/*
?*?Copyright?（c）?2014?Stefano?Sabatini
?*
?*?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.
?*/

/**
?*?@file
?*?libavformat?AVIOContext?API?example.
?*
?*?Make?libavformat?demuxer?access?media?content?through?a?custom
?*?AVIOContext?read?callback.
?*?@example?avio_reading.c
?*/

#include?
#include?
#include?
#include?

struct?buffer_data?{
????uint8_t?*ptr;
????size_t?size;?///};

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?=?NULL;
????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;
????}
????input_filename?=?argv[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?????????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?=?av_malloc（avio_ctx_buffer_size）;
????if?（!avio_ctx_