From bb4394b8a521a544861ddccbf7f0208dc4c5943f Mon Sep 17 00:00:00 2001
From: Robin Gareus <robin@gareus.org>
Date: Wed, 4 Jan 2023 17:26:43 +0100
Subject: [PATCH] Use pipe through ffmpeg, use glib to write output

This is intended to fix an issue with odd filenames on Windows,
particularly forward and backwards single quotes as part of a filename.

Previously the filename was passed as parameter to ffmpeg as
UTF-8 string to SystemExec::make_wargs, which is fragile on Windows
in absence of a execve() call.
---
 libs/ardour/export_graph_builder.cc           | 12 +++---
 .../audiographer/general/cmdpipe_writer.h     | 38 +++++++++++++++++--
 2 files changed, 42 insertions(+), 8 deletions(-)

diff --git a/libs/ardour/export_graph_builder.cc b/libs/ardour/export_graph_builder.cc
index 578432857c..d000c6ac82 100644
--- a/libs/ardour/export_graph_builder.cc
+++ b/libs/ardour/export_graph_builder.cc
@@ -398,7 +398,11 @@ ExportGraphBuilder::Encoder::init_writer (boost::shared_ptr<AudioGrapher::CmdPip
 	argp[a++] = strdup ("-i");
 	argp[a++] = strdup ("pipe:0");
 
-	argp[a++] = strdup ("-y");
+	argp[a++] = strdup ("-f");
+	argp[a++] = strdup ("mp3");
+	argp[a++] = strdup ("-acodec");
+	argp[a++] = strdup ("mp3");
+
 	if (quality <= 0) {
 		/* variable rate, lower is better */
 		snprintf (tmp, sizeof(tmp), "%d", -quality);
@@ -422,16 +426,14 @@ ExportGraphBuilder::Encoder::init_writer (boost::shared_ptr<AudioGrapher::CmdPip
 		argp[a++] = SystemExec::format_key_value_parameter (it->first.c_str(), it->second.c_str());
 	}
 
-	argp[a++] = strdup (writer_filename.c_str());
+	argp[a++] = strdup ("pipe:1");
 	argp[a] = (char *)0;
 
 	/* argp is free()d in ~SystemExec,
 	 * SystemExec is deleted when writer is destroyed */
 	ARDOUR::SystemExec* exec = new ARDOUR::SystemExec (ffmpeg_exe, argp, true);
+
 	PBD::info << "Encode command: { " << exec->to_s () << "}" << endmsg;
-	if (exec->start (SystemExec::MergeWithStdin)) {
-		throw ExportFailed ("External encoder (ffmpeg) cannot be started.");
-	}
 	writer.reset (new AudioGrapher::CmdPipeWriter<T> (exec, writer_filename));
 	writer->FileWritten.connect_same_thread (copy_files_connection, boost::bind (&ExportGraphBuilder::Encoder::copy_files, this, _1));
 }
diff --git a/libs/audiographer/audiographer/general/cmdpipe_writer.h b/libs/audiographer/audiographer/general/cmdpipe_writer.h
index 74dc604b8b..d88eab2d60 100644
--- a/libs/audiographer/audiographer/general/cmdpipe_writer.h
+++ b/libs/audiographer/audiographer/general/cmdpipe_writer.h
@@ -3,14 +3,18 @@
 
 #include <string>
 
+#include <glib.h>
 #include <boost/format.hpp>
 
 #include "audiographer/flag_debuggable.h"
 #include "audiographer/sink.h"
 #include "audiographer/types.h"
 
+#include "pbd/gstdio_compat.h"
 #include "pbd/signals.h"
-#include "pbd/system_exec.h"
+
+#include "ardour/system_exec.h"
+#include "ardour/export_failed.h"
 
 namespace AudioGrapher
 {
@@ -25,16 +29,31 @@ class CmdPipeWriter
   , public FlagDebuggable<>
 {
 public:
-	CmdPipeWriter (PBD::SystemExec* proc, std::string const& path)
+	CmdPipeWriter (ARDOUR::SystemExec* proc, std::string const& path)
 		: samples_written (0)
 		, _proc (proc)
 		, _path (path)
 	{
 		add_supported_flag (ProcessContext<T>::EndOfInput);
+
+		proc->ReadStdout.connect_same_thread (exec_connections, boost::bind (&CmdPipeWriter::write_ffile, this, _1, _2));
+		proc->Terminated.connect_same_thread (exec_connections, boost::bind (&CmdPipeWriter::close_ffile, this));
+
+		encoder_file = g_fopen (path.c_str(), "wb");
+
+		if (!encoder_file) {
+			throw ARDOUR::ExportFailed ("Output file cannot be written to.");
+		}
+
+		if (proc->start (ARDOUR::SystemExec::IgnoreAndClose)) {
+			fclose (encoder_file);
+			throw ARDOUR::ExportFailed ("External encoder (ffmpeg) cannot be started.");
+		}
 	}
 
 	virtual ~CmdPipeWriter () {
 		delete _proc;
+		assert (!encoder_file);
 	}
 
 	samplecnt_t get_samples_written() const { return samples_written; }
@@ -65,7 +84,6 @@ public:
 
 		if (c.has_flag(ProcessContext<T>::EndOfInput)) {
 			_proc->close_stdin ();
-			FileWritten (_path);
 		}
 	}
 
@@ -79,6 +97,20 @@ private:
 	samplecnt_t samples_written;
 	PBD::SystemExec* _proc;
 	std::string _path;
+
+	FILE* encoder_file;
+
+	void write_ffile (std::string d, size_t s) {
+		fwrite (d.c_str(), sizeof(char), s, encoder_file);
+	}
+
+	void close_ffile () {
+		fclose (encoder_file);
+		encoder_file = 0;
+		FileWritten (_path);
+	}
+
+	PBD::ScopedConnectionList exec_connections;
 };
 
 } // namespace