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feature: multi-part m4b merging #120

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ad97b78
Add multi-part M4B merging
benjitobz Aug 31, 2026
86d7961
Merge remote-tracking branch 'upstream/develop' into sync/feature/m4b…
benjitobz Sep 10, 2026
7f91a2e
Merge branch 'Chaptarr:develop' into feature/m4b-merge-multi-part
benjitobz Sep 28, 2026
de309dc
Address review feedback on multi-part M4B merging
benjitobz Oct 3, 2026
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19 changes: 19 additions & 0 deletions frontend/src/Settings/Profiles/Quality/EditQualityProfileModalContent.js
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Original file line number Diff line number Diff line change
Expand Up @@ -180,6 +180,7 @@ class EditQualityProfileModalContent extends Component {
upgradeAllowed,
preferCustomFormatsOverQuality,
convertToQualityId,
mergeMultiPartFiles,
cutoff,
minFormatScore,
cutoffFormatScore,
Expand All @@ -190,6 +191,7 @@ class EditQualityProfileModalContent extends Component {
const upgradeAllowedField = fieldWithDefault(upgradeAllowed, false);
const preferCustomFormatsOverQualityField = fieldWithDefault(preferCustomFormatsOverQuality, false);
const convertToQualityIdField = fieldWithDefault(convertToQualityId, 0);
const mergeMultiPartFilesField = fieldWithDefault(mergeMultiPartFiles, false);
const cutoffField = fieldWithDefault(cutoff, 0);
const minFormatScoreField = fieldWithDefault(minFormatScore, 0);
const cutoffFormatScoreField = fieldWithDefault(cutoffFormatScore, 0);
Expand Down Expand Up @@ -339,6 +341,23 @@ class EditQualityProfileModalContent extends Component {
</FormGroup>
}

{
isAudiobookProfile && Number(convertToQualityIdField.value) > 0 &&
<FormGroup size={sizes.EXTRA_SMALL}>
<FormLabel size={sizes.SMALL}>
{translate('MergeMultiPartFiles')}
</FormLabel>

<FormInputGroup
type={inputTypes.CHECK}
name="mergeMultiPartFiles"
{...mergeMultiPartFilesField}
helpText={translate('MergeMultiPartFilesHelpText')}
onChange={onInputChange}
/>
</FormGroup>
}

{
isAudiobookProfile && Number(convertToQualityIdField.value) > 0 &&
<FormGroup
Expand Down
3 changes: 3 additions & 0 deletions src/Chaptarr.Api.V1/Profiles/Quality/QualityProfileResource.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -17,6 +17,7 @@ public class QualityProfileResource : RestResource
public bool PreferCustomFormatsOverQuality { get; set; }
public bool ConvertMp3ToM4b { get; set; }
public int? ConvertToQualityId { get; set; }
public bool MergeMultiPartFiles { get; set; }
public int Cutoff { get; set; }
public List<QualityProfileQualityItemResource> Items { get; set; }
public int MinFormatScore { get; set; }
Expand Down Expand Up @@ -79,6 +80,7 @@ public static QualityProfileResource ToResource(this QualityProfile model, bool
PreferCustomFormatsOverQuality = model.ProfileType == ProfileType.Audiobook && model.PreferCustomFormatsOverQuality,
ConvertMp3ToM4b = model.ConvertMp3ToM4b,
ConvertToQualityId = convertToQualityId,
MergeMultiPartFiles = model.MergeMultiPartFiles,
Cutoff = cutoff,
Items = items.ConvertAll(ToResource),
MinFormatScore = model.MinFormatScore,
Expand Down Expand Up @@ -140,6 +142,7 @@ public static QualityProfile ToModel(this QualityProfileResource resource)
// toggle. ConvertToQualityId is the canonical conversion target.
ConvertMp3ToM4b = convertToQualityId == NzbDrone.Core.Qualities.Quality.M4B.Id,
ConvertToQualityId = convertToQualityId,
MergeMultiPartFiles = resource.ProfileType == ProfileType.Audiobook && resource.MergeMultiPartFiles,
Cutoff = resource.Cutoff,
Items = (resource.Items ?? new List<QualityProfileQualityItemResource>()).ConvertAll(ToModel),
MinFormatScore = resource.MinFormatScore,
Expand Down
3 changes: 3 additions & 0 deletions src/Chaptarr.Api.V1/openapi.json
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Original file line number Diff line number Diff line change
Expand Up @@ -18337,6 +18337,9 @@
"format": "int32",
"nullable": true
},
"mergeMultiPartFiles": {
"type": "boolean"
},
"cutoff": {
"type": "integer",
"format": "int32"
Expand Down
3 changes: 3 additions & 0 deletions src/Chaptarr.Core.Test/MediaFiles/ConversionJobServiceFixture.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -39,6 +39,7 @@ public ConversionResult ConvertToM4b(string[] inputFiles, string outputFile, Con

