【BIGTREETECH PI开发板】多媒体开发应用

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【BIGTREETECH PI开发板】多媒体开发应用 [复制链接]

 

前言

本开发板接口资源丰富，支持HDMI，板子虽小但是五脏俱全性能强大。

特别适合多媒体终端的开发，本片演示基于ffmpeg进行多媒体开发，实现网络视频播放的Demo。

ffmpeg安装

由于系统运行的ubuntu所以系统就自带了ffmpeg,如果没有则可以sudo apt-get install ffmpeg安装，前提是已经按照之前配置好了wifi可以联网。

 

wget https://github.com/BtbN/FFmpeg-B ... 4-gpl-shared.tar.xz

sudo apt-get install xz-utils

xz -d ffmpeg-master-latest-linuxARM64-gpl-shared.tar.xz

tar -xvf ffmpeg-master-latest-linuxarm64-gpl-shared.tar

Ffmpeg性能测试

下载测试文件wget https://sample-videos.com/video123/mp4/720/big_buck_bunny_720p_20mb.mp4

 

ffmpeg -benchmark -i big_buck_bunny_720p_20mb.mp4 -f null -

分别在WSL和开发板中运行对比性能大概差10倍左右

WSL中

 

 

开发板中

 

Ffmpeg代码开发

 

编码测试

vi encode_video.c

代码如下

#include
#include
#include

#include

#include
#include

static void encode(AVCodecContext *enc_ctx, AVFrame *frame, AVPacket *pkt,
                   FILE *outfile)
{
    int ret;

    /* send the frame to the encoder */
    if (frame)
        printf("Send frame %3"PRId64"\n", frame->pts);

    ret = avcodec_send_frame(enc_ctx, frame);
    if (ret < 0) {
        fprintf(stderr, "Error sending a frame for encoding\n");
        exit(1);
    }

    while (ret >= 0) {
        ret = avcodec_receive_packet(enc_ctx, pkt);
        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
            return;
        else if (ret < 0) {
            fprintf(stderr, "Error during encoding\n");
            exit(1);
        }

        printf("Write packet %3"PRId64" (size=%5d)\n", pkt->pts, pkt->size);
        fwrite(pkt->data, 1, pkt->size, outfile);
        av_packet_unref(pkt);
    }
}

int main(int argc, char **argv)
{
    const char *filename, *codec_name;
    const AVCodec *codec;
    AVCodecContext *c= NULL;
    int i, ret, x, y;
    FILE *f;
    AVFrame *frame;
    AVPacket *pkt;
    uint8_t endcode[] = { 0, 0, 1, 0xb7 };

    if (argc <= 2) {
        fprintf(stderr, "Usage: %s \n", argv[0]);
        exit(0);
    }
    filename = argv[1];
    codec_name = argv[2];

    /* find the mpeg1video encoder */
    codec = avcodec_find_encoder_by_name(codec_name);
    if (!codec) {
        fprintf(stderr, "Codec '%s' not found\n", codec_name);
        exit(1);
    }

    c = avcodec_alloc_context3(codec);
    if (!c) {
        fprintf(stderr, "Could not allocate video codec context\n");
        exit(1);
    }

    pkt = av_packet_alloc();
    if (!pkt)
        exit(1);

    /* put sample parameters */
    c->bit_rate = 400000;
    /* resolution must be a multiple of two */
    c->width = 352;
    c->height = 288;
    /* frames per second */
    c->time_base = (AVRational){1, 25};
    c->framerate = (AVRational){25, 1};

    /* emit one intra frame every ten frames
     * check frame pict_type before passing frame
     * to encoder, if frame->pict_type is AV_PICTURE_TYPE_I
     * then gop_size is ignored and the output of encoder
     * will always be I frame irrespective to gop_size
     */
    c->gop_size = 10;
    c->max_b_frames = 1;
    c->pix_fmt = AV_PIX_FMT_YUV420P;

    if (codec->id == AV_CODEC_ID_H264)
        av_opt_set(c->priv_data, "preset", "slow", 0);

