Modified ffmpeg arguments and added argument checks.

AaxDecrypter/AaxcDownloadConverter.cs

@@ -46,9 +46,8 @@ namespace AaxDecrypter
         private TagLib.Mpeg4.File aaxcTagLib { get; set; }
         private StepSequence steps { get; }
         private DownloadLicense downloadLicense { get; set; }
-        private string metadataPath => Path.Combine(outDir, Path.GetFileName(outputFileName) + ".ffmeta");
 
-        public static async Task<AaxcDownloadConverter> CreateAsync(string outDirectory, DownloadLicense dlLic, ChapterInfo chapters)
+        public static async Task<AaxcDownloadConverter> CreateAsync(string outDirectory, DownloadLicense dlLic, ChapterInfo chapters = null)
         {
             var converter = new AaxcDownloadConverter(outDirectory, dlLic, chapters);           
             await converter.prelimProcessing();
@@ -59,7 +58,6 @@ namespace AaxDecrypter
         {
             ArgumentValidator.EnsureNotNullOrWhiteSpace(outDirectory, nameof(outDirectory));
             ArgumentValidator.EnsureNotNull(dlLic, nameof(dlLic));
-            ArgumentValidator.EnsureNotNull(chapters, nameof(chapters));
 
             if (!Directory.Exists(outDirectory))
                 throw new ArgumentNullException(nameof(outDirectory), "Directory does not exist");
@@ -134,27 +132,35 @@ namespace AaxDecrypter
 
         public bool Step2_DownloadAndCombine()
         {
-            var ffmetaHeader = $";FFMETADATA1\n";
-
-            File.WriteAllText(metadataPath, ffmetaHeader + chapters.ToFFMeta());
 
             var aaxcProcesser = new FFMpegAaxcProcesser(DecryptSupportLibraries.ffmpegPath);
-
             aaxcProcesser.ProgressUpdate += AaxcProcesser_ProgressUpdate;
 
+            string metadataPath = null;
+
+            if (chapters != null)
+            {
+                //Only write chaopters to the metadata file. All other aaxc metadata will be
+                //wiped out but is restored in Step 3.
+                metadataPath = Path.Combine(outDir, Path.GetFileName(outputFileName) + ".ffmeta");
+                File.WriteAllText(metadataPath, chapters.ToFFMeta(true));
+            }
+
             aaxcProcesser.ProcessBook(
                 downloadLicense.DownloadUrl,
                 downloadLicense.UserAgent,
                 downloadLicense.AudibleKey,
                 downloadLicense.AudibleIV,
-                metadataPath,
+                outputFileName,
-                outputFileName)
+                metadataPath)
                 .GetAwaiter()
                 .GetResult();
 
+            if (chapters != null)
+                FileExt.SafeDelete(metadataPath);
+
             DecryptProgressUpdate?.Invoke(this, 0);
 
-            FileExt.SafeDelete(metadataPath);
             return aaxcProcesser.Succeeded;
         }
 
@@ -165,6 +171,10 @@ namespace AaxDecrypter
             DecryptProgressUpdate?.Invoke(this, (int)progressPercent);
         }
 
+        /// <summary>
+        /// Copy all aacx metadata to m4b file.
+        /// </summary>
+        /// <returns></returns>
         public bool Step3_RestoreMetadata()
         {
             var outFile = new TagLib.Mpeg4.File(outputFileName, TagLib.ReadStyle.Average);

AaxDecrypter/Chapters.cs

@@ -1,4 +1,5 @@
-using System.Collections.Generic;
+using Dinah.Core;
+using System.Collections.Generic;
 using System.Linq;
 using System.Text;
 
