From 6133ca613e567be24e09b5da223cf4a67ad6d592 Mon Sep 17 00:00:00 2001
From: Marco su Acerrimo3 <mbanfi@gmail.com>
Date: Mon, 21 Jun 2021 02:28:06 +0200
Subject: [PATCH] It reads info from the correct section (it wasn't accurate
 enough)

---
 README.md | 10 ++++++++--
 vcodec.go | 19 +++++++++++++++++--
 2 files changed, 25 insertions(+), 4 deletions(-)

diff --git a/README.md b/README.md
index b1892c9..4d7634c 100644
--- a/README.md
+++ b/README.md
@@ -4,12 +4,18 @@
 
 ## program written in [GO](https://golang.org)
 
-Scan a RIFF file for the "vids" section, then exit with an error level 1 if the video codec is listed on the command line. The "heavy lift" is made by the image/riff library.
+Scan a RIFF file for the codec (vids in the strh and the structure in the following strf section), then exit with an error level 1 if the video codec is listed on the command line. The "heavy lift" is made by the image/riff library.
 
 It's partially based on one of the examples in the image/riff section (the read chunk,etc...).
 
 i.e.:
 
-vcodec file.avi DIV3 DX50 ...
+vcodec file.avi DIV3 DX50 ... (case insensitive)
 
 It's quite useful when you want to re-encode with ffmpeg or others a bunch of files only if they use certain codecs
+
+Reference (Even if I do need to study them a little more)
+
+- [Microsoft AVI riff file refernce](https://docs.microsoft.com/it-it/windows/win32/directshow/avi-riff-file-reference)
+- [Microsoft bitmapinfoheader info](https://docs.microsoft.com/it-it/windows/win32/api/wingdi/ns-wingdi-bitmapinfoheader)
+- [Alberta's University AVI format description](https://sites.ualberta.ca/dept/chemeng/AIX-43/share/man/info/C/a_doc_lib/ultimdia/ultiprgd/AVI.htm)
diff --git a/vcodec.go b/vcodec.go
index 9207b2c..15b3cf3 100644
--- a/vcodec.go
+++ b/vcodec.go
@@ -15,6 +15,7 @@ import (
 )
 
 var exitValue = 0
+var codecList []string
 
 func main() {
 	flag.Parse()
@@ -22,6 +23,9 @@ func main() {
 		fmt.Print("Usage: vcodec riff_file codec1 codec2 ...\ncodec name is case insensitive\n")
 		os.Exit(2)
 	}
+	//the next step is to allow to load the codecList from a file, as an alternative
+	codecList = flag.Args()[1:]
+
 	//A little trick to handle the "panic", os.Exit doesn't call deferred functions
 	main2()
 	fmt.Printf("Exit Value: %d\n", exitValue)
@@ -39,7 +43,7 @@ func main2() {
 		if r := recover(); r != nil {
 			fmt.Printf("Codec: %s\n", r)
 			codec := fmt.Sprintf("%s", r)
-			for _, v := range flag.Args()[1:] {
+			for _, v := range codecList {
 				if strings.EqualFold(codec, v) {
 					exitValue = 1
 					break
@@ -82,7 +86,18 @@ func scanriff(r *riff.Reader) error {
 			return err
 		}
 		if string(b[0:4]) == "vids" {
-			panic(string(b[4:8]))
+			codec := string(b[4:8])
+			chunkID, _, chunkData, err := r.Next()
+			if err != nil {
+				panic(codec)
+			}
+			if fmt.Sprintf("%s", chunkID) == "strf" {
+				b, err = ioutil.ReadAll(chunkData)
+				if err == nil {
+					codec = string(b[16:20]) // this should be the right codec
+				}
+			}
+			panic(codec)
 		}
 	}
 }