1/*
2 * Copyright (c) 2011 Jonathan Baldwin
3 *
4 * This file is part of FFmpeg.
5 *
6 * Permission to use, copy, modify, and/or distribute this software for any
7 * purpose with or without fee is hereby granted, provided that the above
8 * copyright notice and this permission notice appear in all copies.
9 *
10 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
11 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
12 * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
13 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
14 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
15 * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
16 * PERFORMANCE OF THIS SOFTWARE.
17 */
18
19/**
20 * @file
21 * OpenAL 1.1 capture device for libavdevice
22 **/
23
24#include <AL/al.h>
25#include <AL/alc.h>
26
27#include "libavutil/opt.h"
28#include "libavutil/time.h"
29#include "libavformat/internal.h"
30#include "avdevice.h"
31
32typedef struct {
33    AVClass *class;
34    /** OpenAL capture device context. **/
35    ALCdevice *device;
36    /** The number of channels in the captured audio. **/
37    int channels;
38    /** The sample rate (in Hz) of the captured audio. **/
39    int sample_rate;
40    /** The sample size (in bits) of the captured audio. **/
41    int sample_size;
42    /** The OpenAL sample format of the captured audio. **/
43    ALCenum sample_format;
44    /** The number of bytes between two consecutive samples of the same channel/component. **/
45    ALCint sample_step;
46    /** If true, print a list of capture devices on this system and exit. **/
47    int list_devices;
48} al_data;
49
50typedef struct {
51    ALCenum al_fmt;
52    enum AVCodecID codec_id;
53    int channels;
54} al_format_info;
55
56#define LOWEST_AL_FORMAT FFMIN(FFMIN(AL_FORMAT_MONO8,AL_FORMAT_MONO16),FFMIN(AL_FORMAT_STEREO8,AL_FORMAT_STEREO16))
57
58/**
59 * Get information about an AL_FORMAT value.
60 * @param al_fmt the AL_FORMAT value to find information about.
61 * @return A pointer to a structure containing information about the AL_FORMAT value.
62 */
63static inline al_format_info* get_al_format_info(ALCenum al_fmt)
64{
65    static al_format_info info_table[] = {
66        [AL_FORMAT_MONO8-LOWEST_AL_FORMAT]    = {AL_FORMAT_MONO8, AV_CODEC_ID_PCM_U8, 1},
67        [AL_FORMAT_MONO16-LOWEST_AL_FORMAT]   = {AL_FORMAT_MONO16, AV_NE (AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE), 1},
68        [AL_FORMAT_STEREO8-LOWEST_AL_FORMAT]  = {AL_FORMAT_STEREO8, AV_CODEC_ID_PCM_U8, 2},
69        [AL_FORMAT_STEREO16-LOWEST_AL_FORMAT] = {AL_FORMAT_STEREO16, AV_NE (AV_CODEC_ID_PCM_S16BE, AV_CODEC_ID_PCM_S16LE), 2},
70    };
71
72    return &info_table[al_fmt-LOWEST_AL_FORMAT];
73}
74
75/**
76 * Get the OpenAL error code, translated into an av/errno error code.
77 * @param device The ALC device to check for errors.
78 * @param error_msg_ret A pointer to a char* in which to return the error message, or NULL if desired.
79 * @return The error code, or 0 if there is no error.
80 */
81static inline int al_get_error(ALCdevice *device, const char** error_msg_ret)
82{
83    ALCenum error = alcGetError(device);
84    if (error_msg_ret)
85        *error_msg_ret = (const char*) alcGetString(device, error);
86    switch (error) {
87    case ALC_NO_ERROR:
88        return 0;
89    case ALC_INVALID_DEVICE:
90        return AVERROR(ENODEV);
91        break;
92    case ALC_INVALID_CONTEXT:
93    case ALC_INVALID_ENUM:
94    case ALC_INVALID_VALUE:
95        return AVERROR(EINVAL);
96        break;
97    case ALC_OUT_OF_MEMORY:
98        return AVERROR(ENOMEM);
99        break;
100    default:
101        return AVERROR(EIO);
102    }
103}
104
105/**
106 * Print out a list of OpenAL capture devices on this system.
