diff --git a/libs/ardour/ardour/export_graph_builder.h b/libs/ardour/ardour/export_graph_builder.h
index a91858ee31..8fe3bb8a83 100644
--- a/libs/ardour/ardour/export_graph_builder.h
+++ b/libs/ardour/ardour/export_graph_builder.h
@@ -136,6 +136,7 @@ class LIBARDOUR_API ExportGraphBuilder
 		void remove_children (bool remove_out_files);
 		bool operator== (FileSpec const & other_config) const;
 
+		void set_duration (samplecnt_t);
 		void set_peak_dbfs (float, bool force = false);
 		void set_peak_lufs (AudioGrapher::LoudnessReader const&);
 
diff --git a/libs/ardour/export_graph_builder.cc b/libs/ardour/export_graph_builder.cc
index 0fbd997f9a..0d12cf6a5c 100644
--- a/libs/ardour/export_graph_builder.cc
+++ b/libs/ardour/export_graph_builder.cc
@@ -452,6 +452,7 @@ ExportGraphBuilder::SFC::SFC (ExportGraphBuilder &parent, FileSpec const & new_c
 		samplecnt_t sb = config.format->silence_beginning_at (parent.timespan->get_start(), sample_rate);
 		samplecnt_t se = config.format->silence_end_at (parent.timespan->get_end(), sample_rate);
 		samplecnt_t duration = parent.timespan->get_length () + sb + se;
+
 		max_samples = std::min ((samplecnt_t) 8192 * channels, std::max ((samplecnt_t) 4096 * channels, max_samples));
 		chunker.reset (new Chunker<Sample> (max_samples));
 		analyser.reset (new Analyser (config.format->sample_rate(), channels, max_samples,
@@ -502,6 +503,15 @@ ExportGraphBuilder::SFC::SFC (ExportGraphBuilder &parent, FileSpec const & new_c
 	}
 }
 
+void
+ExportGraphBuilder::SFC::set_duration (samplecnt_t n_samples)
+{
+	/* update after silence trim */
+	if (analyser) {
+		analyser->set_duration (n_samples);
+	}
+}
+
 void
 ExportGraphBuilder::SFC::set_peak_dbfs (float peak, bool force)
 {
@@ -704,14 +714,13 @@ ExportGraphBuilder::Intermediate::process()
 void
 ExportGraphBuilder::Intermediate::prepare_post_processing()
 {
-	if (use_loudness || use_peak) {
-		for (boost::ptr_list<SFC>::iterator i = children.begin(); i != children.end(); ++i) {
-			if (use_peak) {
-				(*i).set_peak_dbfs (peak_reader->get_peak());
-			}
-			if (use_loudness) {
-				(*i).set_peak_lufs (*loudness_reader);
-			}
+	for (boost::ptr_list<SFC>::iterator i = children.begin(); i != children.end(); ++i) {
+		(*i).set_duration (tmp_file->get_samples_written() / config.channel_config->get_n_chans());
+		if (use_peak) {
+			(*i).set_peak_dbfs (peak_reader->get_peak());
+		}
+		if (use_loudness) {
+			(*i).set_peak_lufs (*loudness_reader);
 		}
 	}
 
diff --git a/libs/audiographer/audiographer/general/analyser.h b/libs/audiographer/audiographer/general/analyser.h
index 6271231432..c7b2a72b8c 100644
--- a/libs/audiographer/audiographer/general/analyser.h
+++ b/libs/audiographer/audiographer/general/analyser.h
@@ -34,6 +34,8 @@ class LIBAUDIOGRAPHER_API Analyser : public LoudnessReader
 	void process (ProcessContext<float> const & c);
 	ARDOUR::ExportAnalysisPtr result ();
 
+	void set_duration (samplecnt_t n_samples);
+
 	void set_normalization_gain (float gain) {
 		_result.normalized = true;
 		_result.norm_gain_factor = gain;
diff --git a/libs/audiographer/src/general/analyser.cc b/libs/audiographer/src/general/analyser.cc
index 73f3422f95..60a1c934bf 100644
--- a/libs/audiographer/src/general/analyser.cc
+++ b/libs/audiographer/src/general/analyser.cc
@@ -33,15 +33,7 @@ Analyser::Analyser (float sample_rate, unsigned int channels, samplecnt_t bufsiz
 	assert (bufsize > 1);
 	assert (_bufsize > 0);
 
-
-
-	const size_t peaks = sizeof (_result.peaks) / sizeof (ARDOUR::PeakData::PeakDatum) / 4;
-	_spp = ceil ((_n_samples + 2.f) / (float) peaks);
-
-	const size_t swh = sizeof (_result.spectrum) / sizeof (float);
-	const size_t height = sizeof (_result.spectrum[0]) / sizeof (float);
-	const size_t width = swh / height;
-	_fpp = ceil ((_n_samples + 2.f) / (float) width);
+	set_duration (n_samples);
 
 	_fft_data_size   = _bufsize / 2;
 	_fft_freq_per_bin = sample_rate / _fft_data_size / 2.f;
@@ -57,6 +49,7 @@ Analyser::Analyser (float sample_rate, unsigned int channels, samplecnt_t bufsiz
 		_fft_data_out[i] = 0;
 	}
 
+	const size_t height = sizeof (_result.spectrum[0]) / sizeof (float);
 	const float nyquist = (sample_rate * .5);
 #if 0 // linear
 #define YPOS(FREQ) rint (height * (1.0 - FREQ / nyquist))
@@ -101,6 +94,23 @@ Analyser::~Analyser ()
 	free (_hann_window);
 }
 
+void
+Analyser::set_duration (samplecnt_t n_samples)
+{
+	if (_pos != 0) {
+		return;
+	}
+	_n_samples = n_samples;
+
+	const size_t peaks = sizeof (_result.peaks) / sizeof (ARDOUR::PeakData::PeakDatum) / 4;
+	_spp = ceil ((_n_samples + 2.f) / (float) peaks);
+
+	const size_t swh = sizeof (_result.spectrum) / sizeof (float);
+	const size_t height = sizeof (_result.spectrum[0]) / sizeof (float);
+	const size_t width = swh / height;
+	_fpp = ceil ((_n_samples + 2.f) / (float) width);
+}
+
 void
 Analyser::process (ProcessContext<float> const & ctx)
 {