Hacky workaround for FFmpeg not having a channel layout for any counts between 8 and 16.

3 files changed, 35 insertions, 6 deletions

diff --git a/src/lib/analyse_audio_job.cc b/src/lib/analyse_audio_job.cc
index 769f3762b..d17c4c30b 100644
--- a/src/lib/analyse_audio_job.cc
+++ b/src/lib/analyse_audio_job.cc
@@ -56,7 +56,7 @@ AnalyseAudioJob::AnalyseAudioJob (shared_ptr<const Film> film, shared_ptr<const
 	, _sample_peak (0)
 	, _sample_peak_frame (0)
 #ifdef DCPOMATIC_HAVE_PATCHED_FFMPEG
-	, _ebur128 (new AudioFilterGraph (film->audio_frame_rate(), av_get_default_channel_layout(film->audio_channels())))
+	, _ebur128 (new AudioFilterGraph (film->audio_frame_rate(), film->audio_channels()))
 #endif
 {
 #ifdef DCPOMATIC_HAVE_PATCHED_FFMPEG
diff --git a/src/lib/audio_filter_graph.cc b/src/lib/audio_filter_graph.cc
index fd2492d3b..a43f1881e 100644
--- a/src/lib/audio_filter_graph.cc
+++ b/src/lib/audio_filter_graph.cc
@@ -31,10 +31,19 @@ using std::string;
 using std::cout;
 using boost::shared_ptr;
 
-AudioFilterGraph::AudioFilterGraph (int sample_rate, int64_t channel_layout)
+AudioFilterGraph::AudioFilterGraph (int sample_rate, int channels)
 	: _sample_rate (sample_rate)
-	, _channel_layout (channel_layout)
+	, _channels (channels)
 {
+	/* FFmpeg doesn't know any channel layouts for any counts between 8 and 16,
+	   so we need to tell it we're using 16 channels if we are using more than 8.
+	*/
+	if (_channels > 8) {
+		_channel_layout = av_get_default_channel_layout (16);
+	} else {
+		_channel_layout = av_get_default_channel_layout (_channels);
+	}
+
 	_in_frame = av_frame_alloc ();
 }
 
@@ -95,7 +104,26 @@ AudioFilterGraph::sink_name () const
 void
 AudioFilterGraph::process (shared_ptr<const AudioBuffers> buffers)
 {
-	_in_frame->extended_data = new uint8_t*[buffers->channels()];
+	int const process_channels = av_get_channel_layout_nb_channels (_channel_layout);
+	DCPOMATIC_ASSERT (process_channels >= buffers->channels());
+
+	if (buffers->channels() < process_channels) {
+		/* We are processing more data than we actually have (see the hack in
+		   the constructor) so we need to create new buffers with some extra
+		   silent channels.
+		*/
+		shared_ptr<AudioBuffers> extended_buffers (new AudioBuffers (process_channels, buffers->frames()));
+		for (int i = 0; i < buffers->channels(); ++i) {
+			extended_buffers->copy_channel_from (buffers.get(), i, i);
+		}
+		for (int i = buffers->channels(); i < process_channels; ++i) {
+			extended_buffers->make_silent (i);
+		}
+
+		buffers = extended_buffers;
+	}
+
+	_in_frame->extended_data = new uint8_t*[process_channels];
 	for (int i = 0; i < buffers->channels(); ++i) {
 		if (i < AV_NUM_DATA_POINTERS) {
 			_in_frame->data[i] = reinterpret_cast<uint8_t*> (buffers->data(i));
@@ -107,7 +135,7 @@ AudioFilterGraph::process (shared_ptr<const AudioBuffers> buffers)
 	_in_frame->format = AV_SAMPLE_FMT_FLTP;
 	_in_frame->sample_rate = _sample_rate;
 	_in_frame->channel_layout = _channel_layout;
-	_in_frame->channels = av_get_channel_layout_nb_channels (_channel_layout);
+	_in_frame->channels = process_channels;
 
 	int r = av_buffersrc_write_frame (_buffer_src_context, _in_frame);
 
diff --git a/src/lib/audio_filter_graph.h b/src/lib/audio_filter_graph.h
index 8efff5d8d..90518e2ed 100644
--- a/src/lib/audio_filter_graph.h
+++ b/src/lib/audio_filter_graph.h
@@ -27,7 +27,7 @@ class AudioBuffers;
 class AudioFilterGraph : public FilterGraph
 {
 public:
-	AudioFilterGraph (int sample_rate, int64_t channel_layout);
+	AudioFilterGraph (int sample_rate, int channels);
 	~AudioFilterGraph ();
 
 	void process (boost::shared_ptr<const AudioBuffers> audio);
@@ -40,6 +40,7 @@ protected:
 
 private:
 	int _sample_rate;
+	int _channels;
 	int64_t _channel_layout;
 	AVFrame* _in_frame;
 };