[vlc-devel] [PATCH v2 18/18] audio_output: Add PPAPI plugin

Dennis Hamester dennis.hamester at startmail.com
Mon Mar 13 11:11:52 CET 2017


From: Julian Scheel <julian at jusst.de>

Audio output using PPAPI to allow audio output when running as
NativeClient.

Signed-off-by: Julian Scheel <julian at jusst.de>
---
 modules/audio_output/Makefile.am |   8 ++
 modules/audio_output/ppapi.c     | 261 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 269 insertions(+)
 create mode 100644 modules/audio_output/ppapi.c

diff --git a/modules/audio_output/Makefile.am b/modules/audio_output/Makefile.am
index 9006c257cb..7859de936e 100644
--- a/modules/audio_output/Makefile.am
+++ b/modules/audio_output/Makefile.am
@@ -12,6 +12,14 @@ if HAVE_ANDROID
 aout_LTLIBRARIES += libandroid_audiotrack_plugin.la libopensles_android_plugin.la
 endif
 
+libppapi_audio_plugin_la_SOURCES = audio_output/ppapi.c
+libppapi_audio_plugin_la_CFLAGS = $(AM_CFLAGS)
+libppapi_audio_plugin_la_LIBADD = $(LIBS_nacl)
+
+if HAVE_NACL
+aout_LTLIBRARIES += libppapi_audio_plugin.la
+endif
+
 libadummy_plugin_la_SOURCES = audio_output/adummy.c
 
