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Fixes an issue with m4a incorrectly pass as non-optimized #129

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Merged
dimitris-c merged 1 commit into from
Dec 12, 2025
Merged

Fixes an issue with m4a incorrectly pass as non-optimized #129

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6 changes: 5 additions & 1 deletion AudioStreaming/Streaming/Audio Source/FileAudioSource.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@ final class FileAudioSource: NSObject, CoreAudioStreamSource {
private var inputStream: InputStream?

private var mp4Restructure: Mp4Restructure
private var mp4ProbeBuffer: Data = Data()

init(url: URL,
fileManager: FileManager = .default,
Expand Down Expand Up @@ -120,14 +121,17 @@ final class FileAudioSource: NSObject, CoreAudioStreamSource {
if isMp4, !mp4IsAlreadyOptimized {
if !mp4Restructure.dataOptimized {
do {
switch try mp4Restructure.checkIsOptimized(data: data) {
mp4ProbeBuffer.append(data)
switch try mp4Restructure.checkIsOptimized(data: mp4ProbeBuffer) {
case .undetermined:
// Not enough bytes yet; wait for more data before deciding
break
case .optimized:
mp4IsAlreadyOptimized = true
mp4ProbeBuffer = Data()
delegate?.dataAvailable(source: self, data: data)
case let .needsRestructure(moovOffset):
mp4ProbeBuffer = Data()
try performMp4Restructure(inputStream: inputStream, moovOffset: moovOffset)
}
} catch {
Expand Down
73 changes: 70 additions & 3 deletions AudioStreaming/Streaming/Audio Source/Mp4/Mp4Restructure.swift
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Expand Up @@ -145,17 +145,84 @@ final class Mp4Restructure {

// Handle extended size (64-bit)
if atomSize == 1 {
if atomOffset + 16 > data.count { break }
if atomOffset + 16 > data.count {
// Mark presence from header only to allow early decisions
switch atomType {
case Atoms.ftyp:
if ftyp == nil {
ftyp = MP4Atom(type: atomType, size: Int.max, offset: atomOffset, data: nil)
}
case Atoms.mdat:
foundMdat = true
case Atoms.moov:
foundMoov = true
default:
break
}
if ftyp != nil, foundMoov, !foundMdat {
Logger.debug("🕵️ detected an optimized mp4", category: .generic)
return .optimized
}
// For non-optimized case we need a reliable moov offset; wait for more data
break
}
let ext: UInt64 = try getInteger(data: data, offset: atomOffset + 8)
atomSize = Int(ext)
headerSize = 16
} else if atomSize == 0 {
// Size extends to EOF; with partial data we can't determine full box
// Size extends to EOF; still record what we saw and decide if possible
switch atomType {
case Atoms.ftyp:
if ftyp == nil {
// We only have header; store minimal info
let start = atomOffset
let end = min(data.count, atomOffset + headerSize)
let ftypData = data[start ..< end]
let ftyp = MP4Atom(type: atomType, size: 0, offset: atomOffset, data: ftypData)
self.ftyp = ftyp
}
case Atoms.mdat:
foundMdat = true
case Atoms.moov:
foundMoov = true
default:
break
}
if ftyp != nil, foundMoov, !foundMdat {
Logger.debug("🕵️ detected an optimized mp4", category: .generic)
return .optimized
}
// Otherwise we can't reliably compute moov offset yet
break
}

// Bounds and sanity checks
if atomSize < headerSize || atomOffset + atomSize > data.count { break }
if atomSize < headerSize {
break
}
if atomOffset + atomSize > data.count {
// We have the header but not the full atom yet. Record presence for decision.
switch atomType {
case Atoms.ftyp:
if ftyp == nil {
ftyp = MP4Atom(type: atomType, size: atomSize, offset: atomOffset, data: nil)
}
case Atoms.moov:
foundMoov = true
case Atoms.mdat:
foundMdat = true
default:
break
}

if ftyp != nil {
if foundMoov && !foundMdat {
Logger.debug("🕵️ detected an optimized mp4 (header-only observation)", category: .generic)
return .optimized
}
}
break
}

switch atomType {
case Atoms.ftyp:
Expand Down
13 changes: 13 additions & 0 deletions AudioStreaming/Streaming/Audio Source/Mp4/RemoteMp4Restructure.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -31,6 +31,8 @@ final class RemoteMp4Restructure {

private let mp4Restructure: Mp4Restructure

private var ignoreFailureDueToCancel: Bool = false

init(url: URL, networking: NetworkingClient, restructure: Mp4Restructure = Mp4Restructure()) {
self.url = url
self.networking = networking
Expand Down Expand Up @@ -81,6 +83,7 @@ final class RemoteMp4Restructure {
break // keep streaming until decision can be made
case .optimized:
self.audioData = Data()
self.ignoreFailureDueToCancel = true
self.task?.cancel()
self.task = nil
completion(.success(nil))
Expand All @@ -92,6 +95,7 @@ final class RemoteMp4Restructure {
}
// stop request, fetch moov and restructure
self.audioData = Data()
self.ignoreFailureDueToCancel = true
self.task?.cancel()
self.task = nil
self.fetchAndRestructureMoovAtom(offset: moovOffset) { result in
Expand All @@ -108,6 +112,15 @@ final class RemoteMp4Restructure {
completion(.failure(Mp4RestructureError.invalidAtomSize))
}
case let .stream(.failure(error)):
// Ignore the error if it was caused by our intentional cancel
if ignoreFailureDueToCancel {
ignoreFailureDueToCancel = false
break
}
let nsError = error as NSError
if nsError.domain == NSURLErrorDomain && nsError.code == NSURLErrorCancelled {
break
}
completion(.failure(Mp4RestructureError.networkError(error)))
case .complete:
break
Expand Down