@@ -11,11 +12,16 @@ namespace AaxDecrypter
         public int Count => _chapterList.Count;
         public void AddChapter(Chapter chapter)
         {
+            ArgumentValidator.EnsureNotNull(chapter, nameof(chapter));
             _chapterList.Add(chapter);
         }
-        public string ToFFMeta()
+        public string ToFFMeta(bool includeFFMetaHeader)
         {
             var ffmetaChapters = new StringBuilder();
+
+            if (includeFFMetaHeader)
+                ffmetaChapters.AppendLine(";FFMETADATA1\n");
+
             foreach (var c in Chapters)
             {
                 ffmetaChapters.AppendLine(c.ToFFMeta());
@@ -30,6 +36,10 @@ namespace AaxDecrypter
         public long EndOffsetMs { get; }
         public Chapter(string title, long startOffsetMs, long lengthMs)
         {
+            ArgumentValidator.EnsureNotNullOrEmpty(title, nameof(title));
+            ArgumentValidator.EnsureGreaterThan(startOffsetMs, nameof(startOffsetMs), -1);
+            ArgumentValidator.EnsureGreaterThan(lengthMs, nameof(lengthMs), 0);
+
             Title = title;
             StartOffsetMs = startOffsetMs;
             EndOffsetMs = StartOffsetMs + lengthMs;

AaxDecrypter/DownloadLicense.cs

@@ -1,4 +1,5 @@
-using System;
+using Dinah.Core;
+using System;
 using System.Collections.Generic;
 using System.Linq;
 using System.Text;
@@ -15,6 +16,11 @@ namespace AaxDecrypter
 
         public DownloadLicense(string downloadUrl, string audibleKey, string audibleIV, string userAgent)
         {
+            ArgumentValidator.EnsureNotNullOrEmpty(downloadUrl, nameof(downloadUrl));
+            ArgumentValidator.EnsureNotNullOrEmpty(audibleKey, nameof(audibleKey));
+            ArgumentValidator.EnsureNotNullOrEmpty(audibleIV, nameof(audibleIV));
+            ArgumentValidator.EnsureNotNullOrEmpty(userAgent, nameof(userAgent));
+
             DownloadUrl = downloadUrl;
             AudibleKey = audibleKey;
             AudibleIV = audibleIV;

AaxDecrypter/FFMpegAaxcProcesser.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Diagnostics;
 using System.IO;
+using System.Text;
 using System.Text.RegularExpressions;
 using System.Threading.Tasks;
 
@@ -15,17 +16,20 @@ namespace AaxDecrypter
         public string FFMpegPath { get; }
         public bool IsRunning { get; private set; }
         public bool Succeeded { get; private set; }
+        public string FFMpegStandardError => ffmpegError.ToString();
 
+
+        private StringBuilder ffmpegError = new StringBuilder();
         private static Regex processedTimeRegex = new Regex("time=(\\d{2}):(\\d{2}):(\\d{2}).\\d{2}", RegexOptions.IgnoreCase | RegexOptions.Compiled);
+
         public FFMpegAaxcProcesser(string ffmpegPath)
         {
             FFMpegPath = ffmpegPath;
         }
-        public async Task ProcessBook(string aaxcUrl, string userAgent, string audibleKey, string audibleIV, string outputFile)
+        public async Task ProcessBook(string aaxcUrl, string userAgent, string audibleKey, string audibleIV, string outputFile, string metadataPath = null)
         {
-
             //This process gets the aaxc from the url and streams the decrypted
-            //m4b to the output file. Preserves album art, and ignores metadata.
+            //m4b to the output file.
             var StartInfo = new ProcessStartInfo
             {
                 FileName = FFMpegPath,
@@ -34,71 +38,47 @@ namespace AaxDecrypter
                 WindowStyle = ProcessWindowStyle.Hidden,
                 UseShellExecute = false,
                 WorkingDirectory = Path.GetDirectoryName(FFMpegPath),
-                ArgumentList =
+               
-                    {
-                        "-audible_key",
-                        audibleKey,
-                        "-audible_iv",
-                        audibleIV,
-                        "-user_agent",
-                        userAgent,
-                        "-i",
-                        aaxcUrl,
-                        "-c", //audio codec
-                        "copy", //copy stream
-                        "-f", //force output format: adts
-                        "mp4",
-                        outputFile, //pipe output to standard output
-                        "-y"
-                    }
             };
 
