From d1c62c132481c7314df77b39a6ef681fee3b7e69 Mon Sep 17 00:00:00 2001
From: Karl Blomster <kalle.blomster@gmail.com>
Date: Thu, 14 Aug 2008 16:10:31 +0000
Subject: [PATCH] Fix crash on playing video without audio loaded when using
 the ffmpeg providers. Patch by Manta with minor modifications by me.

Originally committed to SVN as r2303.
---
 aegisub/audio_provider_lavc.cpp | 24 +++++++++++++++++-------
 aegisub/audio_provider_lavc.h   |  3 +--
 2 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/aegisub/audio_provider_lavc.cpp b/aegisub/audio_provider_lavc.cpp
index 5b75ebbca..9e352ee7f 100644
--- a/aegisub/audio_provider_lavc.cpp
+++ b/aegisub/audio_provider_lavc.cpp
@@ -152,6 +152,10 @@ LAVCAudioProvider::LAVCAudioProvider(Aegisub::String _filename)
 	if (!buffer)
 		throw _T("ffmpeg audio provider: Failed to allocate audio decoding buffer, out of memory?");
 
+	overshoot_buffer = (int16_t *)malloc(AVCODEC_MAX_AUDIO_FRAME_SIZE);
+	if (!overshoot_buffer)
+		throw _T("ffmpeg audio provider: Failed to allocate audio decoding buffer, out of memory?");
+
 	leftover_samples = 0;
 
 	} catch (...) {
@@ -170,6 +174,8 @@ void LAVCAudioProvider::Destroy()
 {
 	if (buffer)
 		free(buffer);
+	if (overshoot_buffer)
+		free(overshoot_buffer);
 	if (rsct)
 		audio_resample_close(rsct);
 	if (codecContext)
@@ -193,15 +199,18 @@ void LAVCAudioProvider::GetAudio(void *buf, int64_t start, int64_t count)
 	memset(_buf + samples_to_decode, 0, ((count * channels) - samples_to_decode) * bytes_per_sample);
 
 	/* do we have leftover samples from last time we were called? */
+	/* FIXME: this assumes that requests are always linear! attempts at random access give bogus results! */
 	if (leftover_samples > 0) {
+		int length = (samples_to_decode > leftover_samples) ? leftover_samples : samples_to_decode;
+		samples_to_decode -= length;
+		leftover_samples -= length;
+		
 		/* put them in the output buffer */
 		samples_to_decode -= leftover_samples;
-		for (std::vector<int16_t>::iterator i = overshoot_buffer.begin(); i != overshoot_buffer.end(); i++) {
-			*(_buf++) = *i;
+		while (length > 0) {
+			*(_buf++) = *(overshoot_buffer++);
+			length--;
 		}
-		/* none left */
-		leftover_samples = 0;
-		overshoot_buffer.clear();
 	}
 
 	AVPacket packet;
@@ -244,7 +253,8 @@ void LAVCAudioProvider::GetAudio(void *buf, int64_t start, int64_t count)
 						/* in that case, count them */
 						leftover_samples = decoded_samples - samples_to_decode;
 						/* and put them aside for later */
-						overshoot_buffer = std::vector<int16_t>(&temp_output_buffer[samples_to_decode+1], &temp_output_buffer[decoded_samples+1]);
+						memcpy(buffer, &temp_output_buffer[samples_to_decode+1], leftover_samples * bytes_per_sample);
+						overshoot_buffer = buffer;
 						/* output the other samples that didn't overflow */
 						memcpy(_buf, temp_output_buffer, samples_to_decode * bytes_per_sample);
 						_buf += samples_to_decode;
@@ -261,7 +271,7 @@ void LAVCAudioProvider::GetAudio(void *buf, int64_t start, int64_t count)
 						/* count sheep^H^H^H^H^Hsamples */
 						leftover_samples = decoded_samples - samples_to_decode;
 						/* and put them aside for later (mm, lamb chops) */
-						overshoot_buffer = std::vector<int16_t>(&buffer[samples_to_decode+1], &buffer[decoded_samples+1]);
+						overshoot_buffer = &buffer[samples_to_decode+1];
 						/* output the other samples that didn't overflow */
 						memcpy(_buf, buffer, samples_to_decode * bytes_per_sample);
 
diff --git a/aegisub/audio_provider_lavc.h b/aegisub/audio_provider_lavc.h
index cfd6fb89e..50a0dea7c 100644
--- a/aegisub/audio_provider_lavc.h
+++ b/aegisub/audio_provider_lavc.h
@@ -59,7 +59,6 @@ extern "C" {
 #include "lavc_file.h"
 #include "include/aegisub/audio_provider.h"
 #include "lavc_file.h"
-#include <vector>
 
 
 ///////////////////////
@@ -75,7 +74,7 @@ private:
 	int audStream;
 
 	int16_t *buffer;
-	std::vector<int16_t> overshoot_buffer;
+	int16_t *overshoot_buffer;
 
 	int leftover_samples;