    /* open it */
    ret = avcodec_open2(c, codec, NULL);
    if (ret < 0) {
        fprintf(stderr, "Could not open codec: %s\n", av_err2str(ret));
        exit(1);
    }

    f = fopen(filename, "wb");
    if (!f) {
        fprintf(stderr, "Could not open %s\n", filename);
        exit(1);
    }

    frame = av_frame_alloc();
    if (!frame) {
        fprintf(stderr, "Could not allocate video frame\n");
        exit(1);
    }
    frame->format = c->pix_fmt;
    frame->width  = c->width;
    frame->height = c->height;

    ret = av_frame_get_buffer(frame, 0);
    if (ret < 0) {
        fprintf(stderr, "Could not allocate the video frame data\n");
        exit(1);
    }

    /* encode 1 second of video */
    for (i = 0; i < 25; i++) {
        fflush(stdout);

        /* Make sure the frame data is writable.
           On the first round, the frame is fresh from av_frame_get_buffer()
           and therefore we know it is writable.
           But on the next rounds, encode() will have called
           avcodec_send_frame(), and the codec may have kept a reference to
           the frame in its internal structures, that makes the frame
           unwritable.
           av_frame_make_writable() checks that and allocates a new buffer
           for the frame only if necessary.
         */
        ret = av_frame_make_writable(frame);
        if (ret < 0)
            exit(1);

        /* Prepare a dummy image.
           In real code, this is where you would have your own logic for
           filling the frame. FFmpeg does not care what you put in the
           frame.
         */
        /* Y */
        for (y = 0; y < c->height; y++) {
            for (x = 0; x < c->width; x++) {
                frame->data[0][y * frame->linesize[0] + x] = x + y + i * 3;
            }
        }

        /* Cb and Cr */
        for (y = 0; y < c->height/2; y++) {
            for (x = 0; x < c->width/2; x++) {
                frame->data[1][y * frame->linesize[1] + x] = 128 + y + i * 2;
                frame->data[2][y * frame->linesize[2] + x] = 64 + x + i * 5;
            }
        }

        frame->pts = i;

        /* encode the image */
        encode(c, frame, pkt, f);
    }

    /* flush the encoder */
    encode(c, NULL, pkt, f);

    /* Add sequence end code to have a real MPEG file.
       It makes only sense because this tiny examples writes packets
       directly. This is called "elementary stream" and only works for some
       codecs. To create a valid file, you usually need to write packets
       into a proper file format or protocol; see mux.c.
     */
    if (codec->id == AV_CODEC_ID_MPEG1VIDEO || codec->id == AV_CODEC_ID_MPEG2VIDEO)
        fwrite(endcode, 1, sizeof(endcode), f);
    fclose(f);

    avcodec_free_context(&c);
    av_frame_free(&frame);
    av_packet_free(&pkt);

    return 0;
}

编译

gcc encode_video.c  -Iffmpeg-master-latest-linuxarm64-gpl-shared/include -Lffmpeg-master-latest-linuxarm64-gpl-shared/lib -lavcodec -lavutil -lswresample -o encode

 

运行

export LD_LIBRARY_PATH=/root/ffmpeg-master-latest-linuxarm64-gpl-shared/lib:$LD_LIBRARY_PATH
./encode encode.bin mpeg1video

 

播放编码的文件

ffplay.exe -i encode.bin

 

 

 

解码测试

vi decode_video.c

代码如下

#include
#include
#include

#include

#define INBUF_SIZE 4096

static void pgm_save(unsigned char* buf, int wrap, int xsize, int ysize,
    char* filename)
{
    FILE* f;
    int i;

    f = fopen(filename, "wb");
    fprintf(f, "P5\n%d %d\n%d\n", xsize, ysize, 255);
    for (i = 0; i < ysize; i++)
        fwrite(buf + i * wrap, 1, xsize, f);
    fclose(f);
}

static void decode(AVCodecContext* dec_ctx, AVFrame* frame, AVPacket* pkt,
    const char* filename)
{
    char buf[1024];
    int ret;

    ret = avcodec_send_packet(dec_ctx, pkt);
    if (ret < 0) {
        fprintf(stderr, "Error sending a packet for decoding\n");
        exit(1);
    }

    while (ret >= 0) {
        ret = avcodec_receive_frame(dec_ctx, frame);
        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
            return;
        else if (ret < 0) {
            fprintf(stderr, "Error during decoding\n");
            exit(1);
        }

        printf("saving frame %3"PRId64"\n", dec_ctx->frame_num);
        fflush(stdout);

