SimplePlayer.c

#include <stdio.h>
#include <assert.h>
#include <math.h>

#include <SDL.h>

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>
#include <libavutil/time.h>
#include <libswresample/swresample.h>

#define SDL_AUDIO_BUFFER_SIZE 1024
#define MAX_AUDIO_FRAME_SIZE 192000 //channels(2) * data_size(2) * sample_rate(48000)

#define MAX_AUDIOQ_SIZE (5 * 16 * 1024)
#define MAX_VIDEOQ_SIZE (5 * 256 * 1024)

#define AV_SYNC_THRESHOLD 0.01
#define AV_NOSYNC_THRESHOLD 10.0

#define FF_REFRESH_EVENT (SDL_USEREVENT)
#define FF_QUIT_EVENT (SDL_USEREVENT + 1)

#define VIDEO_PICTURE_QUEUE_SIZE 1


typedef struct PacketQueue {
    AVPacketList *first_pkt, *last_pkt;
    int nb_packets;
    int size;
    SDL_mutex *mutex;
    SDL_cond *cond;
} PacketQueue;


typedef struct VideoPicture {
    AVFrame *frame;
    int width, height; /* source height & width */
    double pts;
} VideoPicture;

typedef struct VideoState {

    //multi-media file
    char filename[1024];
    AVFormatContext *pFormatCtx;
    int videoStream, audioStream;


    double audio_clock;
    double frame_timer;
    double frame_last_pts;
    double frame_last_delay;

    double video_clock; ///<pts of last decoded frame / predicted pts of next decoded frame
    double video_current_pts; ///<current displayed pts (different from video_clock if frame fifos are used)
    int64_t video_current_pts_time;  ///<time (av_gettime) at which we updated video_current_pts - used to have running video pts

    //audio
    AVStream *audio_st;
    AVCodecContext *audio_ctx;
    PacketQueue audioq;
    uint8_t audio_buf[(MAX_AUDIO_FRAME_SIZE * 3) / 2];
    unsigned int audio_buf_size;
    unsigned int audio_buf_index;
    AVFrame audio_frame;

    AVPacket audio_pkt;
    uint8_t *audio_pkt_data;
    int audio_pkt_size;
    int audio_hw_buf_size;
    struct SwrContext *audio_swr_ctx;


    //video
    AVStream *video_st;
    AVCodecContext *video_ctx;
    PacketQueue videoq;


    VideoPicture pictq[VIDEO_PICTURE_QUEUE_SIZE];
    int pictq_size, pictq_rindex
    , pictq_windex;
    SDL_mutex *pictq_mutex;
    SDL_cond *pictq_cond;

    SDL_Thread *parse_tid;
    SDL_Thread *video_tid;

    int quit;
} VideoState;

SDL_mutex *text_mutex;
SDL_Window *win = NULL;
SDL_Renderer *renderer;
SDL_Texture *texture;


static int screen_left = SDL_WINDOWPOS_CENTERED;
static int screen_top = SDL_WINDOWPOS_CENTERED;
static int screen_width = 0;
static int screen_height = 0;
static int resize = 1;


/* Since we only have one decoding thread, the Big Struct
   can be global in case we need it. */
VideoState *global_video_state;

//// 初始化队列
void packet_queue_init(PacketQueue *q) {
    memset(q, 0, sizeof(PacketQueue));
    q->mutex = SDL_CreateMutex();
    q->cond = SDL_CreateCond();
}

int packet_queue_put(PacketQueue *q, AVPacket *pkt) {

    AVPacketList *pkt1;
    if (av_packet_make_refcounted(pkt) < 0) {
        return -1;
    }
    pkt1 = av_malloc(sizeof(AVPacketList));
    if (!pkt1)
        return -1;
    pkt1->pkt = *pkt;
    pkt1->next = NULL;

    SDL_LockMutex(q->mutex);

    if (!q->last_pkt)
        q->first_pkt = pkt1;
    else
        q->last_pkt->next = pkt1;
    q->last_pkt = pkt1;
    q->nb_packets++;
    q->size += pkt1->pkt.size;
    SDL_CondSignal(q->cond);

