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minimal-raw-audio
Shows how to bring alsa's libasound into the lws event loop
This commit is contained in:
Andy Green
parent
fe1d3def00
commit
7a84ca4c83
4 changed files with 326 additions and 0 deletions
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@ -46,6 +46,7 @@ option(LWS_WITH_HTTP_STREAM_COMPRESSION "Support HTTP stream compression" OFF)
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option(LWS_WITH_HTTP_BROTLI "Also offer brotli http stream compression (requires LWS_WITH_HTTP_STREAM_COMPRESSION)" OFF)
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option(LWS_WITH_ACME "Enable support for ACME automatic cert acquisition + maintenance (letsencrypt etc)" OFF)
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option(LWS_WITH_HUBBUB "Enable libhubbub rewriting support" OFF)
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option(LWS_WITH_ALSA "Enable alsa audio example" OFF)
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option(LWS_WITH_FTS "Full Text Search support" OFF)
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option(LWS_WITH_SYS_ASYNC_DNS "Nonblocking internal IPv4 + IPv6 DNS resolver" OFF)
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option(LWS_WITH_SYS_NTPCLIENT "Build in tiny ntpclient good for tls date validation and run via lws_system" OFF)
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77
minimal-examples/raw/minimal-raw-audio/CMakeLists.txt
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77
minimal-examples/raw/minimal-raw-audio/CMakeLists.txt
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@ -0,0 +1,77 @@
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cmake_minimum_required(VERSION 2.8)
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include(CheckCSourceCompiles)
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set(SAMP lws-minimal-raw-audio)
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set(SRCS audio.c)
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# If we are being built as part of lws, confirm current build config supports
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# reqconfig, else skip building ourselves.
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#
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# If we are being built externally, confirm installed lws was configured to
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# support reqconfig, else error out with a helpful message about the problem.
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#
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MACRO(require_lws_config reqconfig _val result)
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if (DEFINED ${reqconfig})
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if (${reqconfig})
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set (rq 1)
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else()
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set (rq 0)
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endif()
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else()
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set(rq 0)
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endif()
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if (${_val} EQUAL ${rq})
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set(SAME 1)
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else()
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set(SAME 0)
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endif()
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if (LWS_WITH_MINIMAL_EXAMPLES AND NOT ${SAME})
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if (${_val})
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message("${SAMP}: skipping as lws being built without ${reqconfig}")
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else()
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message("${SAMP}: skipping as lws built with ${reqconfig}")
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endif()
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set(${result} 0)
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else()
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if (LWS_WITH_MINIMAL_EXAMPLES)
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set(MET ${SAME})
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else()
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CHECK_C_SOURCE_COMPILES("#include <libwebsockets.h>\nint main(void) {\n#if defined(${reqconfig})\n return 0;\n#else\n fail;\n#endif\n return 0;\n}\n" HAS_${reqconfig})
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if (NOT DEFINED HAS_${reqconfig} OR NOT HAS_${reqconfig})
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set(HAS_${reqconfig} 0)
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else()
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set(HAS_${reqconfig} 1)
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endif()
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if ((HAS_${reqconfig} AND ${_val}) OR (NOT HAS_${reqconfig} AND NOT ${_val}))
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set(MET 1)
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else()
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set(MET 0)
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endif()
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endif()
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if (NOT MET)
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if (${_val})
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message(FATAL_ERROR "This project requires lws must have been configured with ${reqconfig}")
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else()
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message(FATAL_ERROR "Lws configuration of ${reqconfig} is incompatible with this project")
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endif()
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endif()
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endif()
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ENDMACRO()
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set(requirements 1)
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require_lws_config(LWS_WITH_ALSA 1 requirements)
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if (requirements)
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add_executable(${SAMP} ${SRCS})
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if (websockets_shared)
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target_link_libraries(${SAMP} websockets_shared asound)
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add_dependencies(${SAMP} websockets_shared)
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else()
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target_link_libraries(${SAMP} websockets asound)
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endif()
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endif()
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37
minimal-examples/raw/minimal-raw-audio/README.md
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37
minimal-examples/raw/minimal-raw-audio/README.md
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@ -0,0 +1,37 @@
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# lws minimal raw audio
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This demonstrates operating ALSA playback and capture using the lws event loop
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via raw file descriptors.
