beep.c (5316B)
1/* 2 * Licensed to the Apache Software Foundation (ASF) under one 3 * or more contributor license agreements. See the NOTICE file 4 * distributed with this work for additional information 5 * regarding copyright ownership. The ASF licenses this file 6 * to you under the Apache License, Version 2.0 (the 7 * "License"); you may not use this file except in compliance 8 * with the License. You may obtain a copy of the License at 9 * 10 * http://www.apache.org/licenses/LICENSE-2.0 11 * 12 * Unless required by applicable law or agreed to in writing, 13 * software distributed under the License is distributed on an 14 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY 15 * KIND, either express or implied. See the License for the 16 * specific language governing permissions and limitations 17 * under the License. 18 */ 19 20#include "beep.h" 21#include "rdp.h" 22#include "settings.h" 23 24#include <freerdp/freerdp.h> 25#include <guacamole/audio.h> 26#include <guacamole/client.h> 27#include <guacamole/mem.h> 28#include <winpr/wtypes.h> 29 30#include <inttypes.h> 31#include <stdlib.h> 32#include <string.h> 33 34/** 35 * Fills the given buffer with signed 8-bit, single-channel PCM at the given 36 * sample rate which will produce a beep of the given frequency. 37 * 38 * @param buffer 39 * The buffer to fill with PCM data. 40 * 41 * @param frequency 42 * The frequency of the beep to generate, in hertz. 43 * 44 * @param rate 45 * The sample rate of the PCM to generate, in samples per second. 46 * 47 * @param buffer_size 48 * The number of bytes of PCM data to write to the given buffer. 49 */ 50static void guac_rdp_beep_fill_triangle_wave(unsigned char* buffer, 51 int frequency, int rate, int buffer_size) { 52 53 /* With the distance between each positive/negative peak and zero being the 54 * amplitude, and with the "bounce" between those peaks occurring once 55 * every two periods, the number of distinct states that the triangle wave 56 * function goes through is twice the peak-to-peak amplitude, or four times 57 * the overall amplitude */ 58 const int wave_period = GUAC_RDP_BEEP_AMPLITUDE * 4; 59 60 /* With the number of distinct states being the wave_period defined above, 61 * the "bounce" point within that period is half the period */ 62 const int wave_bounce_offset = wave_period / 2; 63 64 for (int position = 0; position < buffer_size; position++) { 65 66 /* Calculate relative position within the repeating portion of the wave 67 * (the portion with wave_period unique states) */ 68 int wave_position = (position * frequency * wave_period / rate) % wave_period; 69 70 /* Calculate state of the triangle wave function at the calculated 71 * offset, knowing in advance the relative location that the function 72 * should "bounce" */ 73 *(buffer++) = abs(wave_position - wave_bounce_offset) - GUAC_RDP_BEEP_AMPLITUDE; 74 75 } 76 77} 78 79/** 80 * Writes PCM data to the given guac_audio_stream which produces a beep of the 81 * given frequency and duration. The provided guac_audio_stream may be 82 * configured for any sample rate but MUST be configured for single-channel, 83 * 8-bit PCM. 84 * 85 * @param audio 86 * The guac_audio_stream which should receive the PCM data. 87 * 88 * @param frequency 89 * The frequency of the beep, in hertz. 90 * 91 * @param duration 92 * The duration of the beep, in milliseconds. 93 */ 94static void guac_rdp_beep_write_pcm(guac_audio_stream* audio, 95 int frequency, int duration) { 96 97 size_t buffer_size = guac_mem_ckd_mul_or_die(audio->rate, duration) / 1000; 98 unsigned char* buffer = guac_mem_alloc(buffer_size); 99 100 /* Beep for given frequency/duration using a simple triangle wave */ 101 guac_rdp_beep_fill_triangle_wave(buffer, frequency, audio->rate, buffer_size); 102 guac_audio_stream_write_pcm(audio, buffer, buffer_size); 103 104 guac_mem_free(buffer); 105 106} 107 108BOOL guac_rdp_beep_play_sound(rdpContext* context, 109 const PLAY_SOUND_UPDATE* play_sound) { 110 111 guac_client* client = ((rdp_freerdp_context*) context)->client; 112 guac_rdp_client* rdp_client = (guac_rdp_client*) client->data; 113 guac_rdp_settings* settings = rdp_client->settings; 114 115 /* Ignore if audio is not enabled */ 116 if (!settings->audio_enabled) { 117 guac_client_log(client, GUAC_LOG_DEBUG, "Ignoring request to beep " 118 "for %" PRIu32 " millseconds at %" PRIu32 " Hz as audio is " 119 "disabled.", play_sound->duration, play_sound->frequency); 120 return TRUE; 121 } 122 123 /* Allocate audio stream which sends audio in a format supported by the 124 * connected client(s) */ 125 guac_audio_stream* beep = guac_audio_stream_alloc(client, NULL, 126 GUAC_RDP_BEEP_SAMPLE_RATE, 1, 8); 127 128 /* Stream availability is not guaranteed */ 129 if (beep == NULL) { 130 guac_client_log(client, GUAC_LOG_DEBUG, "Ignoring request to beep " 131 "for %" PRIu32 " millseconds at %" PRIu32 " Hz as no audio " 132 "stream could be allocated.", play_sound->duration, 133 play_sound->frequency); 134 return TRUE; 135 } 136 137 /* Limit maximum duration of each beep */ 138 int duration = play_sound->duration; 139 if (duration > GUAC_RDP_BEEP_MAX_DURATION) 140 duration = GUAC_RDP_BEEP_MAX_DURATION; 141 142 guac_rdp_beep_write_pcm(beep, play_sound->frequency, duration); 143 guac_audio_stream_free(beep); 144 145 return TRUE; 146 147} 148