mirror of https://git.ffmpeg.org/ffmpeg.git
138 lines
3.8 KiB
C
138 lines
3.8 KiB
C
/*
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* copyright (c) 2001 Fabrice Bellard
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*
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* This file is part of Libav.
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*
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* Libav is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2.1 of the License, or (at your option) any later version.
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*
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* Libav is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with Libav; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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/**
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* @file
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* audio decoding with libavcodec API example
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*
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* @example decode_audio.c
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "libavcodec/avcodec.h"
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#include "libavutil/frame.h"
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#define AUDIO_INBUF_SIZE 20480
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#define AUDIO_REFILL_THRESH 4096
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int main(int argc, char **argv)
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{
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const char *outfilename, *filename;
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const AVCodec *codec;
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AVCodecContext *c= NULL;
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int len;
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FILE *f, *outfile;
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uint8_t inbuf[AUDIO_INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
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AVPacket avpkt;
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AVFrame *decoded_frame = NULL;
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if (argc <= 2) {
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fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]);
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exit(0);
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}
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filename = argv[1];
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outfilename = argv[2];
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/* register all the codecs */
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avcodec_register_all();
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av_init_packet(&avpkt);
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/* find the MPEG audio decoder */
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codec = avcodec_find_decoder(AV_CODEC_ID_MP2);
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if (!codec) {
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fprintf(stderr, "codec not found\n");
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exit(1);
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}
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c = avcodec_alloc_context3(codec);
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/* open it */
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if (avcodec_open2(c, codec, NULL) < 0) {
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fprintf(stderr, "could not open codec\n");
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exit(1);
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}
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f = fopen(filename, "rb");
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if (!f) {
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fprintf(stderr, "could not open %s\n", filename);
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exit(1);
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}
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outfile = fopen(outfilename, "wb");
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if (!outfile) {
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av_free(c);
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exit(1);
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}
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/* decode until eof */
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avpkt.data = inbuf;
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avpkt.size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f);
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while (avpkt.size > 0) {
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int got_frame = 0;
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if (!decoded_frame) {
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if (!(decoded_frame = av_frame_alloc())) {
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fprintf(stderr, "out of memory\n");
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exit(1);
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}
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}
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len = avcodec_decode_audio4(c, decoded_frame, &got_frame, &avpkt);
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if (len < 0) {
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fprintf(stderr, "Error while decoding\n");
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exit(1);
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}
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if (got_frame) {
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/* if a frame has been decoded, output it */
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int data_size = av_samples_get_buffer_size(NULL, c->channels,
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decoded_frame->nb_samples,
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c->sample_fmt, 1);
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fwrite(decoded_frame->data[0], 1, data_size, outfile);
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}
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avpkt.size -= len;
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avpkt.data += len;
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if (avpkt.size < AUDIO_REFILL_THRESH) {
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/* Refill the input buffer, to avoid trying to decode
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* incomplete frames. Instead of this, one could also use
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* a parser, or use a proper container format through
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* libavformat. */
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memmove(inbuf, avpkt.data, avpkt.size);
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avpkt.data = inbuf;
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len = fread(avpkt.data + avpkt.size, 1,
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AUDIO_INBUF_SIZE - avpkt.size, f);
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if (len > 0)
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avpkt.size += len;
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}
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}
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fclose(outfile);
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fclose(f);
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avcodec_free_context(&c);
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av_frame_free(&decoded_frame);
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return 0;
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}
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