*(1/24002),此时pts的单位是s
  463.         dbmsg("time_base[%d,%d]", is->vdoStream->time_base.den,is->vdoStream->time_base.num);

  465.         dbmsg("video: after_pts = %lf", pts);
  466.         if(is->frameFinished) {
  467.          is->now_video_pts = synchronize_video(is, pFrame, pts);    //保存当前帧的pts到is->now_vieo_pts
  468.          //dbmsg("is->now_video_pts = %lf", is->now_video_pts);
  469.           if(queue_picture(is, pFrame) < 0) {
  470.             break;
  471.           }
  472.         }
  473.         av_freep(packet);
  474.     }
  475.     av_frame_free(&pFrame);
  476.     return 0;
  477. }

  479. static int decode_thread(void* data)
  480. {
  481.     VideoState* is = (VideoState*)data;
  482.     is->packet = (AVPacket*)av_malloc(sizeof(AVPacket));
  483.     while( (av_read_frame(is->pFormatCtx, is->packet)>=0) && (signal_quit==0))
  484.     {
  485.         if(is->packet->stream_index == is->videoindex)
  486.         {
  487.             packet_queue_put(&is->videoq, is->packet);
  488.         }

  490.         if(is->packet->stream_index == is->sndindex)
  491.         {
  492.             packet_queue_put(&is->audioq, is->packet);
  493.         }
  494.     }
  495.     return 0;
  496. }

  498. static int init_ffmpeg_and_SDL(VideoState* is, const char* video_file)
  499. {
  500.     int i=0;
  501.     SDL_AudioSpec wanted_spec, real_spec;
  502.     is->videoindex = -1;
  503.     is->sndindex = -1;
  504.     if(NULL == video_file)
  505.     {
  506.         dbmsg("input file is NULL");
  507.         return -1;
  508.     }
  509.     SDL_Init(SDL_INIT_EVERYTHING);
  510.     avcodec_register_all();
  511.     //avfilter_register_all();
  512.     av_register_all();

  514.     is->pFormatCtx = avformat_alloc_context();

  516.     if(avformat_open_input(&is->pFormatCtx, video_file, NULL, NULL)!=0)
  517.         return -1;

  519.     if(avformat_find_stream_info(is->pFormatCtx, NULL)<0)
  520.         return -1;
  521.     av_dump_format(is->pFormatCtx,0, 0, 0);

  523.     for(i=0; i<is->pFormatCtx->nb_streams; i++)
  524.     {
  525.         if(is->pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO)
  526.         {
  527.             is->videoindex= i;
  528.             is->vdoStream =is->pFormatCtx->streams[i];                //保存video的stream以后要用到time_base
  529.         }
  530.         if(is->pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO)
  531.         {
  532.             is->sndindex= i;
  533.             is->sndStream =is->pFormatCtx->streams[i];
  534.         }
  535.     }
  536.     if(is->videoindex== -1)
  537.         dbmsg("no video stream found!");
  538.     if(is->sndindex== -1)
  539.         dbmsg("no sound stream found!");
  540.     dbmsg("videoindex=%d, sndindex=%d", is->videoindex, is->sndindex);