    SDL_UnlockMutex(q->mutex);
    return 0;
}

int packet_queue_get(PacketQueue *q, AVPacket *pkt, int block) {
    AVPacketList *pkt1;
    int ret;

    SDL_LockMutex(q->mutex);

    for (;;) {

        if (global_video_state->quit) {
            ret = -1;
            break;
        }

        pkt1 = q->first_pkt;
        if (pkt1) {
            q->first_pkt = pkt1->next;
            if (!q->first_pkt)
                q->last_pkt = NULL;
            q->nb_packets--;
            q->size -= pkt1->pkt.size;
            *pkt = pkt1->pkt;
            av_free(pkt1);
            ret = 1;
            break;
        } else if (!block) {
            ret = 0;
            break;
        } else {
            SDL_CondWait(q->cond, q->mutex);
        }
    }
    SDL_UnlockMutex(q->mutex);
    return ret;
}

double get_audio_clock(VideoState *is) {
    double pts;
    int hw_buf_size, bytes_per_sec, n;

    //上一步获取的PTS
    pts = is->audio_clock;
    // 音频缓冲区还没有播放的数据
    hw_buf_size = is->audio_buf_size - is->audio_buf_index;
    // 每秒钟音频播放的字节数
    bytes_per_sec = 0;
    n = is->audio_ctx->channels * 2;
    if (is->audio_st) {
        bytes_per_sec = is->audio_ctx->sample_rate * n;
    }
    if (bytes_per_sec) {
        pts -= (double) hw_buf_size / bytes_per_sec;
    }
    return pts;
}

//// 音频帧解码
int audio_decode_frame(VideoState *is, uint8_t *audio_buf, int buf_size, double *pts_ptr) {

    int len1, data_size = 0;
    AVPacket *pkt = &is->audio_pkt;
    double pts;
    int n;


    for (;;) {
        while (is->audio_pkt_size > 0) {
            avcodec_send_packet(is->audio_ctx, pkt);
            while (avcodec_receive_frame(is->audio_ctx, &is->audio_frame) == 0) {
                len1 = is->audio_frame.pkt_size;

                if (len1 < 0) {
                    /* if error, skip frame */
                    is->audio_pkt_size = 0;
                    break;
                }

                data_size = 2 * is->audio_frame.nb_samples * 2;
                assert(data_size <= buf_size);

                swr_convert(is->audio_swr_ctx,
                            &audio_buf,
                            MAX_AUDIO_FRAME_SIZE * 3 / 2,
                            (const uint8_t **) is->audio_frame.data,
                            is->audio_frame.nb_samples);

            }
            is->audio_pkt_data += len1;
            is->audio_pkt_size -= len1;
            if (data_size <= 0) {
                /* No data yet, get more frames */
                continue;
            }
            pts = is->audio_clock;
            *pts_ptr = pts;
            n = 2 * is->audio_ctx->channels;
            is->audio_clock += (double) data_size /
                               (double) (n * is->audio_ctx->sample_rate);
            /* We have data, return it and come back for more later */
            return data_size;
        }
        if (pkt->data)
            av_packet_unref(pkt);

        if (is->quit) {
            return -1;
        }
        /* next packet */
        if (packet_queue_get(&is->audioq, pkt, 1) < 0) {
            return -1;
        }
        is->audio_pkt_data = pkt->data;
        is->audio_pkt_size = pkt->size;
        /* if update, update the audio clock w/pts */
        if (pkt->pts != AV_NOPTS_VALUE) {
            is->audio_clock = av_q2d(is->audio_st->time_base) * pkt->pts;
        }
    }
}

//// 音频设备回调
void audio_callback(void *userdata, Uint8 *stream, int len) {

    VideoState *is = (VideoState *) userdata;
    int len1, audio_size;
    double pts;

