ref: 574247f79c5befa97905a92d477a14c8ba6016dd
parent: 41e8906cd65023ef76492098a0d9ed78a7c1c554
author: Jean-Marc Valin <[email protected]>
date: Thu Nov 21 09:33:42 EST 2013
Adds a simple example of Opus encoding+decoding
--- /dev/null
+++ b/doc/trivial_example.c
@@ -1,0 +1,160 @@
+/* Copyright (c) 2013 Jean-Marc Valin */
+/*
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions
+ are met:
+
+ - Redistributions of source code must retain the above copyright
+ notice, this list of conditions and the following disclaimer.
+
+ - Redistributions in binary form must reproduce the above copyright
+ notice, this list of conditions and the following disclaimer in the
+ documentation and/or other materials provided with the distribution.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+ ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+ LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER
+ OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+ EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+ PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+ PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+ LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+ NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+ SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+*/
+
+/* This is meant to be a simple example of encoding and decoding audio
+ using Opus. It should make it easy to understand how the Opus API
+ works. For more information, see the full API documentation at:
+ http://www.opus-codec.org/docs/ */
+
+#include <stdlib.h>
+#include <errno.h>
+#include <string.h>
+#include <opus.h>
+#include <stdio.h>
+
+/*The frame size in hardcoded for this sample code but it doesn't have to be*/
+#define FRAME_SIZE 960
+#define SAMPLE_RATE 48000
+#define CHANNELS 2
+#define APPLICATION OPUS_APPLICATION_AUDIO
+#define BITRATE 64000
+
+#define MAX_FRAME_SIZE 6*960
+#define MAX_PACKET_SIZE (3*1276)
+
+int main(int argc, char **argv)
+{+ char *inFile;
+ FILE *fin;
+ char *outFile;
+ FILE *fout;
+ opus_int16 in[FRAME_SIZE*CHANNELS];
+ opus_int16 out[MAX_FRAME_SIZE*CHANNELS];
+ unsigned char cbits[MAX_PACKET_SIZE];
+ int nbBytes;
+ /*Holds the state of the encoder and decoder */
+ OpusEncoder *encoder;
+ OpusDecoder *decoder;
+ int err;
+
+ if (argc != 3)
+ {+ fprintf(stderr, "usage: trivial_example input.pcm output.pcm\n");
+ fprintf(stderr, "input and output are 16-bit little-endian raw files\n");
+ return EXIT_FAILURE;
+ }
+
+ /*Create a new encoder state */
+ encoder = opus_encoder_create(SAMPLE_RATE, CHANNELS, APPLICATION, &err);
+ if (err<0)
+ {+ fprintf(stderr, "failed to create an encoder: %s\n", opus_strerror(err));
+ return EXIT_FAILURE;
+ }
+ /* Set the desired bit-rate. You can also set other parameters if needed.
+ The Opus library is designed to have good defaults, so only set
+ parameters you know you need. Doing otherwise is likely to result
+ in worse quality, but better. */
+ err = opus_encoder_ctl(encoder, OPUS_SET_BITRATE(BITRATE));
+ if (err<0)
+ {+ fprintf(stderr, "failed to set bitrate: %s\n", opus_strerror(err));
+ return EXIT_FAILURE;
+ }
+ inFile = argv[1];
+ fin = fopen(inFile, "r");
+ if (fin==NULL)
+ {+ fprintf(stderr, "failed to open file: %s\n", strerror(errno));
+ return EXIT_FAILURE;
+ }
+
+
+ /* Create a new decoder state. */
+ decoder = opus_decoder_create(SAMPLE_RATE, CHANNELS, &err);
+ if (err<0)
+ {+ fprintf(stderr, "failed to create decoder: %s\n", opus_strerror(err));
+ return EXIT_FAILURE;
+ }
+ outFile = argv[2];
+ fout = fopen(outFile, "w");
+ if (fout==NULL)
+ {+ fprintf(stderr, "failed to open file: %s\n", strerror(errno));
+ return EXIT_FAILURE;
+ }
+
+ while (1)
+ {+ int i;
+ unsigned char pcm_bytes[MAX_FRAME_SIZE*CHANNELS*2];
+ int frame_size;
+
+ /* Read a 16 bits/sample audio frame. */
+ fread(pcm_bytes, sizeof(short)*CHANNELS, FRAME_SIZE, fin);
+ if (feof(fin))
+ break;
+ /* Convert from little-endian ordering. */
+ for (i=0;i<CHANNELS*FRAME_SIZE;i++)
+ in[i]=pcm_bytes[2*i+1]<<8|pcm_bytes[2*i];
+
+ /* Encode the frame. */
+ nbBytes = opus_encode(encoder, in, FRAME_SIZE, cbits, MAX_PACKET_SIZE);
+ if (nbBytes<0)
+ {+ fprintf(stderr, "encode failed: %s\n", opus_strerror(nbBytes));
+ return EXIT_FAILURE;
+ }
+
+
+ /* Decode the data. In this example, frame_size will be constant because
+ the encoder is using a constant frame size. However, that may not
+ be the case for all encoders, so the decoder must always check
+ the frame size returned. */
+ frame_size = opus_decode(decoder, cbits, nbBytes, out, MAX_FRAME_SIZE, 0);
+ if (frame_size<0)
+ {+ fprintf(stderr, "decoder failed: %s\n", opus_strerror(err));
+ return EXIT_FAILURE;
+ }
+
+ /* Convert to little-endian ordering. */
+ for(i=0;i<CHANNELS*frame_size;i++)
+ {+ pcm_bytes[2*i]=out[i]&0xFF;
+ pcm_bytes[2*i+1]=(out[i]>>8)&0xFF;
+ }
+ /* Write the decoded audio to file. */
+ fwrite(pcm_bytes, sizeof(short), frame_size*CHANNELS, fout);
+ }
+ /*Destroy the encoder state*/
+ opus_encoder_destroy(encoder);
+ opus_decoder_destroy(decoder);
+ fclose(fin);
+ fclose(fout);
+ return EXIT_SUCCESS;
+}