From fa2969355054abbf1586684f712eda9468351118 Mon Sep 17 00:00:00 2001
From: Max Kellermann <max.kellermann@gmail.com>
Date: Wed, 30 Oct 2024 22:46:07 +0100
Subject: [PATCH] filter/ffmpeg: implement method Flush()

---
 src/filter/plugins/FfmpegFilter.cxx | 15 +++++++++++++++
 src/filter/plugins/FfmpegFilter.hxx |  3 +++
 2 files changed, 18 insertions(+)

diff --git a/src/filter/plugins/FfmpegFilter.cxx b/src/filter/plugins/FfmpegFilter.cxx
index 392fee22e..afec2455b 100644
--- a/src/filter/plugins/FfmpegFilter.cxx
+++ b/src/filter/plugins/FfmpegFilter.cxx
@@ -52,6 +52,8 @@ FfmpegFilter::ReadOutput()
 std::span<const std::byte>
 FfmpegFilter::FilterPCM(std::span<const std::byte> src)
 {
+	assert(!flushed);
+
 	/* submit source data into the FFmpeg audio buffer source */
 
 	frame.Unref();
@@ -78,3 +80,16 @@ FfmpegFilter::FilterPCM(std::span<const std::byte> src)
 
 	return ReadOutput();
 }
+
+std::span<const std::byte>
+FfmpegFilter::Flush()
+{
+	if (!flushed) {
+		if (int err = av_buffersrc_add_frame(&buffer_src, nullptr); err < 0)
+			throw MakeFfmpegError(err, "av_buffersrc_write_frame() failed");
+
+		flushed = true;
+	}
+
+	return ReadOutput();
+}
diff --git a/src/filter/plugins/FfmpegFilter.hxx b/src/filter/plugins/FfmpegFilter.hxx
index 7885850e6..eeac8b76a 100644
--- a/src/filter/plugins/FfmpegFilter.hxx
+++ b/src/filter/plugins/FfmpegFilter.hxx
@@ -30,6 +30,8 @@ class FfmpegFilter final : public Filter {
 	const size_t in_audio_frame_size;
 	const size_t out_audio_frame_size;
 
+	bool flushed = false;
+
 public:
 	/**
 	 * @param _graph a checked and configured AVFilterGraph
@@ -46,6 +48,7 @@ public:
 
 	/* virtual methods from class Filter */
 	std::span<const std::byte> FilterPCM(std::span<const std::byte> src) override;
+	std::span<const std::byte> Flush() override;
 
 private:
 	std::span<const std::byte> ReadOutput();