2 * Copyright (c) 2001 Fabrice Bellard
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5 * of this software and associated documentation files (the "Software"), to deal
6 * in the Software without restriction, including without limitation the rights
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8 * copies of the Software, and to permit persons to whom the Software is
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
15 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
16 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
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25 * audio decoding with libavcodec API example
27 * @example decode_audio.c
34 #include <libavutil/frame.h>
35 #include <libavutil/mem.h>
37 #include <libavcodec/avcodec.h>
39 #define AUDIO_INBUF_SIZE 20480
40 #define AUDIO_REFILL_THRESH 4096
42 static void decode(AVCodecContext *dec_ctx, AVPacket *pkt, AVFrame *frame,
48 /* send the packet with the compressed data to the decoder */
49 ret = avcodec_send_packet(dec_ctx, pkt);
51 fprintf(stderr, "Error submitting the packet to the decoder\n");
55 /* read all the output frames (in general there may be any number of them */
57 ret = avcodec_receive_frame(dec_ctx, frame);
58 if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)
61 fprintf(stderr, "Error during decoding\n");
64 data_size = av_get_bytes_per_sample(dec_ctx->sample_fmt);
66 /* This should not occur, checking just for paranoia */
67 fprintf(stderr, "Failed to calculate data size\n");
70 for (i = 0; i < frame->nb_samples; i++)
71 for (ch = 0; ch < dec_ctx->channels; ch++)
72 fwrite(frame->data[ch] + data_size*i, 1, data_size, outfile);
76 int main(int argc, char **argv)
78 const char *outfilename, *filename;
80 AVCodecContext *c= NULL;
81 AVCodecParserContext *parser = NULL;
84 uint8_t inbuf[AUDIO_INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE];
88 AVFrame *decoded_frame = NULL;
91 fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]);
95 outfilename = argv[2];
97 /* register all the codecs */
98 avcodec_register_all();
100 pkt = av_packet_alloc();
102 /* find the MPEG audio decoder */
103 codec = avcodec_find_decoder(AV_CODEC_ID_MP2);
105 fprintf(stderr, "Codec not found\n");
109 parser = av_parser_init(codec->id);
111 fprintf(stderr, "Parser not found\n");
115 c = avcodec_alloc_context3(codec);
117 fprintf(stderr, "Could not allocate audio codec context\n");
122 if (avcodec_open2(c, codec, NULL) < 0) {
123 fprintf(stderr, "Could not open codec\n");
127 f = fopen(filename, "rb");
129 fprintf(stderr, "Could not open %s\n", filename);
132 outfile = fopen(outfilename, "wb");
138 /* decode until eof */
140 data_size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f);
142 while (data_size > 0) {
143 if (!decoded_frame) {
144 if (!(decoded_frame = av_frame_alloc())) {
145 fprintf(stderr, "Could not allocate audio frame\n");
150 ret = av_parser_parse2(parser, c, &pkt->data, &pkt->size,
152 AV_NOPTS_VALUE, AV_NOPTS_VALUE, 0);
154 fprintf(stderr, "Error while parsing\n");
161 decode(c, pkt, decoded_frame, outfile);
163 if (data_size < AUDIO_REFILL_THRESH) {
164 memmove(inbuf, data, data_size);
166 len = fread(data + data_size, 1,
167 AUDIO_INBUF_SIZE - data_size, f);
173 /* flush the decoder */
176 decode(c, pkt, decoded_frame, outfile);
181 avcodec_free_context(&c);
182 av_parser_close(parser);
183 av_frame_free(&decoded_frame);
184 av_packet_free(&pkt);