tutorial04.c

// tutorial04.c
// Based on https://github.com/chelyaev/ffmpeg-tutorial/blob/master/tutorial04.c

#include <libavcodec/avcodec.h>
#include <libavformat/avformat.h>
#include <libswscale/swscale.h>

#include <SDL.h>

#ifdef __MINGW32__
#undef main /* Prevents SDL from overriding main() */
#endif

#define SDL_AUDIO_BUFFER_SIZE 1024
#define MAX_AUDIO_FRAME_SIZE 192000

#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;

PacketQueue audioq;

int quit = 0;

typedef struct VideoPicture {
    SDL_Overlay *bmp;
    int width, height; /* source height & width */
    int allocated;
} VideoPicture;

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;

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;
}

static 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;
}

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;
    }
}

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 main(int argc, char *argv[]) {
    AVFormatContext *pFormatCtx = NULL;
    int i, videoStream, audioStream;
    AVCodecContext *pCodecCtx = NULL;
    AVCodec *pCodec = NULL;
    AVFrame *pFrame = NULL;
    int frameFinished;
    AVPacket packet;

    AVCodecContext *aCodecCtx = NULL;
    AVCodec *aCodec = NULL;

    SDL_Surface *screen = NULL;
    SDL_Overlay *bmp = NULL;
    SDL_Rect rect;
    SDL_Event event;
    SDL_AudioSpec wanted_spec, spec;

    struct SwsContext *sws_ctx = NULL;
    AVDictionary *videoOptionsDict = NULL;
    AVDictionary *audioOptionsDict = NULL;

    if (argc < 2) {
        printf("Please provide a movie file\n");
        exit(1);
    }

    // Register all file formats and codecs
    av_register_all();

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

    // Open video file
    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);

    // 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

    // 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;
    }

    aCodec = avcodec_find_decoder(aCodecCtx->codec_id);
    if (!aCodec) {
        fprintf(stderr, "Unsupported codec!\n");
        return -1;
    }
    avcodec_open2(aCodecCtx, aCodec, &audioOptionsDict);
    packet_queue_init(&audioq);
    SDL_PauseAudio(0);

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

    // 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, &videoOptionsDict) < 0) {
        return -1; // Could not open codec
    }

    // Allocate video frame
    pFrame = avcodec_alloc_frame();

    // Make a screen to put our video
#ifndef __DARWIN__
    screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 0, 0);
#else
    screen = SDL_SetVideoMode(pCodecCtx->width, pCodecCtx->height, 24, 0);
#endif
    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
    bmp = SDL_CreateYUVOverlay(pCodecCtx->width, pCodecCtx->height,
                               SDL_YV12_OVERLAY, screen);

    sws_ctx = sws_getContext(pCodecCtx->width, pCodecCtx->height,
                pCodecCtx->pix_fmt, pCodecCtx->width, pCodecCtx->height,
                PIX_FMT_YUV420P, SWS_BILINEAR, NULL, NULL, NULL);

    // Read frames and process
    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) {
                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);

                rect.x = 0;
                rect.y = 0;
                rect.w = pCodecCtx->width;
                rect.h = pCodecCtx->height;
                SDL_DisplayYUVOverlay(bmp, &rect);
                av_free_packet(&packet);
            }
        } else if (packet.stream_index == audioStream) {
            packet_queue_put(&audioq, &packet);
        } else {
            av_free_packet(&packet);
        }

        // Free the packet that was allocated by av_read_frame
        SDL_PollEvent(&event);
        switch (event.type) {
        case SDL_QUIT:
            quit = 1;
            SDL_Quit();
            exit(0);
            break;
        default:
            break;
        }
    }

    // Free the YUV frame
    av_free(pFrame);

    // Close the codec
    avcodec_close(pCodecCtx);

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

    return 0;
}