  542.     if(is->videoindex != -1)
  543.     {
  544.         is->vdoCodecCtx = is->pFormatCtx->streams[is->videoindex]->codec;
  545.         is->vdoCodec = avcodec_find_decoder(is->vdoCodecCtx->codec_id);
  546.         if(is->vdoCodec == NULL)
  547.         {
  548.             dbmsg("Codec not found");
  549.             return -1;
  550.         }
  551.         if(avcodec_open2(is->vdoCodecCtx, is->vdoCodec, NULL) < 0)
  552.             return -1;
  553.         is->pFrameYUV = av_frame_alloc();
  554.         is->img_convert_ctx = sws_getContext(is->vdoCodecCtx->width, is->vdoCodecCtx->height, is->vdoCodecCtx->pix_fmt,
  555.               is->vdoCodecCtx->width, is->vdoCodecCtx->height, AV_PIX_FMT_YUV420P, SWS_BICUBIC, NULL, NULL, NULL);
  556.         if(is->img_convert_ctx == NULL)
  557.         {
  558.             dbmsg("img_convert error");
  559.             return -1;
  560.         }
  561.         is->psscreen = SDL_SetVideoMode(is->vdoCodecCtx->width, is->vdoCodecCtx->height, 0, SDL_SWSURFACE);
  562.         SDL_WM_SetCaption( "FFMPEG Window", NULL);
  563.         is->overlay = SDL_CreateYUVOverlay(is->vdoCodecCtx->width, is->vdoCodecCtx->height, SDL_YV12_OVERLAY, is->psscreen);
  564.         is->rect.x = 0;
  565.         is->rect.y = 0;
  566.      is->rect.w = is->vdoCodecCtx->width;
  567.         is->rect.h = is->vdoCodecCtx->height;
  568.         packet_queue_init(&is->videoq);
  569.         is->video_tid = SDL_CreateThread(video_thread, is);
  570.         is->frame_timer = (double)av_gettime() / 1000000.0;      //获取当前时间单位是s,因为av_gettime的单位是us
  571.         is->frame_last_delay = 40e-3;
  572.     }
  573.     if(is->sndindex != -1)
  574.     {
  575.         is->sndCodecCtx = is->pFormatCtx->streams[is->sndindex]->codec;
  576.         is->sndCodec = avcodec_find_decoder(is->sndCodecCtx->codec_id);
  577.         if(is->sndCodec == NULL)
  578.         {
  579.             dbmsg("Codec not found");
  580.             return -1;
  581.         }
  582.         if(avcodec_open2(is->sndCodecCtx, is->sndCodec, NULL) < 0)
  583.             return -1;

  585.         wanted_spec.freq = is->sndCodecCtx->sample_rate;
  586.         wanted_spec.format = AUDIO_S16SYS;
  587.         wanted_spec.channels = is->sndCodecCtx->channels;
  588.         wanted_spec.silence = 0;
  589.         wanted_spec.samples = 2048;
  590.         wanted_spec.callback = audio_callback;
  591.         wanted_spec.userdata = is;
  592.         is->audio_buf_size = 0;
  593.         is->audio_buf_index = 0;
  594.         if(SDL_OpenAudio(&wanted_spec, &real_spec) < 0)
  595.         {
  596.             dbmsg("SDL_OpenAudio:%s", SDL_GetError());
  597.             return -1;
  598.         }
  599.         //store infomation for audio swr_convert
  600.         is->wanted_fmt = AV_SAMPLE_FMT_S16; //AUDIO_S16SYS;
  601.         is->wanted_channel_layout = av_get_default_channel_layout(is->sndCodecCtx->channels);
  602.         is->wanted_freq = real_spec.freq;
  603.         is->wanted_samples = real_spec.samples;
  604.         is->wanted_channels = real_spec.channels;
  605.         //dbmsg("freq=%d, channels=%d, samples=%d", is->wanted_freq, is->wanted_channels, is->wanted_samples);
  606.         packet_queue_init(&is->audioq);
  607.         SDL_PauseAudio(0);
  608.     }
  609.     return 0;
  610. }


  613. int main(int argc, char **argv)
  614. {
  615.     int ret;
  616.     SDL_Thread* sdl_thread;
  617.     SDL_Thread* decode_thread_id;
  618.     VideoState* is = (VideoState*) av_mallocz(sizeof(VideoState));
  619.     if(argc < 2)
  620.         dbmsg("usage: ./ffplay \n");

  622.     if( (ret=init_ffmpeg_and_SDL(is, argv[1])) != 0)
  623.     {
  624.         dbmsg("init_ffmpeg_and SDL error");
  625.         return -1;
  626.     }

  628.     is->pictq_mutex = SDL_CreateMutex();
  629.     is->pictq_cond = SDL_CreateCond();

