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avfilter/af_ladspa: add latency compensation

This commit is contained in:
Paul B Mahol 2020-06-21 21:25:56 +02:00
parent 842bc312ad
commit 683a1599d4
2 changed files with 60 additions and 3 deletions
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3
doc/filters.texi
View File

@ -4197,6 +4197,9 @@ If not specified, or the expressed duration is negative, the audio is
supposed to be generated forever.
Only used if plugin have zero inputs.
@item latency, l
Enable latency compensation, by default is disabled.
Only used if plugin have inputs.
@end table
@subsection Examples

60
libavfilter/af_ladspa.c
View File

@ -64,6 +64,9 @@ typedef struct LADSPAContext {
int nb_samples;
int64_t pts;
int64_t duration;
int in_trim;
int out_pad;
int latency;
} LADSPAContext;
#define OFFSET(x) offsetof(LADSPAContext, x)
@ -81,11 +84,28 @@ static const AVOption ladspa_options[] = {
{ "n", "set the number of samples per requested frame", OFFSET(nb_samples), AV_OPT_TYPE_INT, {.i64=1024}, 1, INT_MAX, FLAGS },
{ "duration", "set audio duration", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64=-1}, -1, INT64_MAX, FLAGS },
{ "d", "set audio duration", OFFSET(duration), AV_OPT_TYPE_DURATION, {.i64=-1}, -1, INT64_MAX, FLAGS },
{ "latency", "enable latency compensation", OFFSET(latency), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },
{ "l", "enable latency compensation", OFFSET(latency), AV_OPT_TYPE_BOOL, {.i64=0}, 0, 1, FLAGS },
{ NULL }
};
AVFILTER_DEFINE_CLASS(ladspa);
static int find_latency(AVFilterContext *ctx, LADSPAContext *s)
{
int latency = 0;
for (int ctl = 0; ctl < s->nb_outputcontrols; ctl++) {
if (av_strcasecmp("latency", s->desc->PortNames[s->ocmap[ctl]]))
continue;
latency = lrintf(s->octlv[ctl]);
break;
}
return latency;
}
static void print_ctl_info(AVFilterContext *ctx, int level,
LADSPAContext *s, int ctl, unsigned long *map,
LADSPA_Data *values, int print)
@ -143,12 +163,13 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
AVFilterContext *ctx = inlink->dst;
LADSPAContext *s = ctx->priv;
AVFrame *out;
int i, h, p;
int i, h, p, new_out_samples;
av_assert0(in->channels == (s->nb_inputs * s->nb_handles));
if (!s->nb_outputs ||
(av_frame_is_writable(in) && s->nb_inputs == s->nb_outputs &&
s->in_trim == 0 && s->out_pad == 0 &&
!(s->desc->Properties & LADSPA_PROPERTY_INPLACE_BROKEN))) {
out = in;
} else {
@ -176,6 +197,9 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
}
s->desc->run(s->handles[h], in->nb_samples);
if (s->latency)
s->in_trim = s->out_pad = find_latency(ctx, s);
s->latency = 0;
}
for (i = 0; i < s->nb_outputcontrols; i++)
@ -184,6 +208,25 @@ static int filter_frame(AVFilterLink *inlink, AVFrame *in)
if (out != in)
av_frame_free(&in);
new_out_samples = out->nb_samples;
if (s->in_trim > 0) {
int trim = FFMIN(new_out_samples, s->in_trim);
new_out_samples -= trim;
s->in_trim -= trim;
}
if (new_out_samples <= 0) {
av_frame_free(&out);
return 0;
} else if (new_out_samples < out->nb_samples) {
int offset = out->nb_samples - new_out_samples;
for (int ch = 0; ch < out->channels; ch++)
memmove(out->extended_data[ch], out->extended_data[ch] + sizeof(float) * offset,
sizeof(float) * new_out_samples);
out->nb_samples = new_out_samples;
}
return ff_filter_frame(ctx->outputs[0], out);
}
@ -195,8 +238,19 @@ static int request_frame(AVFilterLink *outlink)
int64_t t;
int i;
if (ctx->nb_inputs)
return ff_request_frame(ctx->inputs[0]);
if (ctx->nb_inputs) {
int ret = ff_request_frame(ctx->inputs[0]);
if (ret == AVERROR_EOF && s->out_pad > 0) {
AVFrame *frame = ff_get_audio_buffer(outlink, FFMIN(2048, s->out_pad));
if (!frame)
return AVERROR(ENOMEM);
s->out_pad -= frame->nb_samples;
return filter_frame(ctx->inputs[0], frame);
}
return ret;
}
t = av_rescale(s->pts, AV_TIME_BASE, s->sample_rate);
if (s->duration >= 0 && t >= s->duration)