input/ffmpeg: use "auto"

src/input/plugins/FfmpegInputPlugin.cxx

@@ -101,9 +101,9 @@ input_ffmpeg_open(const char *uri,
 		return nullptr;
 
 	AVIOContext *h;
-	int ret = avio_open(&h, uri, AVIO_FLAG_READ);
-	if (ret != 0) {
-		error.Set(ffmpeg_domain, ret,
+	auto result = avio_open(&h, uri, AVIO_FLAG_READ);
+	if (result != 0) {
+		error.Set(ffmpeg_domain, result,
 			  "libavformat failed to open the URI");
 		return nullptr;
 	}
@@ -114,17 +114,17 @@ input_ffmpeg_open(const char *uri,
 size_t
 FfmpegInputStream::Read(void *ptr, size_t read_size, Error &error)
 {
-	int ret = avio_read(h, (unsigned char *)ptr, read_size);
-	if (ret <= 0) {
-		if (ret < 0)
+	auto result = avio_read(h, (unsigned char *)ptr, read_size);
+	if (result <= 0) {
+		if (result < 0)
 			error.Set(ffmpeg_domain, "avio_read() failed");
 
 		eof = true;
 		return false;
 	}
 
-	offset += ret;
-	return (size_t)ret;
+	offset += result;
+	return (size_t)result;
 }
 
 bool
@@ -136,9 +136,9 @@ FfmpegInputStream::IsEOF()
 bool
 FfmpegInputStream::Seek(offset_type new_offset, Error &error)
 {
-	int64_t ret = avio_seek(h, new_offset, SEEK_SET);
+	auto result = avio_seek(h, new_offset, SEEK_SET);
 
-	if (ret >= 0) {
+	if (result >= 0) {
 		eof = false;
 		return true;
 	} else {