  631.     //sdl get signal quit
  632.     affmutex = SDL_CreateMutex();
  633.     decode_thread_id = SDL_CreateThread(decode_thread, is);
  634.     sdl_thread = SDL_CreateThread(sdl_event_thread, NULL);

  636.     schedule_refresh(is, 40);

  638.     SDL_WaitThread(sdl_thread, &ret);
  639.     SDL_WaitThread(decode_thread_id, &ret);
  640.     SDL_WaitThread(is->video_tid,&ret);
  641.     SDL_DestroyMutex(affmutex);
  642.     av_freep(is->packet);
  643.     av_free(is->pFrameYUV);
  644.     avcodec_close(is->vdoCodecCtx);
  645.     avcodec_close(is->sndCodecCtx);
  646.     avformat_close_input(&is->pFormatCtx);
  647.     return 0;
  648. }
2.2 Makefile
  1. EXE=sync
  2. CC=gcc
  3. FFMPEG=/work/ffmpeg/ffmpeg-3.0.1/install/
  4. CFLAGS=-g -O0 -I$(FFMPEG)/include
  5. LDFLAGS = -L$(FFMPEG)/lib/ -lz -lswscale -lswresample -lavformat -lavdevice -lavcodec -lavutil -lavfilter -lm -lSDL -pthread -lz -lbz2
  6. SRC=$(wildcard *.c)
  7. OBJ=$(patsubst %.c,%.o,$(SRC))
  8. DEP=$(patsubst %.c,.%.d,$(SRC))
  9. $(EXE):$(OBJ)
  10.     $(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS)

  12. $(DEP):.%.d:%.c
  13.     @set -e; rm -f $@; \
  14.     $(CC) -MM $< > $@.$$$$; \
  15.     sed 's,/($*/)/.o[ :]*,/1.o $@ : ,g' < $@.$$$$ > $@; \
  16.     rm -f $@.$$$$

  18. -include $(DEP)
  19. clean:
  20.     @rm $(EXE) $(OBJ) $(DEP) -f
  21. run:
  22.     export LD_LIBRARY_PATH=$(LD_LIBRARY_PATH):$(FFMPEG)/lib/ \
  23.     && ./$(EXE) ../../san.mp4
  24.     #export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/work/ffmpeg/out/lib/
Makefile也需要修改一下。
3.代码
5sync.rar(下载后改名为5sync.tar.gz)
3.1 几个编译问题
a. -pthread,不加这个会出现以下报错
  1. /usr/bin/ld: /work/ffmpeg/ffmpeg-3.0.1/install//lib//libavcodec.a(h264.o): undefined reference to symbol 'pthread_once@@GLIBC_2.2.5'
  2. //lib/x86_64-linux-gnu/libpthread.so.0: error adding symbols: DSO missing from command line
  3. collect2: error: ld returned 1 exit status
b.  -lz,不加这个会出现以下报错
  1. /usr/bin/ld: /work/ffmpeg/ffmpeg-3.0.1/install//lib//libavformat.a(http.o): undefined reference to symbol 'inflateInit2_'
  2. /usr/lib/gcc/x86_64-linux-gnu/4.8/../../../x86_64-linux-gnu/libz.so: error adding symbols: DSO missing from command line
c.-lbz2，不加这个会出现以下报错
  1. /work/ffmpeg/ffmpeg-3.0.1/install//lib//libavformat.a(matroskadec.o): In function `matroska_decode_buffer':
  2. /work/ffmpeg/ffmpeg-3.0.1/libavformat/matroskadec.c:1327: undefined reference to `BZ2_bzDecompressInit'
  3. /work/ffmpeg/ffmpeg-3.0.1/libavformat/matroskadec.c:1342: undefined reference to `BZ2_bzDecompress'
  4. /work/ffmpeg/ffmpeg-3.0.1/libavformat/matroskadec.c:1335: undefined reference to `BZ2_bzDecompressEnd'
  5. /work/ffmpeg/ffmpeg-3.0.1/libavformat/matroskadec.c:1345: undefined reference to `BZ2_bzDecompressEnd
3.2 pkg-config更新Makefile
a. 重新编译ffmpeg
这儿注意:   
    加入  --enable-shared 生成动态链接库   
     --prefix=/work/ffmpeg/ffmpeg-3.0.1/install  后面跟完整路径名,这样pkg-config后面也是完整的路径，
       否则pkg-config是相对路径，把5sync的代码放在其它的目录中就会找不到库
cong@msi:/work/ffmpeg/ffmpeg-3.0.1$ ./configure --enable-shared --prefix=/work/ffmpeg/ffmpeg-3.0.1/install --disable-ffmpeg --disable-ffprobe --disable-ffserver
cong@msi:/work/ffmpeg/ffmpeg-3.0.1$ make -j16 && make install 
b. ffmpge编译并install之后，需要加入pkg-config的查找路径
export PKG_CONFIG_PATH=$PKG_CONFIG_PATH:/work/ffmpeg/ffmpeg-3.0.1/install/lib/pkgconfig/
测试一下pkg-config --libs libavfilter
c. 重写了一个Makefile
cong@msi:/work/ffmpeg/test/5sync$ cat Makefile 
  1. EXE=sync
  2. FFMPEG=/work/ffmpeg/ffmpeg-3.0.1/install
  3. CC=gcc
  4. SRC:=$(wildcard *.c) $(wildcard *.cpp)
  5. OBJ:=$(patsubst %.c,%.o,$(patsubst %.cpp,%.o,$(SRC)))
  6. FFMPEG_LIBS= libavdevice \
  7.                 libavformat \
  8.                 libavfilter \
  9.                 libavcodec \
  10.                 libswresample \
  11.                 libswscale \
  12.                 libavutil \

