hlsenc-to-memory.c

// An example of how to use the FFmpeg HLS muxer without ever touching the disk.
//
// To compile:
//   cc main.c -lavcodec -lavformat -lavutil
//
// To run:
//   ffmpeg -hide_banner -loglevel error -f lavfi -i testsrc -pix_fmt yuv420p -f mpegts - | ./a.out

#include <unistd.h>

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

int write_packet(void *opaque, uint8_t *data, int size)
{
    printf("write packet %d to file %s\n", size, (char *)opaque);

    return size;
}

int handle_io_open(struct AVFormatContext *s, AVIOContext **pb, const char *url,
                   int flags, AVDictionary **options)
{
    printf("handle io open %s\n", url);

    uint8_t *buf = NULL;
    size_t size = 4096;

    buf = av_malloc(size);

    *pb = avio_alloc_context(buf, size, 1, (void *)url, NULL, write_packet, NULL);

    s->opaque = (void *)url;

    return 0;
}

int handle_io_close(struct AVFormatContext *s, AVIOContext *pb)
{
    printf("handle io close %s\n", (char *)s->opaque);

    avio_context_free(&pb);

    return 0;
}

int main(int argc, char **argv)
{
    AVFormatContext *fmt_ctx;
    uint8_t buf[188];

    AVPacket *pkt = av_packet_alloc();

    // the io: prefix can be anything but is necessary to trick the hls muxer into
    // thinking this is not on disk
    avformat_alloc_output_context2(&fmt_ctx, NULL, "hls", "io:example-prefix");

    fmt_ctx->io_open = handle_io_open;
    fmt_ctx->io_close2 = handle_io_close;

    avformat_new_stream(fmt_ctx, NULL);

    avformat_write_header(fmt_ctx, NULL);

    for (int i = 0;; i++)
    {
        // read 188 byte packet from stdin
        int size = read(0, buf, 188);
        if (size <= 0)
            break;

        pkt->data = buf;
        pkt->size = size;
        pkt->pts = pkt->dts = i * 1000;
        pkt->duration = 1;

        av_write_frame(fmt_ctx, pkt);
    }

    av_write_trailer(fmt_ctx);

    avformat_free_context(fmt_ctx);

    return 0;
}