I'm trying to readout the timestamps for each datablock/frame in a matroska file. It seems however that the TimeCode property in the SimpleBlock object returns a value with little endianness while (according to https://matroska-org.github.io/libebml/specs.html) EBML integer datatypes are big-endian.

This leads to incorrect timestamps (when comparing to another tool like MKVToolNix):

MKVToolNix output:

If I manually revert endianness of the timecode file the values seem to match:

8448 -> 33
16896 -> 66
etc.

Hi,

At first, I wanna thank you for the time you're putting into this project!

I'm trying to record the audio from Chrome, route the WebM opus stream to .NET, convert to another format and re-route the audio to another system, for capturing the audio i'm using something like this:

        const stream = await navigator.mediaDevices.getUserMedia({ audio: true });

        this.mediaRecorder = new MediaRecorder(stream, {
            mimeType: 'audio/webm; codecs=opus'
        });

        this.mediaRecorder.start();

        this.isRecording = true;

        console.log("Starting media recorder ", this.mediaRecorder);

        this.mediaRecorder.ondataavailable = (e) => {
            //Do things, convert bytes to base64 and send the audio to the .NET back-end
        }

Now, following the examples, I'm using this code in order to extract the opus audio from the WebM stream:

        string b64Audio = audioPkt.Audio;
        byte[] webmBytes = Convert.FromBase64String(b64Audio);
        MemoryStream webmStream = new MemoryStream(webmBytes);

        var oggStream = new MemoryStream();

        MatroskaDemuxer.ExtractOggOpusAudio(webmStream, oggStream);

I confirm the webm bytes are the same recorded from the js, so no change in data, but in the line MatroskaDemuxer.ExtractOggOpusAudio(webmStream, oggStream); I got the following error:

System.ArgumentNullException: 'Value cannot be null. Arg_ParamName_Name'

Stack trace:

in Matroska.Muxer.OggOpus.OggOpusAudioStreamDemuxer.CopyTo(MatroskaDocument doc, Stream outputStream, OggOpusAudioStreamDemuxerSettings settings)
in Matroska.Muxer.MatroskaDemuxer.ExtractOggOpusAudio(MatroskaDocument doc, Stream outputStream, OggOpusAudioStreamDemuxerSettings settings)
in PROJECT_NAME.API.Hubs.LiveDataHub.SendAudio(ReceiveAudioDTO audioPkt) in PATH_TO_PROJECT\PROJECT_NAME.API\Hubs\LiveDataHub.cs: riga 70
in Microsoft.Extensions.Internal.ObjectMethodExecutor.<>c__DisplayClass33_0.b__0(Object target, Object[] parameters)
in Microsoft.AspNetCore.SignalR.Internal.DefaultHubDispatcher`1.d__23.MoveNext()

I'm not able to understand what's the cause of the problem looking into the examples and in the various docs of the repo, Am I missing something? Any idea of what can be the issue?

Hello,
var doc = MatroskaSerializer.Deserialize(stream);
Can I export .ts from doc?
Or I can extract auto to mp3 or video to mp4.
Best regards,

I've a Matroska file with multiple attachments and I'm trying to deserialize this file. However, I'm only getting one attachment, instead of all.

Looking into the class (in MatroskaModels.cs), this makes sense. It only exposes one AttachedFile:

public sealed class Attachments : BaseModel
{
	[MatroskaElementDescriptor(MatroskaSpecification.AttachedFile)]
	public AttachedFile AttachedFile { get; set; } = null!;
}

However, according to ebml_matroska.xml, this property has no maxOccurs:

<element name="AttachedFile" path="\Segment\Attachments\AttachedFile" id="0x61A7" type="master" minOccurs="1">
	<documentation lang="en" purpose="definition">An attached file.</documentation>
	<extension type="libmatroska" cppname="Attached"/>
</element>

I'm expecting that the model should contain a collection of AttachedFile. Similar to how multiple tags are handled. If I change manually the model to:

public sealed class Attachments : BaseModel
{
	[MatroskaElementDescriptor(MatroskaSpecification.AttachedFile, typeof(AttachedFile))]
	public List<AttachedFile> AttachedFile { get; set; } = null!;
}

It works as expected. I'm getting a collection of AttachedFile, with the correct information in there. I suspect something is going wrong with the auto-generated class?

My use case is a bit special...

Ideally, I would need to write one or multiple video streams made of individual Jpeg files (a mjpeg stream), plus aditional metadata information per frame.

I don't know how difficult would be to do this, or even if MKV supports this workflow...

Thanks for your work.

When I want to use this NuGet package, it shows me the following message:

I tried a lot of things, also signing my assembly with my .snk file and with the Matroska one.

Nothing works. Can you help me?