        /* the picture is allocated by the decoder. no need to
           free it */
        snprintf(buf, sizeof(buf), "%s-%"PRId64, filename, dec_ctx->frame_num);
        pgm_save(frame->data[0], frame->linesize[0],
            frame->width, frame->height, buf);
    }
}

int main(int argc, char** argv)
{
    const char* filename, * outfilename;
    const AVCodec* codec;
    AVCodecParserContext* parser;
    AVCodecContext* c = NULL;
    FILE* f;
    AVFrame* frame;
    uint8_t inbuf[INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
    uint8_t* data;
    size_t   data_size;
    int ret;
    int eof;
    AVPacket* pkt;

    if (argc <= 2) {
        fprintf(stderr, "Usage: %s 
 \n"
            "And check your input file is encoded by mpeg1video please.\n", argv[0]);
        exit(0);
    }
    filename = argv[1];
    outfilename = argv[2];

    pkt = av_packet_alloc();
    if (!pkt)
        exit(1);

    /* set end of buffer to 0 (this ensures that no overreading happens for damaged MPEG streams) */
    memset(inbuf + INBUF_SIZE, 0, AV_INPUT_BUFFER_PADDING_SIZE);

    /* find the MPEG-1 video decoder */
    codec = avcodec_find_decoder(AV_CODEC_ID_MPEG1VIDEO);
    if (!codec) {
        fprintf(stderr, "Codec not found\n");
        exit(1);
    }

    parser = av_parser_init(codec->id);
    if (!parser) {
        fprintf(stderr, "parser not found\n");
        exit(1);
    }

    c = avcodec_alloc_context3(codec);
    if (!c) {
        fprintf(stderr, "Could not allocate video codec context\n");
        exit(1);
    }

    /* For some codecs, such as msmpeg4 and mpeg4, width and height
       MUST be initialized there because this information is not
       available in the bitstream. */

       /* open it */
    if (avcodec_open2(c, codec, NULL) < 0) {
        fprintf(stderr, "Could not open codec\n");
        exit(1);
    }

    f = fopen(filename, "rb");
    if (!f) {
        fprintf(stderr, "Could not open %s\n", filename);
        exit(1);
    }

    frame = av_frame_alloc();
    if (!frame) {
        fprintf(stderr, "Could not allocate video frame\n");
        exit(1);
    }

    do {
        /* read raw data from the input file */
        data_size = fread(inbuf, 1, INBUF_SIZE, f);
        if (ferror(f))
            break;
        eof = !data_size;

        /* use the parser to split the data into frames */
        data = inbuf;
        while (data_size > 0 || eof) {
            ret = av_parser_parse2(parser, c, &pkt->data, &pkt->size,
                data, data_size, AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);
            if (ret < 0) {
                fprintf(stderr, "Error while parsing\n");
                exit(1);
            }
            data += ret;
            data_size -= ret;

            if (pkt->size)
                decode(c, frame, pkt, outfilename);
            else if (eof)
                break;
        }
    } while (!eof);

    /* flush the decoder */
    decode(c, frame, NULL, outfilename);

    fclose(f);

    av_parser_close(parser);
    avcodec_free_context(&c);
    av_frame_free(&frame);
    av_packet_free(&pkt);

    return 0;
}

编译

gcc decode_video.c  -Iffmpeg-master-latest-linuxarm64-gpl-shared/include -Lffmpeg-master-latest-linuxarm64-gpl-shared/lib -lavcodec -lavutil -lswresample -o decode

运行

export LD_LIBRARY_PATH=/root/ffmpeg-master-latest-linuxarm64-gpl-shared/lib:$LD_LIBRARY_PATH
./decode encode.bin decode.bin

 

网络视频播放

PC上从以下地址下载VLC安装https://www.videolan.org/vlc/

 

电脑上确认IP地址我这里是192.168.31.64

 

开发板上运行

ffmpeg -re -i big_buck_bunny_720p_20mb.mp4 -an -vcodec copy -f rtp rtp://192.168.31.64:5004

 

打印如下,复位红色框中的内容，不包括SDP:这一行

 

PC上新建demo.sdp文件，黏贴上述内容

 

 

右键点击demo.sdp使用VLC打开

即可看到开始播放视频

 

 

总结

得益于开发板强劲的性能和运行完整的Ubuntu系统环境，可以方便的进行多媒体相关的开发。

Jacktang

ffmpeg用于多媒体开发，实现网络视频播放的Demo还是挺实用的