    SDL_memset(stream, 0, len);

    while (len > 0) {
        if (is->audio_buf_index >= is->audio_buf_size) {
            // 音频解码
            audio_size = audio_decode_frame(is, is->audio_buf, sizeof(is->audio_buf), &pts);
            if (audio_size < 0) {
                // 音频解码错误，播放静音
                is->audio_buf_size = 1024 * 2 * 2;
                memset(is->audio_buf, 0, is->audio_buf_size);
            } else {
                is->audio_buf_size = audio_size;
            }
            is->audio_buf_index = 0;
        }
        len1 = is->audio_buf_size - is->audio_buf_index;
        if (len1 > len)
            len1 = len;
        SDL_MixAudio(stream, (uint8_t *) is->audio_buf + is->audio_buf_index, len1, SDL_MIX_MAXVOLUME);
        len -= len1;
        stream += len1;
        is->audio_buf_index += len1;
    }
}

//// 定时器回调函数，发送FF_REFRESH_EVENT事件，更新显示视频帧
static Uint32 sdl_refresh_timer_cb(Uint32 interval, void *opaque) {
    SDL_Event event;
    event.type = FF_REFRESH_EVENT;
    event.user.data1 = opaque;
    SDL_PushEvent(&event);
    return 0;
}

//// 设置定时器
static void schedule_refresh(VideoState *is, int delay) {
    SDL_AddTimer(delay, sdl_refresh_timer_cb, is);
}

//// 视频播放
void video_display(VideoState *is) {

    SDL_Rect rect;
    VideoPicture *vp;

    if (screen_width && resize) {
        SDL_SetWindowSize(win, screen_width, screen_height);
        SDL_SetWindowPosition(win, screen_left, screen_top);
        SDL_ShowWindow(win);

        Uint32 pixformat = SDL_PIXELFORMAT_IYUV;

        //create texture for render
        texture = SDL_CreateTexture(renderer,
                                    pixformat,
                                    SDL_TEXTUREACCESS_STREAMING,
                                    screen_width,
                                    screen_height);
        resize = 0;
    }

    vp = &is->pictq[is->pictq_rindex];

    // 渲染播放
    if (vp->frame) {
        SDL_UpdateYUVTexture(texture, NULL,
                             vp->frame->data[0], vp->frame->linesize[0],
                             vp->frame->data[1], vp->frame->linesize[1],
                             vp->frame->data[2], vp->frame->linesize[2]);

        rect.x = 0;
        rect.y = 0;
        rect.w = is->video_ctx->width;
        rect.h = is->video_ctx->height;
        SDL_LockMutex(text_mutex);
        SDL_RenderClear(renderer);
        SDL_RenderCopy(renderer, texture, NULL, &rect);
        SDL_RenderPresent(renderer);
        SDL_UnlockMutex(text_mutex);
    }
}

//// 视频刷新播放，并预测下一帧的播放时间，设置新的定时器
void video_refresh_timer(void *userdata) {

    VideoState *is = (VideoState *) userdata;
    VideoPicture *vp;
    double actual_delay, delay, sync_threshold, ref_clock, diff;

    if (is->video_st) {
        if (is->pictq_size == 0) {
            schedule_refresh(is, 1);
        } else {
            // 从数组中取出一帧视频帧
            vp = &is->pictq[is->pictq_rindex];

            is->video_current_pts = vp->pts;
            is->video_current_pts_time = av_gettime();
            // 当前Frame时间减去上一帧的时间，获取两帧间的时差
            delay = vp->pts - is->frame_last_pts;
            if (delay <= 0 || delay >= 1.0) {
                // 延时小于0或大于1秒（太长）都是错误的，将延时时间设置为上一次的延时时间
                delay = is->frame_last_delay;
            }
            // 保存延时和PTS，等待下次使用
            is->frame_last_delay = delay;
            is->frame_last_pts = vp->pts;

            // 获取音频Audio_Clock
            ref_clock = get_audio_clock(is);
            // 得到当前PTS和Audio_Clock的差值
            diff = vp->pts - ref_clock;

            /* Skip or repeat the frame. Take delay into account
               FFPlay still doesn't "know if this is the best guess." */
            sync_threshold = (delay > AV_SYNC_THRESHOLD) ? delay : AV_SYNC_THRESHOLD;
            if (fabs(diff) < AV_NOSYNC_THRESHOLD) {
                if (diff <= -sync_threshold) {
                    delay = 0;
                } else if (diff >= sync_threshold) {
                    delay = 2 * delay;
                }
            }
            is->frame_timer += delay;
            // 最终真正要延时的时间
            actual_delay = is->frame_timer - (av_gettime() / 1000000.0);
            if (actual_delay < 0.010) {
                // 延时时间过小就设置最小值
                actual_delay = 0.010;
            }
            // 根据延时时间重新设置定时器，刷新视频
            schedule_refresh(is, (int) (actual_delay * 1000 + 0.5));

