/* * Copyright (c) 2001 Fabrice Bellard * * Permission is hereby granted, free of charge, to any person obtaining a copy * of this software and associated documentation files (the "Software"), to deal * in the Software without restriction, including without limitation the rights * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell * copies of the Software, and to permit persons to whom the Software is * furnished to do so, subject to the following conditions: * * The above copyright notice and this permission notice shall be included in * all copies or substantial portions of the Software. * * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN * THE SOFTWARE. */ /** * @file * audio encoding with libavcodec API example. * * @example encode_audio.c */ #include <stdint.h>#include <stdio.h>#include <stdlib.h> #include <libavcodec/avcodec.h> #include <libavutil/channel_layout.h>#include <libavutil/common.h>#include <libavutil/frame.h>#include <libavutil/samplefmt.h> /* check that a given sample format is supported by the encoder */static int check_sample_fmt(const AVCodec *codec, enum AVSampleFormat sample_fmt){    const enum AVSampleFormat *p = codec->sample_fmts;     while (*p != AV_SAMPLE_FMT_NONE) {        if (*p == sample_fmt)            return 1;        p++;    }    return 0;} /* just pick the highest supported samplerate */static int select_sample_rate(const AVCodec *codec){    const int *p;    int best_samplerate = 0;     if (!codec->supported_samplerates)        return 44100;     p = codec->supported_samplerates;    while (*p) {        if (!best_samplerate || abs(44100 - *p) < abs(44100 - best_samplerate))            best_samplerate = *p;        p++;    }    return best_samplerate;} /* select layout with the highest channel count */static int select_channel_layout(const AVCodec *codec, AVChannelLayout *dst){    const AVChannelLayout *p, *best_ch_layout;    int best_nb_channels   = 0;     if (!codec->ch_layouts)        return av_channel_layout_copy(dst, &(AVChannelLayout)AV_CHANNEL_LAYOUT_STEREO);     p = codec->ch_layouts;    while (p->nb_channels) {        int nb_channels = p->nb_channels;         if (nb_channels > best_nb_channels) {            best_ch_layout   = p;            best_nb_channels = nb_channels;        }        p++;    }    return av_channel_layout_copy(dst, best_ch_layout);} static void encode(AVCodecContext *ctx, AVFrame *frame, AVPacket *pkt,                   FILE *output){    int ret;     /* send the frame for encoding */    ret = avcodec_send_frame(ctx, frame);    if (ret < 0) {        fprintf(stderr, "Error sending the frame to the encoder\n");        exit(1);    }     /* read all the available output packets (in general there may be any     * number of them */    while (ret >= 0) {        ret = avcodec_receive_packet(ctx, pkt);        if (ret == AVERROR(EAGAIN) || ret == AVERROR_EOF)            return;        else if (ret < 0) {            fprintf(stderr, "Error encoding audio frame\n");            exit(1);        }         fwrite(pkt->data, 1, pkt->size, output);        av_packet_unref(pkt);    }} int main(int argc, char **argv){    const char *filename;    const AVCodec *codec;    AVCodecContext *c= NULL;    AVFrame *frame;    AVPacket *pkt;    int i, j, k, ret;    FILE *f;    uint16_t *samples;    float t, tincr;     if (argc <= 1) {        fprintf(stderr, "Usage: %s <output file>\n", argv[0]);        return 0;    }    filename = argv[1];     /* find the MP2 encoder */    codec = avcodec_find_encoder(AV_CODEC_ID_MP2);    if (!codec) {        fprintf(stderr, "Codec not found\n");        exit(1);    }     c = avcodec_alloc_context3(codec);    if (!c) {        fprintf(stderr, "Could not allocate audio codec context\n");        exit(1);    }     /* put sample parameters */    c->bit_rate = 64000;     /* check that the encoder supports s16 pcm input */    c->sample_fmt = AV_SAMPLE_FMT_S16;    if (!check_sample_fmt(codec, c->sample_fmt)) {        fprintf(stderr, "Encoder does not support sample format %s",                av_get_sample_fmt_name(c->sample_fmt));        exit(1);    }     /* select other audio parameters supported by the encoder */    c->sample_rate    = select_sample_rate(codec);    ret = select_channel_layout(codec, &c->ch_layout);    if (ret < 0)        exit(1);     /* open it */    if (avcodec_open2(c, codec, NULL) < 0) {        fprintf(stderr, "Could not open codec\n");        exit(1);    }     f = fopen(filename, "wb");    if (!f) {        fprintf(stderr, "Could not open %s\n", filename);        exit(1);    }     /* packet for holding encoded output */    pkt = av_packet_alloc();    if (!pkt) {        fprintf(stderr, "could not allocate the packet\n");        exit(1);    }     /* frame containing input raw audio */    frame = av_frame_alloc();    if (!frame) {        fprintf(stderr, "Could not allocate audio frame\n");        exit(1);    }     frame->nb_samples     = c->frame_size;    frame->format         = c->sample_fmt;    ret = av_channel_layout_copy(&frame->ch_layout, &c->ch_layout);    if (ret < 0)        exit(1);     /* allocate the data buffers */    ret = av_frame_get_buffer(frame, 0);    if (ret < 0) {        fprintf(stderr, "Could not allocate audio data buffers\n");        exit(1);    }     /* encode a single tone sound */    t = 0;    tincr = 2 * M_PI * 440.0 / c->sample_rate;    for (i = 0; i < 200; i++) {        /* make sure the frame is writable -- makes a copy if the encoder         * kept a reference internally */        ret = av_frame_make_writable(frame);        if (ret < 0)            exit(1);        samples = (uint16_t*)frame->data[0];         for (j = 0; j < c->frame_size; j++) {            samples[2*j] = (int)(sin(t) * 10000);             for (k = 1; k < c->ch_layout.nb_channels; k++)                samples[2*j + k] = samples[2*j];            t += tincr;        }        encode(c, frame, pkt, f);    }     /* flush the encoder */    encode(c, NULL, pkt, f);     fclose(f);     av_frame_free(&frame);    av_packet_free(&pkt);    avcodec_free_context(&c);     return 0;}