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You need the lws cmake option `-DLWS_WITH_ALSA=1`
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This example opens the default ALSA playback and capture devices and pipes the
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capture data into the playback with something over 1s delay via a ringbuffer.
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ALSA doesn't really lend itself to direct use with event loops... this example
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uses the capture channel which does create POLLIN normally as the timesource
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for the playback as well; they're both set to 16000Hz sample rate.
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## build
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```
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$ cmake . && make
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```
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## usage
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```
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$ ./lws-minimal-raw-audio
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[2019/10/14 18:58:49:3288] U: LWS minimal raw audio
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[2019/10/14 18:58:50:3438] N: LWS_CALLBACK_RAW_ADOPT_FILE
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[2019/10/14 18:58:50:3455] N: LWS_CALLBACK_RAW_ADOPT_FILE
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[2019/10/14 18:58:50:4764] N: LWS_CALLBACK_RAW_RX_FILE: 2062 samples
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[2019/10/14 18:58:50:6132] N: LWS_CALLBACK_RAW_RX_FILE: 2205 samples
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[2019/10/14 18:58:50:7592] N: LWS_CALLBACK_RAW_RX_FILE: 2328 samples
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...
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^C[2019/10/14 18:58:56:8460] N: LWS_CALLBACK_RAW_CLOSE_FILE
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[2019/10/14 18:58:56:8461] N: LWS_CALLBACK_RAW_CLOSE_FILE
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[2019/10/14 18:58:56:8461] N: LWS_CALLBACK_PROTOCOL_DESTROY
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$
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```
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211
minimal-examples/raw/minimal-raw-audio/audio.c
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211
minimal-examples/raw/minimal-raw-audio/audio.c
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@ -0,0 +1,211 @@
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/*
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* lws-minimal-raw-audio
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*
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* Written in 2010-2019 by Andy Green <andy@warmcat.com>
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*
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* This file is made available under the Creative Commons CC0 1.0
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* Universal Public Domain Dedication.
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*
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* This demonstrates adopting and managing audio device file descriptors in the
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* event loop.
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*/
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#include <libwebsockets.h>
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#include <string.h>
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#include <signal.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <fcntl.h>
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#include <alsa/asoundlib.h>
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static unsigned int sample_rate = 16000;
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struct raw_vhd {
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uint8_t simplebuf[32768 * 2];
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snd_pcm_t *pcm_capture;
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snd_pcm_t *pcm_playback;
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snd_pcm_hw_params_t *params;
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snd_pcm_uframes_t frames;
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int filefd;
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int rpos;
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int wpos;
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int times;
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};
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static int
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set_hw_params(struct lws_vhost *vh, snd_pcm_t **pcm, int type)
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{
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unsigned int rate = sample_rate;
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snd_pcm_hw_params_t *params;
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lws_sock_file_fd_type u;
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struct pollfd pfd;
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struct lws *wsi1;
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int n;
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n = snd_pcm_open(pcm, "default", type, SND_PCM_NONBLOCK);
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if (n < 0) {
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lwsl_err("%s: Can't open default for playback: %s\n",
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__func__, snd_strerror(n));
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return -1;
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}
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if (snd_pcm_poll_descriptors(*pcm, &pfd, 1) != 1) {
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lwsl_err("%s: failed to get playback desc\n", __func__);
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return -1;
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}
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u.filefd = (lws_filefd_type)(long long)pfd.fd;
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wsi1 = lws_adopt_descriptor_vhost(vh, LWS_ADOPT_RAW_FILE_DESC, u,
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"lws-audio-test", NULL);
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if (!wsi1) {
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lwsl_err("%s: Failed to adopt playback desc\n", __func__);
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goto bail;
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}
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if (type == SND_PCM_STREAM_PLAYBACK)
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lws_rx_flow_control(wsi1, 0); /* no POLLIN */
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snd_pcm_hw_params_malloc(¶ms);
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snd_pcm_hw_params_any(*pcm, params);
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n = snd_pcm_hw_params_set_access(*pcm, params,
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SND_PCM_ACCESS_RW_INTERLEAVED);
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if (n < 0)
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goto bail1;
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n = snd_pcm_hw_params_set_format(*pcm, params, SND_PCM_FORMAT_S16_LE);
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if (n < 0)
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goto bail1;
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n = snd_pcm_hw_params_set_channels(*pcm, params, 1);
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if (n < 0)
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goto bail1;