 libafile_plugin_la_SOURCES = audio_output/file.c
diff --git a/modules/audio_output/ppapi.c b/modules/audio_output/ppapi.c
new file mode 100644
index 0000000000..16aa08cc98
--- /dev/null
+++ b/modules/audio_output/ppapi.c
@@ -0,0 +1,261 @@
+/*****************************************************************************
+ * ppapi.c: Audio output using PPAPI on NativeClient
+ *****************************************************************************
+ * Copyright © 2017 VLC authors and VideoLAN
+ *
+ * Authors: Julian Scheel <julian at jusst.de>
+ *
+ * This program is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation; either version 2.1 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+#ifdef HAVE_CONFIG_H
+# include "config.h"
+#endif
+
+#include <vlc_common.h>
+#include <vlc_atomic.h>
+#include <vlc_plugin.h>
+#include <vlc_aout.h>
+#include <vlc_block_helper.h>
+#include <vlc_plugin.h>
+#include <vlc_threads.h>
+
+#include <ppapi/c/pp_instance.h>
+#include <ppapi/c/ppb_audio_config.h>
+#include <ppapi/c/ppb_audio.h>
+#include <ppapi/c/ppb_core.h>
+#include <ppapi/c/ppb.h>
+
+/*****************************************************************************
+ * Module descriptor
+ *****************************************************************************/
+static int Open(vlc_object_t *);
+static void Close(vlc_object_t *);
+
+vlc_module_begin()
+    set_shortname("PPAPI aout")
+    set_description(N_("PPAPI based audio output"))
+    set_category(CAT_AUDIO)
+    set_subcategory(SUBCAT_AUDIO_AOUT)
+
+    set_capability("audio output", 50)
+    set_callbacks(Open, Close)
+vlc_module_end()
+
+/*****************************************************************************
+ * Local prototypes.
+ *****************************************************************************/
+struct aout_sys_t
+{
+    block_bytestream_t data;
+
+    atomic_bool flushing;
+    vlc_cond_t flushed_signal;
+    vlc_mutex_t mutex;
+
+    vlc_atomic_float latency;
+    unsigned samplerate;
+
+    PP_Instance instance;
+    PP_Resource config;
+    PP_Resource context;
+
+    PPB_AudioConfig *audioconfig;
+    PPB_Audio *audio;
+    PPB_Core *core;
+};
+
+/*****************************************************************************
+ * Implementation
+ *****************************************************************************/
+static void ppapi_audio_callback(void *sample_buffer,
+        uint32_t buffer_size_in_bytes, PP_TimeDelta latency, void* user_data)
+{
+    audio_output_t *aout = user_data;
+    aout_sys_t *sys = aout->sys;
+
+    vlc_atomic_store_float(&sys->latency, latency);
+
+    if (block_GetBytes(&sys->data, sample_buffer, buffer_size_in_bytes) != VLC_SUCCESS) {
+        if (atomic_load(&sys->flushing)) {
+            block_BytestreamEmpty(&sys->data);
+            vlc_mutex_lock(&sys->mutex);
+            vlc_cond_signal(&sys->flushed_signal);
+            vlc_mutex_unlock(&sys->mutex);
+        } else {
+            memset(sample_buffer, 0x00, buffer_size_in_bytes);
+        }
+    }
+
+    block_BytestreamFlush(&sys->data);
+}
+
+static int Start(audio_output_t *aout, audio_sample_format_t *restrict fmt)
+{
+    aout_sys_t *sys = aout->sys;
+
+    sys->samplerate = fmt->i_rate;
+
+    /* Create audio config */
+    uint32_t sample_frame_count = sys->audioconfig->RecommendSampleFrameCount(
+            sys->instance, sys->samplerate, 512);
+
+    msg_Dbg(aout, "Using sample_frame_count of %u", sample_frame_count);
+
+    sys->config = sys->audioconfig->CreateStereo16Bit(sys->instance,
+            sys->samplerate, sample_frame_count);
+    if (unlikely(sys->config) == 0) {
+        msg_Err(aout, "Could not create PPAPI audio config");
+        goto error;
+    }
+
+    /* Create audio context */
+    sys->context = sys->audio->Create(sys->instance, sys->config,
+            ppapi_audio_callback, aout);
+    if (unlikely(sys->context) == 0) {
+        msg_Err(aout, "Could not create PPAPI audio resource");
+        goto error;
+    }
+
+    /* Enforce stereo output S16N output */
+    fmt->i_format = VLC_CODEC_S16N;
+    fmt->i_original_channels = fmt->i_physical_channels = AOUT_CHAN_LEFT | AOUT_CHAN_RIGHT;
+
+    sys->audio->StartPlayback(sys->context);
+
+    return VLC_SUCCESS;
+
+error:
+    if (sys->config != 0)
+        sys->core->ReleaseResource(sys->config);
+
+    return VLC_EGENERIC;
+}
+
+static void Stop(audio_output_t *aout)
+{
+    aout_sys_t *sys = aout->sys;
+
+    if (unlikely(sys->context == 0))
+        return;
+
+    if (sys->audio->StopPlayback(sys->context) != PP_TRUE)
+        msg_Warn(aout, "Failed to stop playback");
+
+    sys->core->ReleaseResource(sys->context);
+    sys->context = 0;
+}
+
+static int TimeGet(audio_output_t *aout, mtime_t *delay)
+{
+    aout_sys_t *sys = aout->sys;
+
+    *delay = vlc_atomic_load_float(&sys->latency) * CLOCK_FREQ +
+        (block_BytestreamRemaining(&sys->data) / 4) * CLOCK_FREQ / sys->samplerate;
+
+    return VLC_SUCCESS;
+}
+
+static void Play(audio_output_t *aout, block_t *block)
+{
+    aout_sys_t *sys = aout->sys;
+
+    block_BytestreamPush(&sys->data, block);
+}
+
+static void Flush(audio_output_t *aout, bool wait)
+{
+    aout_sys_t *sys = aout->sys;
+
+    if (wait) {
+        atomic_store(&sys->flushing, true);
+        vlc_mutex_lock(&sys->mutex);
+        vlc_cond_wait(&sys->flushed_signal, &sys->mutex);
+        vlc_mutex_unlock(&sys->mutex);
+        atomic_store(&sys->flushing, false);
+    } else {
+        block_BytestreamEmpty(&sys->data);
+    }
+}
+
+static int Open(vlc_object_t *obj)
+{
+    audio_output_t *aout = (audio_output_t *)obj;
+    aout_sys_t *sys;
+
+    sys = calloc(1, sizeof(*sys));
+    if (unlikely(sys == NULL))
+        return VLC_ENOMEM;
+    aout->sys = sys;
+
+    PPB_GetInterface ppb_get_interface = var_InheritAddress(obj, "ppapi-ppb-get-interface");
+    if (ppb_get_interface == NULL) {
+        msg_Err(aout, "Variable ppapi-ppb-get-interface is not set");
+        goto error;
+    }
+
+    sys->instance = (int)var_InheritInteger(obj, "ppapi-instance");
+    if (unlikely(sys->instance == 0)) {
+        msg_Err(aout, "Variable ppapi-instance is not set");
+        goto error;
+    }
+
+    sys->core = (PPB_Core*)ppb_get_interface(PPB_CORE_INTERFACE);
+    if (sys->core == NULL) {
+        msg_Err(aout, "Failed to get PPB_CORE_INTERFACE");
+        goto error;
+    }
+
+    sys->audio = (PPB_Audio*)ppb_get_interface(PPB_AUDIO_INTERFACE);
+    if (unlikely(sys->audio == NULL)) {
+        msg_Err(aout, "Failed to get PPB_AUDIO_INTERFACE");
+        goto error;
+    }
+
+    sys->audioconfig = (PPB_AudioConfig*)ppb_get_interface(PPB_AUDIO_CONFIG_INTERFACE);
+    if (unlikely(sys->audioconfig == NULL)) {
+        msg_Err(aout, "Failed to get PPB_AUDIO_CONFIG_INTERFACE");
+        goto error;
+    }
+
+    block_BytestreamInit(&sys->data);
+
+    aout->start = Start;
+    aout->stop = Stop;
+    aout->time_get = TimeGet;
+    aout->play = Play;
+    aout->flush = Flush;
+
+    return VLC_SUCCESS;
+
+error:
+    Close(obj);
+    return VLC_EGENERIC;
+}
+
+static void Close(vlc_object_t *obj)
+{
+    audio_output_t *aout = (audio_output_t *)obj;
+    aout_sys_t *sys = aout->sys;
+
+    block_BytestreamRelease(&sys->data);
+
+    if (sys->context != 0)
+        sys->core->ReleaseResource(sys->context);
+
+    if (sys->config != 0)
+        sys->core->ReleaseResource(sys->config);
+
+    free(sys);
+}
-- 
2.12.0



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