  14. CFLAGS += -Wall -g
  15. CPPFLAGS := $(shell pkg-config --cflags $(FFMPEG_LIBS)) $(shell pkg-config --cflags sdl)
  16. LDFLAGS:= $(shell pkg-config --libs $(FFMPEG_LIBS)) $(shell pkg-config --libs sdl)
  17. DEP:=$(patsubst %.c,.%.d,$(patsubst %.cpp,.%.d,$(SRC)))

  19. $(EXE):$(OBJ)
  20.     $(CC) $^ -o $@ $(LDFLAGS)
  21.   
  22. %.o: %.c
  23.     $(CC) $(CPPFLAGS) -c $< -o $@
  24.   
  25. %.o: %.cpp
  26.     $(CC) $(CPPFLAGS) -c $< -o $@
  27.   
  28. -include $(DEP)
  29.   
  30. define gen_dep
  31. @set -e; rm -f $@; \
  32. $(CC) -MM $(CPPFLAGS) $< > $@.$$$$; \
  33. sed 's,\($*\)\.o[ :]*,\1.o $@ : ,g' < $@.$$$$ > $@; \
  34. rm -f $@.$$$$
  35. endef
  36.   
  37. .%.d: %.c
  38.     $(gen_dep)
  39.   
  40. .%.d: %.cpp
  41.     $(gen_dep)
  42.   
  43. .PHONY: clean
  44. clean:
  45.     rm -f all $(OBJ) $(DEP)
  46.   
  47. echo:
  48.     @echo SRC=$(SRC)
  49.     @echo OBJ=$(OBJ)
  50.     @echo DEP=$(DEP)
  51.     @echo CPPFLAGS=$(CPPFLAGS)
  52. run:
  53.     export LD_LIBRARY_PATH=$(LD_LIBRARY_PATH):$(FFMPEG)/lib/ \
  54.     && ./$(EXE) ../../san.mp4
  55.     #export LD_LIBRARY_PATH=$LD_LIBRARY_PATH:/work/ffmpeg/out/lib/
这样5sync的代码在任何地方都可以编译了

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