diff options
author | Anton Khirnov <anton@khirnov.net> | 2016-10-19 21:05:22 +0200 |
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committer | Anton Khirnov <anton@khirnov.net> | 2016-11-02 10:13:27 +0100 |
commit | f5df897c4b61985e3afc89ba1290649712ff438e (patch) | |
tree | eacdf748857871291a715e81d31aacc40b217003 /doc/examples/decode_audio.c | |
parent | f76698e759a08e8d3b629c06edb0439f474e7fee (diff) |
examples/avcodec: split audio decoding into a separate example
The four examples (audio/video encoding/decoding) are completely
independent so it makes little sense to have them all in one file.
Diffstat (limited to 'doc/examples/decode_audio.c')
-rw-r--r-- | doc/examples/decode_audio.c | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/doc/examples/decode_audio.c b/doc/examples/decode_audio.c new file mode 100644 index 0000000000..4378281dbd --- /dev/null +++ b/doc/examples/decode_audio.c @@ -0,0 +1,137 @@ +/* + * copyright (c) 2001 Fabrice Bellard + * + * This file is part of Libav. + * + * Libav is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; either + * version 2.1 of the License, or (at your option) any later version. + * + * Libav is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with Libav; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +/** + * @file + * audio decoding with libavcodec API example + * + * @example decode_audio.c + */ + +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +#include "libavcodec/avcodec.h" + +#include "libavutil/frame.h" + +#define AUDIO_INBUF_SIZE 20480 +#define AUDIO_REFILL_THRESH 4096 + +int main(int argc, char **argv) +{ + const char *outfilename, *filename; + AVCodec *codec; + AVCodecContext *c= NULL; + int len; + FILE *f, *outfile; + uint8_t inbuf[AUDIO_INBUF_SIZE + AV_INPUT_BUFFER_PADDING_SIZE]; + AVPacket avpkt; + AVFrame *decoded_frame = NULL; + + if (argc <= 2) { + fprintf(stderr, "Usage: %s <input file> <output file>\n", argv[0]); + exit(0); + } + filename = argv[1]; + outfilename = argv[2]; + + /* register all the codecs */ + avcodec_register_all(); + + av_init_packet(&avpkt); + + /* find the MPEG audio decoder */ + codec = avcodec_find_decoder(AV_CODEC_ID_MP2); + if (!codec) { + fprintf(stderr, "codec not found\n"); + exit(1); + } + + c = avcodec_alloc_context3(codec); + + /* open it */ + if (avcodec_open2(c, codec, NULL) < 0) { + fprintf(stderr, "could not open codec\n"); + exit(1); + } + + f = fopen(filename, "rb"); + if (!f) { + fprintf(stderr, "could not open %s\n", filename); + exit(1); + } + outfile = fopen(outfilename, "wb"); + if (!outfile) { + av_free(c); + exit(1); + } + + /* decode until eof */ + avpkt.data = inbuf; + avpkt.size = fread(inbuf, 1, AUDIO_INBUF_SIZE, f); + + while (avpkt.size > 0) { + int got_frame = 0; + + if (!decoded_frame) { + if (!(decoded_frame = av_frame_alloc())) { + fprintf(stderr, "out of memory\n"); + exit(1); + } + } + + len = avcodec_decode_audio4(c, decoded_frame, &got_frame, &avpkt); + if (len < 0) { + fprintf(stderr, "Error while decoding\n"); + exit(1); + } + if (got_frame) { + /* if a frame has been decoded, output it */ + int data_size = av_samples_get_buffer_size(NULL, c->channels, + decoded_frame->nb_samples, + c->sample_fmt, 1); + fwrite(decoded_frame->data[0], 1, data_size, outfile); + } + avpkt.size -= len; + avpkt.data += len; + if (avpkt.size < AUDIO_REFILL_THRESH) { + /* Refill the input buffer, to avoid trying to decode + * incomplete frames. Instead of this, one could also use + * a parser, or use a proper container format through + * libavformat. */ + memmove(inbuf, avpkt.data, avpkt.size); + avpkt.data = inbuf; + len = fread(avpkt.data + avpkt.size, 1, + AUDIO_INBUF_SIZE - avpkt.size, f); + if (len > 0) + avpkt.size += len; + } + } + + fclose(outfile); + fclose(f); + + avcodec_free_context(&c); + av_frame_free(&decoded_frame); + + return 0; +} |