| /* |
| * 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) |
| { |
| const uint64_t *p; |
| uint64_t best_ch_layout = 0; |
| int best_nb_channels = 0; |
| |
| if (!codec->channel_layouts) |
| return AV_CH_LAYOUT_STEREO; |
| |
| p = codec->channel_layouts; |
| while (*p) { |
| int nb_channels = av_get_channel_layout_nb_channels(*p); |
| |
| if (nb_channels > best_nb_channels) { |
| best_ch_layout = *p; |
| best_nb_channels = nb_channels; |
| } |
| p++; |
| } |
| return 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); |
| c->channel_layout = select_channel_layout(codec); |
| c->channels = av_get_channel_layout_nb_channels(c->channel_layout); |
| |
| /* 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; |
| frame->channel_layout = c->channel_layout; |
| |
| /* 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->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; |
| } |