107 */
108static inline void print_al_capture_devices(void *log_ctx)
109{
110    const char *devices;
111
112    if (!(devices = alcGetString(NULL, ALC_CAPTURE_DEVICE_SPECIFIER)))
113        return;
114
115    av_log(log_ctx, AV_LOG_INFO, "List of OpenAL capture devices on this system:\n");
116
117    for (; *devices != '\0'; devices += strlen(devices) + 1)
118        av_log(log_ctx, AV_LOG_INFO, "  %s\n", devices);
119}
120
121static int read_header(AVFormatContext *ctx)
122{
123    al_data *ad = ctx->priv_data;
124    static const ALCenum sample_formats[2][2] = {
125        { AL_FORMAT_MONO8,  AL_FORMAT_STEREO8  },
126        { AL_FORMAT_MONO16, AL_FORMAT_STEREO16 }
127    };
128    int error = 0;
129    const char *error_msg;
130    AVStream *st = NULL;
131    AVCodecContext *codec = NULL;
132
133    if (ad->list_devices) {
134        print_al_capture_devices(ctx);
135        return AVERROR_EXIT;
136    }
137
138    ad->sample_format = sample_formats[ad->sample_size/8-1][ad->channels-1];
139
140    /* Open device for capture */
141    ad->device =
142        alcCaptureOpenDevice(ctx->filename[0] ? ctx->filename : NULL,
143                             ad->sample_rate,
144                             ad->sample_format,
145                             ad->sample_rate); /* Maximum 1 second of sample data to be read at once */
146
147    if (error = al_get_error(ad->device, &error_msg)) goto fail;
148
149    /* Create stream */
150    if (!(st = avformat_new_stream(ctx, NULL))) {
151        error = AVERROR(ENOMEM);
152        goto fail;
153    }
154
155    /* We work in microseconds */
156    avpriv_set_pts_info(st, 64, 1, 1000000);
157
158    /* Set codec parameters */
159    codec = st->codec;
160    codec->codec_type = AVMEDIA_TYPE_AUDIO;
161    codec->sample_rate = ad->sample_rate;
162    codec->channels = get_al_format_info(ad->sample_format)->channels;
163    codec->codec_id = get_al_format_info(ad->sample_format)->codec_id;
164
165    /* This is needed to read the audio data */
166    ad->sample_step = (av_get_bits_per_sample(get_al_format_info(ad->sample_format)->codec_id) *
167                       get_al_format_info(ad->sample_format)->channels) / 8;
168
169    /* Finally, start the capture process */
170    alcCaptureStart(ad->device);
171
172    return 0;
173
174fail:
175    /* Handle failure */
176    if (ad->device)
177        alcCaptureCloseDevice(ad->device);
178    if (error_msg)
179        av_log(ctx, AV_LOG_ERROR, "Cannot open device: %s\n", error_msg);
180    return error;
181}
182
183static int read_packet(AVFormatContext* ctx, AVPacket *pkt)
184{
185    al_data *ad = ctx->priv_data;
186    int error=0;
187    const char *error_msg;
188    ALCint nb_samples;
189
190    /* Get number of samples available */
191    alcGetIntegerv(ad->device, ALC_CAPTURE_SAMPLES, (ALCsizei) sizeof(ALCint), &nb_samples);
192    if (error = al_get_error(ad->device, &error_msg)) goto fail;
193
194    /* Create a packet of appropriate size */
195    av_new_packet(pkt, nb_samples*ad->sample_step);
196    pkt->pts = av_gettime();
197
198    /* Fill the packet with the available samples */
199    alcCaptureSamples(ad->device, pkt->data, nb_samples);
200    if (error = al_get_error(ad->device, &error_msg)) goto fail;
201
202    return pkt->size;
203fail:
204    /* Handle failure */
205    if (pkt->data)
206        av_destruct_packet(pkt);
207    if (error_msg)
208        av_log(ctx, AV_LOG_ERROR, "Error: %s\n", error_msg);
209    return error;
210}
211
212static int read_close(AVFormatContext* ctx)
213{
214    al_data *ad = ctx->priv_data;
215
216    if (ad->device) {
217        alcCaptureStop(ad->device);
218        alcCaptureCloseDevice(ad->device);
219    }
220    return 0;
221}
222
223#define OFFSET(x) offsetof(al_data, x)
224
225static const AVOption options[] = {
226    {"channels", "set number of channels",     OFFSET(channels),     AV_OPT_TYPE_INT, {.i64=2},     1, 2,      AV_OPT_FLAG_DECODING_PARAM },
227    {"sample_rate", "set sample rate",         OFFSET(sample_rate),  AV_OPT_TYPE_INT, {.i64=44100}, 1, 192000, AV_OPT_FLAG_DECODING_PARAM },
228    {"sample_size", "set sample size",         OFFSET(sample_size),  AV_OPT_TYPE_INT, {.i64=16},    8, 16,     AV_OPT_FLAG_DECODING_PARAM },
229    {"list_devices", "list available devices", OFFSET(list_devices), AV_OPT_TYPE_INT, {.i64=0},     0, 1,      AV_OPT_FLAG_DECODING_PARAM, "list_devices"  },
230    {"true",  "", 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
231    {"false", "", 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, AV_OPT_FLAG_DECODING_PARAM, "list_devices" },
232    {NULL},
233};
234
235static const AVClass class = {
236    .class_name = "openal",
237    .item_name = av_default_item_name,
238    .option = options,
239    .version = LIBAVUTIL_VERSION_INT,
240    .category = AV_CLASS_CATEGORY_DEVICE_AUDIO_INPUT,
241};
242
243AVInputFormat ff_openal_demuxer = {
244    .name = "openal",
245    .long_name = NULL_IF_CONFIG_SMALL("OpenAL audio capture device"),
246    .priv_data_size = sizeof(al_data),
247    .read_probe = NULL,
248    .read_header = read_header,
249    .read_packet = read_packet,
250    .read_close = read_close,
251    .flags = AVFMT_NOFILE,
252    .priv_class = &class
253};
254