#include <stdio.h>
#include <stdlib.h>
extern "C"{//
#include "avcodec.h"
#include "avformat.h"
}
Int main (char Arg, char * argv [])
{
Char * filename = "02.swf ";
Av_register_all (); // register all decoded types
Avformatcontext * pinfmtctx = NULL; // File Format
Avcodeccontext * pincodecctx = NULL; // encoding format
If (av_open_input_file (& pinfmtctx, filename, null, 0, null )! = 0) // obtain the file format
Printf ("av_open_input_file error/N ");
If (av_find_stream_info (pinfmtctx) <0) // obtain audio and video stream information in the file
Printf ("av_find_stream_info error/N ");
Unsigned Int J;
// Find the first audio stream
Int audiostream =-1;
For (j = 0; j <pinfmtctx-> nb_streams; j ++) // find the stream corresponding to the audio
If (pinfmtctx-> streams [J]-> codec-> codec_type = codec_type_audio)
{
Audiostream = J;
Break;
}
If (audiostream =-1)
{
Printf ("input file has no audio stream/N ");
Return 0; // didn't find a audio stream
}
Printf ("audio stream num: % d/N", audiostream );
Pincodecctx = pinfmtctx-> streams [audiostream]-> codec; // Audio Encoding Context
Avcodec * pincodec = NULL;
/* File * file3 = fopen ("codec_private_data_size.txt", "W ");
For (INT I = 0; I <200000; I ++)
{
Pincodec = avcodec_find_decoder (codecid) I );
If (pincodec! = NULL)
{
Fprintf (file3, "% S % d/N", pincodec-> name, pincodec-> priv_data_size );
}
}
Fclose (file3 );
System ("pause ");
*/
Pincodec = avcodec_find_decoder (pincodecctx-> codec_id); // locate the structure used for Decoding Based on the encoding ID
If (pincodec = NULL)
{
Printf ("error no codec found/N ");
Return-1; // codec not found
}
// Decoding can also be completed by replacing pincodecctx with test. It can be seen that decoding and re-sampling can be realized as long as the following important information is obtained.
Avcodeccontext * test = avcodec_alloc_context ();
Test-> bit_rate = pincodecctx-> bit_rate; // used for re-sampling
Test-> sample_rate = pincodecctx-> sample_rate; // used for re-sampling
Test-> channels = pincodecctx-> channels; // used for re-sampling
Test-> extradata = pincodecctx-> extradata; // If yes
Test-> extradata_size = pincodecctx-> extradata_size; // if necessary
Test-> codec_type = codec_type_audio; // unnecessary
Test-> block_align = pincodecctx-> block_align; // required
If (avcodec_open (test, pincodec) <0) // combine the two to call the corresponding decoding function in pincodec in the following decoding function
{
Printf ("error avcodec_open failed./N ");
Return-1; // cocould not open Codec
}
If (avcodec_open (pincodecctx, pincodec) <0)
{
Printf ("error avcodec_open failed./N ");
Return-1; // cocould not open Codec
}
Static avpacket packet;
Printf ("bit_rate = % d/R/N", pincodecctx-> bit_rate );
Printf ("sample_rate = % d/R/N", pincodecctx-> sample_rate );
Printf ("channels = % d/R/N", pincodecctx-> channels );
Printf ("code_name = % S/R/N", pincodecctx-> codec-> name );
// Printf ("extra data size: % d: Data % x/N", pincodecctx-> extradata_size, pincodecctx-> extradata [0]
//, Pincodecctx-> extradata [1], pincodecctx-> extradata [2], pincodecctx-> extradata [3]);
Printf ("block_align = % d/N", pincodecctx-> block_align );
// System ("pause ");
//////////////////////////////////////// //////////////////////////////////
Uint8_t * pktdata;
Int pktsize;
Int out_size = avcodec_max_audio_frame_size * 100;
Uint8_t * inbuf = (uint8_t *) malloc (out_size );
File * PCM, * packetinfo;
Packetinfo = fopen ("packetinfo.txt", "W ");
PCM = fopen ("result. PCM", "WB ");
Long start = clock ();
While (av_read_frame (pinfmtctx, & Packet)> = 0) // call the corresponding packet format in pinfmtctx to obtain the Function
{
// Fprintf (packetinfo, "packet {PTS = % d; DTS = % d; % x, % x; size = % d; stream_index = % d; Pos = % d;}/N ",
// Packet. PTS, packet. DTS, packet. data [0], packet. data [1], packet. data [2], packet. data [3], packet. size, packet. stream_index, packet. pos );
If (packet. stream_index = audiostream) // If the audio
{
Pktdata = packet. Data;
Pktsize = packet. size;
While (pktsize> 0)
{
// Fprintf (packetinfo, "packet data: % x/N", pktdata [0], pktdata [1], pktdata [2], pktdata [3], pktdata [4]);
// Fprintf (packetinfo, "packet size: % d/n", pktsize );
Out_size = avcodec_max_audio_frame_size * 100;
// Decoding
Int Len = avcodec_decode_audio2 (pincodecctx, (short *) inbuf, & out_size, pktdata, pktsize );
If (LEN <0)
{
Printf ("error while decoding./N ");
Break;
}
If (out_size> 0)
{
Fwrite (inbuf, 1, out_size, PCM); // PCM record
Fflush (PCM );
}
Pktsize-= Len;
Pktdata + = Len;
}
}
Av_free_packet (& Packet );
}
Long end = clock ();
Printf ("cost time: % F/N", double (end-Start)/(double) clocks_per_sec );
Free (inbuf );
Fclose (PCM );
Fclose (packetinfo );
If (pincodecctx! = NULL)
{
Avcodec_close (pincodecctx );
}
If (test! = NULL)
{
Avcodec_close (test );
}
Av_free (test );
Av_close_input_file (pinfmtctx );
Return 0;
}
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