            // 视频帧显示
            video_display(is);

            // 更新视频帧数组下标
            if (++is->pictq_rindex == VIDEO_PICTURE_QUEUE_SIZE) {
                is->pictq_rindex = 0;
            }
            SDL_LockMutex(is->pictq_mutex);
            // 视频帧数组减一
            is->pictq_size--;
            SDL_CondSignal(is->pictq_cond);
            SDL_UnlockMutex(is->pictq_mutex);
        }
    } else {
        schedule_refresh(is, 100);
    }
}

////解码后视频帧保存
int queue_picture(VideoState *is, AVFrame *pFrame, double pts) {

    VideoPicture *vp;

    /* wait until we have space for a new pic */
    SDL_LockMutex(is->pictq_mutex);
    while (is->pictq_size >= VIDEO_PICTURE_QUEUE_SIZE && !is->quit) {
        SDL_CondWait(is->pictq_cond, is->pictq_mutex);
    }
    SDL_UnlockMutex(is->pictq_mutex);

    if (is->quit)
        return -1;

    // windex is set to 0 initially
    vp = &is->pictq[is->pictq_windex];


//    /* allocate or resize the buffer! */
    if (!vp->frame ||
        vp->width != is->video_ctx->width ||
        vp->height != is->video_ctx->height) {

        vp->frame = av_frame_alloc();
        if (is->quit) {
            return -1;
        }
    }

    /* We have a place to put our picture on the queue */
    if (vp->frame) {

        vp->pts = pts;

        vp->frame = pFrame;
        /* now we inform our display thread that we have a pic ready */
        if (++is->pictq_windex == VIDEO_PICTURE_QUEUE_SIZE) {
            is->pictq_windex = 0;
        }

        SDL_LockMutex(is->pictq_mutex);
        is->pictq_size++;
        SDL_UnlockMutex(is->pictq_mutex);
    }
    return 0;
}

////  视频同步，获取正确的视频PTS
double synchronize_video(VideoState *is, AVFrame *src_frame, double pts) {

    double frame_delay;

    if (pts != 0) {
        is->video_clock = pts;
    } else {
        pts = is->video_clock;
    }
    /* update the video clock */
    frame_delay = av_q2d(is->video_ctx->time_base);
    /* if we are repeating a frame, adjust clock accordingly */
    frame_delay += src_frame->repeat_pict * (frame_delay * 0.5);
    is->video_clock += frame_delay;
    return pts;
}


//// 视频解码
int decode_video_thread(void *arg) {
    VideoState *is = (VideoState *) arg;
    AVPacket pkt1, *packet = &pkt1;
    AVFrame *pFrame;
    double pts;

    pFrame = av_frame_alloc();

    for (;;) {
        if (packet_queue_get(&is->videoq, packet, 1) < 0) {
            // means we quit getting packets
            break;
        }

        // Decode video frame
        avcodec_send_packet(is->video_ctx, packet);
        while (avcodec_receive_frame(is->video_ctx, pFrame) == 0) {
            if ((pts = pFrame->best_effort_timestamp) != AV_NOPTS_VALUE) {
            } else {
                pts = 0;
            }
            pts *= av_q2d(is->video_st->time_base);

            pts = synchronize_video(is, pFrame, pts);
            if (queue_picture(is, pFrame, pts) < 0) {
                break;
            }
            av_packet_unref(packet);
        }
    }
    av_frame_free(&pFrame);
    return 0;
}

