avio_reading简单使用

/*

* Copyright (c) 2011 Reinhard Tartler

*

* Permission is hereby granted, free of charge, to any person obtaining a copy

* of this software and associated documentation files (the "Software"), to deal

* in the Software without restriction, including without limitation the rights

* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell

* copies of the Software, and to permit persons to whom the Software is

* furnished to do so, subject to the following conditions:

*

* The above copyright notice and this permission notice shall be included in

* all copies or substantial portions of the Software.

*

* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR

* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL

* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER

* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,

* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN

* THE SOFTWARE.

*/

#pragma comment(lib, "avformat.lib")

#pragma comment(lib, "avcodec.lib")

#pragma comment(lib, "avdevice.lib")

#pragma comment(lib, "avfilter.lib")

#pragma comment(lib, "avutil.lib")

#pragma comment(lib, "postproc.lib")

#pragma comment(lib, "swresample.lib")

#pragma comment(lib, "swscale.lib")

/**

* @file

* libavformat AVIOContext API example.

*

* Make libavformat demuxer access media content through a custom

* AVIOContext read callback.

* @example avio_reading.c

*/

extern "C" {

#include <libavcodec/avcodec.h>

#include <libavformat/avformat.h>

#include <libavformat/avio.h>

#include <libavutil/file.h>

}

struct buffer_data {

       uint8_t *ptr;

       size_t size; ///< size left in the buffer

};

static int read_packet(void *opaque, uint8_t *buf, int buf_size)

{

       struct buffer_data *bd = (struct buffer_data *)opaque;

       buf_size = FFMIN(buf_size, bd->size);

       printf("ptr:%p size:%zu\n", bd->ptr, bd->size);

       /* copy internal buffer data to buf */

       memcpy(buf, bd->ptr, buf_size);

       bd->ptr += buf_size;

       bd->size -= buf_size;

       return buf_size;

}

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

{

       AVFormatContext *fmt_ctx = NULL;

       AVIOContext *avio_ctx = NULL;

       uint8_t *buffer = NULL, *avio_ctx_buffer = NULL;

       size_t buffer_size, avio_ctx_buffer_size = 4096;

       char *input_filename = "E:/video_source/1.mp4";

       int ret = 0;

       struct buffer_data bd = { 0 };

       /*

       if (argc != 2) {

              fprintf(stderr, "usage: %s input_file\n"

                     "API example program to show how to read from a custom buffer "

                     "accessed through AVIOContext.\n", argv[0]);

              return 1;

       }*/

       

       /* register codecs and formats and other lavf/lavc components*/

       av_register_all();

       /* slurp file content into buffer */

       ret = av_file_map(input_filename, &buffer, &buffer_size, 0, NULL);

       if (ret < 0)

              goto end;

       /* fill opaque structure used by the AVIOContext read callback */

       bd.ptr = buffer;

       bd.size = buffer_size;

       if (!(fmt_ctx = avformat_alloc_context())) {

              ret = AVERROR(ENOMEM);

              goto end;

       }

       avio_ctx_buffer = (uint8_t*)av_malloc(avio_ctx_buffer_size);

       if (!avio_ctx_buffer) {

              ret = AVERROR(ENOMEM);

              goto end;

       }

       avio_ctx = avio_alloc_context(avio_ctx_buffer, avio_ctx_buffer_size,

              0, &bd, &read_packet, NULL, NULL);

       if (!avio_ctx) {

              ret = AVERROR(ENOMEM);

              goto end;

       }

       fmt_ctx->pb = avio_ctx;

       ret = avformat_open_input(&fmt_ctx, NULL, NULL, NULL);

       if (ret < 0) {

              fprintf(stderr, "Could not open input\n");

              goto end;

       }

       ret = avformat_find_stream_info(fmt_ctx, NULL);

       if (ret < 0) {

              fprintf(stderr, "Could not find stream information\n");

              goto end;

       }

       av_dump_format(fmt_ctx, 0, input_filename, 0);

end:

       avformat_close_input(&fmt_ctx);

       /* note: the internal buffer could have changed, and be != avio_ctx_buffer */

       if (avio_ctx) {

              av_freep(&avio_ctx->buffer);

              av_freep(&avio_ctx);

       }

       av_file_unmap(buffer, buffer_size);

       if (ret < 0) {

              fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));

              return 1;

       }

       while (true)

       {

       }

       return 0;

}

运行结果：