static int process_callback(jack_nframes_t nframes, void *arg)
{
/* Warning: this function runs in realtime. One mustn't allocate memory here
* or do any other thing that could block. */
int i, j;
JackData *self = arg;
float * buffer;
jack_nframes_t latency, cycle_delay;
AVPacket pkt;
float *pkt_data;
double cycle_time;
if (!self->client)
return 0;
/* The approximate delay since the hardware interrupt as a number of frames */
cycle_delay = jack_frames_since_cycle_start(self->client);
/* Retrieve filtered cycle time */
cycle_time = ff_timefilter_update(self->timefilter,
av_gettime() / 1000000.0 - (double) cycle_delay / self->sample_rate,
self->buffer_size);
/* Check if an empty packet is available, and if there's enough space to send it back once filled */
if ((av_fifo_size(self->new_pkts) < sizeof(pkt)) || (av_fifo_space(self->filled_pkts) < sizeof(pkt))) {
self->pkt_xrun = 1;
return 0;
}
/* Retrieve empty (but allocated) packet */
av_fifo_generic_read(self->new_pkts, &pkt, sizeof(pkt), NULL);
pkt_data = (float *) pkt.data;
latency = 0;
/* Copy and interleave audio data from the JACK buffer into the packet */
for (i = 0; i < self->nports; i++) {
latency += jack_port_get_total_latency(self->client, self->ports[i]);
buffer = jack_port_get_buffer(self->ports[i], self->buffer_size);
for (j = 0; j < self->buffer_size; j++)
pkt_data[j * self->nports + i] = buffer[j];
}
/* Timestamp the packet with the cycle start time minus the average latency */
pkt.pts = (cycle_time - (double) latency / (self->nports * self->sample_rate)) * 1000000.0;
/* Send the now filled packet back, and increase packet counter */
av_fifo_generic_write(self->filled_pkts, &pkt, sizeof(pkt), NULL);
sem_post(&self->packet_count);
return 0;
}
static int audio_read_packet(AVFormatContext *s1, AVPacket *pkt)
{
AlsaData *s = s1->priv_data;
int res;
int64_t dts;
snd_pcm_sframes_t delay = 0;
if (av_new_packet(pkt, s->period_size * s->frame_size) < 0) {
return AVERROR(EIO);
}
while ((res = snd_pcm_readi(s->h, pkt->data, s->period_size)) < 0) {
if (res == -EAGAIN) {
av_packet_unref(pkt);
return AVERROR(EAGAIN);
}
if (ff_alsa_xrun_recover(s1, res) < 0) {
av_log(s1, AV_LOG_ERROR, "ALSA read error: %s\n",
snd_strerror(res));
av_packet_unref(pkt);
return AVERROR(EIO);
}
ff_timefilter_reset(s->timefilter);
}
dts = av_gettime();
snd_pcm_delay(s->h, &delay);
dts -= av_rescale(delay + res, 1000000, s->sample_rate);
pkt->pts = ff_timefilter_update(s->timefilter, dts, s->last_period);
s->last_period = res;
pkt->size = res * s->frame_size;
return 0;
}
int main(void)
{
AVLFG prng;
double n0,n1;
#define SAMPLES 1000
double ideal[SAMPLES];
double samples[SAMPLES];
#if 1
for(n0= 0; n0<40; n0=2*n0+1){
for(n1= 0; n1<10; n1=2*n1+1){
#else
{{
n0=7;
n1=1;
#endif
double best_error= 1000000000;
double bestpar0=1;
double bestpar1=0.001;
int better, i;
av_lfg_init(&prng, 123);
for(i=0; i<SAMPLES; i++){
ideal[i] = 10 + i + n1*i/(1000);
samples[i] = ideal[i] + n0 * (av_lfg_get(&prng) - LFG_MAX / 2)
/ (LFG_MAX * 10LL);
}
do{
double par0, par1;
better=0;
for(par0= bestpar0*0.8; par0<=bestpar0*1.21; par0+=bestpar0*0.05){
for(par1= bestpar1*0.8; par1<=bestpar1*1.21; par1+=bestpar1*0.05){
double error=0;
TimeFilter *tf= ff_timefilter_new(1, par0, par1);
for(i=0; i<SAMPLES; i++){
double filtered;
filtered= ff_timefilter_update(tf, samples[i], 1);
error += (filtered - ideal[i]) * (filtered - ideal[i]);
}
ff_timefilter_destroy(tf);
if(error < best_error){
best_error= error;
bestpar0= par0;
bestpar1= par1;
better=1;
}
}
}
}while(better);
#if 0
double lastfil=9;
TimeFilter *tf= ff_timefilter_new(1, bestpar0, bestpar1);
for(i=0; i<SAMPLES; i++){
double filtered;
filtered= ff_timefilter_update(tf, samples[i], 1);
printf("%f %f %f %f\n", i - samples[i] + 10, filtered - samples[i], samples[FFMAX(i, 1)] - samples[FFMAX(i-1, 0)], filtered - lastfil);
lastfil= filtered;
}
ff_timefilter_destroy(tf);
#else
printf(" [%f %f %9f]", bestpar0, bestpar1, best_error);
#endif
}
printf("\n");
}
return 0;
}