//// 打开流，准备解码
int stream_component_open(VideoState *is, int stream_index) {

    AVFormatContext *pFormatCtx = is->pFormatCtx;
    AVCodecContext *codecCtx = NULL;
    AVCodec *codec = NULL;
    SDL_AudioSpec wanted_spec;

    if (stream_index < 0 || stream_index >= pFormatCtx->nb_streams) {
        return -1;
    }

    codecCtx = avcodec_alloc_context3(NULL);
    int ret = avcodec_parameters_to_context(codecCtx, pFormatCtx->streams[stream_index]->codecpar);
    if (ret < 0)
        return -1;

    codec = avcodec_find_decoder(codecCtx->codec_id);
    if (!codec) {
        fprintf(stderr, "Unsupported codec!\n");
        return -1;
    }

    // 打开解码器
    if (avcodec_open2(codecCtx, codec, NULL) < 0) {
        fprintf(stderr, "Unsupported codec!\n");
        return -1;
    }

    switch (codecCtx->codec_type) {
        // 音频流参数配置，打开音频设备，播放音频
        case AVMEDIA_TYPE_AUDIO:
            // Set audio settings from codec info
            wanted_spec.freq = codecCtx->sample_rate;
            wanted_spec.format = AUDIO_S16SYS;
            wanted_spec.channels = 2;//codecCtx->channels;
            wanted_spec.silence = 0;
            wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
            wanted_spec.callback = audio_callback;
            wanted_spec.userdata = is;

            fprintf(stderr, "wanted spec: channels:%d, sample_fmt:%d, sample_rate:%d \n",
                    2, AUDIO_S16SYS, codecCtx->sample_rate);

            // 打开音频设备
            if (SDL_OpenAudio(&wanted_spec, NULL) < 0) {
                fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
                return -1;
            }

            is->audioStream = stream_index;
            is->audio_st = pFormatCtx->streams[stream_index];
            is->audio_ctx = codecCtx;
            is->audio_buf_size = 0;

            is->audio_buf_index = 0;
            memset(&is->audio_pkt, 0, sizeof(is->audio_pkt));
            packet_queue_init(&is->audioq);

            //Out Audio Param
            uint64_t out_channel_layout = AV_CH_LAYOUT_STEREO;

            int out_nb_samples = is->audio_ctx->frame_size;

            int out_sample_rate = is->audio_ctx->sample_rate;
            int out_channels = av_get_channel_layout_nb_channels(out_channel_layout);


            int64_t in_channel_layout = av_get_default_channel_layout(is->audio_ctx->channels);

            // 音频重采样
            struct SwrContext *audio_convert_ctx;
            audio_convert_ctx = swr_alloc();
            swr_alloc_set_opts(audio_convert_ctx,
                               out_channel_layout,
                               AV_SAMPLE_FMT_S16,
                               out_sample_rate,
                               in_channel_layout,
                               is->audio_ctx->sample_fmt,
                               is->audio_ctx->sample_rate,
                               0,
                               NULL);

            swr_init(audio_convert_ctx);
            is->audio_swr_ctx = audio_convert_ctx;

            // 开始播放音频，audio_callback回调
            SDL_PauseAudio(0);

            break;
            // 视频播放准备，解码、播放视频
        case AVMEDIA_TYPE_VIDEO:
            is->videoStream = stream_index;
            is->video_st = pFormatCtx->streams[stream_index];
            is->video_ctx = codecCtx;

            is->frame_timer = (double) av_gettime() / 1000000.0;
            is->frame_last_delay = 40e-3;
            is->video_current_pts_time = av_gettime();

            packet_queue_init(&is->videoq);

            // 创建视频解码线程
            is->video_tid = SDL_CreateThread(decode_video_thread, "decode_video_thread", is);
            break;
        default:
            break;
    }
}

// 解复用，获取音频、视频流，并将packet放入队列中
int demux_thread(void *arg) {

    int err_code;
    char errors[1024] = {0,};

    int w, h;

    VideoState *is = (VideoState *) arg;
    AVFormatContext *pFormatCtx = NULL;
    AVPacket pkt1, *packet = &pkt1;

    int video_index = -1;
    int audio_index = -1;
    int i;

    is->videoStream = -1;
    is->audioStream = -1;

    global_video_state = is;

