#include <libavformat/avformat.h>

int main(int argc, char *argv[]) {
    // Register all file formats and codecs
    av_register_all();

    return 0;
}

// Open video file
AVFormatContext *pFormatCtx = NULL;
if (avformat_open_input(&pFormatCtx, argv[1], NULL, NULL) != 0) {
    return -1; // Couldn't open file
}

// 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, argv[1], 0);

AVCodecContext *pCodecCtx = NULL;
int i, videoStream;
// Find the first video stream
videoStream=-1;
for (i = 0; i < pFormatCtx->nb_streams; i++) {
    if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO) {
        videoStream = i;
        break;
    }
}
if (videoStream == -1) {
    return -1; // Didn't find a video stream
}

// Get a pointer to the codec context for the video stream
pCodecCtx = pFormatCtx->streams[videoStream]->codec;

AVCodec *pCodec = NULL;
AVDictionary *optionsDict = NULL;
// Find the decoder for the video stream
pCodec = avcodec_find_decoder(pCodecCtx->codec_id);
if (pCodec == NULL) {
    fprintf(stderr, "Unsupported codec!\n");
    return -1; // Codec not found
}
// Open codec
if (avcodec_open2(pCodecCtx, pCodec, &optionsDict) < 0) {
    return -1; // Could not open codec
}

AVFrame *pFrame = NULL;
// Allocate video frame
pFrame = avcodec_alloc_frame();

// Allocate an AVFrame structure
AVFrame *pFrameRGB = NULL;
pFrameRGB = avcodec_alloc_frame();
if (pFrameRGB == NULL) {
    return -1;
}

uint8_t *buffer;
int numBytes;
// Determine required buffer size and allocate buffer
numBytes = avpicture_get_size(PIX_FMT_RGB24, pCodecCtx->width,
                              pCodecCtx->height);
buffer = (uint8_t *) av_malloc(numBytes*sizeof(uint8_t));

// Assign appropriate parts of buffer to image planes in pFrameRGB
// Note that pFrameRGB is an AVFrame, but AVFrame is a superset
// of AVPicture
avpicture_fill((AVPicture *)pFrameRGB. buffer, PIX_FMT_RGB24,
               pCodecCtx->width, pCodecCtx->height);

int frameFinished;
AVPacket packet;
struct SwsContext *sws_ctx = NULL;

sws_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height,
            pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height,
            PIX_FMT_RGB24, SWS_BILINEAR, NULL, NULL, NULL);

// Read frames and save first five frames to disk
i = 0;
while (av_read_frame(pFormatCtx, &packet) >= 0) {
    // Is this a packet from the video stream?
    if (packet.stream_index == videoStream) {
        // Decode video frame
        avcodec_decode_video2(pCodecCtx, pFrame, &frameFinished,
                             &packet);

        // Did we get a video frame?
        if (frameFinished) {
            // Convert the image from its native format to RGB
            sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data,
                      pFrame->linesize, 0, pCodecCtx->height,
                      pFrameRGB->data, pFrameRGB->linesize);

            // Save the frame to disk
            if (++i <= 5) {
                SaveFrame(pFrameRGB, pCodecCtx->width,
                          pCodecCtx->height, i);
            }
        }
    }

    // Free the packet that was allocated by av_read_frame
    av_free_packet(&packet);
}

void SaveFrame(AVFrame *pFrame, int width, int height, int iFrame) {
    FILE *pFile;
    char szFilename[32];
    int y;

    // Open file
    sprintf(szFilename, "frame%d.ppm", iFrame);
    pFile = fopen(szFilename, "wb");
    if (pFile == NULL) {
        return;
    }

    // Write header
    fprintf(pFile, "P6\n%d %d\n255\n", width, height);

    // Write pixel data
    for (y = 0; y < height; y++) {
        fwrite(pFrame->data[0] + y * pFrame->linesize[0], 1, width * 3, pFile);
    }

    // Close file
    fclose(pFile);
}

// Free the RGB image
av_free(buffer);
av_free(pFrameRGB);

// Free the YUV frame
av_free(pFrame);

// Close the codec
avcodec_close(pCodecCtx);

// Close the video file
avformat_close_input(&pFormatCtx);

#include <SDL.h>

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

    if (SDL_Init(SDL_INIT_VIDEO | SDL_INIT_AUDIO | SDL_INIT_TIMER)) {
        fprintf(stderr, "Could not initialize SDL - %s\n", SDL_GetError());
        exit(1);
    }
    return 0;
}

// Make a screen to put our video
SDL_Surface *screen = NULL;
screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);
if (!screen) {
    fprintf(stderr, "SDL: could not set video mode - exiting\n");
    exit(1);
}

// Allocate a place to put our YUV image on that screen
SDL_Overlay *bmp = NULL;
bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height,
                           SDL_YV12_OVERLAY, screen);

if (frameFinished) {
    SDL_LockYUVOverlay(bmp);

    AVPicture pict;
    pict.data[0] = bmp->pixels[0];
    pict.data[1] = bmp->pixels[2];
    pict.data[2] = bmp->pixels[1];

    pict.linesize[0] = bmp->pitches[0];
    pict.linesize[1] = bmp->pitches[2];
    pict.linesize[2] = bmp->pitches[1];

    // Convert the image into YUV format that SDL uses
    sws_scale(sws_ctx, (uint8_t const * const *)pFrame->data,
              pFrame->linesize, 0, pCodecCtx->height,
              pict.data, pict.linesize);

    SDL_UnlockYUVOverlay(bmp);
}

SDL_Rect rect;
/* ... code ... */
SDL_UnlockYUVOverlay(bmp);

rect.x = 0;
rect.y = 0;
rect.w = pCodecCtx->width;
rect.h = pCodecCtx->height;
SDL_DisplayYUVOverlay(bmp, &rect);

