linux 仿mplayer

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <libavformat/avformat.h>
#include <libavcodec/avcodec.h>
#include <libavutil/imgutils.h>
#include <libswscale/swscale.h>

int main(int argc, char *argv[]) {
    if (argc < 2) {
        fprintf(stderr, "Usage: %s <input_file>\n", argv[0]);
        return -1;
    }

    const char *filename = argv[1];

    AVFormatContext *fmt_ctx = NULL;
    if (avformat_open_input(&fmt_ctx, filename, NULL, NULL) < 0) {
        fprintf(stderr, "Could not open file '%s'\n", filename);
        return -1;
    }

    if (avformat_find_stream_info(fmt_ctx, NULL) < 0) {
        fprintf(stderr, "Could not find stream information\n");
        return -1;
    }

    int video_stream_index = -1;
    for (int i = 0; i < fmt_ctx->nb_streams; i++) {
        if (fmt_ctx->streams[i]->codecpar->codec_type == AVMEDIA_TYPE_VIDEO) {
            video_stream_index = i;
            break;
        }
    }

    if (video_stream_index == -1) {
        fprintf(stderr, "Could not find video stream\n");
        return -1;
    }

    AVCodecParameters *codecpar = fmt_ctx->streams[video_stream_index]->codecpar;
    const AVCodec *codec = avcodec_find_decoder(codecpar->codec_id);
    if (!codec) {
        fprintf(stderr, "Codec not found\n");
        return -1;
    }

    AVCodecContext *codec_ctx = avcodec_alloc_context3(codec);
    if (!codec_ctx) {
        fprintf(stderr, "Could not allocate video codec context\n");
        return -1;
    }

    if (avcodec_parameters_to_context(codec_ctx, codecpar) < 0) {
        fprintf(stderr, "Failed to copy codec parameters to decoder context\n");
        return -1;
    }

    if (avcodec_open2(codec_ctx, codec, NULL) < 0) {
        fprintf(stderr, "Could not open codec\n");
        return -1;
    }

    AVPacket pkt;
    AVFrame *frame = av_frame_alloc();
    AVFrame *rgb_frame = av_frame_alloc();
    uint8_t *buffer = NULL;
    int num_bytes;

    num_bytes = av_image_get_buffer_size(AV_PIX_FMT_RGB24, codec_ctx->width, codec_ctx->height, 1);
    buffer = (uint8_t *)av_malloc(num_bytes * sizeof(uint8_t));
    av_image_fill_arrays(rgb_frame->data, rgb_frame->linesize, buffer, AV_PIX_FMT_RGB24, codec_ctx->width, codec_ctx->height, 1);

    struct SwsContext *sws_ctx = sws_getContext(codec_ctx->width, codec_ctx->height, codec_ctx->pix_fmt,
                                               codec_ctx->width, codec_ctx->height, AV_PIX_FMT_RGB24,
                                               SWS_BILINEAR, NULL, NULL, NULL);

    while (av_read_frame(fmt_ctx, &pkt) >= 0) {
        if (pkt.stream_index == video_stream_index) {
            int ret = avcodec_send_packet(codec_ctx, &pkt);
            if (ret < 0) {
                fprintf(stderr, "Error sending a packet for decoding\n");
                break;
            }

            while (ret >= 0) {
                ret = avcodec_receive_frame(codec_ctx, frame);
                if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF) {
                    break;
                } else if (ret < 0) {
                    fprintf(stderr, "Error during decoding\n");
                    break;
                }

                sws_scale(sws_ctx, (const uint8_t * const *)frame->data, frame->linesize, 0, codec_ctx->height,
                          rgb_frame->data, rgb_frame->linesize);

                // 在这里处理RGB帧数据，例如显示在屏幕上
            }
        }
        av_packet_unref(&pkt);
    }

    av_frame_free(&frame);
    av_frame_free(&rgb_frame);
    avcodec_free_context(&codec_ctx);
    avformat_close_input(&fmt_ctx);
    av_free(buffer);
    sws_freeContext(sws_ctx);

    return 0;
}