stride3d/stride · error · InvalidOperationException

AVAssetReader create failed

Error message

AVAssetReader create failed: {error.LocalizedDescription}

What it means

AVAssetReader.FromAsset failed to construct an AVAssetReader for the extracted asset slice; Apple reported an NSError whose LocalizedDescription is embedded in the message. This wraps the underlying AVFoundation failure so the backend can abort loading/seeking cleanly.

Solutions

1. Inspect error.LocalizedDescription in the message for the concrete AVFoundation cause
2. Verify the temp file exists and is a valid movie (test with AVAsset status)
3. Re-encode the video to an Apple-supported format (H.264/H.265 in MP4/MOV)
4. Check disk space and sandbox write permissions for the temp directory
5. Confirm the URL/slice arguments (startPosition, length) point at a complete asset

var asset = AVAsset.FromUrl(NSUrl.FromFilename(tempFilePath));
if (asset == null || !asset.Playable || asset.Tracks.Length == 0)
    throw new InvalidOperationException("Asset missing or not playable before CreateReader");

bool AssetReadable(NSUrl url) => NSFileManager.DefaultManager.FileExists(url.Path) && AVAsset.FromUrl(url)?.Playable == true;

try { backend.Initialize(url, start, len); }
catch (InvalidOperationException ex) when (ex.Message.StartsWith("AVAssetReader create failed"))
{ /* log AVFoundation error; fall back to software decode or re-encode */ }

When it happens

Trigger: The asset slice file extracted to the temp path is not readable/valid video; the media format is unsupported by AVAssetReader; the NSUrl points at a missing or empty temp file; internal AVFoundation errors (e.g. failed to open, unsupported codec).

Common situations: Downloading/streamed videos with unsupported codecs (e.g. certain VP9/AV1 containers); temp file extraction partially failed (disk full, sandbox restrictions); URLs pointing at assets not present in the app bundle.

Related errors

• AVAssetReader.StartReading failed
• AVFoundationVideoBackend already initialized.
• AVAssetReader (audio) create failed
• AVAssetReader.StartReading (audio) failed
• Failed to compile a video asset, ffmpeg was not found.

AI-assisted analysis of stride3d/stride@96fad776d2 (2026-09-14). Data as JSON: /api/errors/80aefad6349d2741. Report an issue: GitHub.

Appendix: source

Thrown at sources/engine/Stride.Video/Backends/AVFoundationVideoBackend.cs:261

        {
            if (imageBuffer is CVPixelBuffer pixelBuffer)
            {
                UploadFrameToTarget(pixelBuffer);
            }
        }
        adjustedTicksSinceLastFrame %= frameDurationTicks;

        presentedSampleBuffer?.Dispose();
        presentedSampleBuffer = sampleBuffer;
    }

    private void CreateReader(TimeSpan startTime)
    {
        DisposeReader();

        reader = AVAssetReader.FromAsset(asset, out var error);
        if (error != null)
            throw new InvalidOperationException($"AVAssetReader create failed: {error.LocalizedDescription}");

        if (startTime > TimeSpan.Zero)
        {
            // Timescale 600 covers all common video framerates exactly (24/25/30/50/60 fps all
            // hit integer tick counts at 600).
            var startCMTime = new CMTime((long)(startTime.TotalSeconds * 600), 600);
            reader.TimeRange = new CMTimeRange { Start = startCMTime, Duration = CMTime.PositiveInfinity };
        }

        // Ask the reader to deliver decoded BGRA pixel buffers backed by IOSurface. BGRA is the
        // VideoToolbox native output format for H.264/HEVC SDR content — picking it avoids an
        // internal NV12→RGB conversion. The IOSurface is imported as a VkImage in UploadFrameToTarget.
        var settings = new NSMutableDictionary
        {
            [CVPixelBuffer.PixelFormatTypeKey] = NSNumber.FromInt32((int)CVPixelFormatType.CV32BGRA),
            [CVPixelBuffer.IOSurfacePropertiesKey] = new NSDictionary(),
        };
        videoOutput = new AVAssetReaderTrackOutput(videoTrack, settings)

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