Streaming Ogg Opus file

This example shows how to stream an Ogg Opus file to a voice channel. This example requires some additional dependencies, namely libogg and opusfile.

#include <dpp/dpp.h>
#include <iomanip>
#include <sstream>
 
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <ogg/ogg.h>
#include <opus/opusfile.h>
 
int main(int argc, char const *argv[])
{
    /* Load an ogg opus file into memory.
     * The bot expects opus packets to be 2 channel stereo, 48000Hz.
     * 
     * You may use ffmpeg to encode songs to ogg opus:
     * ffmpeg -i /path/to/song -c:a libopus -ar 48000 -ac 2 -vn -b:a 96K /path/to/opus.ogg 
     */
    dpp::cluster bot("token");
 
    /* Use the on_message_create event to look for commands */
    bot.on_message_create([&bot](const dpp::message_create_t & event) {
        std::stringstream ss(event.msg->content);
        std::string command;
        ss >> command;
 
        /* Tell the bot to join the discord voice channel the user is on. Syntax: .join */
        if (command == ".join") {
            dpp::guild * g = dpp::find_guild(event.msg->guild_id);
            if (!g->connect_member_voice(event.msg->author->id)) {
                bot.message_create(dpp::message(event.msg->channel_id, "You don't seem to be on a voice channel! :("));
            }
        }
 
        /* Tell the bot to play the sound file */
        if (command == ".play") {
            dpp::voiceconn* v = event.from->get_voice(event.msg->guild_id);
            if (v && v->voiceclient && v->voiceclient->is_ready()) {
                ogg_sync_state oy; 
                ogg_stream_state os;
                ogg_page og;
                ogg_packet op;
                OpusHead header;
                char *buffer;
 
                FILE *fd;
 
                fd = fopen("/path/to/opus.ogg", "rb");
 
                fseek(fd, 0L, SEEK_END);
                size_t sz = ftell(fd);
                rewind(fd);
 
                ogg_sync_init(&oy);
 
                int eos = 0;
                int i;
 
                buffer = ogg_sync_buffer(&oy, sz);
                fread(buffer, 1, sz, fd);
 
                ogg_sync_wrote(&oy, sz);
 
                if (ogg_sync_pageout(&oy, &og) != 1)
                {
                    fprintf(stderr,"Does not appear to be ogg stream.\n");
                    exit(1);
                }
 
                ogg_stream_init(&os, ogg_page_serialno(&og));
 
                if (ogg_stream_pagein(&os,&og) < 0) {
                    fprintf(stderr,"Error reading initial page of ogg stream.\n");
                    exit(1);
                }
 
                if (ogg_stream_packetout(&os,&op) != 1)
                {
                    fprintf(stderr,"Error reading header packet of ogg stream.\n");
                    exit(1);
                }
 
                /* We must ensure that the ogg stream actually contains opus data */
                if (!(op.bytes > 8 && !memcmp("OpusHead", op.packet, 8)))
                {
                    fprintf(stderr,"Not an ogg opus stream.\n");
                    exit(1);
                }
 
                /* Parse the header to get stream info */
                int err = opus_head_parse(&header, op.packet, op.bytes);
                if (err)
                {
                    fprintf(stderr,"Not a ogg opus stream\n");
                    exit(1);
                }
                /* Now we ensure the encoding is correct for Discord */
                if (header.channel_count != 2 && header.input_sample_rate != 48000)
                {
                    fprintf(stderr,"Wrong encoding for Discord, must be 48000Hz sample rate with 2 channels.\n");
                    exit(1);
                }
 
                /* Now loop though all the pages and send the packets to the vc */
                while (ogg_sync_pageout(&oy, &og) == 1){
                    ogg_stream_init(&os, ogg_page_serialno(&og));
 
                    if(ogg_stream_pagein(&os,&og)<0){
                        fprintf(stderr,"Error reading page of Ogg bitstream data.\n");
                        exit(1);
                    }
 
                    while (ogg_stream_packetout(&os,&op) != 0)
                    {
                        /* Read remaining headers */
                        if (op.bytes > 8 && !memcmp("OpusHead", op.packet, 8))
                        {
                            int err = opus_head_parse(&header, op.packet, op.bytes);
                            if (err)
                            {
                                fprintf(stderr,"Not a ogg opus stream\n");
                                exit(1);
                            }
                            if (header.channel_count != 2 && header.input_sample_rate != 48000)
                            {
                                fprintf(stderr,"Wrong encoding for Discord, must be 48000Hz sample rate with 2 channels.\n");
                                exit(1);
                            }
                            continue;
                        }
                        /* Skip the opus tags */
                        if (op.bytes > 8 && !memcmp("OpusTags", op.packet, 8))
                            continue; 
 
                        /* Send the audio */
                        int samples = opus_packet_get_samples_per_frame(op.packet, 48000);
 
                        v->voiceclient->send_audio_opus(op.packet, op.bytes, samples / 48);
                    }
                }
 
                /* Cleanup */
                ogg_stream_clear(&os);
                ogg_sync_clear(&oy);
            }
        }
    });
    
    /* Start bot */
    bot.start(false);
    return 0;
}

You can compile this example using the following command

c++ /path/to/source.cc -ldpp -lopus -lopusfile -logg -I/usr/include/opus