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n = snd_pcm_hw_params_set_rate_near(*pcm, params, &rate, 0);
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if (n < 0)
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goto bail1;
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n = snd_pcm_hw_params(*pcm, params);
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snd_pcm_hw_params_free(params);
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if (n < 0)
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goto bail;
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return 0;
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bail1:
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snd_pcm_hw_params_free(params);
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bail:
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lwsl_err("%s: Set hw params failed: %s\n", __func__, snd_strerror(n));
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return -1;
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}
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static int
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callback_raw_test(struct lws *wsi, enum lws_callback_reasons reason,
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void *user, void *in, size_t len)
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{
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struct raw_vhd *vhd = (struct raw_vhd *)lws_protocol_vh_priv_get(
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lws_get_vhost(wsi), lws_get_protocol(wsi));
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int n;
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switch (reason) {
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case LWS_CALLBACK_PROTOCOL_INIT:
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vhd = lws_protocol_vh_priv_zalloc(lws_get_vhost(wsi),
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lws_get_protocol(wsi), sizeof(struct raw_vhd));
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if (set_hw_params(lws_get_vhost(wsi), &vhd->pcm_playback,
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SND_PCM_STREAM_PLAYBACK)) {
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lwsl_err("%s: Can't open default for playback\n",
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__func__);
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return -1;
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}
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if (set_hw_params(lws_get_vhost(wsi), &vhd->pcm_capture,
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SND_PCM_STREAM_CAPTURE)) {
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lwsl_err("%s: Can't open default for capture\n",
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__func__);
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return -1;
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}
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break;
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case LWS_CALLBACK_PROTOCOL_DESTROY:
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lwsl_notice("LWS_CALLBACK_PROTOCOL_DESTROY\n");
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if (vhd && vhd->pcm_playback) {
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snd_pcm_drain(vhd->pcm_playback);
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snd_pcm_close(vhd->pcm_playback);
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vhd->pcm_playback = NULL;
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}
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if (vhd && vhd->pcm_capture) {
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snd_pcm_close(vhd->pcm_capture);
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vhd->pcm_capture = NULL;
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}
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break;
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case LWS_CALLBACK_RAW_RX_FILE:
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if (vhd->times >= 6) { /* delay amount decided by this */
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n = snd_pcm_writei(vhd->pcm_playback,
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&vhd->simplebuf[vhd->rpos],
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((vhd->wpos - vhd->rpos) &
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(sizeof(vhd->simplebuf) - 1)) / 2);
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vhd->rpos = (vhd->rpos + (n * 2)) &
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(sizeof(vhd->simplebuf) - 1);
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}
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n = snd_pcm_readi(vhd->pcm_capture, &vhd->simplebuf[vhd->wpos],
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(sizeof(vhd->simplebuf) - vhd->wpos) / 2);
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lwsl_notice("LWS_CALLBACK_RAW_RX_FILE: %d samples\n", n);
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vhd->times++;
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vhd->wpos = (vhd->wpos + (n * 2)) & (sizeof(vhd->simplebuf) - 1);
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break;
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default:
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break;
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}
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return 0;
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}
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static struct lws_protocols protocols[] = {
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{ "lws-audio-test", callback_raw_test, 0, 0 },
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{ NULL, NULL, 0, 0 } /* terminator */
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};
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static int interrupted;
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void sigint_handler(int sig)
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{
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interrupted = 1;
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}
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int main(int argc, const char **argv)
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{
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struct lws_context_creation_info info;
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struct lws_context *context;
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int n = 0;
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signal(SIGINT, sigint_handler);
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memset(&info, 0, sizeof info);
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lws_cmdline_option_handle_builtin(argc, argv, &info);
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lwsl_user("LWS minimal raw audio\n");
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info.port = CONTEXT_PORT_NO_LISTEN_SERVER;
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info.protocols = protocols;
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context = lws_create_context(&info);
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if (!context) {
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lwsl_err("lws init failed\n");
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return 1;
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}
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while (n >= 0 && !interrupted)
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n = lws_service(context, 0);
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lws_context_destroy(context);
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return 0;
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}
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