public bool CanConvert(string[] inputFiles) => true;
public ConversionEstimate EstimateConversion(string[] inputFiles) => new() { CanConvert = true };
public M4bMergeSourceInfo ProbeMergeSources(string[] inputFiles) => new();
}

private sealed class BlockingConversionService : IM4bConversionService
Expand All @@ -59,6 +60,7 @@ public ConversionResult ConvertToM4b(string[] inputFiles, string outputFile, Con

public bool CanConvert(string[] inputFiles) => true;
public ConversionEstimate EstimateConversion(string[] inputFiles) => new() { CanConvert = true };
public M4bMergeSourceInfo ProbeMergeSources(string[] inputFiles) => new();
}

private sealed class TokenRecordingConversionService : IM4bConversionService
Expand Down Expand Up @@ -90,6 +92,7 @@ public ConversionResult ConvertToM4b(string[] inputFiles, string outputFile, Con

public bool CanConvert(string[] inputFiles) => true;
public ConversionEstimate EstimateConversion(string[] inputFiles) => new() { CanConvert = true };
public M4bMergeSourceInfo ProbeMergeSources(string[] inputFiles) => new();
}

private class RecordingCommandQueueProxy : DispatchProxy
Expand Down
185 changes: 185 additions & 0 deletions src/Chaptarr.Core.Test/MediaFiles/ImportApprovedBooksAdditionalCopyFixture.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -231,6 +231,8 @@ private sealed class FailingM4bConversionService : IM4bConversionService
EstimatedOutputSize = 1024
};

public M4bMergeSourceInfo ProbeMergeSources(string[] inputFiles) => new();

public ConversionResult ConvertToM4b(string[] inputFiles, string outputFile, ConversionOptions options = null)
{
ConvertCalls++;
Expand Down Expand Up @@ -262,6 +264,10 @@ private sealed class SuccessfulM4bConversionService : IM4bConversionService
EstimatedOutputSize = 1024
};

public M4bMergeSourceInfo MergeSources { get; set; } = new();

public M4bMergeSourceInfo ProbeMergeSources(string[] inputFiles) => MergeSources;

public ConversionResult ConvertToM4b(string[] inputFiles, string outputFile, ConversionOptions options = null)
{
ConvertCalls++;
Expand Down Expand Up @@ -2596,6 +2602,185 @@ public void should_stage_matched_provider_chapters_when_source_duration_matches(
}
}

[Test]
public void should_merge_multi_part_m4b_with_embedded_chapters_without_reencoding()
{
var tempDir = Path.Combine(TestContext.CurrentContext.WorkDirectory, $"m4b-merge-{Guid.NewGuid():N}");
var destinationDir = Path.Combine(TestContext.CurrentContext.WorkDirectory, $"conversion-destination-{Guid.NewGuid():N}");
var destinationPath = Path.Combine(destinationDir, "Black Sheep.m4b");
Directory.CreateDirectory(tempDir);
Directory.CreateDirectory(destinationDir);

var part1 = Path.Combine(tempDir, "Black Sheep (1).m4b");
var part2 = Path.Combine(tempDir, "Black Sheep (2).m4b");
File.WriteAllText(part1, "fake m4b");
File.WriteAllText(part2, "fake m4b");

try
{
var (qualityProfile, author, book, edition) = CreateAudiobookConversionGraph(26);
qualityProfile.MergeMultiPartFiles = true;

var conversion = new SuccessfulM4bConversionService
{
MergeSources = new M4bMergeSourceInfo
{
CanCopyAudio = true,
EmbeddedChapterCount = 2,
ChaptersTxtContent = "## total-length 00:20:00.000\n00:00:00.000 Opening\n00:10:00.000 Chapter 1"
}
};

var service = new ImportApprovedBooks(
new StubMediaFileService(),
new StubMetadataTagService(),
new StubMediaInfoExtractor(),
Proxy<IAuthorService>(),
Proxy<IBookService>(),
CreateEditionService(new List<Edition> { edition }),
Proxy<IRecycleBinProvider>(),
Proxy<IExtraService>(),
new StubMoveBookFiles { DestinationPath = destinationPath },
Proxy<IHistoryService>(),
Proxy<NzbDrone.Core.Download.History.IDownloadHistoryService>(),
new NoOpEventAggregator(),
Proxy<IManageCommandQueue>(),
Proxy<ISeriesBookLinkService>(),
Proxy<ISeriesService>(),
Proxy<IQualityProfileService>(),
conversion,
LogManager.GetLogger("ImportApprovedBooksAdditionalCopyFixture"));

