2 * Copyright (c) 2014 Stefano Sabatini
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5 * of this software and associated documentation files (the "Software"), to deal
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9 * furnished to do so, subject to the following conditions:
11 * The above copyright notice and this permission notice shall be included in
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14 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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25 * libavformat AVIOContext API example.
27 * Make libavformat demuxer access media content through a custom
28 * AVIOContext read callback.
29 * @example avio_reading.c
32 #include <libavcodec/avcodec.h>
33 #include <libavformat/avformat.h>
34 #include <libavformat/avio.h>
35 #include <libavutil/file.h>
39 size_t size; ///< size left in the buffer
42 static int read_packet(void *opaque, uint8_t *buf, int buf_size)
44 struct buffer_data *bd = (struct buffer_data *)opaque;
45 buf_size = FFMIN(buf_size, bd->size);
47 printf("ptr:%p size:%zu\n", bd->ptr, bd->size);
49 /* copy internal buffer data to buf */
50 memcpy(buf, bd->ptr, buf_size);
57 int main(int argc, char *argv[])
59 AVFormatContext *fmt_ctx = NULL;
60 AVIOContext *avio_ctx = NULL;
61 uint8_t *buffer = NULL, *avio_ctx_buffer = NULL;
62 size_t buffer_size, avio_ctx_buffer_size = 4096;
63 char *input_filename = NULL;
65 struct buffer_data bd = { 0 };
68 fprintf(stderr, "usage: %s input_file\n"
69 "API example program to show how to read from a custom buffer "
70 "accessed through AVIOContext.\n", argv[0]);
73 input_filename = argv[1];
75 /* register codecs and formats and other lavf/lavc components*/
78 /* slurp file content into buffer */
79 ret = av_file_map(input_filename, &buffer, &buffer_size, 0, NULL);
83 /* fill opaque structure used by the AVIOContext read callback */
85 bd.size = buffer_size;
87 if (!(fmt_ctx = avformat_alloc_context())) {
88 ret = AVERROR(ENOMEM);
92 avio_ctx_buffer = av_malloc(avio_ctx_buffer_size);
93 if (!avio_ctx_buffer) {
94 ret = AVERROR(ENOMEM);
97 avio_ctx = avio_alloc_context(avio_ctx_buffer, avio_ctx_buffer_size,
98 0, &bd, &read_packet, NULL, NULL);
100 ret = AVERROR(ENOMEM);
103 fmt_ctx->pb = avio_ctx;
105 ret = avformat_open_input(&fmt_ctx, NULL, NULL, NULL);
107 fprintf(stderr, "Could not open input\n");
111 ret = avformat_find_stream_info(fmt_ctx, NULL);
113 fprintf(stderr, "Could not find stream information\n");
117 av_dump_format(fmt_ctx, 0, input_filename, 0);
120 avformat_close_input(&fmt_ctx);
121 /* note: the internal buffer could have changed, and be != avio_ctx_buffer */
123 av_freep(&avio_ctx->buffer);
126 av_file_unmap(buffer, buffer_size);
129 fprintf(stderr, "Error occurred: %s\n", av_err2str(ret));