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avfilter/avf_showspectrum: add zoom mode to showspectrumpic

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This commit is contained in:
Paul B Mahol 2018-10-05 14:22:07 +02:00
parent 3e687be4fa
commit fe447c0609
2 changed files with 17 additions and 2 deletions

6
doc/filters.texi

@ -20872,6 +20872,12 @@ Draw time and frequency axes and legends. Default is enabled.
@item rotation
Set color rotation, must be in [-1.0, 1.0] range.
Default value is @code{0}.
@item start
Set start frequency from which to display spectrogram. Default is @code{0}.
@item stop
Set stop frequency to which to display spectrogram. Default is @code{0}.
@end table
@subsection Examples

13
libavfilter/avf_showspectrum.c

@ -1128,6 +1128,8 @@ static const AVOption showspectrumpic_options[] = {
{ "gain", "set scale gain", OFFSET(gain), AV_OPT_TYPE_FLOAT, {.dbl = 1}, 0, 128, FLAGS },
{ "legend", "draw legend", OFFSET(legend), AV_OPT_TYPE_BOOL, {.i64 = 1}, 0, 1, FLAGS },
{ "rotation", "color rotation", OFFSET(rotation), AV_OPT_TYPE_FLOAT, {.dbl = 0}, -1, 1, FLAGS },
{ "start", "start frequency", OFFSET(start), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT32_MAX, FLAGS },
{ "stop", "stop frequency", OFFSET(stop), AV_OPT_TYPE_INT, {.i64 = 0}, 0, INT32_MAX, FLAGS },
{ NULL }
};
@ -1240,6 +1242,11 @@ static int showspectrumpic_request_frame(AVFilterLink *outlink)
drawtext(s->outpicref, 2, outlink->h - 10, "CREATED BY LIBAVFILTER", 0);
drawtext(s->outpicref, outlink->w - 2 - strlen(text) * 10, outlink->h - 10, text, 0);
if (s->stop) {
char *text = av_asprintf("Zoom: %d Hz - %d Hz", s->start, s->stop);
drawtext(s->outpicref, outlink->w - 2 - strlen(text) * 10, 3, text, 0);
av_freep(&text);
}
av_freep(&text);
@ -1283,7 +1290,8 @@ static int showspectrumpic_request_frame(AVFilterLink *outlink)
dst[x] = 200;
}
for (y = 0; y < h; y += 40) {
float hertz = y * (inlink->sample_rate / 2) / (float)(1 << (int)ceil(log2(h)));
float range = s->stop ? s->stop - s->start : inlink->sample_rate / 2;
float hertz = s->start + y * range / (float)(1 << (int)ceil(log2(h)));
char *units;
if (hertz == 0)
@ -1348,7 +1356,8 @@ static int showspectrumpic_request_frame(AVFilterLink *outlink)
dst[x] = 200;
}
for (x = 0; x < w - 79; x += 80) {
float hertz = x * (inlink->sample_rate / 2) / (float)(1 << (int)ceil(log2(w)));
float range = s->stop ? s->stop - s->start : inlink->sample_rate / 2;
float hertz = s->start + x * range / (float)(1 << (int)ceil(log2(w)));
char *units;
if (hertz == 0)