From 50f8389615623c711bb533d5c5d8e1eb2c940105 Mon Sep 17 00:00:00 2001
From: Thomas Goyne <plorkyeran@aegisub.org>
Date: Thu, 4 Nov 2010 04:58:27 +0000
Subject: [PATCH] Add support for delay in FFmpegSourceAudioProvider as FFMS2
 only handles it automatically in the avisynth plugin

Originally committed to SVN as r4828.
---
 aegisub/src/audio_provider_ffmpegsource.cpp | 19 ++++++++++++++++---
 aegisub/src/audio_provider_ffmpegsource.h   | 11 +++++++----
 2 files changed, 23 insertions(+), 7 deletions(-)

diff --git a/aegisub/src/audio_provider_ffmpegsource.cpp b/aegisub/src/audio_provider_ffmpegsource.cpp
index 70fd9d086..0fbb109d6 100644
--- a/aegisub/src/audio_provider_ffmpegsource.cpp
+++ b/aegisub/src/audio_provider_ffmpegsource.cpp
@@ -184,8 +184,9 @@ void FFmpegSourceAudioProvider::LoadAudio(wxString filename) {
 
 	channels	= AudioInfo.Channels;
 	sample_rate	= AudioInfo.SampleRate;
-	num_samples = AudioInfo.NumSamples;
-	if (channels <= 0 || sample_rate <= 0 || num_samples <= 0)
+	delay       = AudioInfo.FirstTime * sample_rate;
+	num_samples = AudioInfo.NumSamples + delay;
+	if (channels <= 0 || sample_rate <= 0 || num_samples <= 0 || delay < 0)
 		throw AudioOpenError("sanity check failed, consult your local psychiatrist");
 
 	// FIXME: use the actual sample format too?
@@ -222,7 +223,19 @@ void FFmpegSourceAudioProvider::Close() {
 /// @param Count 
 ///
 void FFmpegSourceAudioProvider::GetAudio(void *Buf, int64_t Start, int64_t Count) {
-	if (FFMS_GetAudio(AudioSource, Buf, Start, Count, &ErrInfo)) {
+	uint8_t *Buf2 = static_cast<uint8_t*>(Buf);
+	Start -= delay;
+	if (Start < 0) {
+		size_t Bytes = std::min(-Start, Count) * bytes_per_sample * channels;
+		memset(Buf2, 0, Bytes);
+
+		Count += Start;
+		if (Count <= 0) return;
+
+		Start = 0;
+		Buf2 += Bytes;
+	}
+	if (FFMS_GetAudio(AudioSource, Buf2, Start, Count, &ErrInfo)) {
 		throw AudioDecodeError(std::string("Failed to get audio samples: ") + ErrInfo.Buffer);
 	}
 }
diff --git a/aegisub/src/audio_provider_ffmpegsource.h b/aegisub/src/audio_provider_ffmpegsource.h
index 3cb24e600..6e9314f3e 100644
--- a/aegisub/src/audio_provider_ffmpegsource.h
+++ b/aegisub/src/audio_provider_ffmpegsource.h
@@ -43,15 +43,18 @@
 /// @brief Implements audio loading with the FFMS library.
 class FFmpegSourceAudioProvider : public AudioProvider, FFmpegSourceProvider {
 private:
-	FFMS_AudioSource *AudioSource;	/// audio source object
-	bool COMInited;					/// COM initialization state
+	FFMS_AudioSource *AudioSource;	///< audio source object
+	bool COMInited;					///< COM initialization state
 
-	char FFMSErrMsg[1024];			/// FFMS error message
-	FFMS_ErrorInfo ErrInfo;			/// FFMS error codes/messages
+	char FFMSErrMsg[1024];			///< FFMS error message
+	FFMS_ErrorInfo ErrInfo;			///< FFMS error codes/messages
 
 	void Close();
 	void LoadAudio(wxString filename);
 
+	/// Audio delay in samples
+	int64_t delay;
+
 public:
 	FFmpegSourceAudioProvider(wxString filename);
 	virtual ~FFmpegSourceAudioProvider();