ffmpeg encode/decode example

00001 /*
00002  * Copyright (c) 2001 Fabrice Bellard
00003  *
00004  * Permission is hereby granted, free of charge, to any person obtaining a copy
00005  * of this software and associated documentation files (the "Software"), to deal
00006  * in the Software without restriction, including without limitation the rights
00007  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
00008  * copies of the Software, and to permit persons to whom the Software is
00009  * furnished to do so, subject to the following conditions:
00010  *
00011  * The above copyright notice and this permission notice shall be included in
00012  * all copies or substantial portions of the Software.
00013  *
00014  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
00015  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
00016  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
00017  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
00018  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
00019  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
00020  * THE SOFTWARE.
00021  */
00022 
00033 #include <math.h>
00034 
00035 #include <libavutil/opt.h>
00036 #include <libavcodec/avcodec.h>
00037 #include <libavutil/channel_layout.h>
00038 #include <libavutil/common.h>
00039 #include <libavutil/imgutils.h>
00040 #include <libavutil/mathematics.h>
00041 #include <libavutil/samplefmt.h>
00042 
00043 #define INBUF_SIZE 4096
00044 #define AUDIO_INBUF_SIZE 20480
00045 #define AUDIO_REFILL_THRESH 4096
00046 
00047 /* check that a given sample format is supported by the encoder */
00048 static int check_sample_fmt(AVCodec *codec, enum AVSampleFormat sample_fmt)
00049 {
00050     const enum AVSampleFormat *p = codec->sample_fmts;
00051 
00052     while (*p != AV_SAMPLE_FMT_NONE) {
00053         if (*p == sample_fmt)
00054             return 1;
00055         p++;
00056     }
00057     return 0;
00058 }
00059 
00060 /* just pick the highest supported samplerate */
00061 static int select_sample_rate(AVCodec *codec)
00062 {
00063     const int *p;
00064     int best_samplerate = 0;
00065 
00066     if (!codec->supported_samplerates)
00067         return 44100;
00068 
00069     p = codec->supported_samplerates;
00070     while (*p) {
00071         best_samplerate = FFMAX(*p, best_samplerate);
00072         p++;
00073     }
00074     return best_samplerate;
00075 }
00076 
00077 /* select layout with the highest channel count */
00078 static int select_channel_layout(AVCodec *codec)
00079 {
00080     const uint64_t *p;
00081     uint64_t best_ch_layout = 0;
00082     int best_nb_channells   = 0;
00083 
00084     if (!codec->channel_layouts)
00085         return AV_CH_LAYOUT_STEREO;
00086 
00087     p = codec->channel_layouts;
00088     while (*p) {
00089         int nb_channels = av_get_channel_layout_nb_channels(*p);
00090 
00091         if (nb_channels > best_nb_channells) {
00092             best_ch_layout    = *p;
00093             best_nb_channells = nb_channels;
00094         }
00095         p++;
00096     }
00097     return best_ch_layout;
00098 }
00099 
00100 /*
00101  * Audio encoding example
00102  */
00103 static void audio_encode_example(const char *filename)
00104 {
00105     AVCodec *codec;
00106     AVCodecContext *c= NULL;
00107     AVFrame *frame;
00108     AVPacket pkt;
00109     int i, j, k, ret, got_output;
00110     int buffer_size;
00111     FILE *f;
00112     uint16_t *samples;
00113     float t, tincr;
00114 
00115     printf("Encode audio file %s\n", filename);
00116 
00117     /* find the MP2 encoder */
00118     codec = avcodec_find_encoder(AV_CODEC_ID_MP2);
00119     if (!codec) {
00120         fprintf(stderr, "Codec not found\n");
00121         exit(1);
00122     }
00123 
00124     c = avcodec_alloc_context3(codec);
00125     if (!c) {
00126         fprintf(stderr, "Could not allocate audio codec context\n");
00127         exit(1);
00128     }
00129 
00130     /* put sample parameters */
00131     c->bit_rate = 64000;
00132 
00133     /* check that the encoder supports s16 pcm input */
00134     c->sample_fmt = AV_SAMPLE_FMT_S16;
00135     if (!check_sample_fmt(codec, c->sample_fmt)) {
00136         fprintf(stderr, "Encoder does not support sample format %s",
00137                 av_get_sample_fmt_name(c->sample_fmt));
00138         exit(1);
00139     }
00140 
00141     /* select other audio parameters supported by the encoder */
00142     c->sample_rate    = select_sample_rate(codec);
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