-            await ProcessBool(StartInfo);
+            if (metadataPath != null)
+            {
+                StartInfo.ArgumentList.Add("-ignore_chapters"); //prevents ffmpeg from copying chapter info from aaxc to output file
+                StartInfo.ArgumentList.Add("true");
             }
 
-        public async Task ProcessBook(string aaxcUrl, string userAgent, string audibleKey, string audibleIV, string metadataPath, string outputFile)
+            StartInfo.ArgumentList.Add("-audible_key");
-        {
+            StartInfo.ArgumentList.Add(audibleKey);
+            StartInfo.ArgumentList.Add("-audible_iv");
+            StartInfo.ArgumentList.Add(audibleIV);
+            StartInfo.ArgumentList.Add("-user_agent");
+            StartInfo.ArgumentList.Add(userAgent);
+            StartInfo.ArgumentList.Add("-i");
+            StartInfo.ArgumentList.Add(aaxcUrl);
 
-            //This process gets the aaxc from the url and streams the decrypted
+            if (metadataPath != null)
-            //m4b to the output file. Preserves album art, but replaces metadata.
-            var StartInfo = new ProcessStartInfo
             {
-                FileName = FFMpegPath,
+                StartInfo.ArgumentList.Add("-f");
-                RedirectStandardError = true,
+                StartInfo.ArgumentList.Add("ffmetadata");
-                CreateNoWindow = true,
+                StartInfo.ArgumentList.Add("-i");
-                WindowStyle = ProcessWindowStyle.Hidden,
+                StartInfo.ArgumentList.Add(metadataPath);
-                UseShellExecute = false,
+                StartInfo.ArgumentList.Add("-map_metadata");
-                WorkingDirectory = Path.GetDirectoryName(FFMpegPath),
+                StartInfo.ArgumentList.Add("1");
-                ArgumentList =
-                    {
-                        "-ignore_chapters", //prevents ffmpeg from copying chapter info from aaxc to output file
-                        "true",
-                        "-audible_key",
-                        audibleKey,
-                        "-audible_iv",
-                        audibleIV,
-                        "-user_agent",
-                        userAgent,
-                        "-i",
-                        aaxcUrl,
-                        "-f",
-                        "ffmetadata",
-                        "-i",
-                        metadataPath,
-                        "-map_metadata",
-                        "1",
-                        "-c", //audio codec
-                        "copy", //copy stream
-                        "-f", //force output format: adts
-                        "mp4",
-                        outputFile, //pipe output to standard output
-                        "-y"
-                    }
-            };
-            await ProcessBool(StartInfo);
             }
 
-        private async Task ProcessBool(ProcessStartInfo startInfo)
+            StartInfo.ArgumentList.Add("-c"); //copy all codecs to output
+            StartInfo.ArgumentList.Add("copy");
+            StartInfo.ArgumentList.Add("-f"); //force output format: mp4
+            StartInfo.ArgumentList.Add("mp4");
+            StartInfo.ArgumentList.Add("-movflags"); //don't add nero format chapter flags
+            StartInfo.ArgumentList.Add("disable_chpl+faststart");
+            StartInfo.ArgumentList.Add(outputFile);
+            StartInfo.ArgumentList.Add("-y"); //overwrite existing file
+
+            await ProcessBook(StartInfo);
+        }
+
+        private async Task ProcessBook(ProcessStartInfo startInfo)
         {
             var downloader = new Process
             {
@@ -124,6 +104,8 @@ namespace AaxDecrypter
             if (string.IsNullOrEmpty(e.Data))
                 return;
 
+            ffmpegError.AppendLine(e.Data);
+
             if (processedTimeRegex.IsMatch(e.Data))
             {
                 //get timestamp of of last processed audio stream position