LocalBook LocalBookFor(string path) => new()
{
Path = path,
Book = book,
Author = author,
Edition = edition,
Quality = new QualityModel { Quality = Quality.M4B, Revision = new Revision() },
RawTags = new RawFileTags
{
AllTags = new Dictionary<string, List<string>>
{
["title"] = new() { "Black Sheep" },
["album"] = new() { "Black Sheep (Unabridged)" }
}
}
};

service.Import(
new List<ImportDecision<LocalBook>>
{
new(LocalBookFor(part1)),
new(LocalBookFor(part2))
},
replaceExisting: false,
downloadClientItem: new DownloadClientItem { DownloadId = "m4b-merge" },
importMode: ImportMode.Move,
cancellationToken: CancellationToken.None);

Assert.That(conversion.ConvertCalls, Is.EqualTo(1));
Assert.That(conversion.LastOptions.NoConversion, Is.True);
Assert.That(conversion.LastOptions.TagOptions.Name, Is.EqualTo("Black Sheep"));
Assert.That(conversion.LastOptions.TagOptions.RemoveTags, Is.EquivalentTo(new[] { "track", "tracks", "disk", "disks" }));
Assert.That(conversion.LastOptions.TagOptions.UseFilenamesAsChapters, Is.False);

var chaptersPath = Path.Combine(Path.GetDirectoryName(conversion.LastInputFiles[0]), "chapters.txt");
Assert.That(File.ReadAllText(chaptersPath), Does.Contain("00:10:00.000 Chapter 1"));
}
finally
{
if (Directory.Exists(tempDir))
{
Directory.Delete(tempDir, recursive: true);
}

if (Directory.Exists(destinationDir))
{
Directory.Delete(destinationDir, recursive: true);
}
}
}

[Test]
public void should_import_parts_unmerged_when_optional_m4b_merge_fails()
{
var tempDir = Path.Combine(TestContext.CurrentContext.WorkDirectory, $"m4b-merge-fails-{Guid.NewGuid():N}");
var destinationDir = Path.Combine(TestContext.CurrentContext.WorkDirectory, $"conversion-destination-{Guid.NewGuid():N}");
var destinationPath = Path.Combine(destinationDir, "Black Sheep.m4b");
Directory.CreateDirectory(tempDir);
Directory.CreateDirectory(destinationDir);

var part1 = Path.Combine(tempDir, "Black Sheep (1).m4b");
var part2 = Path.Combine(tempDir, "Black Sheep (2).m4b");
File.WriteAllText(part1, "fake m4b");
File.WriteAllText(part2, "fake m4b");

try
{
var (qualityProfile, author, book, edition) = CreateAudiobookConversionGraph(27);
qualityProfile.MergeMultiPartFiles = true;

var conversion = new FailingM4bConversionService();
var service = new ImportApprovedBooks(
new StubMediaFileService(),
new StubMetadataTagService(),
new StubMediaInfoExtractor(),
Proxy<IAuthorService>(),
Proxy<IBookService>(),
CreateEditionService(new List<Edition> { edition }),
Proxy<IRecycleBinProvider>(),
Proxy<IExtraService>(),
new StubMoveBookFiles { DestinationPath = destinationPath },
Proxy<IHistoryService>(),
Proxy<NzbDrone.Core.Download.History.IDownloadHistoryService>(),
new NoOpEventAggregator(),
Proxy<IManageCommandQueue>(),
Proxy<ISeriesBookLinkService>(),
Proxy<ISeriesService>(),
Proxy<IQualityProfileService>(),
conversion,
LogManager.GetLogger("ImportApprovedBooksAdditionalCopyFixture"));

LocalBook LocalBookFor(string path) => new()
{
Path = path,
Book = book,
Author = author,
Edition = edition,
Quality = new QualityModel { Quality = Quality.M4B, Revision = new Revision() }
};

var results = service.Import(
new List<ImportDecision<LocalBook>>
{
new(LocalBookFor(part1)),
new(LocalBookFor(part2))
},
replaceExisting: false,
downloadClientItem: new DownloadClientItem { DownloadId = "m4b-merge-fails" },
importMode: ImportMode.Move,
cancellationToken: CancellationToken.None);

Assert.That(conversion.ConvertCalls, Is.EqualTo(1));
Assert.That(results.SelectMany(r => r.Errors), Does.Not.Contain("synthetic conversion failure"));
Assert.That(results.Select(r => r.ImportDecision.Item.Path), Is.EquivalentTo(new[] { part1, part2 }));
Assert.That(Directory.Exists(Path.Combine(destinationDir, ".chaptarr-conversions")), Is.False);
}
finally
{
if (Directory.Exists(tempDir))
{
Directory.Delete(tempDir, recursive: true);
}

if (Directory.Exists(destinationDir))
{
Directory.Delete(destinationDir, recursive: true);
}
}
}

[Test]
public void should_not_stage_provider_chapters_when_source_duration_does_not_match()
{
Expand Down
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