SDL_Event event;
/* ... code ... */
av_free_packet(&packet);

SDL_PollEvent(&event);
switch (event.type) {
case SDL_QUIT:
    SDL_Quit();
    exit(0);
    break;
default:
    break;
}

// Find the first video stream
videoStream = -1;
audioStream = -1;
for (i = 0; i < pFormatCtx->nb_streams; i++) {
    if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_VIDEO &&
           videoStream < 0) {
        videoStream = i;
    }
    if (pFormatCtx->streams[i]->codec->codec_type == AVMEDIA_TYPE_AUDIO &&
            audioStream < 0) {
         audioStream = i;
     }
}
if (videoStream == -1) {
    return -1; // Didn't find a video stream
}
if (audioStream == -1)
    return -1; // Didn't find an audio stream

#define SDL_AUDIO_BUFFER_SIZE 1024

AVCodecContext *aCodecCtx = NULL;
SDL_AudioSpec wanted_spec, spec;

// Seta audio settings from codec info
aCodecCtx = pFormatCtx->streams[audioStream]->codec;
wanted_spec.freq = aCodecCtx->sample_rate;
wanted_spec.format = AUDIO_S16SYS;
wanted_spec.channels = aCodecCtx->channels;
wanted_spec.silence = 0;
wanted_spec.samples = SDL_AUDIO_BUFFER_SIZE;
wanted_spec.callback = audio_callback;
wanted_spec.userdata = aCodecCtx;

if (SDL_OpenAudio(&wanted_spec, &spec) < 0) {
    fprintf(stderr, "SDL_OpenAudio: %s\n", SDL_GetError());
    return -1;
}

AVCodec *aCodec = NULL;
AVDictionary *audioOptionsDict = NULL;

aCodec = avcodec_find_decoder(aCodecCtx->codec_id);
if (!aCodec) {
    fprintf(stderr, "Unsupported codec!\n");
    return -1;
}
avcodec_open2(aCodecCtx, aCodec, &audioOptionsDict);

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

PacketQueue audioq;

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_dup_packet(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 quit = 0;

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

    SDL_LockMutex(q->mutex);

    for (;;) {
        if (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;
}

PacketQueue audioq;
main() {
...
avcodec_open(aCodecCtx, aCodec);

packet_queue_init(&audioq);
SDL_PauseAudio(0);

while(av_read_frame(pFormatCtx, &packet)>=0) {
  // Is this a packet from the video stream?
  if(packet.stream_index==videoStream) {
    // Decode video frame
    ....
    }
  } else if(packet.stream_index==audioStream) {
    packet_queue_put(&audioq, &packet);
  } else {
    av_free_packet(&packet);
  }

void audio_callback(void *userdata, Uint8 *stream, int len) {
    AVCodecContext *aCodeCtx = (AVCodecContext *)userdata;
    int len1, audio_size;

    static uint8_t audio_buf[(MAX_AUDIO_FRAME_SIZE * 3) / 2];
    static unsigned int audio_buf_size = 0;
    static unsigned int audio_buf_index = 0;

    while (len > 0) {
        if (audio_buf_index >= audio_buf_size) {
            // we have already sent all our data; get more
            audio_size = audio_decode_frame(aCodeCtx, audio_buf, audio_buf_size);
            if (audio_size < 0) {
                // If error, output silence
                audio_buf_size = 1024; // arbitrary?
                memset(audio_buf, 0, audio_buf_size);
            } else {
                audio_buf_size = audio_size;
            }
            audio_buf_index = 0;
        }
        len1 = audio_buf_size - audio_buf_index;
        if (len1 > len) {
            len1 = len;
        }
        memcpy(stream, (uint8_t *)audio_buf + audio_buf_index, len1);
        len -= len1;
        stream += len1;
        audio_buf_index += len1;
    }
}

int audio_decode_frame(AVCodecContext *aCodecCtx, uint8_t *audio_buf,
                       int buf_size) {
    static AVPacket pkt;
    static uint8_t *audio_pkt_data = NULL;
    static int audio_pkt_size = 0;
    static AVFrame frame;

    int len1, data_size;

    for (;;) {
        while (audio_pkt_size > 0) {
            int got_frame = 0;
            len1 = avcodec_decode_audio4(aCodecCtx, &frame, &got_frame, &pkt);
            if (len1 < 0) {
                // if error, skip frame
                audio_pkt_size = 0;
                break;
            }
            audio_pkt_data += len1;
            audio_pkt_size -= len1;
            if (got_frame) {
                data_size = av_samples_get_buffer_size(NULL,
                                                       aCodecCtx->channels,
                                                       frame.nb_samples,
                                                       aCodecCtx->sample_fmt,
                                                       1);
                memcpy(audio_buf, frame.data[0], data_size);
            }
            if (data_size <= 0) {
                // No data yet, get more frames
                continue;
            }
            // We have data, return it and come back for more later
            return data_size;
        }
        if (pkt.data) {
            av_free_packet(&pkt);
        }
        if (quit) {
            return -1;
        }
        if (packet_queue_get(&audioq, &pkt, 1) < 0) {
            return -1;
        }
        audio_pkt_data = pkt.data;
        audio_pkt_size = pkt.size;
    }
}

typedef struct VideoState {
    AVFormatContext *pFormatCtx;
    int videoStream, audioStream;
    AVStream *audio_st;
    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;
    AVStream *video_st;
    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;

    char filename[1024];
    int quit;
    AVIOContext *io_context;
    struct SwsContext *sws_ctx;
} VideoState;