1 #include "audio_encoder.h"
4 #include <libavcodec/avcodec.h>
5 #include <libavformat/avformat.h>
6 #include <libavresample/avresample.h>
7 #include <libavutil/channel_layout.h>
8 #include <libavutil/frame.h>
9 #include <libavutil/rational.h>
10 #include <libavutil/samplefmt.h>
11 #include <libavutil/opt.h>
24 AudioEncoder::AudioEncoder(const string &codec_name, int bit_rate, const vector<Mux *> &muxes)
27 AVCodec *codec = avcodec_find_encoder_by_name(codec_name.c_str());
28 if (codec == nullptr) {
29 fprintf(stderr, "ERROR: Could not find codec '%s'\n", codec_name.c_str());
33 ctx = avcodec_alloc_context3(codec);
34 ctx->bit_rate = bit_rate;
35 ctx->sample_rate = OUTPUT_FREQUENCY;
36 ctx->sample_fmt = codec->sample_fmts[0];
38 ctx->channel_layout = AV_CH_LAYOUT_STEREO;
39 ctx->time_base = AVRational{1, TIMEBASE};
40 ctx->flags |= CODEC_FLAG_GLOBAL_HEADER;
41 if (avcodec_open2(ctx, codec, NULL) < 0) {
42 fprintf(stderr, "Could not open codec '%s'\n", codec_name.c_str());
46 resampler = avresample_alloc_context();
47 if (resampler == nullptr) {
48 fprintf(stderr, "Allocating resampler failed.\n");
52 av_opt_set_int(resampler, "in_channel_layout", AV_CH_LAYOUT_STEREO, 0);
53 av_opt_set_int(resampler, "out_channel_layout", AV_CH_LAYOUT_STEREO, 0);
54 av_opt_set_int(resampler, "in_sample_rate", OUTPUT_FREQUENCY, 0);
55 av_opt_set_int(resampler, "out_sample_rate", OUTPUT_FREQUENCY, 0);
56 av_opt_set_int(resampler, "in_sample_fmt", AV_SAMPLE_FMT_FLT, 0);
57 av_opt_set_int(resampler, "out_sample_fmt", ctx->sample_fmt, 0);
59 if (avresample_open(resampler) < 0) {
60 fprintf(stderr, "Could not open resample context.\n");
64 audio_frame = av_frame_alloc();
67 AudioEncoder::~AudioEncoder()
69 av_frame_free(&audio_frame);
70 avresample_free(&resampler);
71 avcodec_free_context(&ctx);
74 void AudioEncoder::encode_audio(const vector<float> &audio, int64_t audio_pts)
76 if (ctx->frame_size == 0) {
77 // No queueing needed.
78 assert(audio_queue.empty());
79 assert(audio.size() % 2 == 0);
80 encode_audio_one_frame(&audio[0], audio.size() / 2, audio_pts);
84 int64_t sample_offset = audio_queue.size();
86 audio_queue.insert(audio_queue.end(), audio.begin(), audio.end());
89 sample_num + ctx->frame_size * 2 <= audio_queue.size();
90 sample_num += ctx->frame_size * 2) {
91 int64_t adjusted_audio_pts = audio_pts + (int64_t(sample_num) - sample_offset) * TIMEBASE / (OUTPUT_FREQUENCY * 2);
92 encode_audio_one_frame(&audio_queue[sample_num],
96 audio_queue.erase(audio_queue.begin(), audio_queue.begin() + sample_num);
98 last_pts = audio_pts + audio.size() * TIMEBASE / (OUTPUT_FREQUENCY * 2);
101 void AudioEncoder::encode_audio_one_frame(const float *audio, size_t num_samples, int64_t audio_pts)
103 audio_frame->pts = audio_pts;
104 audio_frame->nb_samples = num_samples;
105 audio_frame->channel_layout = AV_CH_LAYOUT_STEREO;
106 audio_frame->format = ctx->sample_fmt;
107 audio_frame->sample_rate = OUTPUT_FREQUENCY;
109 if (av_samples_alloc(audio_frame->data, nullptr, 2, num_samples, ctx->sample_fmt, 0) < 0) {
110 fprintf(stderr, "Could not allocate %ld samples.\n", num_samples);
114 if (avresample_convert(resampler, audio_frame->data, 0, num_samples,
115 (uint8_t **)&audio, 0, num_samples) < 0) {
116 fprintf(stderr, "Audio conversion failed.\n");
121 av_init_packet(&pkt);
125 avcodec_encode_audio2(ctx, &pkt, audio_frame, &got_output);
127 pkt.stream_index = 1;
129 for (Mux *mux : muxes) {
130 mux->add_packet(pkt, pkt.pts, pkt.dts);
134 av_freep(&audio_frame->data[0]);
136 av_frame_unref(audio_frame);
137 av_free_packet(&pkt);
140 void AudioEncoder::encode_last_audio()
142 if (!audio_queue.empty()) {
143 // Last frame can be whatever size we want.
144 assert(audio_queue.size() % 2 == 0);
145 encode_audio_one_frame(&audio_queue[0], audio_queue.size() / 2, last_pts);
149 if (ctx->codec->capabilities & AV_CODEC_CAP_DELAY) {
150 // Collect any delayed frames.
154 av_init_packet(&pkt);
157 avcodec_encode_audio2(ctx, &pkt, nullptr, &got_output);
158 if (!got_output) break;
160 pkt.stream_index = 1;
162 for (Mux *mux : muxes) {
163 mux->add_packet(pkt, pkt.pts, pkt.dts);
165 av_free_packet(&pkt);