    /* open input file, and allocate format context */
    if ((err_code = avformat_open_input(&pFormatCtx, is->filename, NULL, NULL)) < 0) {
        av_strerror(err_code, errors, 1024);
        fprintf(stderr, "Could not open source file %s, %d(%s)\n", is->filename, err_code, errors);
        return -1;
    }

    is->pFormatCtx = pFormatCtx;

    // Retrieve stream information
    if (avformat_find_stream_info(pFormatCtx, NULL) < 0)
        return -1; // Couldn't find stream information

    // Dump information about file onto standard error
    av_dump_format(pFormatCtx, 0, is->filename, 0);

    // Find the first video stream
    for (i = 0; i < pFormatCtx->nb_streams; i++) {
        if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
            video_index < 0) {
            video_index = i;
        }
        if (pFormatCtx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_AUDIO &&
            audio_index < 0) {
            audio_index = i;
        }
    }
    if (audio_index >= 0) {
        stream_component_open(is, audio_index);
    }
    if (video_index >= 0) {
        stream_component_open(is, video_index);
    }

    if (is->videoStream < 0 || is->audioStream < 0) {
        fprintf(stderr, "%s: could not open codecs\n", is->filename);
        goto fail;
    }

    screen_width = is->video_ctx->width;
    screen_height = is->video_ctx->height;


    for (;;) {
        if (is->quit) {
            break;
        }
        // seek stuff goes here
        if (is->audioq.size > MAX_AUDIOQ_SIZE ||
            is->videoq.size > MAX_VIDEOQ_SIZE) {
            SDL_Delay(10);
            continue;
        }
        if (av_read_frame(is->pFormatCtx, packet) < 0) {
            if (is->pFormatCtx->pb->error == 0) {
                SDL_Delay(100); /* no error; wait for user input */
                continue;
            } else {
                break;
            }
        }
        // Is this a packet from the video stream?
        if (packet->stream_index == is->videoStream) {
            packet_queue_put(&is->videoq, packet);
        } else if (packet->stream_index == is->audioStream) {
            packet_queue_put(&is->audioq, packet);
        } else {
            av_packet_unref(packet);
        }
    }
    /* all done - wait for it */
    while (!is->quit) {
        SDL_Delay(100);
    }

    fail:
    if (1) {
        SDL_Event event;
        event.type = FF_QUIT_EVENT;
        event.user.data1 = is;
        SDL_PushEvent(&event);
    }
    return 0;
}

int WinMain(int argc, char *argv[]) {

    char *file = "C:\\Users\\lenovo\\Desktop\\MyProject\\IMG_5950.mp4";

    SDL_Event event;

    VideoState *is;

    is = av_mallocz(sizeof(VideoState));

    if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
        fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
        exit(1);
    }

    //创建SDL Window
    win = SDL_CreateWindow("Media Player",
                           100,
                           100,
                           640, 480,
                           SDL_WINDOW_RESIZABLE);
    if (!win) {
        fprintf(stderr, "\nSDL: could not set video mode:%s - exiting\n", SDL_GetError());
        exit(1);
    }

    renderer = SDL_CreateRenderer(win, -1, 0);
    text_mutex = SDL_CreateMutex();
    strlcpy(is->filename, file, sizeof(is->filename));
    is->pictq_mutex = SDL_CreateMutex();
    is->pictq_cond = SDL_CreateCond();

    // 定时刷新器
    schedule_refresh(is, 40);

    // 创建解复用线程
    is->parse_tid = SDL_CreateThread(demux_thread, "demux_thread", is);
    if (!is->parse_tid) {
        av_free(is);
        return -1;
    }


    for (;;) {
        // 等待SDL事件，否则阻塞
        SDL_WaitEvent(&event);
        switch (event.type) {
            case FF_QUIT_EVENT:
            case SDL_QUIT: // 退出
                is->quit = 1;
                goto Destroy;
            case SDL_KEYDOWN:
                if (event.key.keysym.sym == SDLK_ESCAPE) {
                    is->quit = 1;
                    goto Destroy;
                }
                break;
            case FF_REFRESH_EVENT: // 定时器刷新事件
                video_refresh_timer(event.user.data1);
                break;
            default:
                break;
        }
    }

    Destroy:
    SDL_Quit();
    return 0;

}