ExternalVendorCode/genode
1
0
Fork 0
mirror of https://github.com/genodelabs/genode.git synced 2025-02-20 17:52:52 +00:00
Code Issues Actions Packages Projects Releases Wiki Activity

libports: fix delay in SDL audio backend

Browse Source 
Instead of using the 'alloc()' method to allocate new packets use
the 'next()' method with the previous packet. This is needed because
the last audio stack changes broke the semantics assumed by 'alloc()'.

We now keep track of the already queued packets by hand.

Fixes #1827.
This commit is contained in:
Josef Söntgen 2015-12-17 18:56:34 +01:00 committed by Christian Helmuth
parent 56c637c1f6
commit 9fb08e045a
1 changed files with 40 additions and 31 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

71
repos/libports/src/lib/sdl/audio/SDL_genodeaudio.cc
View File

@ -56,6 +56,7 @@ struct SDL_PrivateAudioData {
Uint8 *mixbuf;
Uint32 mixlen;
Audio_out::Connection *audio[AUDIO_CHANNELS];
Audio_out::Packet *packet[AUDIO_CHANNELS];
};
@ -146,7 +147,8 @@ static SDL_AudioDevice *GENODEAUD_CreateDevice(int devindex)
for (int channel = 0; channel < AUDIO_CHANNELS; channel++) {
try {
_this->hidden->audio[channel] = new (env()->heap())
Audio_out::Connection(channel_names[channel]);
Audio_out::Connection(channel_names[channel],
false, channel == 0 ? true : false);
_this->hidden->audio[channel]->start();
} catch(Genode::Parent::Service_denied) {
PERR("Could not connect to 'Audio_out' service.");
@ -171,47 +173,48 @@ AudioBootStrap GENODEAUD_bootstrap = {
};
/* This function waits until it is possible to write a full sound buffer */
static void GENODEAUD_WaitAudio(_THIS)
{
for (int channel = 0; channel < AUDIO_CHANNELS; channel++) {
Audio_out::Connection *connection = _this->hidden->audio[channel];
Audio_out::Connection *con = _this->hidden->audio[0];
Audio_out::Packet *p = _this->hidden->packet[0];
/* wait until allocation is possible */
if (connection->stream()->full())
connection->wait_for_alloc();
unsigned const packet_pos = con->stream()->packet_position(p);
unsigned const play_pos = con->stream()->pos();
unsigned queued = packet_pos < play_pos
? ((Audio_out::QUEUE_SIZE + packet_pos) - play_pos)
: packet_pos - play_pos;
/* wait until there is only one packet left to play */
while (queued > 1) {
con->wait_for_progress();
queued--;
}
}
static void GENODEAUD_PlayAudio(_THIS)
{
/*
* Synchronize the play pointer when this function is first called
*/
static bool initial_reset = true;
if (initial_reset) {
for (int channel = 0; channel < AUDIO_CHANNELS; channel++) {
Audio_out::Connection *connection = _this->hidden->audio[channel];
connection->stream()->reset();
}
initial_reset = false;
Audio_out::Connection *c[AUDIO_CHANNELS];
Audio_out::Packet *p[AUDIO_CHANNELS];
for (int channel = 0; channel < AUDIO_CHANNELS; channel++) {
c[channel] = _this->hidden->audio[channel];
p[channel] = _this->hidden->packet[channel];
}
Audio_out::Packet *p[AUDIO_CHANNELS];
/* get the currently played packet initially */
static bool init = false;
if (!init) {
p[0] = c[0]->stream()->next();
init = true;
}
for (int channel = 0; channel < AUDIO_CHANNELS; channel++)
while (1) {
Audio_out::Connection *connection = _this->hidden->audio[channel];
try {
p[channel] = connection->stream()->alloc();
break;
} catch (Audio_out::Stream::Alloc_failed) {
/* wait for next finished packet */
connection->wait_for_alloc();
}
}
/*
* Get new packet for left channel and use it to synchronize
* the right channel
*/
p[0] = c[0]->stream()->next(p[0]);
unsigned ppos = c[0]->stream()->packet_position(p[0]);
p[1] = c[1]->stream()->get(ppos);
if (signal_receiver()->pending()) {
signal_receiver()->wait_for_signal();
@ -224,8 +227,14 @@ static void GENODEAUD_PlayAudio(_THIS)
p[channel]->content()[sample] =
volume * (float)(((int16_t*)_this->hidden->mixbuf)[sample * AUDIO_CHANNELS + channel]) / 32768;
for (int channel = 0; channel < AUDIO_CHANNELS; channel++)
for (int channel = 0; channel < AUDIO_CHANNELS; channel++) {
_this->hidden->audio[channel]->submit(p[channel]);
/*
* Save current packet to query packet position next time and
* when in GENODEAUD_WaitAudio
*/
_this->hidden->packet[channel] = p[channel];
}
}